PackBitmapIndex: Not buffer inflated bitmap in BasePackBitmapIndex
Currently we're buffering the inflated bitmap entry in BasePackBitmapIndex
to optimize running time. However, this will use lots of memory during
the construction of the pack bitmap index file which may cause failure of
garbage collection.
The running time didn't increase significantly, if there's any increase,
after removing the buffering here. The report about usage of time/memory
will come in the next commit.
Change-Id: I874503ecc85714acab7ca62a6a7968c2dc0b56b3
Signed-off-by: Yunjie Li <yunjieli@google.com>
PackBitmapIndex: Remove convertedBitmaps in the Remapper
The convertedBitmaps serves for time-optimization purpose. But it's
actually not saving time much but using lots of memory. So remove the
field here to save memory.
Currently the remapper class is only used in the construction of the
bitmap index file. And during the preparation of the file, we're only
getting bitmaps from the remapper when finding objects accessible from
a commit, so bitmap associated with each commit will only be fetched once
and thus the convertedBitmaps would hardly be read, which means that it's
not saving time.
Change-Id: Ic942a8e485135fb177ec21d09282d08ca6646fdb
Signed-off-by: Yunjie Li <yunjieli@google.com>
Currently, the garbage collection is consistently failing for some large
repositories in the building bitmap phase, e.g.Linux-MSM project:
https://source.codeaurora.org/quic/la/kernel/msm-3.18
Historically, bitmap index creation happened in 3 phases:
1. Select the commits to which bitmaps should be attached.
2. Create all bitmaps for these commits, stored in uncompressed format
in the PackBitmapIndexBuilder.
3. Deltify the bitmaps and write them to disk.
We investigated the process. For phase 2 it's most efficient to create
bitmaps starting with oldest commit and moving to the newest commit,
because the newer commits are able to reuse the work for the old ones.
But for bitmap deltification in phase 3, it's better when a newer
commit's bitmap is the base, and the current disk format writes bitmaps
out for the newest commits first.
This change introduces a new collection to hold the deltified and
compressed representations of the bitmaps, keeping a smaller subset of
commits in the PackBitmapIndexBuilder to help make the bitmap index
creation more memory efficient.
And in this commit, we're setting DISTANCE_THRESHOLD to 0 in the
PackWriterBitmapPreparer, which means the garbage collection will not
have much behavoir change and will still use as much memory as before.
Change-Id: I6ec2c3e8dde11805af47874d67d33cf1ef83660e
Signed-off-by: Yunjie Li <yunjieli@google.com>
Refactor: Make retriveCompressed an method of the Bitmap class
Make retrieveCompressed() a method of Bitmap interface to avoid type
casting and later reuse in improving the memory footprint of GC's bitmap
generation phase.
Change-Id: I098d85105cf17af845d43b8c71b4ca48b02fd7da
Signed-off-by: Yunjie Li <yunjieli@google.com>
The change Ic0b974fa (c217d33, "Documentation/technical/reftable:
improve repo layout") defines a new repository layout, which was
agreed with the git-core mailing list.
It addresses the following problems:
* old git clients will not recognize reftable-based repositories, and
look at encompassing directories.
* Poorly written tools might write directly into
.git/refs/heads/BRANCH.
Since we consider JGit reftable as experimental (git-core doesn't
support it yet), we have no backward compatibility. If you created a
repository with reftable between mid-Nov 2019 and now, you can do the
following to convert:
mv .git/refs .git/reftable/tables.list
git config core.repositoryformatversion 1
git config extensions.refStorage reftable
Change-Id: I80df35b9d22a8ab893dcbe9fbd051d924788d6a5
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Move array designators from the variable to the type
As reported by Sonar Lint:
Array designators should always be located on the type for better code
readability. Otherwise, developers must look both at the type and the
variable name to know whether or not a variable is an array.
Change-Id: If6b41fed3483d0992d402d8680552ab4bef89ffb
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Reorder modifiers to follow Java Language Specification
The Java Language Specification recommends listing modifiers in
the following order:
1. Annotations
2. public
3. protected
4. private
5. abstract
6. static
7. final
8. transient
9. volatile
10. synchronized
11. native
12. strictfp
Not following this convention has no technical impact, but will reduce
the code's readability because most developers are used to the standard
order.
This was detected using SonarLint.
