Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години Rewrite reference handling to be abstract and accurate
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
преди 14 години |
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- /*
- * Copyright (C) 2007, Dave Watson <dwatson@mimvista.com>
- * Copyright (C) 2008-2010, Google Inc.
- * Copyright (C) 2006-2010, Robin Rosenberg <robin.rosenberg@dewire.com>
- * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org>
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.lib;
-
- import java.io.BufferedOutputStream;
- import java.io.File;
- import java.io.FileNotFoundException;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.text.MessageFormat;
- import java.util.Collection;
- import java.util.Collections;
- import java.util.HashMap;
- import java.util.HashSet;
- import java.util.LinkedList;
- import java.util.List;
- import java.util.Map;
- import java.util.Set;
- import java.util.concurrent.atomic.AtomicInteger;
-
- import org.eclipse.jgit.dircache.DirCache;
- import org.eclipse.jgit.errors.AmbiguousObjectException;
- import org.eclipse.jgit.errors.CorruptObjectException;
- import org.eclipse.jgit.errors.IncorrectObjectTypeException;
- import org.eclipse.jgit.errors.MissingObjectException;
- import org.eclipse.jgit.errors.NoWorkTreeException;
- import org.eclipse.jgit.errors.RevisionSyntaxException;
- import org.eclipse.jgit.events.IndexChangedEvent;
- import org.eclipse.jgit.events.IndexChangedListener;
- import org.eclipse.jgit.events.ListenerList;
- import org.eclipse.jgit.events.RepositoryEvent;
- import org.eclipse.jgit.internal.JGitText;
- import org.eclipse.jgit.revwalk.RevBlob;
- import org.eclipse.jgit.revwalk.RevCommit;
- import org.eclipse.jgit.revwalk.RevObject;
- import org.eclipse.jgit.revwalk.RevTree;
- import org.eclipse.jgit.revwalk.RevWalk;
- import org.eclipse.jgit.storage.file.ReflogEntry;
- import org.eclipse.jgit.storage.file.ReflogReader;
- import org.eclipse.jgit.treewalk.TreeWalk;
- import org.eclipse.jgit.util.FS;
- import org.eclipse.jgit.util.FileUtils;
- import org.eclipse.jgit.util.IO;
- import org.eclipse.jgit.util.RawParseUtils;
- import org.eclipse.jgit.util.io.SafeBufferedOutputStream;
-
- /**
- * Represents a Git repository.
- * <p>
- * A repository holds all objects and refs used for managing source code (could
- * be any type of file, but source code is what SCM's are typically used for).
- * <p>
- * This class is thread-safe.
- */
- public abstract class Repository {
- private static final ListenerList globalListeners = new ListenerList();
-
- /** @return the global listener list observing all events in this JVM. */
- public static ListenerList getGlobalListenerList() {
- return globalListeners;
- }
-
- private final AtomicInteger useCnt = new AtomicInteger(1);
-
- /** Metadata directory holding the repository's critical files. */
- private final File gitDir;
-
- /** File abstraction used to resolve paths. */
- private final FS fs;
-
- private final ListenerList myListeners = new ListenerList();
-
- /** If not bare, the top level directory of the working files. */
- private final File workTree;
-
- /** If not bare, the index file caching the working file states. */
- private final File indexFile;
-
- /**
- * Initialize a new repository instance.
- *
- * @param options
- * options to configure the repository.
- */
- protected Repository(final BaseRepositoryBuilder options) {
- gitDir = options.getGitDir();
- fs = options.getFS();
- workTree = options.getWorkTree();
- indexFile = options.getIndexFile();
- }
-
- /** @return listeners observing only events on this repository. */
- public ListenerList getListenerList() {
- return myListeners;
- }
-
- /**
- * Fire an event to all registered listeners.
- * <p>
- * The source repository of the event is automatically set to this
- * repository, before the event is delivered to any listeners.
- *
- * @param event
- * the event to deliver.
- */
- public void fireEvent(RepositoryEvent<?> event) {
- event.setRepository(this);
- myListeners.dispatch(event);
- globalListeners.dispatch(event);
- }
-
- /**
- * Create a new Git repository.
- * <p>
- * Repository with working tree is created using this method. This method is
- * the same as {@code create(false)}.
- *
- * @throws IOException
- * @see #create(boolean)
- */
- public void create() throws IOException {
- create(false);
- }
-
- /**
- * Create a new Git repository initializing the necessary files and
- * directories.
- *
- * @param bare
- * if true, a bare repository (a repository without a working
- * directory) is created.
- * @throws IOException
- * in case of IO problem
- */
- public abstract void create(boolean bare) throws IOException;
-
- /** @return local metadata directory; null if repository isn't local. */
- public File getDirectory() {
- return gitDir;
- }
-
- /**
- * @return the object database which stores this repository's data.
