Sanjay Ghemawat ac1d69da31 LevelDB now attempts to reuse the preceding MANIFEST and log file when re-opened. ... (Based on a suggestion by cmumford.) "open" benchmark on my workstation speeds up significantly since we can now avoid three fdatasync calls and a compaction per open: Before: ~80000 microseconds After: ~130 microseconds Details: (1) Added Options::reuse_logs (currently defaults to false) to control new behavior. The intention is to change the default to true after some baking. (2) Added Env::NewAppendableFile() whose default implementation returns a not-supported error. (3) VersionSet::Recovery attempts to reuse the MANIFEST from which it is recovering. (4) DBImpl recovery attempts to reuse the last log file and memtable. (5) db_test.cc now tests a new configuration that sets reuse_logs to true. (6) fault_injection_test also tests a reuse_logs==true config. (7) Added a new recovery_test.		2015-08-11 14:56:39 -07:00
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memenv	LevelDB now attempts to reuse the preceding MANIFEST and log file when re-opened.	2015-08-11 14:56:39 -07:00