Allow PackWriter callers to manage the thread pool
By permitting the caller of PackWriter to select the Executor it
uses for task execution, we give the caller the ability to manage
the lifecycle of the thread pool, including reusing it across
concurrent pack generators.
This is the first step to supporting application thread pools
within Daemon or another managed service like Gerrit Code Review.
Change-Id: I96bee7b9c30ff9885f2bd261d0b6daaac713b5a4 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These need to be dynamic based on the current thread's environment
at time of execution in order to be properly localized for the end
user that will be seeing these messages.
Change-Id: I4976f462cfe606edd2761c0e36b2f6b20f63d53c Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jeff Schumacher [Thu, 22 Jul 2010 19:55:28 +0000 (12:55 -0700)]
Break dissimilar file pairs during diff
File pairs that are very dissimilar during a diff were not being
broken apart into their constituent ADD/DELETE pairs. The leads to
sub-optimal rename detection. Take, for example, this situation:
A file exists at src/a.txt containing "foo". A user renames src/a.txt
to src/b.txt, then adds a new src/a.txt containing "bar".
Even though the old a.txt and the new b.txt are identical, the
rename detection algorithm would not detect it as a rename since
it was already paired in a MODIFY. I added code to split all
MODIFYs below a certain score into their constituent ADD/DELETE
pairs. This allows situations like the one I described above to be
more correctly handled.
Change-Id: I22c04b70581f206bbc68c4cd1ee87a1f663b418e Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Add methods to the Repository class which write into MERGE_HEAD
and MERGE_MSG files. Since we have the read methods in the same
class this seems to be the right place.
Change-Id: I5dd65306ceb06e008fcc71b37ca3a649632ba462 Signed-off-by: Christian Halstrick <christian.halstrick@sap.com> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Make StoredConfig an abstraction above FileBasedConfig
This exposes a load and save method, allowing a Repository to denote
that it has a persistent configuration of some kind which can be
accessed by the application, without needing to know exact details
of how its stored .
Change-Id: I7c414bc0f975b80f083084ea875eca25c75a07b2 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
* delta: (103 commits)
Discard the uncompressed delta as soon as its compressed
Honor pack.windowlimit to cap memory usage during packing
Honor pack.threads and perform delta search in parallel
Cache small deltas during packing
Implement delta generation during packing
debug-show-packdelta: Dump a pack delta to the console
Initial pack format delta generator
Add debugging toString() method to ObjectToPack
Make ObjectToPack clearReuseAsIs signal available to subclasses
Correctly classify the compressing objects phase
Refactor ObjectToPack's delta depth setting
Configure core.bigFileThreshold into PackWriter
Add doNotDelta flag to ObjectToPack
Add more configuration options to PackWriter
Save object path hash codes during packing
Add path hash code to ObjectWalk
Add getObjectSize to ObjectReader
Allow TemporaryBuffer.Heap to allocate smaller than 8 KiB
Define a constant for 127 in DeltaEncoder
Cap delta copy instructions at 64k
...
Stefan Lay [Thu, 22 Jul 2010 12:57:00 +0000 (14:57 +0200)]
Allow client of Add command to set a WorkingTreeIterator
This is e.g. useful when a client of the AddCommand has
additional rules to ignore files. In Eclipse a resource can
be set to derived or be excluded by preferences.
Change-Id: I6c47e54a1ce26315faf5ed0723298ad2c2db197c Signed-off-by: Stefan Lay <stefan.lay@sap.com>
Move ignore node handling into WorkingTreeIterator
The working tree iterator has perfect knowledge of the path structure
as well as immediate information about whether or not an ignore file
even exists at this level. We can exploit that to simplify the
logic and running time for testing ignored file status by pushing
all of the checks down into the iterator itself.
Change-Id: I22ff534853e8c5672cc5c2d9444aeb14e294070e Signed-off-by: Shawn O. Pearce <spearce@spearce.org> CC: Charley Wang <chwang@redhat.com> CC: Chris Aniszczyk <caniszczyk@gmail.com> CC: Stefan Lay <stefan.lay@sap.com> CC: Matthias Sohn <matthias.sohn@sap.com>
The WorkingTreeIterator has a method to check whether
the current file differs from the corresponding index
entry. This commit improves this check to also handle
racy git situations.
See http://git.kernel.org/?p=git/git.git;a=blob;f=Documentation/technical/racy-git.txt;hb=HEAD
Change-Id: I3ad0897211dcbb2eac9eebcb19d095a5052fb06b Signed-off-by: Christian Halstrick <christian.halstrick@sap.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Smudge racily clean index entries by truncating length (like git.git)
To mark an entry racily clean we set its length to 0 (like native git
does). Entries which are not racily clean and have zero length can be
distinguished from racily clean entries by checking P_OBJECTID
against the SHA1 of empty content. When length is 0 and P_OBJECTID is
different from SHA1 of empty content we know the entry is marked
racily clean.