- */
- public abstract ObjectDatabase getObjectDatabase();
-
- /** @return a new inserter to create objects in {@link #getObjectDatabase()} */
- public ObjectInserter newObjectInserter() {
- return getObjectDatabase().newInserter();
- }
-
- /** @return a new reader to read objects from {@link #getObjectDatabase()} */
- public ObjectReader newObjectReader() {
- return getObjectDatabase().newReader();
- }
-
- /** @return the reference database which stores the reference namespace. */
- public abstract RefDatabase getRefDatabase();
-
- /**
- * @return the configuration of this repository
- */
- public abstract StoredConfig getConfig();
-
- /**
- * @return the used file system abstraction
- */
- public FS getFS() {
- return fs;
- }
-
- /**
- * @param objectId
- * @return true if the specified object is stored in this repo or any of the
- * known shared repositories.
- */
- public boolean hasObject(AnyObjectId objectId) {
- try {
- return getObjectDatabase().has(objectId);
- } catch (IOException e) {
- // Legacy API, assume error means "no"
- return false;
- }
- }
-
- /**
- * Open an object from this repository.
- * <p>
- * This is a one-shot call interface which may be faster than allocating a
- * {@link #newObjectReader()} to perform the lookup.
- *
- * @param objectId
- * identity of the object to open.
- * @return a {@link ObjectLoader} for accessing the object.
- * @throws MissingObjectException
- * the object does not exist.
- * @throws IOException
- * the object store cannot be accessed.
- */
- public ObjectLoader open(final AnyObjectId objectId)
- throws MissingObjectException, IOException {
- return getObjectDatabase().open(objectId);
- }
-
- /**
- * Open an object from this repository.
- * <p>
- * This is a one-shot call interface which may be faster than allocating a
- * {@link #newObjectReader()} to perform the lookup.
- *
- * @param objectId
- * identity of the object to open.
- * @param typeHint
- * hint about the type of object being requested;
- * {@link ObjectReader#OBJ_ANY} if the object type is not known,
- * or does not matter to the caller.
- * @return a {@link ObjectLoader} for accessing the object.
- * @throws MissingObjectException
- * the object does not exist.
- * @throws IncorrectObjectTypeException
- * typeHint was not OBJ_ANY, and the object's actual type does
- * not match typeHint.
- * @throws IOException
- * the object store cannot be accessed.
- */
- public ObjectLoader open(AnyObjectId objectId, int typeHint)
- throws MissingObjectException, IncorrectObjectTypeException,
- IOException {
- return getObjectDatabase().open(objectId, typeHint);
- }
-
- /**
- * Create a command to update, create or delete a ref in this repository.
- *
- * @param ref
- * name of the ref the caller wants to modify.
- * @return an update command. The caller must finish populating this command
- * and then invoke one of the update methods to actually make a
- * change.
- * @throws IOException
- * a symbolic ref was passed in and could not be resolved back
- * to the base ref, as the symbolic ref could not be read.
- */
- public RefUpdate updateRef(final String ref) throws IOException {
- return updateRef(ref, false);
- }
-
- /**
- * Create a command to update, create or delete a ref in this repository.
- *
- * @param ref
- * name of the ref the caller wants to modify.
- * @param detach
- * true to create a detached head
- * @return an update command. The caller must finish populating this command
- * and then invoke one of the update methods to actually make a
- * change.
- * @throws IOException
- * a symbolic ref was passed in and could not be resolved back
- * to the base ref, as the symbolic ref could not be read.
- */
- public RefUpdate updateRef(final String ref, final boolean detach) throws IOException {
- return getRefDatabase().newUpdate(ref, detach);
- }
-
- /**
- * Create a command to rename a ref in this repository
- *
- * @param fromRef
- * name of ref to rename from
- * @param toRef
- * name of ref to rename to
- * @return an update command that knows how to rename a branch to another.
- * @throws IOException
- * the rename could not be performed.
- *
- */
- public RefRename renameRef(final String fromRef, final String toRef) throws IOException {
- return getRefDatabase().newRename(fromRef, toRef);
- }
-
- /**
- * Parse a git revision string and return an object id.
