Prevent race in SingleDirectoryDbLedgerStorage metrics collection #4307
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How do you guarantee they won't swap during L214-L217? It seems problem is not solved. |
dlg99
requested changes
May 30, 2024
Comment on lines
+214
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+218
| final AtomicLong finalWriteCacheSize = writeCache.cacheSize; | ||
| final AtomicLong finalWriteCacheBeingFlushedSize = writeCacheBeingFlushed.cacheSize; | ||
| final LongAdder finalWriteCacheCounter = writeCache.cacheCount; | ||
| final LongAdder finalWriteCacheBeingFlushedCounter = writeCacheBeingFlushed.cacheCount; | ||
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I don't think this is right.
Lambdas in the DbLedgerStorageStats() constructor used to provide a way to access to metrics of current writeCache/.. instance.
With this change it will provide metrics for the first used instance, one before the very first swap, so the stats will stop changing after the cache swaps couple of times.
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Motivation
We swap the
writeCacheand thewriteCacheBeingFlushedon flush. Therefore, it is not safe to call each to get the size/count metrics. Instead, if we expose the underlying accumulators, we can safely get the stats.Changes
Expose the
AtomicLongand theLongAdderobjects in theWriteCachefor safer metrics reporting.