See http://dev.eclipse.org/mhonarc/lists/jgit-dev/msg00488.html
Change-Id: I689552931441ab51964b430b303160c9126b66af Signed-off-by: Christian Halstrick <christian.halstrick@sap.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Use proper constants for .gitignore and .git directory
We have a constant for .gitignore, so use it. While we are in
the same method, correct the reference of ".git" to be the actual
GIT_DIR given. This might not be within the work tree if the
GIT_DIR and GIT_WORK_TREE environment variables were used.
Change-Id: I38e1cec13405109b9c347858b38dd9fb2f1f2560 Signed-off-by: Shawn O. Pearce <spearce@spearce.org> CC: Charley Wang <chwang@redhat.com> CC: Chris Aniszczyk <caniszczyk@gmail.com> CC: Stefan Lay <stefan.lay@sap.com> CC: Matthias Sohn <matthias.sohn@sap.com>
Remove gitIgnoreTimestamp from abstract iterator API
This never should have been exposed on the top of the
AbstractTreeIterator type hierarchy. There is no concept of a
timestamp in a canonical tree read from the object database, and
the time in the DirCache isn't what we want here either.
Actually all that we need is to find the files whose names are
".gitignore" and are below the root directory. We can accomplish
that with a suffix filter, and process them immediately.
Change-Id: Ib09cbf81a9e038452ce491385c65498312e2916b Signed-off-by: Shawn O. Pearce <spearce@spearce.org> CC: Charley Wang <chwang@redhat.com> CC: Chris Aniszczyk <caniszczyk@gmail.com> CC: Stefan Lay <stefan.lay@sap.com> CC: Matthias Sohn <matthias.sohn@sap.com>
If we have two adds of the same object but no deletes the detector
threw an NPE because the entry that came back from the deleted map
was null (no matching objects). In this case we need to put the
adds all back onto the list of left over additions since they did
not match a delete.
We didn't correctly handle the zlib trailer for an object. If the
trailer bytes were outside of the current buffer window but we had
fully inflated the object itself, we broke out of the loop (as we had
our target size) but inflate wasn't finished (as it did not yet get
the trailer) so we failed the test and threw a corruption exception.
Use an infinite loop and only break out when the inflater is done.
Change-Id: I7c9bbbeb577a990d9bc56a50ebd485935460f6c8 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jonathan Gossage [Fri, 16 Jul 2010 23:53:23 +0000 (01:53 +0200)]
Fully implement Logger interface
On April 27, 2010 the Logger interface was upgraded with a number of new methods
to make it consistent with the implementations it was meant to support.
This patch makes RecordingLogger consistent with the Logger interface and allows to
also use Jetty 7.1.5 released with Helios which can be installed from the p2 repository
at http://download.eclipse.org/jetty/7.1.5.v20100705/repository
Change-Id: I5645436bbe7492f82d4069e4d9cbebede0bf764e Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Discard the uncompressed delta as soon as its compressed
The DeltaCache will most likely need to copy the compressed delta
into a new buffer in order to compact away the wasted space at the
end caused by over allocation. Since we don't need the uncompressed
format anymore, null out our only reference to it so the GC can
reclaim this memory if it needs to perform a collection in order
to satisfy the cache's allocation attempt.
Change-Id: I50403cfd2e3001b093f93a503cccf7adab43cc9d Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
* js/rename:
Implemented file path based tie breaking to exact rename detection
Added more test cases for RenameDetector
Added very small optimization to exact rename detection
Fixed Misleading Javadoc
Added file path similarity to scoring metric in rename detection
Fixed potential div by zero bug
Added file size based rename detection optimization
Create FileHeader from DiffEntry
log: Implement --follow
Cache the diff configuration section
log: Add whitespace ignore options
Format submodule links during differences
Redo DiffFormatter API to be easier to use
log, diff: Add rename detection support
Implement similarity based rename detection
Added a preliminary version of rename detection
Refactored code out of FileHeader to facilitate rename detection
A programming error using the Inflater API led to an infinite
loop within IndexPack, caused by the Inflater returning 0 from
the inflate() method, but it didn't want more input. This happens
when it has reached the end of the stream, or has reached a spot
asking for an external dictionary. Such a case is a failure for us,
and we should abort out.
Thanks to Alex for pointing out that we had 3 implementations of
the inflate rountine, which should be consolidated into one and
use a switch to determine where to load data from.
Bug: 317416
Change-Id: I34120482375b687ea36ed9154002d77047e94b1f Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jeff Schumacher [Tue, 13 Jul 2010 19:21:12 +0000 (12:21 -0700)]
Implemented file path based tie breaking to exact rename detection
During the exact rename detection phase in RenameDetector, ties were
resolved on a first-found basis. I added support for file path based
tie breaking during that phase. Basically, there are four situations
that have to be handled:
One add matching one delete:
In this simple case, we pair them as a rename.
One add matching many deletes:
Find the delete whos path matches the add the closest, and
pair them as a rename.
Many adds matching one delete:
Similar to the above case, we find the add that matches the
delete the closest, and pair them as a rename. The other adds
are marked as copies of the delete.