- *
- * Combinations of these operators are supported:
- * <ul>
- * <li><b>HEAD</b>, <b>MERGE_HEAD</b>, <b>FETCH_HEAD</b></li>
- * <li><b>SHA-1</b>: a complete or abbreviated SHA-1</li>
- * <li><b>refs/...</b>: a complete reference name</li>
- * <li><b>short-name</b>: a short reference name under {@code refs/heads},
- * {@code refs/tags}, or {@code refs/remotes} namespace</li>
- * <li><b>tag-NN-gABBREV</b>: output from describe, parsed by treating
- * {@code ABBREV} as an abbreviated SHA-1.</li>
- * <li><i>id</i><b>^</b>: first parent of commit <i>id</i>, this is the same
- * as {@code id^1}</li>
- * <li><i>id</i><b>^0</b>: ensure <i>id</i> is a commit</li>
- * <li><i>id</i><b>^n</b>: n-th parent of commit <i>id</i></li>
- * <li><i>id</i><b>~n</b>: n-th historical ancestor of <i>id</i>, by first
- * parent. {@code id~3} is equivalent to {@code id^1^1^1} or {@code id^^^}.</li>
- * <li><i>id</i><b>:path</b>: Lookup path under tree named by <i>id</i></li>
- * <li><i>id</i><b>^{commit}</b>: ensure <i>id</i> is a commit</li>
- * <li><i>id</i><b>^{tree}</b>: ensure <i>id</i> is a tree</li>
- * <li><i>id</i><b>^{tag}</b>: ensure <i>id</i> is a tag</li>
- * <li><i>id</i><b>^{blob}</b>: ensure <i>id</i> is a blob</li>
- * </ul>
- *
- * <p>
- * The following operators are specified by Git conventions, but are not
- * supported by this method:
- * <ul>
- * <li><b>ref@{n}</b>: n-th version of ref as given by its reflog</li>
- * <li><b>ref@{time}</b>: value of ref at the designated time</li>
- * </ul>
- *
- * @param revstr
- * A git object references expression
- * @return an ObjectId or null if revstr can't be resolved to any ObjectId
- * @throws AmbiguousObjectException
- * {@code revstr} contains an abbreviated ObjectId and this
- * repository contains more than one object which match to the
- * input abbreviation.
- * @throws IncorrectObjectTypeException
- * the id parsed does not meet the type required to finish
- * applying the operators in the expression.
- * @throws RevisionSyntaxException
- * the expression is not supported by this implementation, or
- * does not meet the standard syntax.
- * @throws IOException
- * on serious errors
- */
- public ObjectId resolve(final String revstr)
- throws AmbiguousObjectException, IOException {
- RevWalk rw = new RevWalk(this);
- try {
- return resolve(rw, revstr);
- } finally {
- rw.release();
- }
- }
-
- private ObjectId resolve(final RevWalk rw, final String revstr) throws IOException {
- char[] rev = revstr.toCharArray();
- RevObject ref = null;
- for (int i = 0; i < rev.length; ++i) {
- switch (rev[i]) {
- case '^':
- if (ref == null) {
- ref = parseSimple(rw, new String(rev, 0, i));
- if (ref == null)
- return null;
- }
- if (i + 1 < rev.length) {
- switch (rev[i + 1]) {
- case '0':
- case '1':
- case '2':
- case '3':
- case '4':
- case '5':
- case '6':
- case '7':
- case '8':
- case '9':
- int j;
- ref = rw.parseCommit(ref);
- for (j = i + 1; j < rev.length; ++j) {
- if (!Character.isDigit(rev[j]))
- break;
- }
- String parentnum = new String(rev, i + 1, j - i - 1);
- int pnum;
- try {
- pnum = Integer.parseInt(parentnum);
- } catch (NumberFormatException e) {
- throw new RevisionSyntaxException(
- JGitText.get().invalidCommitParentNumber,
- revstr);
- }
- if (pnum != 0) {
- RevCommit commit = (RevCommit) ref;
- if (pnum > commit.getParentCount())
- ref = null;
- else
- ref = commit.getParent(pnum - 1);
- }
- i = j - 1;
- break;
- case '{':
- int k;
- String item = null;
- for (k = i + 2; k < rev.length; ++k) {
- if (rev[k] == '}') {
- item = new String(rev, i + 2, k - i - 2);
- break;
- }
- }
- i = k;
- if (item != null)
- if (item.equals("tree")) {
- ref = rw.parseTree(ref);
- } else if (item.equals("commit")) {
- ref = rw.parseCommit(ref);
- } else if (item.equals("blob")) {
- ref = rw.peel(ref);
- if (!(ref instanceof RevBlob))
- throw new IncorrectObjectTypeException(ref,
- Constants.TYPE_BLOB);
- } else if (item.equals("")) {
- ref = rw.peel(ref);
- } else
- throw new RevisionSyntaxException(revstr);
- else
- throw new RevisionSyntaxException(revstr);
- break;
- default:
- ref = rw.parseAny(ref);
- if (ref instanceof RevCommit) {
- RevCommit commit = ((RevCommit) ref);
- if (commit.getParentCount() == 0)
- ref = null;
- else
- ref = commit.getParent(0);
- } else
- throw new IncorrectObjectTypeException(ref,
- Constants.TYPE_COMMIT);
-
- }
- } else {
- ref = rw.peel(ref);
- if (ref instanceof RevCommit) {
- RevCommit commit = ((RevCommit) ref);
- if (commit.getParentCount() == 0)
- ref = null;
- else
- ref = commit.getParent(0);
- } else
- throw new IncorrectObjectTypeException(ref,
- Constants.TYPE_COMMIT);
- }
- break;
- case '~':
- if (ref == null) {
- ref = parseSimple(rw, new String(rev, 0, i));
