Change Ide3445e652 introduced the `--pack-kept-objects` option to GC for
including the objects contained in the locked packfiles during the
repack phase.
Whilst this allowed to explicitly pass a command line argument to the
jgit gc program, it did not allow the option to be read from
configuration.
Allow the pack kept objects option to be configured exactly as C-Git
documents [1], by introducing a new `repack.packKeptObjects`
configuration.
`repack.packKeptObjects` defaults to `true`, when the
`pack.buildBitmaps` is `true` (which is the default case), `false`
otherwise.
[1] https://git-scm.com/docs/git-config#Documentation/git-config.txt-repackpackKeptObjects
Bug: 582292
Change-Id: Ia931667277410d71bc079d27c097a57094299840
Packfiles having an equivalent .keep file are associated with in-flight
pushes that haven't been completed, with potentially a set of git
objects not yet referenced by a ref.
If the Git client is not up-to-date, it may result in pushing a
packfile, generating a <packfile>.keep on the server, which
may also contain existing commits due to the lack of Git protocol
negotiation in the git-receive-pack.
The Git protocol negotiation is the phase where the client and the
server exchange the list of refs they have for trying to find a common
base and minimise the amount of objects to be transferred.
The repack phase in GC was previously skipping all objects that were
contained in all packfiles having a <packfile>.keep file associated
(aka "locked packfiles"), which did not take into consideration the
fact that excluding the existing commits would have resulted in the
generation of an invalid bitmap file.
The code for excluding the objects in the locked packfiles was written
well before the bitmap was introduced, hence could not consider a use
case that did not exist at that time.
However, when the bitmap was introduced, the exclusion of locked
packfiles was not changed, hence creating a potential problem.
The issue went unnoticed for many years because the bitmap generation
was disabled when JGit noticed any locked packfiles; however, the
bitmaps are enabled again since Id722e68d9f , and the the issue is now
visible and is impacting the GC repack phase.
Introduce the '--pack-kept-objects' option in GC for including the
objects contained in the locked packfiles during the repack phase,
which is not an issue because of the following:
- If there are any existing commits duplicated in the packfiles
they will be just considered once anyway because the repack doesn't
generate duplicates in the output packfile.
- If there are any new commits that do not have any ref pointing to
them, they will be automatically excluded from the output repacked
packfile.
The same identical solution is adopted in the C implementation of git
in repack.c.
Because the locked packfile is not pruned, any new commits not pointed
by any refs will remain in the repository and there will not be any
accidental pruning or object loss as it is today before this change.
As a side-effect of this change, it is now potentially possible to still
have duplicate BLOBs after GC when the keep packfile contained existing
objects. However, it is way better to keep the duplication until the
next GC phase rather than omitting existing objects from repacking and,
therefore generating an invalid bitmap and incorrect packfile.
Bug: 582292
Bug: 582455
Change-Id: Ide3445e652fcf256a7912f881cb898897c99b8f8
Add an explicit flag to PackWriter for allowing the
GC.repack() phase to explicitly generate bitmaps only for the
heads packfile and not for the others.
Previously the bitmap generation was conditioned to the
presence of object ids exclusion from the PackWriter.
The introduction of the bitmap generation in the PackWriter
done in Icdb0cdd66 has accidentally made the .keep files not
completely transparent, because their presence have disabled
the generation of the bitmap index, even if the generation
of bitmaps is enabled.
This bug has been an accidental consequence of the intention
of the bitmap generator to avoid generating bitmaps for the
non-heads packfile, however the implementation done by Colby
decided to use the excludeInPacks variable (see [1]) which
is unfortunately also used for excluding the packfiles having
an associated .keep file (see [2]).
[1] https://git.eclipse.org/r/c/jgit/jgit/+/7940/18/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java#1617
[2] dafcb8f6db/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/GC.java (506)
Bug: 582039
Change-Id: Id722e68d9ff4ac24e73bf765ab11017586b6766e
When loosening the objects inside the packfiles to be pruned, make sure
that the packfile list is stable and prune all the files after the
loosening is done.
This prevents a series of exceptions previously thrown when loosening
the packfiles, due to the too early pruning of the packfiles that were
still in the pack list.