Many adds matching many deletes:
Build a scoring matrix similar to the one used for content-
based matching, scoring instead by file path. Some of the
utility functions in SimilarityRenameDetector are used in
this case, as we use the same encoding scheme. Once the
matrix is built, scan it for the best matches, marking them
as renames. The rest are marked as copies.
I don't particularly like the idea of using utility functions right
out of SimilarityRenameDetector, but it works for the moment. A later
commit will likely refactor this into a common utility class, as well
as bringing exact rename detection out of RenameDetector and into a
separate class, much like SimilarityRenameDetector.
Added possibility to compare the current entry of a WorkingTreeIterator
to a given DirCacheEntry. This is done to detect whether an entry
in the index is dirty or not. 'Dirty' means that the file in the working tree
is different from what's in the index. Merge algorithms will make use of
this to detect conflicts.
Change-Id: I3ff847f4bf392553dcbd6ee236c6ca32a13eedeb Signed-off-by: Christian Halstrick <christian.halstrick@sap.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
After refactoring ReadTreeTest the tests failed for filesystems
with coarse modification time granularity. This is fixed by
explicitly telling the repo to reread the index after we build
a new index.
Additionally the test testDirectoryFileSimple was simplified
by using buildTree() instead of misusing GitIndex to construct
trees.
Change-Id: I20d2f097491e4cc8c657a696beabc7026b485017 Signed-off-by: Christian Halstrick <christian.halstrick@sap.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Charley Wang [Mon, 12 Jul 2010 22:34:15 +0000 (00:34 +0200)]
Add compatibility with gitignore specifications
This patch adds ignore compatibility to jgit. It encompasses
exclude files as well as .gitignore. Uses TreeWalk and
FileTreeIterator to find nodes and parses .gitignore
files when required. The patch includes a simple cache that
can be used to save results and avoid excessive gitignore
parsing.
CQ: 4302
Bug: 303925
Change-Id: Iebd7e5bb534accca4bf00d25bbc1f561d7cad11b Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com> Signed-off-by: Stefan Lay <stefan.lay@sap.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Jeff Schumacher [Mon, 12 Jul 2010 18:48:56 +0000 (11:48 -0700)]
Added very small optimization to exact rename detection
Optimized a small loop in findExactRenames. The loop would go through
all the items in a list of DiffEntries even after it already found
what it was looking for. I made it break out of the loop as soon as
a good match was found.
Jeff Schumacher [Mon, 12 Jul 2010 17:37:10 +0000 (10:37 -0700)]
Fixed Misleading Javadoc
The javadoc for the setRenameLimit method in RenameDetector said
that you could only have limits in the range (0,100), implying
that 0 and 100 were illegal inputs. The code, however, allowed 0 and
100. I changed the javadoc to say that the range [0,100] was legal.
I also documented the IllegalArgumentException that is thrown if the
limit is outside that range.
Jeff Schumacher [Fri, 9 Jul 2010 22:11:54 +0000 (15:11 -0700)]
Added file path similarity to scoring metric in rename detection
The scoring method was not taking into account the similarity of
the file paths and file names. I changed the metric so that it is 99%
based on content (which used to be 100% of the old metric), and 1%
based on path similarity. Of that 1%, half (.5% of the total final
score) is based on the actual file names (e.g. "foo.java"), and half
on the directory (e.g. "src/com/foo/bar/").
Jeff Schumacher [Fri, 9 Jul 2010 19:53:57 +0000 (12:53 -0700)]
Fixed potential div by zero bug
The scoring logic in SimilarityIndex was dividing by the max file
size. If both files are empty, this would cause a div by zero
error. This case cannot currently happen, since two empty files
would have the same SHA1, and would therefore be caught in the
earlier SHA1 based detection pass. Still, if this logic eventually
gets separated from that pass, a div by zero error would occur.
I changed the logic to instead consider two empty files to have a
similarity score of 100.
Jeff Schumacher [Fri, 9 Jul 2010 18:18:50 +0000 (11:18 -0700)]
Added file size based rename detection optimization
Prior to this change, files that were very different in size (enough
so that they could not have enough in common to be detected as
renames) were still having their scores calculated. I added an
optimization to skip such files. For example, if the rename detection
threshold is 60%, the larger file is 200kb, and the smaller file is
50kb, the pair cannot be counted as a rename since they cannot
possibly share 60% of their content in common. (200*.6=120, 120>50)
Honor pack.windowlimit to cap memory usage during packing
The pack.windowlimit configuration parameter places an upper bound
on the number of bytes used by the DeltaWindow class as it scans
through the object list. If memory usage would exceed the limit
the window is temporarily decreased in size to keep memory used
within that bound.
Change-Id: I09521b8f335475d8aee6125826da8ba2e545060d Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Honor pack.threads and perform delta search in parallel
If we have multiple CPUs available, packing usually goes faster
when each CPU is assigned a slice of the available search space.
