b2ce59537c
Summary: Move the manual memtable flush for databases containing data that has bypassed the WAL from DBImpl's destructor to CancleAllBackgroundWork(). CancelAllBackgroundWork() is a publicly exposed API which allows async operations performed by background threads to be disabled on a database. In effect, this places the database into a "shutdown" state in advance of calling the database object's destructor. No compactions or flushing of SST files can occur once a call to this API completes. When writes are issued to a database with WriteOptions::disableWAL set to true, DBImpl::has_unpersisted_data_ is set so that memtables can be flushed when the database object is destroyed. If CancelAllBackgroundWork() has been called prior to DBImpl's destructor, this flush operation is not possible and is skipped, causing unnecessary loss of data. Since CancelAllBackgroundWork() is already invoked by DBImpl's destructor in order to perform the thread join portion of its cleanup processing, moving the manual memtable flush to CancelAllBackgroundWork() ensures data is persisted regardless of client behavior. Test Plan: Write an amount of data that will not cause a memtable flush to a rocksdb database with all writes marked with WriteOptions::disableWAL. Properly "close" the database. Reopen database and verify that the data was persisted. Reviewers: IslamAbdelRahman, yiwu, yoshinorim, sdong Reviewed By: sdong Subscribers: andrewkr, dhruba Differential Revision: https://reviews.facebook.net/D62277
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it specially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/master/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/