Change-Id: I9cddecb4f4234dae1021b677e915be23d349a380
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
The ReftableCompactor supported a byteLimit, but this is currently
unused. The FileReftableStack has a more sophisticated strategy that
amortizes compaction costs.
Rename min/maxUpdateIndex to reflogExpire{Min,Max}UpdateIndex to
reflect their purpose more accurately.
Since reflogs are generally pruned chronologically (oldest entries are
expired first), one can only prune entries on full compaction, so they
should not be set by default.
Rephrase the function Reader#minUpdateIndex and maxUpdateIndex. These
vars are documented to affect log entries, but semantically, they are
about ref entries. Since ref entries have their timestamps
delta-compressed, it is important for the min/maxUpdateIndex values to
be coherent between different tables.
The logical timestamps for log entries do not have to be coherent in
different tables, as the timestamps of a log entry is part of the key.
For example, a table written at update index 20 may contain a tombstone
log entry at timestamp 1.
Therefore, we set ReftableWriter's min/maxUpdateIndex from the merged
tables we are compacting, rather than from the compaction settings
(which should only control reflog expiry.)
The previous behavior could drop log entries erroneously, especially
in the presence of tombstone log entries. Unfortunately, testing this
properly requires both an API for adding log tombstones, and a more
refined API for controlling automatic compaction. Hence, no test.
Change-Id: I2f4eb7866f607fddd0629809e8e61f0b9097717f
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
The merged table contains handles to open files. A full compaction
causes those files to be closed, and so further lookups would fail
with EBADF.
Change-Id: I7bb74f7228ecc7fec9535b00e56a617a9c18e00e
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Using the batch cleanup operation via Source -> Cleanup -> "Use lambdas
where possible" from standard JDT.
Change-Id: I5452bd94fdccc920ade071228aeed3a8b9fdbe62
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
WindowCache: add metric for cached bytes per repository
Since ObjectDatabase and PackFile don't know their repository use the
packfile's grand-grand-parent directory as an identifier for the
repository the packfile resides in.
Remove metric for a repository if the number of cached bytes for the
repository drops to 0 in order to ensure the map of cached bytes per
repository doesn't contain repositories which have no data cached in the
WindowCache.
Change-Id: I969ab8029db0a292e7585cbb36ca0baa797da20b
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Enable UnusedException at ERROR level which causes the build to fail
in many places with:
[UnusedException] This catch block catches an symbol and re-throws
another, but swallows the caught symbol rather than setting it as a
cause. This can make debugging harder.
Fix it by setting the caught exception as cause on the subsequently
thrown exception.
Note: The grammatically incorrect error message is copy-pasted as-is
from the version of ErrorProne currently used in Bazel; it has been
fixed by [1] in the latest version.
[1] https://github.com/google/error-prone/commit/d57a39c
Change-Id: I11ed38243091fc12f64f1b2db404ba3f1d2e98b5
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
WindowCache: add option to use strong refs to reference ByteWindows
Java GC evicts all SoftReferences when the used heap size comes close to
the maximum heap size. This means peaks in heap memory consumption can
flush the complete WindowCache which was observed to have negative
impact on performance of upload-pack in Gerrit.
Hence add a boolean option core.packedGitUseStrongRefs to allow using
strong references to reference packfile pages cached in the WindowCache.
If this option is set to true Java gc can no longer flush the
WindowCache to free memory if the used heap comes close to the maximum
heap size. On the other hand this provides more predictable performance.
Bug: 553573
Change-Id: I9de406293087ab0fa61130c8e0829775762ece8d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Set config "extensions" option when converting ref storage format
When converting to reftable format the option extensions.refStorage must
be set to "reftable" [1]. When converting back to refdir format this
config option needs to be removed.
Introduce constants for refStorage config options, also for the
"reftree" format.
[1] https://git.eclipse.org/r/plugins/gitiles/jgit/jgit/+/master/Documentation/technical/reftable.md#Version-1
Change-Id: I190222fa5edc1ad7309daa9be17ca934ff7971e3
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Add the following statistics
- cache hit count and hit ratio
- cache miss count and miss ratio
- count of successful and failed loads
- rate of failed loads
- load, eviction and request count
- average and total load time
Use LongAdder instead of AtomicLong to implement counters in order to
improve scalability.
Optionally expose these metrics via JMX, they are registered with the
platform MBean server if the config option jmx.WindowCacheStats = true
in the user or system level git config.