The number of threads to use is guessed from the runtime if it
wasn't set by the caller, or wasn't set in the configuration.
Change-Id: If554fd8973db77632a52a0f45377dd6ec13fc220 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter now caches small deltas, or deltas that are very tiny
compared to their source inputs, so that the writing phase goes
faster by reusing those cached deltas.
The cached data is stored compressed, which usually translates to
a bigger footprint due to deltas being very hard to compress, but
saves time during writing by avoiding the deflate step. They are
held under SoftReferences so that the JVM GC can clear out deltas
if memory gets very tight. We would rather continue working and
spend a bit more CPU time during writing than crash due to OOME.
To avoid OutOfMemoryErrors during the caching phase we also trap
OOME and just abort out of the caching.
Because deflateBound() always produces something larger than what
we need to actually store the deflated data, we copy it over into
a new buffer if the actual length doesn't match the buffer length.
When packing jgit.git this saves over 111 KiB in the cache, and is
thus a worthwhile hit on CPU time.
To further save memory we store the inflated size of the delta
(which we need for the object header) in the same field as the
pathHash, as the pathHash is no longer necessary by this phase
of the packing algorithm.
Change-Id: I0da0c600d845e8ec962289751f24e65b5afa56d7 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter now produces new deltas if there is not a suitable delta
available for reuse from an existing pack file. This permits JGit to
send less data on the wire by sending a delta relative to an object
the other side already has, instead of sending the whole object.
The delta searching algorithm is similar in style to what C Git
uses, but apparently has some differences (see below for more on).
Briefly, objects that should be considered for delta compression are
pushed onto a list. This list is then sorted by a rough similarity
score, which is derived from the path name the object was discovered
at in the repository during object counting. The list is then
walked in order.
At each position in the list, up to $WINDOW objects prior to it
are attempted as delta bases. Each object in the window is tried,
and the shortest delta instruction sequence selects the base object.
Some rough rules are used to prevent pathological behavior during
this matching phase, like skipping pairings of objects that are
not similar enough in size.
PackWriter intentionally excludes commits and annotated tags from
this new delta search phase. In the JGit repository only 28 out
of 2600+ commits can be delta compressed by C Git. As the commit
count tends to be a fair percentage of the total number of objects
in the repository, and they generally do not delta compress well,
skipping over them can improve performance with little increase in
the output pack size.
Because this implementation was rebuilt from scratch based on my own
memory of how the packing algorithm has evolved over the years in
C Git, PackWriter, DeltaWindow, and DeltaEncoder don't use exactly
the same rules everywhere, and that leads JGit to produce different
(but logically equivalent) pack files.
For the above tests pack.threads was set to 1, window size=10,
delta depth=50, and delta and object reuse was disabled for both
implementations. Both implementations were reading from an already
fully packed repository on local disk. The running time reported
is after 1 warm-up run of the tested implementation.
PackWriter is writing 771 KiB more data on git.git, 3M more on
linux-2.6, but is actually 39.5 KiB smaller on jgit.git. Being
larger by less than 0.7% on linux-2.6 isn't bad, nor is taking an
extra 2 minutes to pack. On the running time side, JGit is at a
major disadvantage because linux-2.6 doesn't fit into the default
WindowCache of 20M, while C Git is able to mmap the entire pack and
have it available instantly in physical memory (assuming hot cache).
CGit also has a feature where it caches deltas that were created
during the compression phase, and uses those cached deltas during
the writing phase. PackWriter does not implement this (yet),
and therefore must create every delta twice. This could easily
account for the increased running time we are seeing.
Change-Id: I6292edc66c2e95fbe45b519b65fdb3918068889c Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
debug-show-packdelta: Dump a pack delta to the console
This is a horribly crude application, it doesn't even verify that
the object its dumping is delta encoded. Its method of getting the
delta is pretty abusive to the public PackWriter API, because right
now we don't want to expose the real internal low-level methods
actually required to do this.
Change-Id: I437a17ceb98708b5603a2061126eb251e82f4ed4 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
DeltaIndex is a simple pack style delta generator. The function works
by creating a compact index of a source buffer's blocks, and then
walking a sliding window along a desired result buffer, searching for
the window in the index. When a match is found, the window is
stretched to the longest possible length that is common with the
source buffer, and a copy instruction is created.
Rabin's polynomial hash function is used to compute the hash for a
block, permitting efficient sliding of the window in single byte
increments. The update function to slide one byte originated from
David Mazieres' work in LBFS, and our implementation of the update
step was certainly inspired by the initial work Geert Bosch proposed
for C Git in http://marc.info/?l=git&m=114565424620771&w=2.
To ensure the encoder runs in linear time with respect to the size of
the two input buffers (source and result), the maximum number of
blocks that can share the same position in the index's hashtable is
capped at a constant number. This prevents bad inputs from causing
the encoder to run in quadratic time, but comes with a penalty of
creating a longer delta due to fewer considered copy positions.