- if (ref == null)
- return null;
- }
- ref = rw.peel(ref);
- if (!(ref instanceof RevCommit))
- throw new IncorrectObjectTypeException(ref,
- Constants.TYPE_COMMIT);
- int l;
- for (l = i + 1; l < rev.length; ++l) {
- if (!Character.isDigit(rev[l]))
- break;
- }
- int dist;
- if (l - i > 1) {
- String distnum = new String(rev, i + 1, l - i - 1);
- try {
- dist = Integer.parseInt(distnum);
- } catch (NumberFormatException e) {
- throw new RevisionSyntaxException(
- JGitText.get().invalidAncestryLength, revstr);
- }
- } else
- dist = 1;
- while (dist > 0) {
- RevCommit commit = (RevCommit) ref;
- if (commit.getParentCount() == 0) {
- ref = null;
- break;
- }
- commit = commit.getParent(0);
- rw.parseHeaders(commit);
- ref = commit;
- --dist;
- }
- i = l - 1;
- break;
- case '@':
- int m;
- String time = null;
- for (m = i + 2; m < rev.length; ++m) {
- if (rev[m] == '}') {
- time = new String(rev, i + 2, m - i - 2);
- break;
- }
- }
- if (time != null) {
- String refName = new String(rev, 0, i);
- Ref resolved = getRefDatabase().getRef(refName);
- if (resolved == null)
- return null;
- ref = resolveReflog(rw, resolved, time);
- i = m;
- } else
- i = m - 1;
- break;
- case ':': {
- RevTree tree;
- if (ref == null) {
- // We might not yet have parsed the left hand side.
- ObjectId id;
- try {
- if (i == 0)
- id = resolve(rw, Constants.HEAD);
- else
- id = resolve(rw, new String(rev, 0, i));
- } catch (RevisionSyntaxException badSyntax) {
- throw new RevisionSyntaxException(revstr);
- }
- if (id == null)
- return null;
- tree = rw.parseTree(id);
- } else {
- tree = rw.parseTree(ref);
- }
-
- if (i == rev.length - 1)
- return tree.copy();
-
- TreeWalk tw = TreeWalk.forPath(rw.getObjectReader(),
- new String(rev, i + 1, rev.length - i - 1), tree);
- return tw != null ? tw.getObjectId(0) : null;
- }
-
- default:
- if (ref != null)
- throw new RevisionSyntaxException(revstr);
- }
- }
- return ref != null ? ref.copy() : resolveSimple(revstr);
- }
-
- private static boolean isHex(char c) {
- return ('0' <= c && c <= '9') //
- || ('a' <= c && c <= 'f') //
- || ('A' <= c && c <= 'F');
- }
-
- private static boolean isAllHex(String str, int ptr) {
- while (ptr < str.length()) {
- if (!isHex(str.charAt(ptr++)))
- return false;
- }
- return true;
- }
-
- private RevObject parseSimple(RevWalk rw, String revstr) throws IOException {
- ObjectId id = resolveSimple(revstr);
- return id != null ? rw.parseAny(id) : null;
- }
-
- private ObjectId resolveSimple(final String revstr) throws IOException {
- if (ObjectId.isId(revstr))
- return ObjectId.fromString(revstr);
-
- Ref r = getRefDatabase().getRef(revstr);
- if (r != null)
- return r.getObjectId();
-
- if (AbbreviatedObjectId.isId(revstr))
- return resolveAbbreviation(revstr);
-
- int dashg = revstr.indexOf("-g");
- if ((dashg + 5) < revstr.length() && 0 <= dashg
- && isHex(revstr.charAt(dashg + 2))
- && isHex(revstr.charAt(dashg + 3))
- && isAllHex(revstr, dashg + 4)) {
- // Possibly output from git describe?
- String s = revstr.substring(dashg + 2);
- if (AbbreviatedObjectId.isId(s))
- return resolveAbbreviation(s);
- }
-
- return null;
- }
-
- private RevCommit resolveReflog(RevWalk rw, Ref ref, String time)
- throws IOException {
- int number;
- try {
- number = Integer.parseInt(time);
- } catch (NumberFormatException nfe) {
- throw new RevisionSyntaxException(MessageFormat.format(
- JGitText.get().invalidReflogRevision, time));
- }
- if (number < 0)
- throw new RevisionSyntaxException(MessageFormat.format(
- JGitText.get().invalidReflogRevision, time));
-
- ReflogReader reader = new ReflogReader(this, ref.getName());
- ReflogEntry entry = reader.getReverseEntry(number);
- if (entry == null)
- throw new RevisionSyntaxException(MessageFormat.format(
- JGitText.get().reflogEntryNotFound,
- Integer.valueOf(number), ref.getName()));
-
- return rw.parseCommit(entry.getNewId());
- }
-
- private ObjectId resolveAbbreviation(final String revstr) throws IOException,
- AmbiguousObjectException {
- AbbreviatedObjectId id = AbbreviatedObjectId.fromString(revstr);
- ObjectReader reader = newObjectReader();
- try {
- Collection<ObjectId> matches = reader.resolve(id);
- if (matches.size() == 0)
- return null;
- else if (matches.size() == 1)
- return matches.iterator().next();
- else
- throw new AmbiguousObjectException(id, matches);
- } finally {
- reader.release();
- }
- }
-
- /** Increment the use counter by one, requiring a matched {@link #close()}. */
- public void incrementOpen() {
- useCnt.incrementAndGet();
- }
-
- /** Decrement the use count, and maybe close resources. */
- public void close() {
- if (useCnt.decrementAndGet() == 0) {
- doClose();
- }
- }
-
- /**
- * Invoked when the use count drops to zero during {@link #close()}.