Bug: 553573
Change-Id: Ia2d5246ef69b9c2bd594a23934424bc5800774aa
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
The reftable format supports fast inverse (SHA1 => ref) queries.
If the ref database does not support fast inverse queries, it may be
advantageous to build a complete SHA1 to ref map in advance for
multiple uses. To let applications decide, this function indicates
whether the inverse map is available.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Change-Id: Idaf7e01075906972ec21332cade285289619c2b3
Use lambda style comparators where possible. They are easier to read.
Change-Id: I5b80cfcd90909c94286742fa83af71015532809f
Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de>
Reftable is a binary, block-based storage format for the ref-database.
It provides several advantages over the traditional packed + loose
storage format:
* O(1) write performance, even for deletions and transactions.
* atomic updates to the ref database.
* O(log N) lookup and prefix scans
* free from restrictions imposed by the file system: it is
case-sensitive even on case-insensitive file systems, and has
no inherent limitations for directory/file conflicts
* prefix compression reduces space usage for repetitive ref names,
such as gerrit's refs/changes/xx/xxxxx format.
FileReftableDatabase is based on FileReftableStack, which does
compactions inline. This is simple, and has good median performance,
but every so often it will rewrite the entire ref database.
For testing, a FileReftableTest (mirroring RefUpdateTest) is added to
check for Reftable specific behavior. This must be done separately, as
reflogs have different semantics.
Add a reftable flavor of BatchRefUpdateTest.
Add a FileReftableStackTest to exercise compaction.
Add FileRepository#convertToReftable so existing testdata can be
reused.
CQ: 21007
Change-Id: I1837f268e91c6b446cb0155061727dbaccb714b8
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Enable and fix "Statement unnecessarily nested within else clause" warnings
Since [1] the gerrit project includes jgit as a submodule, and has this
warning enabled, resulting in 100s of warnings in the console.
Also enable the warning here, and fix them.
At the same time, add missing braces around adjacent and nearby one-line
blocks.
[1] https://gerrit-review.googlesource.com/c/gerrit/+/227897
Change-Id: I81df3fc7ed6eedf6874ce1a3bedfa727a1897e4c
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Also correctly parse the "always" value (allowed in canonical git
since git 2.12.0[1]). Adapt the ReflogWriter.
[1] https://github.com/git/git/commit/341fb2862
Bug: 551664
Change-Id: I051c76ca355a2ac8d6092de65f44b18bf9aeb125
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
BatchRefUpdate: repro racy atomic update, and fix it
PackedBatchRefUpdate was creating a new packed-refs list that was
potentially unsorted. This would be papered over when the list was
read back from disk in parsePackedRef, which detects unsorted ref
lists on reading, and sorts them. However, the BatchRefUpdate also
installed the new (unsorted) list in-memory in
RefDirectory#packedRefs.
With the timestamp granularity code committed to stable-5.1, we can
more often accurately decide that the packed-refs file is clean, and
will return the erroneous unsorted data more often. Unluckily timed
delays also cause the file to be clean, hence this problem was
exacerbated under load.
The symptom is that refs added by a BatchRefUpdate would stop being
visible directly after they were added. In particular, the Gerrit
integration tests uses BatchRefUpdate in its setup for creating the
Admin group, and then tries to read it out directly afterward.
The tests recreates one failure case. A better approach would be to
revise RefList.Builder, so it detects out-of-order lists and
automatically sorts them.
Fixes https://bugs.eclipse.org/bugs/show_bug.cgi?id=548716 and
https://bugs.chromium.org/p/gerrit/issues/detail?id=11373.
Bug: 548716
Change-Id: I613c8059964513ce2370543620725b540b3cb6d1
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
UploadPack: support custom packfile-to-URI mapping
Teach UploadPack to take a provider of URIs corresponding to cached
packs. When fetching, if the client supports the packfile-uri feature,
and if such a cached pack were to be streamed, instead send the
corresponding URI.
This packfile-uri feature is implemented in the jt/fetch-cdn-offload
branch of Git. There is interest in this feature [1], but it is not yet
merged.
[1] https://public-inbox.org/git/cover.1552073690.git.jonathantanmy@google.com/
Change-Id: I9a32dae131c9c56ad2ff4a8a9638ae3b5e44dc15
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Cache user global and system-wide git configurations
So far the git configuration and the system wide git configuration were
always reloaded when jgit accessed these global configuration files to
access global configuration options which are not in the context of a
single git repository. Cache these configurations in SystemReader and
only reload them if their file metadata observed using FileSnapshot
indicates a modification.
