On a local non-NFS filesystem the .git/config file will be orphaned if
it is replaced by a new process while the current process is reading the
old file. The current process successfully continues to read the
orphaned file until it closes the file handle.
Since NFS servers do not keep track of open files, instead of orphaning
the old .git/config file, such a replacement on an NFS filesystem will
instead cause the old file to be garbage collected (deleted). A stale
file handle exception will be raised on NFS clients if the file is
garbage collected (deleted) on the server while it is being read. Since
we no longer have access to the old file in these cases, the previous
code would just fail. However, in these cases, reopening the file and
rereading it will succeed (since it will open the new replacement file).
Since retrying the read is a viable strategy to deal with stale file
handles on the .git/config file, implement such a strategy.
Since it is possible that the .git/config file could be replaced again
while rereading it, loop on stale file handle exceptions, up to 5 extra
times, trying to read the .git/config file again, until we either read
the new file, or find that the file no longer exists. The limit of 5 is
arbitrary, and provides a safe upper bounds to prevent infinite loops
consuming resources in a potential unforeseen persistent error
condition.
Change-Id: I6901157b9dfdbd3013360ebe3eb40af147a8c626 Signed-off-by: Nasser Grainawi <nasser@codeaurora.org> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
When running on NFS there was a chance that JGits LockFile
semantic is broken because File#createNewFile() may allow
multiple clients to create the same file in parallel. This
change provides a fix which is only used when the new config
option core.supportsAtomicCreateNewFile is set to false. The
default for this option is true. This option can only be set in the
global or the system config file. The repository config file is not
taken into account in this case.
If the config option core.supportsAtomicCreateNewFile is true
then File#createNewFile() is trusted and the behaviour doesn't
change.
But if core.supportsAtomicCreateNewFile is set to false then after
successful creation of the lock file a hardlink to that lock file is
created and the attribute nlink of the lock file is checked to be 2. If
multiple clients manage to create the same lock file nlink would be
greater than 2 showing the error.
This expensive workaround is described in
https://www.time-travellers.org/shane/papers/NFS_considered_harmful.html
section III.d) "Exclusive File Creation"
Honor trustFolderStats also when reading packed-refs
Then list of packed refs was cached in RefDirectory based on mtime of
the packed-refs file. This may fail on NFS when attributes are cached.
A cached mtime of the packed-refs file could cause JGit to trust the
cached content of this file and to overlook that the file is modified.
Honor the config option trustFolderStats and always read the packed-refs
content if the option is false. By default this option is set to true
and this fix is not active.
Fix exception handling for opening bitmap index files
When creating a new PackFile instance it is specified whether this pack
has an associated bitmap index file or not. This information is cached
and the public method getBitmapIndex() will always assume a bitmap index
file must exist if the cached data tells so. But it may happen that the
packfiles are repacked during a gc in a different process causing the
packfile, bitmap-index and index file to be deleted. Since JGit still
has an open FileHandle on the packfile this file is not really deleted
and can still be accessed. But index and bitmap index file are deleted.
Fix getBitmapIndex() to invalidate the cached packfile instance if such
a situation occurs.
This problem showed up when a gerrit server was serving repositories
which where garbage collected with native git regularly. Fetch and
clone commands for certain repositories failed permanently after a
native git gc had deleted old bitmap index files.
