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Replace whole cache entries atomically #296
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This will help refactoring to write first to a temporary folder and replace.
This guarantees that the whole cache entry is replaced atomically. This precents cache corruption when the clcache process is terminated in the middle of a write.
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Hmm, good stuff - I can't think of much when reviewing this code. I suppose it's hard to write a test for this, so I'll merge. Thanks! |
siu
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Oct 16, 2017
The signal handlers were introduced to avoid cache corruption when the clcache process is stopped in the middle of a write to the cache (statistics, manifests or objects). See frerich#233. Even if SIGINT and SIGTERM were ignored the cache still had a chance to be corrupted in the event of a SIGTERM (which cannot be ignored). Since frerich#233 the writing of files to the cache has been improved to replace the files atomically, reducing the risk of storing corrupted files in the cache. See pull requests frerich#286, frerich#292 and frerich#296. Therefore ignoring these signals is not needed anymore.
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siu
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Oct 30, 2017
The signal handlers were introduced to avoid cache corruption when the clcache process is stopped in the middle of a write to the cache (statistics, manifests or objects). See frerich#233. Even if SIGINT and SIGTERM were ignored the cache still had a chance to be corrupted in the event of a SIGTERM (which cannot be ignored). Since frerich#233 the writing of files to the cache has been improved to replace the files atomically, reducing the risk of storing corrupted files in the cache. See pull requests frerich#286, frerich#292 and frerich#296. Therefore ignoring these signals is not needed anymore.
siu
pushed a commit
to siu/clcache
that referenced
this pull request
Oct 30, 2017
The signal handlers were introduced to avoid cache corruption when the clcache process is stopped in the middle of a write to the cache (statistics, manifests or objects). See frerich#233. Even if SIGINT and SIGTERM were ignored the cache still had a chance to be corrupted in the event of a SIGTERM (which cannot be ignored). Since frerich#233 the writing of files to the cache has been improved to replace the files atomically, reducing the risk of storing corrupted files in the cache. See pull requests frerich#286, frerich#292 and frerich#296. Therefore ignoring these signals is not needed anymore.
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This is a follow-up of #286. This time the cache entry directory is replaced atomically.
With these changes all the files written by clcache are replaced atomically on disk, preventing cache corruption when the clcache process is terminated in the middle of a write.