- * <p>
- * The default implementation closes the object and ref databases.
- */
- protected void doClose() {
- getObjectDatabase().close();
- getRefDatabase().close();
- }
-
- public String toString() {
- String desc;
- if (getDirectory() != null)
- desc = getDirectory().getPath();
- else
- desc = getClass().getSimpleName() + "-"
- + System.identityHashCode(this);
- return "Repository[" + desc + "]";
- }
-
- /**
- * Get the name of the reference that {@code HEAD} points to.
- * <p>
- * This is essentially the same as doing:
- *
- * <pre>
- * return getRef(Constants.HEAD).getTarget().getName()
- * </pre>
- *
- * Except when HEAD is detached, in which case this method returns the
- * current ObjectId in hexadecimal string format.
- *
- * @return name of current branch (for example {@code refs/heads/master}) or
- * an ObjectId in hex format if the current branch is detached.
- * @throws IOException
- */
- public String getFullBranch() throws IOException {
- Ref head = getRef(Constants.HEAD);
- if (head == null)
- return null;
- if (head.isSymbolic())
- return head.getTarget().getName();
- if (head.getObjectId() != null)
- return head.getObjectId().name();
- return null;
- }
-
- /**
- * Get the short name of the current branch that {@code HEAD} points to.
- * <p>
- * This is essentially the same as {@link #getFullBranch()}, except the
- * leading prefix {@code refs/heads/} is removed from the reference before
- * it is returned to the caller.
- *
- * @return name of current branch (for example {@code master}), or an
- * ObjectId in hex format if the current branch is detached.
- * @throws IOException
- */
- public String getBranch() throws IOException {
- String name = getFullBranch();
- if (name != null)
- return shortenRefName(name);
- return name;
- }
-
- /**
- * Objects known to exist but not expressed by {@link #getAllRefs()}.
- * <p>
- * When a repository borrows objects from another repository, it can
- * advertise that it safely has that other repository's references, without
- * exposing any other details about the other repository. This may help
- * a client trying to push changes avoid pushing more than it needs to.
- *
- * @return unmodifiable collection of other known objects.
- */
- public Set<ObjectId> getAdditionalHaves() {
- return Collections.emptySet();
- }
-
- /**
- * Get a ref by name.
- *
- * @param name
- * the name of the ref to lookup. May be a short-hand form, e.g.
- * "master" which is is automatically expanded to
- * "refs/heads/master" if "refs/heads/master" already exists.
- * @return the Ref with the given name, or null if it does not exist
- * @throws IOException
- */
- public Ref getRef(final String name) throws IOException {
- return getRefDatabase().getRef(name);
- }
-
- /**
- * @return mutable map of all known refs (heads, tags, remotes).
- */
- public Map<String, Ref> getAllRefs() {
- try {
- return getRefDatabase().getRefs(RefDatabase.ALL);
- } catch (IOException e) {
- return new HashMap<String, Ref>();
- }
- }
-
- /**
- * @return mutable map of all tags; key is short tag name ("v1.0") and value
- * of the entry contains the ref with the full tag name
- * ("refs/tags/v1.0").
- */
- public Map<String, Ref> getTags() {
- try {
- return getRefDatabase().getRefs(Constants.R_TAGS);
- } catch (IOException e) {
- return new HashMap<String, Ref>();
- }
- }
-
- /**
- * Peel a possibly unpeeled reference to an annotated tag.
- * <p>
- * If the ref cannot be peeled (as it does not refer to an annotated tag)
- * the peeled id stays null, but {@link Ref#isPeeled()} will be true.
- *
- * @param ref
- * The ref to peel
- * @return <code>ref</code> if <code>ref.isPeeled()</code> is true; else a
- * new Ref object representing the same data as Ref, but isPeeled()
- * will be true and getPeeledObjectId will contain the peeled object
- * (or null).
- */
- public Ref peel(final Ref ref) {
- try {
- return getRefDatabase().peel(ref);
- } catch (IOException e) {
- // Historical accident; if the reference cannot be peeled due
- // to some sort of repository access problem we claim that the
- // same as if the reference was not an annotated tag.