Bug: 581532
Change-Id: I776776e2e083f1fa749d53f965bf50f919823b4f
This reverts commit 9c33f7364d.
Reason for revert: This change was based on the false claim that the
packedrefs file lock is held while the CAS is being done, but it is
actually released before the CAS (the in memory lock is still held,
however that does not prevent external actors from updating the
packedrefs files and then another thread from subsequently re-reading it
and updating the in memory packedRefList). Although reverting this
change can cause the CAS to fail, it should not actually matter since
the failure would indicate that another thread has already updated the
in memory packedRefList to either the same version this thread was
trying to update it too, or to a more recent version. Either way,
failing the CAS is then appropriate and should not be problematic.
Although this change reverts the code in the RefDirectory class, it
keeps the "improvements" to the test so that it continues to pass
reliably. The reason for the quotes around the word "improvements" is
because I believe the test alteration actually dramatically changes the
intent of the test, and that the original intent of the test is
untestable with the GC and RefDirectory classes as is.
Bug: 582044
Change-Id: I3acee7527bb542996dcdfaddfb2bdb45ec444db5
Signed-off-by: Martin Fick <quic_mfick@quicinc.com>
(cherry picked from commit c5617711a1)
* stable-5.12:
Add missing since tag for SshBasicTestBase
Add missing since tag for SshTestHarness#publicKey2
Silence API errors
Prevent infinite loop rescanning the pack list on
PackMismatchException
Remove blank in maven.config
Change-Id: Ibe6652374ab5971105e62b05279f218c8c130fee
* stable-5.11:
Add missing since tag for SshBasicTestBase
Add missing since tag for SshTestHarness#publicKey2
Silence API errors
Prevent infinite loop rescanning the pack list on PackMismatchException
Remove blank in maven.config
Change-Id: I25bb99687b969f9915a7cbda8d1332bec778096a
* stable-5.10:
Add missing since tag for SshTestHarness#publicKey2
Silence API errors
Prevent infinite loop rescanning the pack list on
PackMismatchException
Remove blank in maven.config
Migrated "Prevent infinite loop rescanning the pack list on
PackMismatchException" to refactoring done in
https://git.eclipse.org/r/q/topic:restore-preserved-packs
Change-Id: I0fb77bb9b498d48d5da88a93486b99bf8121e3bd
* stable-5.9:
Prevent infinite loop rescanning the pack list on
PackMismatchException
Remove blank in maven.config
Change-Id: I15ff2d7716ecaceb0eb87b8823d85670f5db709d
We found, when analysing an incident where Gerrit's gc runner thread got
stuck, that we can end up in an infinite loop in
ObjectDirectory#openPackedObject which tries to rescan the pack
list and starts over trying to open a packed object in an unconfined
loop if it catches a PackMismatchException.
Here the relevant part of a thread dump we created while the gc runner
was stuck:
"WorkQueue-2[java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask@350812a3[Not
completed,
task = java.util.concurrent.Executors$RunnableAdapter@5425d7ee]]" #72
tid=0x00007f73cee1c800 nid=0x584
runnable [0x00007f7392d57000]
java.lang.Thread.State: RUNNABLE
at org.eclipse.jgit.internal.storage.file.WindowCache.removeAll(WindowCache.java:716)
at org.eclipse.jgit.internal.storage.file.WindowCache.purge(WindowCache.java:399)
at org.eclipse.jgit.internal.storage.file.PackFile.close(PackFile.java:296)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.reuseMap(ObjectDirectory.java:973)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.scanPacksImpl(ObjectDirectory.java:904)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.scanPacks(ObjectDirectory.java:895)
- locked <0x000000050a498f60> (a
java.util.concurrent.atomic.AtomicReference)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.searchPacksAgain(ObjectDirectory.java:794)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.openPackedObject(ObjectDirectory.java:465)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.openPackedFromSelfOrAlternate(ObjectDirectory.java:417)
