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>
FS determines FileStore attributes in a background thread and tries to
save the results to the global git configuration. This competed with
LocalDiskRepositoryTestCase#setup trying to save changes to the same
file requiring the same lock. This frequently led to one of the threads
failing to acquire the lock.
Fix this by first initiating determination of FileStore attributes which
then uses a MockSystemReader not using a userConfig stored to disk which
avoids this race for the lock.
Change-Id: I30fcd96bc15100f8ef9b2a9eb3320bb5ace97c67
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
FS#getFileStoreAttributes used the real userConfig and not the mocked
one. This led to test errors when running tests with Bazel since it
sandboxes tests which prevents they can write to ~/.gitconfig.
Fix this by first preparing the MockedSystemReader and the mocked config
before calling FS#getFileStoreAttributes.
Also fix ConfigTest which broke due to this change since it inherits
from LocalDiskRepositoryTestCase and calls its setup method which was
changed here. We can no longer assert by comparing plain text since FS
adds FileStoreAttributes to the mocked userConfig. Also the default
options seen by this test changed since we now use a mocked config.
Change-Id: I76bc7c94953fe979266147d3b309a68dda9d4dfe
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
This ensures we don't try to persist MockConfig using its superclasses
save() method which fails with an NPE since MockConfig has no backing
file.
Change-Id: Ifba2d24c9438bb30d3828ed31a4c131f940b45eb
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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>
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>
Replace redundant complex implementation of recursive delete by the one
in FileUtils.
Change-Id: Iced1468b96c4f32381a9cf0c651b2bf6a9a9af35
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Use the same JDT core settings as used in org.eclipse.jgit but ignore
non-externalized strings.
Change-Id: If30013c76a197e571601a8abc882ac6a99592374
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
In order to enable counting how frequently a test fails if repeated add
option abortOnFailure. If it is true the test aborts on the first
failure. Otherwise it runs the configured number of repetitions and, if
there was any failure, throws a RepeatException reporting how many of
the test repetitions failed.
Change-Id: Ic47de44d4a6273fddf04b9993ad989903efb40c3
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
This helps to avoid some time critical tests can't prepare the test
fixture intended since measuring timestamp resolution takes time.
Change-Id: Ib34023e682a106070ca97e98ef16789a4dfb97b4
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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>
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)
RepositoryTestCase.fsTick() was was waiting 64, 128, 256, ... milliseconds
until it detected that the filesystem timer has ticked. Make use of
the filesystemtimer resolution information in FS to sleep a fraction
of the filesystem timer resolution. That raises probability to wake up
shortly after the filesystem timer has ticked.
Change-Id: Ibcc38576e42ece13b2fd4423a29c459eed167a69
FileSnapshot.notRacyClean() assumed a worst case filesystem timestamp
resolution of 2.5 sec (FAT has a resolution of 2 sec). Instead measure
timestamp resolution to avoid unnecessary IO caused by false positives
in detecting the racy git problem caused by finite filesystem timestamp
resolution [1].
Cache the measured resolution per FileStore since timestamp resolution
depends on the respective filesystem type. If timestamp resolution
cannot be measured or fails due to an exception fallback to the worst
case FAT timestamp resolution and avoid caching this value.
Add a 10% safety margin in FileSnapshot.notRacyClean(), though running
FsTest.testFsTimestampResolution() 1000 times which is not using a
safety margin didn't fail on Mac using APFS and Java 8, 11, 12.
Measured Java file timestamp resolution: [2]
[1] https://github.com/git/git/blob/master/Documentation/technical/racy-git.txt
[2] https://docs.google.com/spreadsheets/d/1imy0y6WmRqBf0kjCxzxj2X7M50eIVfa7oaUIzEOHmjo
Bug: 546891
Change-Id: I493f3b57b6b306285ffa7d392339d253e5966ab8
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
David Pursehouse
Matthias Sohn
Christian Halstrick