- return ref;
- }
- }
-
- /**
- * @return a map with all objects referenced by a peeled ref.
- */
- public Map<AnyObjectId, Set<Ref>> getAllRefsByPeeledObjectId() {
- Map<String, Ref> allRefs = getAllRefs();
- Map<AnyObjectId, Set<Ref>> ret = new HashMap<AnyObjectId, Set<Ref>>(allRefs.size());
- for (Ref ref : allRefs.values()) {
- ref = peel(ref);
- AnyObjectId target = ref.getPeeledObjectId();
- if (target == null)
- target = ref.getObjectId();
- // We assume most Sets here are singletons
- Set<Ref> oset = ret.put(target, Collections.singleton(ref));
- if (oset != null) {
- // that was not the case (rare)
- if (oset.size() == 1) {
- // Was a read-only singleton, we must copy to a new Set
- oset = new HashSet<Ref>(oset);
- }
- ret.put(target, oset);
- oset.add(ref);
- }
- }
- return ret;
- }
-
- /**
- * @return the index file location
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- */
- public File getIndexFile() throws NoWorkTreeException {
- if (isBare())
- throw new NoWorkTreeException();
- return indexFile;
- }
-
- /**
- * Create a new in-core index representation and read an index from disk.
- * <p>
- * The new index will be read before it is returned to the caller. Read
- * failures are reported as exceptions and therefore prevent the method from
- * returning a partially populated index.
- *
- * @return a cache representing the contents of the specified index file (if
- * it exists) or an empty cache if the file does not exist.
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- * @throws IOException
- * the index file is present but could not be read.
- * @throws CorruptObjectException
- * the index file is using a format or extension that this
- * library does not support.
- */
- public DirCache readDirCache() throws NoWorkTreeException,
- CorruptObjectException, IOException {
- return DirCache.read(this);
- }
-
- /**
- * Create a new in-core index representation, lock it, and read from disk.
- * <p>
- * The new index will be locked and then read before it is returned to the
- * caller. Read failures are reported as exceptions and therefore prevent
- * the method from returning a partially populated index.
- *
- * @return a cache representing the contents of the specified index file (if
- * it exists) or an empty cache if the file does not exist.
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- * @throws IOException
- * the index file is present but could not be read, or the lock
- * could not be obtained.
- * @throws CorruptObjectException
- * the index file is using a format or extension that this
- * library does not support.
- */
- public DirCache lockDirCache() throws NoWorkTreeException,
- CorruptObjectException, IOException {
- // we want DirCache to inform us so that we can inform registered
- // listeners about index changes
- IndexChangedListener l = new IndexChangedListener() {
-
- public void onIndexChanged(IndexChangedEvent event) {
- notifyIndexChanged();
- }
- };
- return DirCache.lock(this, l);
- }
-
- static byte[] gitInternalSlash(byte[] bytes) {
- if (File.separatorChar == '/')
- return bytes;
- for (int i=0; i<bytes.length; ++i)
- if (bytes[i] == File.separatorChar)
- bytes[i] = '/';
- return bytes;
- }
-
- /**
- * @return an important state
- */
- public RepositoryState getRepositoryState() {
- if (isBare() || getDirectory() == null)
- return RepositoryState.BARE;
-
- // Pre Git-1.6 logic
- if (new File(getWorkTree(), ".dotest").exists())
- return RepositoryState.REBASING;
- if (new File(getDirectory(), ".dotest-merge").exists())
- return RepositoryState.REBASING_INTERACTIVE;
-
- // From 1.6 onwards
- if (new File(getDirectory(),"rebase-apply/rebasing").exists())
- return RepositoryState.REBASING_REBASING;
- if (new File(getDirectory(),"rebase-apply/applying").exists())
- return RepositoryState.APPLY;
- if (new File(getDirectory(),"rebase-apply").exists())
- return RepositoryState.REBASING;
-
- if (new File(getDirectory(),"rebase-merge/interactive").exists())
- return RepositoryState.REBASING_INTERACTIVE;
- if (new File(getDirectory(),"rebase-merge").exists())
- return RepositoryState.REBASING_MERGE;
-
- // Both versions
- if (new File(getDirectory(), Constants.MERGE_HEAD).exists()) {
- // we are merging - now check whether we have unmerged paths
- try {
- if (!readDirCache().hasUnmergedPaths()) {
- // no unmerged paths -> return the MERGING_RESOLVED state
- return RepositoryState.MERGING_RESOLVED;
- }
- } catch (IOException e) {
- // Can't decide whether unmerged paths exists. Return
- // MERGING state to be on the safe side (in state MERGING
- // you are not allow to do anything)
- }
- return RepositoryState.MERGING;
- }
-
- if (new File(getDirectory(), "BISECT_LOG").exists())
- return RepositoryState.BISECTING;
-
- if (new File(getDirectory(), Constants.CHERRY_PICK_HEAD).exists()) {
- try {
- if (!readDirCache().hasUnmergedPaths()) {
- // no unmerged paths
- return RepositoryState.CHERRY_PICKING_RESOLVED;
- }
- } catch (IOException e) {
- // fall through to CHERRY_PICKING
- }
-
- return RepositoryState.CHERRY_PICKING;
- }
-
- return RepositoryState.SAFE;
- }
-
- /**
- * Check validity of a ref name. It must not contain character that has
- * a special meaning in a Git object reference expression. Some other
- * dangerous characters are also excluded.