at org.eclipse.jgit.internal.storage.file.ObjectDirectory.openObject(ObjectDirectory.java:408)
at org.eclipse.jgit.internal.storage.file.WindowCursor.open(WindowCursor.java:132)
at org.eclipse.jgit.lib.ObjectReader$1.open(ObjectReader.java:279)
at org.eclipse.jgit.revwalk.RevWalk$2.next(RevWalk.java:1031)
at org.eclipse.jgit.internal.storage.pack.PackWriter.findObjectsToPack(PackWriter.java:1911)
at org.eclipse.jgit.internal.storage.pack.PackWriter.preparePack(PackWriter.java:960)
at org.eclipse.jgit.internal.storage.pack.PackWriter.preparePack(PackWriter.java:876)
at org.eclipse.jgit.internal.storage.file.GC.writePack(GC.java:1168)
at org.eclipse.jgit.internal.storage.file.GC.repack(GC.java:852)
at org.eclipse.jgit.internal.storage.file.GC.doGc(GC.java:269)
at org.eclipse.jgit.internal.storage.file.GC.gc(GC.java:220)
at org.eclipse.jgit.api.GarbageCollectCommand.call(GarbageCollectCommand.java:179)
at com.google.gerrit.server.git.GarbageCollection.run(GarbageCollection.java:112)
at com.google.gerrit.server.git.GarbageCollection.run(GarbageCollection.java:75)
at com.google.gerrit.server.git.GarbageCollection.run(GarbageCollection.java:71)
at com.google.gerrit.server.git.GarbageCollectionRunner.run(GarbageCollectionRunner.java:76)
at com.google.gerrit.server.logging.LoggingContextAwareRunnable.run(LoggingContextAwareRunnable.java:103)
at java.util.concurrent.Executors$RunnableAdapter.call(java.base@11.0.18/Executors.java:515)
at java.util.concurrent.FutureTask.runAndReset(java.base@11.0.18/FutureTask.java:305)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(java.base@11.0.18/ScheduledThreadPoolExecutor.java:305)
at com.google.gerrit.server.git.WorkQueue$Task.run(WorkQueue.java:612)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@11.0.18/ThreadPoolExecutor.java:1128)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@11.0.18/ThreadPoolExecutor.java:628)
at java.lang.Thread.run(java.base@11.0.18/Thread.java:829)
The code in ObjectDirectory#openPackedObject [1] apparently assumes that
this is caused by a transient problem which it can resume from by
retrying. We use `core.trustFolderStat = false` on this server since it
uses NFS. The incident we had showed that we can enter into an infinite
loop here if there is a permanent mismatch between a pack file and its
corresponding pack index. I am not yet sure how this can happen.
Break the infinite loop by limiting the number of attempts rescanning
the pack list to 5 retries. When we exceed this threshold set the type
of the PackMismatchException to permanent and rethrow it which breaks
the infinite loop.
Also apply the same limit in #getPackedObjectSize
and #selectObjectRepresentation where we use similar retry loops.
[1] 011c26ff36/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java (465)
Change-Id: I20fb63bcc1fdc3a03d39b963f06a90e6f0ba73dc
Support the new option index.skipHash which was introduced in git 2.40
[1]. If it is set to true skip computing the git index checksum. This
accelerates Git commands that manipulate the index, such as git add, git
commit, or git status. Instead of storing the checksum, write a trailing
set of bytes with value zero, indicating that the computation was
skipped.
Accept a skipped checksum consisting of 20 null bytes when reading the
index since the option could have been set to true at the time when the
index was written.
[1] https://git-scm.com/docs/git-config#Documentation/git-config.txt-indexskipHash
Bug: 581723
Change-Id: I28ebe44c5ca1cbcb882438665d686452a0c111b2
From File#lines javadoc: The returned stream from File Lines
encapsulates a Reader. If timely disposal of file system resources is
required, the try-with-resources construct should be used to ensure
that the stream's close method is
invoked after the stream operations are completed.
Wrap File.lines with try-with-resources.
Change-Id: I82c6faa3ef1083f6c7e964f96e9540b4db18eee8
Signed-off-by: Xing Huang <xingkhuang@google.com>
(cherry picked from commit 172a207945)
This broke the test GcConcurrentTest#testInterruptGc which expects
ClosedByInterruptException when the thread doing gc is interrupted.