Strange hackery is used to cap the amount of memory used by the index
to be no more than 12 bytes for every 16 bytes of source buffer, no
matter what the JVM per-object overhead is. This permits an index to
always be no larger than 1.75x the source buffer length, which is an
important feature to support large windows of candidates to match
against while packing. Here the strange hackery is nothing more than
a manually managed chained hashtable, where pointers are array indexes
into storage arrays rather than object references.
Computation of the hash function for a single fixed sized block is
done through an unrolled loop, where the first 4 iterations have been
manually reduced down to eliminate unnecessary instructions. The
pattern is derived from ObjectId.equals(byte[], int, byte[], int),
where we have unrolled the loop required to compare two 20 byte
arrays. Hours of testing with the Sun 1.6 JRE concluded that the
non-obvious "foo[idx + 1]" style of reference is faster than
"foo[idx++]", and so that is what we use here during hashing.
Change-Id: If9fb2a1524361bc701405920560d8ae752221768 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Make ObjectToPack clearReuseAsIs signal available to subclasses
A subclass may want to use this method to release handles that are
caching reuse information. Make it protected so they can override
it and update themselves.
Change-Id: I2277a56ad28560d2d2d97961cbc74bc7405a70d4 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Searching for reuse candidates should be fast compared to actually
doing delta compression. So pull the progress monitor out of this
phase and rename it back to identify the compressing objects state.
Change-Id: I5eb80919f21c1251e0e3420ff7774126f1f79b27 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Long ago when PackWriter is first written we thought that the delta
depth could be updated automatically. But its never used. Instead
make this a simple standard setter so the caller can more directly
set the delta depth of this object. This permits us to configure a
depth that takes into account more than just the depth of another
object in this same pack.
Change-Id: I1d71b74f2edd7029b8743a2c13b591098ce8cc8f Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
C Git's fast-import uses this to determine the maximum file size
that it tries to delta compress, anything equal to or above this
setting is stored with as a whole object with simple deflate.
Define the configuration so we can use it later.
Change-Id: Iea46e787d019a1b6c51135cc73d7688a02e207f5 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This flag will later control whether or not PackWriter search for a
delta base for this object. Edge objects will never get searched,
as the writer won't be outputting them, so they should always have
this flag set on. Sometime in the future this flag should also be
set for file blobs on file paths that have the "-delta" gitattribute
set in the repository's attributes file.
Change-Id: I6e518e1a6996c8ce00b523727f1b605e400e82c6 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter wants to categorize objects that are similar in path name,
so blobs that are probably from the same file (or same sort of file)
can be delta compressed against each other. Avoid converting into
a string by performing the hashing directly against the path buffer
in the tree iterator.
We only hash the last 16 bytes of the path, and we try avoid any
spaces, as we want the suffix of a file such as ".java" to be more
important than the directory it is in, like "src".
Change-Id: I31770ee711526306769a6f534afb19f937e0ba85 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is an informational function used by PackWriter to help it
better organize objects for delta compression. Storage systems
can implement it to provide up more detailed size information,
or they can simply rely on the default behavior that uses the
ObjectLoader obtained from open.
For local file storage, we can obtain this information faster
through specialized routines that parse a pack object header.
Change-Id: I13a09b4effb71ea5151b51547f7d091564531e58 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Allow TemporaryBuffer.Heap to allocate smaller than 8 KiB
If the heap limit was set to something smaller than 8 KiB, we were
still allocating the full 8 KiB block size, and accepting up to
the amount we allocated by. Instead actually put a hard cap on
the limit.
Change-Id: Id1da26fde2102e76510b1da4ede8493928a981cc Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jeff Schumacher [Thu, 8 Jul 2010 16:59:36 +0000 (09:59 -0700)]
Create FileHeader from DiffEntry
Added support for converting DiffEntrys to FileHeaders. FileHeaders
are DiffEntrys with a buffer containing the diff output as well as
a list of HunkHeaders. The HunkHeaders contain EditLists. The
createFileHeader(DiffEntry) method in DiffFormatter performs a Myers
Diff on the files refered to by the DiffEntry, then puts the returned
EditList into a single HunkHeader, which is then put into the
FileHeader to be returned. It also generates the appropriate diff
header an puts it into the FileHeader's buffer. The rest of the diff
output, which would normally be parsed to generate the HunkHeaders,
is not generated. In fact, the purpose of this method is to avoid
the costly diff output generation and parsing normally required to
create a FileHeader.
ReadTreeTest was hardcoded to test WorkDirCheckout. Since we want
alternative checkout implementations (especially DirCacheCheckout)
this class has been refactored so that the tests can be reused
to test other implementations
The following changes have been done:
- abstract methods for checkout and prescanTwoTrees have been
introduced. Parameters are only the two trees. As index we
will implicitly use the current index of the repo.
