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>
* fix equals() and hashCode() methods to consider size
* fix toString() to show size
Change-Id: I5485db55eda5110121efd65d86c7166b3b2e93d0
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Keep track of the original cause for a packfile invalidation.
It is needed for the sysadmin to understand if there is a real
underlying filesystem problem and repository corruption or if it is
simply a consequence of a concurrency of Git operations (e.g. repack
or GC).
Change-Id: I06ddda9ec847844ec31616ab6d17f153a5a34e33
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Do not reload packfiles when their associated filesnapshot is not
modified on disk compared to the one currently stored in memory.
Fix the regression introduced by fef78212 which, in conjunction with
core.trustfolderstats = false, caused any lookup of objects inside
the packlist to loop forever when the object was not found in the pack
list.
Bug: 546190
Change-Id: I38d752ebe47cefc3299740aeba319a2641f19391
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
The prune method did not delete empty fanout directories when loose
objects moved to a new pack file but only when loose unreferenced
objects were pruned.
Change-Id: Ia068f4914c54d9cf9f40b75e8ea50759402b5000
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
When reading from a packfile, make sure that is valid
and has a non-null file-descriptor.
Because of concurrency between a thread invalidating a packfile
and another trying to read it, the read() may result into a NPE
that won't be able to be automatically recovered.
Throwing a PackInvalidException would instead cause the packlist
to be refreshed and the read to eventually succeed.
Bug: 544199
Change-Id: I27788b3db759d93ec3212de35c0094ecaafc2434
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
When a packfile is invalid, throw an exception explicitly
outside any catch scope, so that is not accidentally caught
by the generic catch-all cause, which would set the packfile
as valid again.
Flagging an invalid packfile as valid again would have
dangerous consequences such as the corruption of the in-memory
packlist.
Bug: 544199
Change-Id: If7a3188a68d7985776b509d636d5ddf432bec798
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Do not redundantly call File.lastModified() for extracting the
timestamp of the PackFile but rather use consistently the FileSnapshot
which reads all file attributes in a single bulk call.
Change-Id: I932675ae4fe56dcd3833dac249816f097303bb09
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Due to finite filesystem timestamp resolution the last modified
timestamp of files cannot detect file changes which happened in the
immediate past (less than one filesystem timer tick ago).
Read and consider file size also, so that differing file size can help
to more accurately detect file changes without reading the file content.
Use bulk read to avoid multiple stat calls to retrieve file attributes.
Change-Id: I974288fff78ac78c52245d9218b5639603f67a46
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
The pack reload mechanism from the filesystem works only by name
and does not check the actual last modified date of the packfile.
This lead to concurrency issues where multiple threads were loading
and removing from each other list of packfiles when one of those
was failing the checksum.
Rely on FileSnapshot rather than directly checking lastModified
timestamp so that more checks can be performed.
Bug: 544199
Change-Id: I173328f29d9914007fd5eae3b4c07296ab292390
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
In case of concurrent pack file access, threads may wait on the idx()
function even for already open files. This happens especially with a
slow file system.
Performance numbers are listed in the bug report.
Bug: 543739
Change-Id: Iff328d347fa65ae07ecce3267d44184161248978
Signed-off-by: Juergen Denner <j.denner@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
When the packfile checksum does not match the expected one
report the correct checksum error instead of reporting that
the number of objects is incorrect.
Change-Id: I040f36dacc4152ae05453e7acbf8dfccceb46e0d
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
(cherry picked from commit 436c99ce59)
Externalize the message and log the pack file with absolute path.
Change-Id: I019052dfae8fd96ab67da08b3287d699287004cb
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
(cherry picked from commit 9665d86ba1)
Display extra logging, including the exception with the associated
stacktrace, whenever a packFile can't be read and thus removed
from the packlist.
Change-Id: I97a4e31dc427bfcc0baae438dcbe2dcd4704b824
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
(cherry picked from commit 962babc4b2)
When the packfile checksum does not match the expected one
report the correct checksum error instead of reporting that
the number of objects is incorrect.
Change-Id: I040f36dacc4152ae05453e7acbf8dfccceb46e0d
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Externalize the message and log the pack file with absolute path.
Change-Id: I019052dfae8fd96ab67da08b3287d699287004cb
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Display extra logging, including the exception with the associated
stacktrace, whenever a packFile can't be read and thus removed
from the packlist.
Change-Id: I97a4e31dc427bfcc0baae438dcbe2dcd4704b824
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
The AdvertiseRefsHook can be called twice if the following conditions
hold:
1. This AdvertiseRefsHook doesn't set this.refs.
2. getAdvertisedOrDefaultRefs is called after getFilteredRefs.
For example, this can happen when fetchV2 is called after lsRefsV2
when using a stateful bidirectional transport.
The second call does not accomplish anything useful. Guard it with
'if (!advertiseRefsHookCalled)' to avoid wasted work.
Reported-by: Jonathan Tan <jonathantanmy@google.com>
Change-Id: Ib746582e4ef645b767a5b3fb969596df99ac2ab5
Signed-off-by: Jonathan Nieder <jrn@google.com>
Matthias Sohn
Luca Milanesio
Juergen Denner
David Pursehouse
Jonathan Nieder