- *
- * For portability reasons '\' is excluded
- *
- * @param refName
- *
- * @return true if refName is a valid ref name
- */
- public static boolean isValidRefName(final String refName) {
- final int len = refName.length();
- if (len == 0)
- return false;
- if (refName.endsWith(".lock"))
- return false;
-
- int components = 1;
- char p = '\0';
- for (int i = 0; i < len; i++) {
- final char c = refName.charAt(i);
- if (c <= ' ')
- return false;
- switch (c) {
- case '.':
- switch (p) {
- case '\0': case '/': case '.':
- return false;
- }
- if (i == len -1)
- return false;
- break;
- case '/':
- if (i == 0 || i == len - 1)
- return false;
- components++;
- break;
- case '{':
- if (p == '@')
- return false;
- break;
- case '~': case '^': case ':':
- case '?': case '[': case '*':
- case '\\':
- return false;
- }
- p = c;
- }
- return components > 1;
- }
-
- /**
- * Strip work dir and return normalized repository path.
- *
- * @param workDir Work dir
- * @param file File whose path shall be stripped of its workdir
- * @return normalized repository relative path or the empty
- * string if the file is not relative to the work directory.
- */
- public static String stripWorkDir(File workDir, File file) {
- final String filePath = file.getPath();
- final String workDirPath = workDir.getPath();
-
- if (filePath.length() <= workDirPath.length() ||
- filePath.charAt(workDirPath.length()) != File.separatorChar ||
- !filePath.startsWith(workDirPath)) {
- File absWd = workDir.isAbsolute() ? workDir : workDir.getAbsoluteFile();
- File absFile = file.isAbsolute() ? file : file.getAbsoluteFile();
- if (absWd == workDir && absFile == file)
- return "";
- return stripWorkDir(absWd, absFile);
- }
-
- String relName = filePath.substring(workDirPath.length() + 1);
- if (File.separatorChar != '/')
- relName = relName.replace(File.separatorChar, '/');
- return relName;
- }
-
- /**
- * @return true if this is bare, which implies it has no working directory.
- */
- public boolean isBare() {
- return workTree == null;
- }
-
- /**
- * @return the root directory of the working tree, where files are checked
- * out for viewing and editing.
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- */
- public File getWorkTree() throws NoWorkTreeException {
- if (isBare())
- throw new NoWorkTreeException();
- return workTree;
- }
-
- /**
- * Force a scan for changed refs.
- *
- * @throws IOException
- */
- public abstract void scanForRepoChanges() throws IOException;
-
- /**
- * Notify that the index changed
- */
- public abstract void notifyIndexChanged();
-
- /**
- * @param refName
- *
- * @return a more user friendly ref name
- */
- public static String shortenRefName(String refName) {
- if (refName.startsWith(Constants.R_HEADS))
- return refName.substring(Constants.R_HEADS.length());
- if (refName.startsWith(Constants.R_TAGS))
- return refName.substring(Constants.R_TAGS.length());
- if (refName.startsWith(Constants.R_REMOTES))
- return refName.substring(Constants.R_REMOTES.length());
- return refName;
- }
-
- /**
- * @param refName
- * @return a {@link ReflogReader} for the supplied refname, or null if the
- * named ref does not exist.
- * @throws IOException the ref could not be accessed.
- */
- public abstract ReflogReader getReflogReader(String refName)
- throws IOException;
-
- /**
- * Return the information stored in the file $GIT_DIR/MERGE_MSG. In this
- * file operations triggering a merge will store a template for the commit
- * message of the merge commit.
