854a4be03f
Summary: There is a bug when the write queue leader is blocked on a write delay/stop, and the queue has writers with WriteOptions::no_slowdown set to true. They are not woken up until the write stall is cleared. The fix introduces a dummy writer inserted at the tail to indicate a write stall and prevent further inserts into the queue, and a condition variable that writers who can tolerate slowdown wait on before adding themselves to the queue. The leader calls WriteThread::BeginWriteStall() to add the dummy writer and then walk the queue to fail any writers with no_slowdown set. Once the stall clears, the leader calls WriteThread::EndWriteStall() to remove the dummy writer and signal the condition variable. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4475 Differential Revision: D10285827 Pulled By: anand1976 fbshipit-source-id: 747465e5e7f07a829b1fb0bc1afcd7b93f4ab1a9
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/
License
RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.