Change-Id: I8e620bec74dd3f310ba42024f9a657062f868f0e Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
David Pursehouse [Mon, 27 Mar 2017 01:14:50 +0000 (10:14 +0900)]
Merge branch 'stable-4.5' into stable-4.6
* stable-4.5:
Only mark packfile invalid if exception signals permanent problem
Don't flag a packfile invalid if opening existing file failed
Prepare 4.5.2-SNAPSHOT builds
Change-Id: I20b50981adc54c426666015ff04fe3bb1db9abd9 Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Matthias Sohn [Sat, 25 Mar 2017 01:33:06 +0000 (02:33 +0100)]
Only mark packfile invalid if exception signals permanent problem
Add NoPackSignatureException and UnsupportedPackVersionException to
explicitly mark permanent unrecoverable problems with a pack
Assume problem with a pack is permanent only if we are sure the
exception signals a non-transient problem we can't recover from:
- AccessDeniedException: we lack permissions
- CorruptObjectException: we detected corruption
- EOFException: file ended unexpectedly
- NoPackSignatureException: pack has no pack signature
- NoSuchFileException: file has gone missing
- PackMismatchException: pack no longer matches its index
- UnpackException: unpacking failed
- UnsupportedPackIndexVersionException: unsupported pack index version
- UnsupportedPackVersionException: unsupported pack version
Do not attempt to handle Errors since they are thrown for serious
problems applications should not try to recover from.
Change-Id: I2c416ce2b0e23255c4fb03a3f9a0ee237f7a484a Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Luca Milanesio [Fri, 24 Mar 2017 00:18:12 +0000 (00:18 +0000)]
Don't flag a packfile invalid if opening existing file failed
A packfile random file open operation may fail with a
FileNotFoundException even if the file exists, possibly
for the temporary lack of resources.
Instead of managing the FileNotFoundException as any generic
IOException it is best to rethrow the exception but prevent
the packfile for being flagged as invalid until it is actually
opened and read successfully or unsuccessfully.
Luca Milanesio [Fri, 10 Mar 2017 00:20:23 +0000 (00:20 +0000)]
Don't remove pack when FileNotFoundException is transient
The FileNotFoundException is typically raised in three conditions:
1. file doesn't exist
2. incompatible read vs. read/write open modes
3. filesystem locking
4. temporary lack of resources (e.g. too many open files)
1. is already managed, 2. would never happen as packs are not
overwritten while with 3. and 4. it is worth logging the exception and
retrying to read the pack again.
Log transient errors using an exponential backoff strategy to avoid
flooding the logs with the same error if consecutive retries to access
the pack fail repeatedly.
Jonathan Nieder [Sun, 26 Feb 2017 23:09:04 +0000 (15:09 -0800)]
Update Jetty to 9.4.1.v20170120 in buck build
5e8e2179b218ede7d14b69dc5149b0691b5859cf (Update Jetty to
9.4.1.v201470120, 2017-01-26) updated Jetty in the maven build.
Update the buck build to match so buck builds work again.
The buck build will go away soon, but in the meantime (until the bazel
build gets the same level of support) it is convenient as a faster way
of running tests than using maven.
The bazel build doesn't need this change since it doesn't build or run
http tests yet.
Matthias Sohn [Mon, 30 Jan 2017 00:24:45 +0000 (01:24 +0100)]
GC: delete empty directories after purging loose objects
In order to limit the number of directories we check for emptiness only
consider fanout directories which contained unreferenced loose objects
we deleted in the same gc run.
Change-Id: Idf8d512867ee1c8ed40bd55752122ce83a98ffa2 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Hongkai Liu [Mon, 23 Jan 2017 16:33:40 +0000 (11:33 -0500)]
Clean up orphan files in GC
An orphan file is either a bitmap or an idx file in pack folder,
and its corresponding pack file is missing.
Change-Id: I3c4cb1f7aa99dd7b398bdb8d513f528d7761edff Signed-off-by: Hongkai Liu <hongkai.liu@ericsson.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Sun, 18 Dec 2016 09:37:47 +0000 (10:37 +0100)]
Update maven-source-plugin to 3.0.1 to fix OOM during build
Recently we frequently suffer from OutOfMemoryError when creating source
archives in the Maven build. maven-source-plugin 3.0.0 has a bug [1]
causing OOM which is fixed in 3.0.1.
When a repository is being GCed and a concurrent push is received, there
is the possibility of having a missing object. This is due to the fact
that after the list of objects to delete is built, there is a window of
time when an unreferenced and ready to delete object can be referenced
by the incoming push. In that case, the object would be deleted because
there is no way to know it is no longer unreferenced. This will leave
the repository in an inconsistent state and most of the operations fail
with a missing tree/object error.