- *
- * @return a String containing the content of the MERGE_MSG file or
- * {@code null} if this file doesn't exist
- * @throws IOException
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- */
- public String readMergeCommitMsg() throws IOException, NoWorkTreeException {
- if (isBare() || getDirectory() == null)
- throw new NoWorkTreeException();
-
- File mergeMsgFile = new File(getDirectory(), Constants.MERGE_MSG);
- try {
- return RawParseUtils.decode(IO.readFully(mergeMsgFile));
- } catch (FileNotFoundException e) {
- // MERGE_MSG file has disappeared in the meantime
- // ignore it
- return null;
- }
- }
-
- /**
- * Write new content to the file $GIT_DIR/MERGE_MSG. In this file operations
- * triggering a merge will store a template for the commit message of the
- * merge commit. If <code>null</code> is specified as message the file will
- * be deleted
- *
- * @param msg
- * the message which should be written or <code>null</code> to
- * delete the file
- *
- * @throws IOException
- */
- public void writeMergeCommitMsg(String msg) throws IOException {
- File mergeMsgFile = new File(gitDir, Constants.MERGE_MSG);
- if (msg != null) {
- FileOutputStream fos = new FileOutputStream(mergeMsgFile);
- try {
- fos.write(msg.getBytes(Constants.CHARACTER_ENCODING));
- } finally {
- fos.close();
- }
- } else {
- FileUtils.delete(mergeMsgFile, FileUtils.SKIP_MISSING);
- }
- }
-
- /**
- * Return the information stored in the file $GIT_DIR/MERGE_HEAD. In this
- * file operations triggering a merge will store the IDs of all heads which
- * should be merged together with HEAD.
- *
- * @return a list of commits which IDs are listed in the MERGE_HEAD
- * file or {@code null} if this file doesn't exist. Also if the file
- * exists but is empty {@code null} will be returned
- * @throws IOException
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- */
- public List<ObjectId> readMergeHeads() throws IOException, NoWorkTreeException {
- if (isBare() || getDirectory() == null)
- throw new NoWorkTreeException();
-
- byte[] raw = readGitDirectoryFile(Constants.MERGE_HEAD);
- if (raw == null)
- return null;
-
- LinkedList<ObjectId> heads = new LinkedList<ObjectId>();
- for (int p = 0; p < raw.length;) {
- heads.add(ObjectId.fromString(raw, p));
- p = RawParseUtils
- .nextLF(raw, p + Constants.OBJECT_ID_STRING_LENGTH);
- }
- return heads;
- }
-
- /**
- * Write new merge-heads into $GIT_DIR/MERGE_HEAD. In this file operations
- * triggering a merge will store the IDs of all heads which should be merged
- * together with HEAD. If <code>null</code> is specified as list of commits
- * the file will be deleted
- *
- * @param heads
- * a list of commits which IDs should be written to
- * $GIT_DIR/MERGE_HEAD or <code>null</code> to delete the file
- * @throws IOException
- */
- public void writeMergeHeads(List<ObjectId> heads) throws IOException {
- writeHeadsFile(heads, Constants.MERGE_HEAD);
- }
-
- /**
- * Return the information stored in the file $GIT_DIR/CHERRY_PICK_HEAD.
- *
- * @return object id from CHERRY_PICK_HEAD file or {@code null} if this file
- * doesn't exist. Also if the file exists but is empty {@code null}
- * will be returned
- * @throws IOException
- * @throws NoWorkTreeException
- * if this is bare, which implies it has no working directory.
- * See {@link #isBare()}.
- */
- public ObjectId readCherryPickHead() throws IOException,
- NoWorkTreeException {
- if (isBare() || getDirectory() == null)
- throw new NoWorkTreeException();
-
- byte[] raw = readGitDirectoryFile(Constants.CHERRY_PICK_HEAD);
- if (raw == null)
- return null;
-
- return ObjectId.fromString(raw, 0);
- }
-
- /**
- * Write cherry pick commit into $GIT_DIR/CHERRY_PICK_HEAD. This is used in
- * case of conflicts to store the cherry which was tried to be picked.
- *
- * @param head
- * an object id of the cherry commit or <code>null</code> to
- * delete the file
- * @throws IOException
- */
- public void writeCherryPickHead(ObjectId head) throws IOException {
- List<ObjectId> heads = (head != null) ? Collections.singletonList(head)
- : null;
- writeHeadsFile(heads, Constants.CHERRY_PICK_HEAD);
- }
-
- /**
- * Read a file from the git directory.
- *
- * @param filename
- * @return the raw contents or null if the file doesn't exist or is empty
- * @throws IOException
- */
- private byte[] readGitDirectoryFile(String filename) throws IOException {
- File file = new File(getDirectory(), filename);
- try {
- byte[] raw = IO.readFully(file);
- return raw.length > 0 ? raw : null;
- } catch (FileNotFoundException notFound) {
- return null;
- }
- }
-
- /**
- * Write the given heads to a file in the git directory.
- *
- * @param heads
- * a list of object ids to write or null if the file should be
- * deleted.
- * @param filename
- * @throws FileNotFoundException
- * @throws IOException
- */
- private void writeHeadsFile(List<ObjectId> heads, String filename)
- throws FileNotFoundException, IOException {
- File headsFile = new File(getDirectory(), filename);
- if (heads != null) {
- BufferedOutputStream bos = new SafeBufferedOutputStream(
- new FileOutputStream(headsFile));
- try {
- for (ObjectId id : heads) {
- id.copyTo(bos);
- bos.write('\n');
- }
- } finally {
- bos.close();
- }
- } else {
- FileUtils.delete(headsFile, FileUtils.SKIP_MISSING);
- }
- }
- }
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