2d9efc9ab2
Summary: In Linux, when reopening DB with many SST files, profiling shows that 100% system cpu time spent for a couple of seconds for `GetLogicalBufferSize`. This slows down MyRocks' recovery time when site is down. This PR introduces two new APIs: 1. `Env::RegisterDbPaths` and `Env::UnregisterDbPaths` lets `DB` tell the env when it starts or stops using its database directories . The `PosixFileSystem` takes this opportunity to set up a cache from database directories to the corresponding logical block sizes. 2. `LogicalBlockSizeCache` is defined only for OS_LINUX to cache the logical block sizes. Other modifications: 1. rename `logical buffer size` to `logical block size` to be consistent with Linux terms. 2. declare `GetLogicalBlockSize` in `PosixHelper` to expose it to `PosixFileSystem`. 3. change the functions `IOError` and `IOStatus` in `env/io_posix.h` to have external linkage since they are used in other translation units too. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6457 Test Plan: 1. A new unit test is added for `LogicalBlockSizeCache` in `env/io_posix_test.cc`. 2. A new integration test is added for `DB` operations related to the cache in `db/db_logical_block_size_cache_test.cc`. `make check` Differential Revision: D20131243 Pulled By: cheng-chang fbshipit-source-id: 3077c50f8065c0bffb544d8f49fb10bba9408d04
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 especially 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.