Change-Id: I092fe11a5d95f1c5799273cacfc7a415d0b7786c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
[error prone] suppress AmbiguousMethodReference in AnyObjectId
Move the implementation of the static equals() method to a new method
and suppress the error. Deprecate the old method to signal that we
intend to remove it in the next major release.
See https://errorprone.info/bugpattern/AmbiguousMethodReference
Change-Id: I5e29c97f4db3e11770be589a6ccd785e2c9ac7f2
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Fix NarrowingCompoundAssignment warnings from Error Prone
Error Prone reports:
[NarrowingCompoundAssignment] Compound assignments from long to int
hide lossy casts
and
[NarrowingCompoundAssignment] Compound assignments from int to byte
hide lossy casts
See https://errorprone.info/bugpattern/NarrowingCompoundAssignment
Fix the warnings by adding explicit casts or changing types as
necessary.
Now that all occurrences of the warning are fixed, increase its
severity to ERROR.
Change-Id: Idb3670e6047b146ae37daee07212ff9455512623
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Increase the safety factor to 2.5x for extra safety if max of measured
timestamp resolution and measured minimal racy threshold is < 100ms, use
1.25 otherwise since for large filesystem resolution values the
influence of finite resolution of the system clock should be negligible.
Before, not yet using the newly introduced minRacyThreshold measurement,
the threshold was 1.1x FS resolution, and we could issue the
following sequence of events,
start
create-file
read-file (currentTime)
end
which had the following timestamps:
create-file 1564589081
start 1564589082
read 1564589082
end 1564589082
In this case, the difference between create-file and read is 5ms,
which exceeded the 4ms FS resolution, even though the events together
took just 2ms of runtime.
Reproduce with:
bazel test --runs_per_test=100 \
//org.eclipse.jgit.test:org_eclipse_jgit_internal_storage_file_FileSnapshotTest
The file system timestamp resolution is 4ms in this case.
This code assumes that the kernel and the JVM use the same clock that
is synchronized with the file system clock. This seems plausible,
given the resolution of System.currentTimeMillis() and the latency for
a gettimeofday system call (typically ~1us), but it would be good to
justify this with specifications.
Also cover a source of flakiness: if the test runs under extreme load,
then we could have
start
create-file
<long delay>
read
end
which would register as an unmodified file. Avoid this by skipping the
test if end-start is too big.
[msohn]:
- downported from master to stable-5.1
- skip test if resolution is below 10ms
- adjust safety factor to 1.25 for resolutions above 100ms
Change-Id: I87d2cf035e01c44b7ba8364c410a860aa8e312ef
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
In LockFile#waitForStatChange wait in units of file time resolution
Since we now measure file time resolution we can use it to replace the
hard coded wait time of 25ms. FileSnapshot#equals will return true until
the mtime of the old (o) and the new FileSnapshot (n) differ by at least
one file time resolution.
Change-Id: Icb713a80ce9eb929242ed083406bfb6650c72223
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Fix FileSnapshot#save(long) and FileSnapshot#save(Instant)
Use the fallback timestamp resolution as already described in the
javadoc of these methods. Using zero file timestamp resolution doesn't
make sense.
Change-Id: Iaad2a0f99c3be3678e94980a0a368181b6aed38c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Persist minimal racy threshold and allow manual configuration
To enable persisting the minimal racy threshold per FileStore add a
new config option to the user global git configuration:
- Config section is "filesystem"
- Config subsection is concatenation of
- Java vendor (system property "java.vendor")
- Java version (system property "java.version")
- FileStore's name, on Windows we use the attribute volume:vsn instead
since the name is not necessarily unique.
- separated by '|'
e.g.
"AdoptOpenJDK|1.8.0_212-b03|/dev/disk1s1"
The same prefix is used as for filesystem timestamp resolution, so
both values are stored in the same config section
- The config key for minmal racy threshold is "minRacyThreshold" as a
time value, supported time units are those supported by
DefaultTypedConfigGetter#getTimeUnit
- measure for 3 seconds to limit runtime which depends on hardware, OS
and Java version being used
If the minimal racy threshold is configured for a given FileStore the
configured value is used instead of measuring it.
When the minimal racy threshold was measured it is persisted in the user
global git configuration.
Rename FileStoreAttributeCache to FileStoreAttributes since this class
is now declared public in order to enable exposing all attributes in one
object.