- whenever tests needed a manipulated index before checkout
and prescanTwoTrees it was ensured that the correct index was
persisted (before we could use not-persisted instantiations of GitIndex
passed as parameters to checkout, prescanTwoTrees
- abstract methods for getting updated, conflicting, removed entries
resulting from the last checkout, prescanTwoTrees have been introduced
- an implementation for all these abstract methods using WorkDirCheckout
has been added
- method to assert a certain state of the index and the working tree has
been added
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Change-Id: Icf177cf8043487169a32ddd72b6f8f9246a433f7
The special value 127 here means how many bytes we can put into
a single insert command. Rather than use the magical value 127,
lets name it to better document the code.
Change-Id: I5a326f4380f6ac87987fa833e9477700e984a88e Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Although all modern delta decoders can process copy instructions
with a count as large as 0xffffff (~15.9 MiB), pack version 2 streams
are only supposed to use delta copy instructions up to 64 KiB.
Rewrite our copy instruction encode loop to use the lower 64 KiB
limit, even though modern decoders would support longer copies.
To improve encoding performance we now try to encode up to four full
copy commands in our buffer before we flush it to the stream, but
we don't try to implement full buffering here. We are just trying
to amortize the virtual method call to the destination stream when
we have to do a large copy.
Change-Id: I9410a16e6912faa83180a9788dc05f11e33fabae Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
amend commit: Support large delta packed objects as streams
Rename the ByteWindow's inflate() method to setInput. We have
completely refactored the purpose of this method to be feeding part
(or all) of the window as input to the Inflater, and the actual
inflate activity happens in the caller.
Change-Id: Ie93a5bae0e9e637b5e822d56993ce6b562c6ad15 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
amend commit: Support large loose objects as streams
We need to validate the stream state after the InflaterInputStream
thinks the stream is done. Git expects a higher level of service from
the Inflater than the InflaterInputStream usually gives, we need to
ensure the embedded CRC is valid, and that there isn't trailing
garbage at the end of the file.
Change-Id: I1c9642a82dbd76b69e607dceccf8b85dc869a3c1 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The FollowFilter can be installed on a RevWalk to cause the path
to be updated through rename detection when the affected file is
found to be added to the project.
The filter works reasonably well, for example we can follow the
history of the fsck command in git-core:
Similar to what we did with diff, implement whitespace ignore options
for log too. This requires us to define some means of creating any
RawText object type at will inside of DiffFormatter, so we define a
new factory interface to construct RawText instances on demand.
Unfortunately we have to copy the entire block of common options.
args4j only processes the options/arguments on the one command class
and Java doesn't support multiple inheritance.
Change-Id: Ia16cd3a11b850fffae9fbe7b721d7e43f1d0e8a5 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Passing around the OutputStream and the Repository is crazy. Instead
put the stream in the constructor, since this formatter exists only to
output to the stream, and put the repository as a member variable that
can be optionally set.
Change-Id: I2bad012fee7f40dc1346700ebd19f1e048982878 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Implement rename detection in the command line diff and log commands.
Also support --name-status, -p and -U flags, as these can be quite
useful to view more detail.
All of the Git patch file formatting code is now moved over to the
DiffFormatter class. This permits us to reuse it in any context,
including inside of IDEs.
Change-Id: I687ccba34e18105a07e0a439d2181c323209d96c Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Content similarity based rename detection is performed only after
a linear time detection is performed using exact content match on
the ObjectIds. Any names which were paired up during that exact
match phase are excluded from the inexact similarity based rename,
which reduces the space that must be considered.
During rename detection two entries cannot be marked as a rename
if they are different types of files. This prevents a symlink from
being renamed to a regular file, even if their blob content appears
to be similar, or is identical.
Efficiently comparing two files is performed by building up two
hash indexes and hashing lines or short blocks from each file,
counting the number of bytes that each line or block represents.
Instead of using a standard java.util.HashMap, we use a custom
open hashing scheme similiar to what we use in ObjecIdSubclassMap.
This permits us to have a very light-weight hash, with very little
memory overhead per cell stored.
As we only need two ints per record in the map (line/block key and
number of bytes), we collapse them into a single long inside of
a long array, making very efficient use of available memory when
we create the index table. We only need object headers for the
index structure itself, and the index table, but not per-cell.
This offers a massive space savings over using java.util.HashMap.
The score calculation is done by approximating how many bytes are
the same between the two inputs (which for a delta would be how much
is copied from the base into the result). The score is derived by
dividing the approximate number of bytes in common into the length
of the larger of the two input files.
Right now the SimilarityIndex table should average about 1/2 full,
which means we waste about 50% of our memory on empty entries
after we are done indexing a file and sort the table's contents.
If memory becomes an issue we could discard the table and copy all
records over to a new array that is properly sized.
Building the index requires O(M + N log N) time, where M is the
size of the input file in bytes, and N is the number of unique
lines/blocks in the file. The N log N time constraint comes
from the sort of the index table that is necessary to perform
linear time matching against another SimilarityIndex created for
a different file.
To actually perform the rename detection, a SxD matrix is created,
placing the sources (aka deletions) along one dimension and the
destinations (aka additions) along the other. A simple O(S x D)
loop examines every cell in this matrix.