Given the incoming push change the last modified date for the now
referenced object, verify this one is still a candidate to delete
before actually performing the delete operation.
FileSnapshot.isModified may have reported a file to be clean although it
was actually dirty.
Imagine you have a FileSnapshot on file f. lastmodified and lastread are
both t0. Now time is t1 and you
1) modify the file
2) update the FileSnapshot of the file (lastModified=t1, lastRead=t1)
3) modify the file again
4) wait 3 seconds
5) ask the Filesnapshot whether the file is dirty or not. It erroneously
answered it's clean.
Any file which has been modified longer than 2.5 seconds ago was
reported to be clean. As the test shows that's not always correct.
The real-world problem fixed by this change is the following:
* A gerrit server using JGit to serve git repositories is processing
fetch requests while simultaneously a native git garbage collection
runs on the repo.
* At time t1 native git writes temporary files in the pack folder
setting the mtime of the pack folder to t1.
* A fetch request causes JGit to search for new packfiles and JGit
remembers this scan in a Filesnapshot on the packs folder. Since the gc
is not finished JGit doesn't see any new packfiles.
* The fetch is processed and the gc ends while the filesystem timer is
still t1. GC writes a new packfile and deletes the old packfile.
* 3 seconds later another request arrives. JGit does not yet know about
the new packfile but is also not rescanning the pack folder because it
cached that the last scan happened at time t1 and pack folder's mtime is
also t1. Now JGit will not be able to resolve any object contained in
this new pack. This behavior may be persistent if objects referenced by
the ref/meta/config branch are affected so gerrit can't read permissions
stored in the refs/meta/config branch anymore and will not allow any
pushes anymore. The pack folder will not change its mtime and therefore
no rescan will take place.
Change-Id: I3efd0ccffeb97b01207dc3e7a6b85c6b06928fad Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Zhen Chen [Wed, 23 Nov 2016 00:39:27 +0000 (16:39 -0800)]
Decide whether to "Accept-Encoding: gzip" on a request-by-request basis
When the reply is already compressed (e.g. a packfile fetched using dumb
HTTP), "Content-Encoding: gzip" wastes bandwidth relative to sending the
content raw. So don't "Accept-Encoding: gzip" for such requests.
Jacek Centkowski [Thu, 24 Nov 2016 09:58:14 +0000 (10:58 +0100)]
Expose getObjectToTransfer method of FileLfsServlet
Providing own implementation to doGet/doPut methods is troublesome when
this method is private.
Change-Id: I098cdc5cb90410eaaebc56c88c2d9e168584dd6d Signed-off-by: Jacek Centkowski <geminica.programs@gmail.com> Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Fix JGits merge-base calculation in case of inconsistent commit times.
JGit was potentially failing to compute correct merge-bases when the
commit times where inconsistent (a parent commit was younger than a
child commit). The code in MergeBaseGenerator was aware of the fact that
sometimes the discovery of a merge base x can occur after the parents of
x have been seen (see comment in #carryOntoOne()). But in the light of
inconsistent commit times it was possible that these parents of a
merge-base have already been returned as a merge-base.
This commit fixes the bug by buffering all commits generated by
MergeBaseGenerator. It is expected that this buffer will be small
because the number of merge-bases will be small. Additionally a new
flag is used to mark the ancestors of merge-bases. This allows to filter
out the unwanted commits.
