Direct I/O Close() shouldn't rewrite the last block (#4771) #200
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Summary: In Direct I/O case, WritableFileWriter::Close() rewrites the last block again, even if there is nothing new. The reason is that, Close() flushes the buffer. For non-direct I/O case, the buffer is empty in this case so it is a no-op. However, in direct I/O case, the partial data in the last block is kept in the buffer because it needs to be rewritten for the next write. This piece of data is flushed again. This commit fixes it by skipping this write out if `pending_sync_` flag shows that there isn't new data sync last sync. Pull Request resolved: facebook/rocksdb#4771 Differential Revision: D13420426 Pulled By: siying fbshipit-source-id: 9d39ec9a215b1425d4ed40d85e0eba1f5daa75c6
yapple
approved these changes
Jan 5, 2022
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Summary:
In Direct I/O case, WritableFileWriter::Close() rewrites the last block again, even if there is nothing new. The reason is that, Close() flushes the buffer. For non-direct I/O case, the buffer is empty in this case so it is a no-op. However, in direct I/O case, the partial data in the last block is kept in the buffer because it needs to be rewritten for the next write. This piece of data is flushed again. This commit fixes it by skipping this write out if
pending_sync_flag shows that there isn't new data sync last sync.Pull Request resolved: facebook/rocksdb#4771
Differential Revision: D13420426
Pulled By: siying
fbshipit-source-id: 9d39ec9a215b1425d4ed40d85e0eba1f5daa75c6