Change-Id: I89e02fc37aceeccb04c20cfc5b71cb8fa21793d6
Git guards gc by locking a lock file "gc.pid" before starting execution.
The lock file contains the pid and hostname of the process holding the
lock. Git tries to kill the process holding that lock if the lock file
wasn't modified in the last 12 hours and was started from the same host.
Teach JGit to acquire this lock before running gc but skip execution if
another process already holds the lock. Killing the other process could
be undesired if it's a long running application.
If the lock file wasn't modified in the last 12 hours try to lock it and
run gc if locking succeeds.
Register a shutdown hook for the lock file to ensure it is cleaned up if
the process is gracefully killed.
Change-Id: I00b838dcbf4fb0d03863bf7a2cd86b743c6c6971
Add the options
- pack.preserveOldPacks
- pack.prunePreserved
This allows to configure in git config if old packs should be preserved
during gc and pruned during the next gc.
The original implementation in 91132bb0 only allows to set these options
using the API.
Change-Id: I5b23ab4f317d12f5ccd234401419913e8263cc9a
Add another newBatchUpdate method in the RefDirectory where we can
control if the created PackedBatchRefUpdate will lock the loose refs or
not.
This can be useful in cases when we run programs which have exclusive
access to a Git repository and we know that locking loose refs is
unnecessary and just a performance loss.
Change-Id: I7d0932eb1598a3871a2281b1a049021380234df9
(cherry picked from commit cb90ed0852)
The FetchProcess needs to verify that all the refs received point
to objects that are reachable from the local refs, which could be
very expensive but is needed to avoid missing objects exceptions
because of broken chains.
When the local repository has a lot of refs (e.g. millions) and the
client is fetching a non-commit object (e.g. refs/sequences/changes in
Gerrit) the reachability check on all local refs can be very expensive
compared to the time to fetch the remote ref.
Example for a 2M refs repository:
- fetching a single non-commit object: 50ms
- checking the reachability of local refs: 30s
A ref pointing to a non-commit object doesn't have any parent or
successor objects, hence would never need to have a reachability check
done. Skipping the askForIsComplete() altogether would save the 30s
time spent in an unnecessary phase.
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Change-Id: I09ac66ded45cede199ba30f9e71cc1055f00941b
FetchCommand#fetchSubmodules assumed that FETCH_HEAD can always be
parsed as a tree. This isn't true if it refers to a Ref referring to a
BLOB. This is e.g. used in Gerrit for Refs like refs/sequences/changes
which are used to implement sequences stored in git.
Change-Id: I414f5b7d9f2184b2d7d53af1dfcd68cccb725ca4
When running a GC.repack() against a repository with over one
thousands of refs/heads and tens of millions of ObjectIds,
the calculation of all bitmaps associated with all the refs
would result in an unreasonable big file that would take up to
several hours to compute.
Test scenario: repo with 2500 heads / 10M obj Intel Xeon E5-2680 2.5GHz
Before this change: 20 mins
After this change and 2300 heads excluded: 10 mins (90s for bitmap)
Having such a large bitmap file is also slow in the runtime
processing and have negligible or even negative benefits, because
the time lost in reading and decompressing the bitmap in memory
would not be compensated by the time saved by using it.
It is key to preserve the bitmaps for those refs that are mostly
used in clone/fetch and give the ability to exlude some refs
prefixes that are known to be less frequently accessed, even
though they may actually be actively written.
Example: Gerrit sandbox branches may even be actively
used and selected automatically because its commits are very
recent, however, they may bloat the bitmap, making it ineffective.
A mono-repo with tens of thousands of developers may have
a relatively small number of active branches where the
CI/CD jobs are continuously fetching/cloning the code. However,
because Gerrit allows the use of sandbox branches, the
total number of refs/heads may be even tens to hundred
thousands.
Change-Id: I466dcde69fa008e7f7785735c977f6e150e3b644
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
The annotated tags should be excluded from the bitmap associated
with the heads-only packfile. However, this was not happening
because of the check of exclusion of the peeled object instead
of the objectId to be excluded from the bitmap.