David Pursehouse [Fri, 18 Nov 2016 01:30:27 +0000 (17:30 -0800)]
Enable error-prone for the Maven build
- update maven-compiler-plugin to 3.6.0
- exclude InsecureCipherFactory from errorprone checks
See
https://maven.apache.org/guides/mini/guide-default-execution-ids.html#Example:_Configuring_compile_to_run_twice
https://groups.google.com/d/topic/error-prone-discuss/pzT45ZMCQOc/discussion
Change-Id: Ic16d3f15cf2ef40de62fe6bfe4b8b35f0c1edc4e Signed-off-by: David Pursehouse <david.pursehouse@gmail.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Zhen Chen [Tue, 22 Nov 2016 23:53:06 +0000 (15:53 -0800)]
dump HTTP: Avoid being confused by Content-Length of a gzipped stream
TransportHttp sets 'Accept-Encoding: gzip' to allow the server to
compress HTTP responses. When fetching a loose object over HTTP, it
uses the following code to read the response:
InputStream in = openInputStream(c);
int len = c.getContentLength();
return new FileStream(in, len);
If the content is gzipped, openInputStream decompresses it and produces
the correct content for the object. Unfortunately the Content-Length
header contains the length of the compressed stream instead of the
actual content length. Use a length of -1 instead since we don't know
the actual length.
Loose objects are already compressed, so the gzip encoding typically
produces a longer compressed payload. The value from the Content-Length
is too high, producing EOFException: Short read of block.
Change-Id: I8d5284dad608e3abd8217823da2b365e8cd998b0 Signed-off-by: Zhen Chen <czhen@google.com> Helped-by: Jonathan Nieder <jrn@google.com>
Zhen Chen [Tue, 22 Nov 2016 01:15:15 +0000 (17:15 -0800)]
Fix content length in HttpClientConnection
Per the interface specification, the getContentLength method should
return -1 if content length is unknown or greater than
Integer.MAX_VALUE.
For chunked transfer encoding, the content length is not included in the
header, hence will cause a NullPointerException when trying to parse the
content length header.
Shawn Pearce [Wed, 16 Nov 2016 01:34:07 +0000 (17:34 -0800)]
Define MonotonicClock interface for advanced timestamps
MonotonicClock can be implemented to provide more certainity about
time than the standard System.currentTimeMillis() can provide. This
can be used by classes such as PersonIdent and Ketch to rely on
more certainity about time moving in a strictly ascending order.
Gerrit Code Review can also leverage this interface through its
embedding of JGit and use MonotonicClock and ProposedTimestamp to
provide stronger assurance that NoteDb time is moving forward.
Shawn Pearce [Sun, 13 Nov 2016 19:24:41 +0000 (11:24 -0800)]
Deprecate SafeBufferedOutputStream
Java 8 fixed the silent flush during close issue by
FilterOutputStream (base class of BufferedOutputStream)
using try-with-resources to close the stream, getting a
behavior matching what JGit's SafeBufferedOutputStream
was doing:
try {
flush();
} finally {
out.close();
}
With Java 8 as the minimum required version to run JGit
it is no longer necessary to override close() or have
this class. Deprecate the class, and use the JRE's version
of close.
Shawn Pearce [Mon, 14 Nov 2016 21:59:59 +0000 (13:59 -0800)]
Support {get,set}GitwebDescription on InMemoryRepository
This simplifies testing for Gerrit Code Review where
application code is updating the repository description
and the test harness uses InMemoryRepository.
Shawn Pearce [Mon, 14 Nov 2016 19:00:34 +0000 (11:00 -0800)]
Add {get,set}GitwebDescription to Repository
This method pair allows the caller to read and modify the description
file that is traditionally used by gitweb and cgit when rendering a
repository on the web.
Gerrit Code Review has offered this feature for years as part of
its GitRepositoryManager interface, but its fundamentally a feature
of JGit and its Repository abstraction.
git-core typically initializes a repository with a default value
inside the description file. During getDescription() this string
is converted to null as it is never a useful description.
Shawn Pearce [Sun, 13 Nov 2016 19:52:12 +0000 (11:52 -0800)]
Extract insecure Cipher factory
Bazel runs ErrorProne by default and ErrorProne rightly complains that
allowing the user to specify any Cipher can lead to insecure code
(in particular, getCipher("AES") operates in ECB mode). Unfortunately
this is required to support existing repositories insecurely stored
on S3.
Extract the insecure factory code to its own class so this can be built
as a java_library() with this check disabled.
projects / jgit.git / log