Example:
[filesystem "AdoptOpenJDK|11.0.3|/dev/disk1s1"]
timestampResolution = 7000 nanoseconds
minRacyThreshold = 3440 microseconds
Change-Id: I22195e488453aae8d011b0a8e3276fe3d99deaea
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Also-By: Marc Strapetz <marc.strapetz@syntevo.com>
Measure minimum racy interval to auto-configure FileSnapshot
By running FileSnapshotTest#detectFileModified we found that the sum of
measured filesystem timestamp resolution and measured clock resolution
may yield a too small interval after a file has been modified which we
need to consider racily clean. In our tests we didn't find this behavior
on all systems we tested on, e.g. on MacOS using APFS and Java 8 and 11
this effect was not observed.
On Linux (SLES 15, kernel 4.12.14-150.22-default) we collected the
following test results using Java 8 and 11:
In 23-98% of 10000 test runs (depending on filesystem type and Java
version) the test failed, which means the effective interval which needs
to be considered racily clean after a file was modified is larger than
the measured file timestamp resolution.
"delta" is the observed interval after a file has been modified but
FileSnapshot did not yet detect the modification:
"resolution" is the measured sum of file timestamp resolution and clock
resolution seen in Java.
Java version filesystem failures resolution min delta max delta
1.8.0_212-b04 btrfs 98.6% 1 ms 3.6 ms 6.6 ms
1.8.0_212-b04 ext4 82.6% 3 ms 1.1 ms 4.1 ms
1.8.0_212-b04 xfs 23.8% 4 ms 3.7 ms 3.9 ms
1.8.0_212-b04 zfs 23.1% 3 ms 4.8 ms 5.0 ms
11.0.3+7 btrfs 98.1% 3 us 0.7 ms 4.7 ms
11.0.3+7 ext4 98.1% 6 us 0.7 ms 4.7 ms
11.0.3+7 xfs 98.5% 7 us 0.1 ms 8.0 ms
11.0.3+7 zfs 98.4% 7 us 0.7 ms 5.2 ms
Mac OS
1.8.0_212 APFS 0% 1 s
11.0.3+7 APFS 0% 6 us
The observed delta is not distributed according to a normal gaussian
distribution but rather random in the observed range between "min delta"
and "max delta".
Run this test after measuring file timestamp resolution in
FS.FileAttributeCache to auto-configure JGit since it's unclear what
mechanism is causing this effect.
In FileSnapshot#isRacyClean use the maximum of the measured timestamp
resolution and the measured "delta" as explained above to decide if a
given FileSnapshot is to be considered racily clean. Add a 30% safety
margin to ensure we are on the safe side.
Change-Id: I1c8bb59f6486f174b7bbdc63072777ddbe06694d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
These are useful to avoid typos, and also for tab completion.
Change-Id: I0f2d267e46b36bc40297c9657c447f3fd8b9f831
Signed-off-by: David Turner <dturner@twosigma.com>
Repeat the test 10000 times to get statistics if measured
fsTimestampResolution is working in practice to detect racy git
situations.
Add a class to compute statistics for this test. Log delta between
lastModified and time when FileSnapshot failed to detect modification.
This happens if the racy git limit determined by measuring filesystem
timestamp resolution and clock resolution is too small. If it would be
correct FileSnapshot would always detect modification or mark it
modified if time since modification is smaller than the racy git limit.
Change-Id: Iabe7af1a7211ca58480f8902d4fa4e366932fc77
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
We should not use configuration when creating FileSnapshot when
accessing FileBasedConfig.
Change-Id: Ic521632870f18bb004751642b9d30648dd94049a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Use Instant instead of milliseconds for filesystem timestamp handling
This enables higher file timestamp resolution on filesystems like ext4,
Mac APFS (1ns) or NTFS (100ns) providing high timestamp resolution on
filesystem level.
Note:
- on some OSes Java 8,9 truncate milliseconds, see
https://bugs.openjdk.java.net/browse/JDK-8177809, fixed in Java 10
- UnixFileAttributes truncates timestamp resolution to microseconds when
converting the internal representation to FileTime exposed in the API,
see https://bugs.openjdk.java.net/browse/JDK-8181493
- WindowsFileAttributes also provides only microsecond resolution
Change-Id: I25ffff31a3c6f725fc345d4ddc2f26da3b88f6f2
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Checking lastModified is time critical hence debug trace is the only way
to analyze issues since debugging is impractical.