A SimilarityIndex is built along the row and reused for each
column compare along that row, avoiding the costly index rebuild
at the row level. A future improvement would be to load a smaller
square matrix into SimilarityIndexes and process everything in that
sub-matrix before discarding the column dimension and moving down
to the next sub-matrix block along that same grid of rows.
An optional ProgressMonitor is permitted to be passed in, allowing
applications to see the progress of the detector as it works through
the matrix cells. This provides some indication of current status
for very long running renames.
The default line/block hash function used by the SimilarityIndex
may not be optimal, and may produce too many collisions. It is
borrowed from RawText's hash, which is used to quickly skip out of
a longer equality test if two lines have different hash functions.
We may need to refine this hash in the future, in order to minimize
the number of collisions we get on common source files.
Based on a handful of test commits in JGit (especially my own
recent rename repository refactoring series), this rename detector
produces output that is very close to C Git. The content similarity
scores are sometimes off by 1%, which is most probably caused by
our SimilarityIndex type using a different hash function than C
Git uses when it computes the delta size between any two objects
in the rename matrix.
Bug: 318504
Change-Id: I11dff969e8a2e4cf252636d857d2113053bdd9dc Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Improve description of isBare and NoWorkTreeException
Alex pointed out that my description of a bare repository might be
confusing for some readers. Reword the description of the error,
and make it consistent throughout the Repository class's API.
Change-Id: I87929ddd3005f578a7022f363270952d1f7f8664 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
amend commit: Refactor repository construction to builder class
During code review, Alex raised a few comments about commit 532421d98925 ("Refactor repository construction to builder class").
Due to the size of the related series we aren't going to go back
and rebase in something this minor, so resolve them as a follow-up
commit instead.
Change-Id: Ied52f7a8f7252743353c58d20bfc3ec498933e00 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Now that any large objects are forced through a streaming loader
when its bigger than getStreamFileThreshold(), and that threshold
is pegged at Integer.MAX_VALUE as its largest size, we will never
be able to reach this code path where we threw OutOfMemoryError.
Robin pointed out that we probably should include a message here,
but the code is effectively unreachable, so there isn't any value
in adding a message at this point.
So remove it.
Change-Id: Ie611d005622e38a75537f1350246df0ab89dd500 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Since we don't know the type of object we are parsing, we don't
know if its a massive blob, or some small commit or annotated tag.
Avoid pulling the cached bytes until we have checked the type and
decided if we actually need them to continue parsing right now.
This way large blobs which won't fit in memory and would throw
a LargeObjectException don't abort parsing.
Change-Id: Ifb70df5d1c59f616aa20ee88898cb69524541636 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Callers don't necessarily need the getSize() result from a large
delta. They instead should be always using openStream() or copyTo()
for blobs going to local files, or they should be checking the
result of the constant-time isLarge() method to determine the type
of access they can use on the ObjectLoader. Avoid inflating the
delta instruction stream twice by delaying the decoding of the size
until after we have created the DeltaStream and decoded the header.
Likewise with the type, callers don't necessarily always need it
to be present in an ObjectLoader. Delay looking at it as late as
we can, thereby avoiding an ugly O(N^2) loop looking up the type
for every single object in the entire delta chain.
Change-Id: I6487b75b52a5d201d811a8baed2fb4fcd6431320 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We used our LICENSE file to describe both the license of the package,
and also the header template that should appear at the start of
all Java files we create. This creates a confusing situation for
readers who just want to consume the package, because our file
header template starts off in the middle of a sentence.
Move our template header to a separate file, and reformat the text
of the license to be something more readable by a person reviewing
the project's terms of use.
Change-Id: If318e64c06683ea14e0240914c2d057c9199ce98 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Use core.streamFileThreshold to set our streaming limit
We default this to 1 MiB for now, but we allow users to modify
it through the Repository's configuration file to be a different
value. A new repository listener is used to identify when the
setting has been updated and trigger a reconfiguration of any
active ObjectReaders.
To prevent a horrible explosion we cap core.streamFileThreshold
at no more than 1/4 of the maximum JVM heap size. We do this
because we need at least 2 byte arrays equal in size to the
stream threshold for the worst case delta inflation scenario,
and our host application probably also needs some amount of the
heap for their working set size.
Change-Id: I103b3a541dc970bbf1a6d92917a12c5a1ee34d6c Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Very large delta instruction streams, or deltas which use very large
base objects, are now streamed through as large objects rather than
being inflated into a byte array.
This isn't the most efficient way to access delta encoded content, as
we may need to rewind and reprocess the base object when there was a
block moved within the file, but it will at least prevent the JVM from
having its heap explode.
When streaming a delta we have an inflater open for each level in the
delta chain, to inflate the instruction set of the delta, as well as
an inflater for the base level object. The base object is buffered,
as is the top level delta requested by the application, but we do not
buffer the intermediate delta streams. This keeps memory usage lower,
so its closer to 1024 bytes per level in the chain, without having an
adverse impact on raw throughput as the top-level buffer gets pushed
down to the lowest stream that has the next region.