Sample use-case:
refs/heads/main
^
|
commit1 <-- commit2 <- annotated-tag1 <- tag1
^
|
commit0
When creating a bitmap for the above commit graph, before this
change all the commits are included (3 bitmaps), which is
incorrect, because all commits reachable from annotated tags
should not be included.
The heads-only bitmap should include only commit0 and commit1
but because PackWriterBitPreparer was checking for the peeled
pointer of tag1 to be excluded (commit2) which was not found in
the list of tags to exclude (annotated-tag1), the commit2 was
included, even if it wasn't reachable only from the head.
Add an additional check for exclusion of the original objectId
for allowing the exclusion of annotated tags and their pointed
commits. Add one specific test associated with an annotated tag
for making sure that this use-case is covered also.
Example repository benchmark for measuring the improvement:
# refs: 400k (2k heads, 88k tags, 310k changes)
# objects: 11M (88k of them are annotate tags)
# packfiles: 2.7G
Before this change:
GC time: 5h
clone --bare time: 7 mins
After this change:
GC time: 20 mins
clone --bare time: 3 mins
Bug: 581267
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Change-Id: Iff2bfc6587153001837220189a120ead9ac649dc
When cloning huge repositories I observed percentage of object counts
turning negative. This happened if lastWork * 100 exceeded
Integer.MAX_VALUE.
Change-Id: Ic5f5cf5a911a91338267aace4daba4b873ab3900
GC needs to get a ReflogReader for all existing refs to list all objects
referenced from reflogs. The existing Repository#getReflogReader method
accepts the ref name and then resolves the Ref to create a ReflogReader.
GC calling that for a huge number of Refs one by one is very slow. GC
first gets all Refs in bulk and then calls getReflogReader for each of
them.
Fix this by adding another getReflogReader method to Repository which
accepts a Ref directly.
This speeds up running JGit gc on a mirror clone of the Gerrit
repository from 15:36 min to 1:08 min. The repository used in this test
had 45k refs, 275k commits and 1.2m git objects.
Change-Id: I474897fdc6652923e35d461c065a29f54d9949f4
introduced by
- addition of configurable SHA1 implementation in 5.13.2
- 3-digit @since 5.9.1 annotations on GitServlet methods
Change-Id: If19853fcc5e3677e5b18e8e3fbbcd2773378dffc
The change If6da9833 moved the computation of SHA1 from the JVM's
JCE to a pure Java implementation with collision detection.
The extra security for public sites comes with a cost of slower
SHA1 processing compared to the native implementation in the JDK.
When JGit is used internally and not exposed to any traffic from
external or untrusted users, the extra cost of the pure Java SHA1
implementation can be avoided, falling back to the previous
native MessageDigest implementation.
Bug: 580310
Change-Id: Ic24c0ba1cb0fb6282b8ca3025ffbffa84035565e
Trying to register/unregister a shutdown hook when the JVM is already in
shutdown throws an IllegalStateException. Ignore this exception since we
can't do anything about it.
Bug: 580953
Change-Id: I8fc6fdd5585837c81ad0ebd6944430856556d90e
In uploadWithExceptionPropagation don't prematurely terminate timer in
case of error to enable reporting it to the client. Expose a close
method so that callers can terminate it at the appropriate time.
If the timer is already terminated when trying to report it to the
client this failed with the error java.lang.IllegalStateException:
"Timer already terminated".
Bug: 579670
Change-Id: I95827442ccb0f9b1ede83630cf7c51cf619c399a
When using JGit on a non-bare repository, the CloneCommand
it previously created local reflogs for all branches including remote
tracking ones, causing the generation of a potentially large
number of files on the local filesystem.
The creation of the remote-tracking branches (refs/remotes/*) during
clone is not an issue for the local filesystem because all of them are
stored in a single packed-refs file. However, the creation of a large
number of ref logs on a local filesystem IS an issue because it
may not be tuned or initialised in term of inodes to contain a very
large number of files.
When a user (or a CI system) performs the CloneCommand against
a potentially large repository (e.g., millions of branches), it is
interested in working or validating a single branch or tag and is
unlikely to work with all the remote-tracking branches.
The eager creation of a reflogs for all the remote-tracking branches is
not just a performance issue but may also compromise the ability to
use JGit for cloning a large repository.
