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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>stable-5.1
Matthias Sohn
6 years ago
6 changed files with 192 additions and 14 deletions
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