Delta instructions transparently collapse here, if the top level does
not copy a region from its base, the base won't materialize that part
from its own base, etc. This allows us to avoid copying around a lot
of segments which have been deleted from the final version.
Change-Id: I724d45245cebb4bad2deeae7b896fc55b2dd49b3 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Similar to the loose object support, whole packed objects can
now be streamed back to the caller. The streaming is less
efficient as we copy the data from the cached window array
into the InflaterInputStream's internal buffer, then inflate
it there before returning to the application.
Like with unpacked objects, there is plenty of room for some
optimization, especially for the copyTo method, where we don't
necessarily need so much buffering to exist.
Change-Id: Ie23be81289e37e24b91d17b0891e47b9da988008 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Big loose objects can now be streamed if they are over the large
object size threshold. This prevents the JVM heap from exploding
with a very large byte array to hold the slurped file, and then
again with its uncompressed copy.
We may have slightly slowed down the simple case for small
loose objects, as the loader no longer slurps the entire thing
and decompresses in memory. To try and keep good performance
for the very common small objects that are below 8 KiB in size,
buffers are set to 8 KiB, causing the reader to slurp most of the
file anyway. However the data has to be copied at least once,
from the BufferedInputStream into the InflaterInputStream.
New unit tests are supplied to get nearly 100% code coverage on the
unpacked code paths, for both standard and pack style loose objects.
We tested a fair chunk of the code elsewhere, but these new tests
are better isolated to the specific branches in the code path.
Change-Id: I87b764ab1b84225e9b5619a2a55fd8eaa640e1fe Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jeff Schumacher [Thu, 1 Jul 2010 22:30:46 +0000 (15:30 -0700)]
Added a preliminary version of rename detection
JGit does not currently do rename detection during diffs. I added
a class that, given a TreeWalk to iterate over, can output a list
of DiffEntry's for that TreeWalk, taking into account renames. This
class only detects renames by SHA1's. More complex rename detection,
along the lines of what C Git does will be added later.
Assume that the argument of compareTo won't be mutated while we
are doing the compare, and support the wider AnyObjectId type so
MutableObjectId is suitable on either side of the compareTo call.
Change-Id: I2a63a496c0a7b04f0e5f27d588689c6d5e149d98 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Instead of loading the entire object as a byte array and passing
that into the deflater, let the ObjectLoader copy the object onto
the DeflaterOutputStream. This has the nice side effect of using
some sort of stride hack in the Sun implementation that may improve
compression performance.
Change-Id: I3f3d681b06af0da93ab96c75468e00e183ff32fe Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Blobs that are too large to read as a single byte array should be
accessed through an InputStream based interface instead, allowing
the application to walk through the data stream incrementally.
Define the basic interface to support streaming contents, but don't
implement it yet for the file based backend.
Change-Id: If9e4442e9ef4ed52c3e0f1af9398199a73145516 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jeff Schumacher [Wed, 30 Jun 2010 23:21:49 +0000 (16:21 -0700)]
Refactored code out of FileHeader to facilitate rename detection
Refactored a superclass out of FileHeader called DiffEntry that holds
the more general data from FileHeader that is useful in rename
detection (old/new Ids, modes, names, as well as changeType and
score). FileHeader is now a DiffEntry that adds Hunks, parsing
abilities, etc.
Dmitry Neverov [Wed, 30 Jun 2010 17:46:53 +0000 (10:46 -0700)]
Fix missing flush in StreamCopyThread
It is possible that StreamCopyThread will not flush everything
from it's src to it's dst. In most cases StreamCopyThread works
like this:
in loop:
n = src.read(buf);
dst.write(buf, 0, n);
and when we want to flush, we interrupt() StreamCopyThread and it
flushes everything it wrote to dst.
The problem is that our interrupt() could interrupt reading. In this
case we will flush everything we wrote to dst, but not everything
we wrote to src.
Change-Id: Ifaf4d8be87535c7364dd59b217dfc631460018ff Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Shawn O. Pearce [Wed, 30 Jun 2010 17:39:00 +0000 (10:39 -0700)]
Move DirCache factory methods to Repository
Instead of creating the DirCache from a static factory method, use
an instance method on Repository, permitting the implementation to
override the method with a completely different type of DirCache
reading and writing. This would better support a repository in the
cloud strategy, or even just an in-memory unit test environment.
Change-Id: I6399894b12d6480c4b3ac84d10775dfd1b8d13e7 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Shawn O. Pearce [Wed, 30 Jun 2010 16:48:36 +0000 (09:48 -0700)]
Create NoWorkTreeException for bare repositories
Using a custom exception type makes it easire for an application
developer to understand why an exception was thrown out of a method
we declare. To remain compatiable with existing callers, we still
extend off IllegalStateException.
Change-Id: Ideeef2399b11ca460a2dbb3cd80eb76aa0a025ba Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
projects / jgit.git / log