The behaviour implemented in this change is also consistent with the
optimisation done in the C code-base [1].
We differentiate between clone and fetch commands using --branch
<initialBranch> option, that is only available in clone command,
and is set as HEAD per default.
[1] 58f233ce1e
Bug: 579805
Change-Id: I58d0d36a8a4ce42e0f59b8bf063747c4b81bd859
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
When JGit needs to serve a Git client requesting SHA1s
during the want phase, it needs to make a full reachability
check from the advertised refs to the ones requested to
keep all objects in the correct scope of confidentiality
allowed by the avertised refs.
The check is also performed when the SHA1 corresponds to
one of the tips of the advertised refs which is a waste of
resources.
Example:
fetch> ref-prefix refs/heads/foo
fetch< 900505eb8ce8ced2a1757906da1b25c357b9654e refs/heads/foo
fetch< 0000
fetch> command=fetch
fetch> 0001
fetch> thin-pack
fetch> ofs-delta
fetch> want 900505eb8ce8ced2a1757906da1b25c357b9654e
The SHA1 in the want is the tip of refs/heads/foo and therefore
the full reachability check can be shortened and resolved more
quickly.
Change-Id: I49bd9e2464e0bd3bca2abf14c6e9df550d07383b
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Class org.eclipse.jgit.util.Monitoring uses JMX hence we need this
import otherwise OSGi applications can face ClassNotFoundException.
Bug: 577018
Change-Id: Ifd75337b87c7faec95d333b771bb0a2f3e46a418
Updating the AmazonS3 class to support AWS Signature version 4 because
version 2 is no longer supported in all AWS regions. The version can be
selected with the new 'aws.api.signature.version' property (defaults to
2 for backwards compatibility). When set to '4', the user must also
specify the AWS region via the 'region' property. The 'region' property
must match the region that the 'domain' property resolves to.
Bug: 579907
Change-Id: If289dbc6d0f57323cfeaac2624c4eb5028f78d13
SmartHttpPushConnection: close InputStream and OutputStream after
processing. Wrap IOExceptions which aren't TransportExceptions already
as a TransportException.
Also-By: Matthias Sohn <matthias.sohn@sap.com>
Change-Id: I8e11d899672fc470c390a455dc86367e92ef9076
NOTE: port back from master branch.
On process exit, it was possible that the filesystem timestamp
resolution measurement left behind .probe files or even a lock file
for the jgit.config.
Ensure the SAVE_RUNNER is shut down when the process exits (via
System.exit() or otherwise). Move lf.lock() into the try-finally
block when saving the config file.
Delete .probe files on JVM shutdown -- they are created in daemon
threads that may terminate abruptly, not executing the "finally"
clause that normally removes these files.
Bug: 579445
Change-Id: Iaee2301eb14e6201406398a90228ad10cfea6098
BasePackConnection::readAdvertisedRefsImpl was creating an exception by
calling `noRepository`, and then blindly calling `initCause` on it. As
`noRepository` can be overridden, it's not guaranteed to be missing a
cause.
BasePackPushConnection overrides `noRepository` and initiates a fetch,
which may throw a `NoRemoteRepositoryException` with a cause.
In this case calling `initCause` threw an `IllegalStateException`.
In order to throw the correct exception, we now return the
BasePackPushConnection exception and suppress the one thrown by
BasePackConnection
Bug: 578511
Change-Id: Ic1018b214be1e83d895979ee6c7cbce3f6765f6f
The fetch of a single orphan ref (for example Gerrit meta ref:
refs/changes/21/21/meta) did not stop the negotiation so client
had to advertise all refs. This impacts the fetch performance
on repositories with a large number of refs (for example on
Gerrit repository it takes 20 seconds to fetch meta ref
comparing to 1.2 second to fetch ref with parent).
To avoid this issue UploadPack, used on the server side,
now checks if all `want` refs have parents, if not this
means that client doesn't need any extra objects, hence
the server responds with `ready` and finishes the
negotiation phase.
Bug: 577937
Change-Id: Ia3001b400b415d5cf6aae45e72345ca08d3af058