Also add configuration for buffering of log4j output to reduce runtime
impact when debug trace is on. Limit buffer to 1MiB and comment this
configuration out since we may not always want to use buffering.
Change-Id: Ib1a0537b67c8dc3fac994a77b42badd974ce6c97
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Persist filesystem timestamp resolution and allow manual configuration
To enable persisting filesystem timestamp resolution per FileStore add a
new config section to the user global git configuration:
- Config section is "filesystem"
- Config subsection is concatenation of
- Java vendor (system property "java.vm.vendor")
- runtime version (system property "java.vm.version")
- FileStore's name
- separated by '|'
e.g.
"AdoptOpenJDK|1.8.0_212-b03|/dev/disk1s1"
The prefix is needed since some Java versions do not expose the full
timestamp resolution of the underlying filesystem. This may also
depend on the underlying operating system hence concrete key values
may not be portable.
- Config key for timestamp resolution is "timestampResolution" as a time
value, supported time units are those supported by
DefaultTypedConfigGetter#getTimeUnit
If timestamp resolution is already configured for a given FileStore
the configured value is used instead of measuring the resolution.
When timestamp resolution was measured it is persisted in the user
global git configuration.
Example:
[filesystem "AdoptOpenJDK|1.8.0_212-b03|/dev/disk1s1"]
timestampResolution = 1 seconds
If locking the git config file fails retry saving the resolution up to 5
times in order to workaround races with another thread.
In order to avoid stack overflow use the fallback filesystem timestamp
resolution when loading FileBasedConfig which creates itself a
FileSnapshot to help checking if the config changed.
Note:
- on some OSes Java 8,9 truncate to milliseconds or seconds, see
https://bugs.openjdk.java.net/browse/JDK-8177809, fixed in Java 10
- UnixFileAttributes up to Java 12 truncates timestamp resolution to
microseconds when converting the internal representation to FileTime
exposed in the API, see https://bugs.openjdk.java.net/browse/JDK-8181493
- WindowsFileAttributes also provides only microsecond resolution up to
Java 12
Hence do not attempt to manually configure a higher timestamp resolution
than supported by the Java version being used at runtime.
Bug: 546891
Bug: 548188
Change-Id: Iff91b8f9e6e5e2295e1463f87c8e95edf4abbcf8
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Add a unittest.
In commit I5485db55 ("Fix FileSnapshot's consideration of file size"),
the special casing of UNKNOWN_SIZE was forgotten.
This change, together with I493f3b57b ("Measure file timestamp
resolution used in FileSnapshot") introduced a regression that would
occasionally surface in Gerrit integration tests marked UseLocalDisk,
with the symptom that creating the Admin user in NoteDb failed with a
LOCK_FAILURE.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Change-Id: I7ffd972581f815c144f810481103c7985af5feb0
As reported by Error Prone:
An inner class should be static unless it references members of its
enclosing class. An inner class that is made non-static unnecessarily
uses more memory and does not make the intent of the class clear.
See https://errorprone.info/bugpattern/ClassCanBeStatic
Change-Id: Ib99d120532630dba63cf400cc1c61c318286fc41
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
(cherry picked from commit ee40efcea4)
Error Prone: Increase severity of NonOverridingEquals to ERROR
Error Prone reports the warning on several classes:
[NonOverridingEquals] equals method doesn't override Object.equals;
if this is a type-specific helper for a method that does override
Object.equals, either inline it into the callers or rename it to
avoid ambiguity.
See https://errorprone.info/bugpattern/NonOverridingEquals
Most of these are in the public API, so we can't rename or inline them
without breaking the API. FileSnapshot is not part of the public API,
but clients may be using it anyway, so we also shouldn't change that.
Suppress all the warnings instead. Having the check at severity ERROR
will at least make sure we don't introduce any new occurrences.
Change-Id: I92345c11256f06b4fa03ccc13337f72af5a43591
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Reference comparison with EMPTY and MISSING_FILE is intended; these
are static instances used as markers, and will always be the same
instances.
Change-Id: Ic27f5b797bdb9370cf8f6b3b7bb3f1523d4a454c
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Yunjie Li
Han-Wen Nienhuys
David Pursehouse
Lars Vogel
Matthias Sohn
Michael Keppler
Thomas Wolf
Jonathan Tan
David Turner