rocksdb/env/mock_env.h
Cheng Chang 2d9efc9ab2 Cache result of GetLogicalBufferSize in Linux (#6457)
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
2020-03-11 18:40:05 -07:00

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <atomic>
#include <map>
#include <string>
#include <vector>
#include "rocksdb/env.h"
#include "rocksdb/status.h"
#include "port/port.h"
#include "util/mutexlock.h"
namespace ROCKSDB_NAMESPACE {
class MemFile;
class MockEnv : public EnvWrapper {
public:
explicit MockEnv(Env* base_env);
~MockEnv() override;
// Partial implementation of the Env interface.
Status RegisterDbPaths(const std::vector<std::string>& /*paths*/) override {
return Status::OK();
}
Status UnregisterDbPaths(const std::vector<std::string>& /*paths*/) override {
return Status::OK();
}
Status NewSequentialFile(const std::string& fname,
std::unique_ptr<SequentialFile>* result,
const EnvOptions& soptions) override;
Status NewRandomAccessFile(const std::string& fname,
std::unique_ptr<RandomAccessFile>* result,
const EnvOptions& soptions) override;
Status NewRandomRWFile(const std::string& fname,
std::unique_ptr<RandomRWFile>* result,
const EnvOptions& options) override;
Status ReuseWritableFile(const std::string& fname,
const std::string& old_fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& options) override;
Status NewWritableFile(const std::string& fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& env_options) override;
Status NewDirectory(const std::string& name,
std::unique_ptr<Directory>* result) override;
Status FileExists(const std::string& fname) override;
Status GetChildren(const std::string& dir,
std::vector<std::string>* result) override;
void DeleteFileInternal(const std::string& fname);
Status DeleteFile(const std::string& fname) override;
Status Truncate(const std::string& fname, size_t size) override;
Status CreateDir(const std::string& dirname) override;
Status CreateDirIfMissing(const std::string& dirname) override;
Status DeleteDir(const std::string& dirname) override;
Status GetFileSize(const std::string& fname, uint64_t* file_size) override;
Status GetFileModificationTime(const std::string& fname,
uint64_t* time) override;
Status RenameFile(const std::string& src, const std::string& target) override;
Status LinkFile(const std::string& src, const std::string& target) override;
Status NewLogger(const std::string& fname,
std::shared_ptr<Logger>* result) override;
Status LockFile(const std::string& fname, FileLock** flock) override;
Status UnlockFile(FileLock* flock) override;
Status GetTestDirectory(std::string* path) override;
// Results of these can be affected by FakeSleepForMicroseconds()
Status GetCurrentTime(int64_t* unix_time) override;
uint64_t NowMicros() override;
uint64_t NowNanos() override;
Status CorruptBuffer(const std::string& fname);
// Doesn't really sleep, just affects output of GetCurrentTime(), NowMicros()
// and NowNanos()
void FakeSleepForMicroseconds(int64_t micros);
private:
std::string NormalizePath(const std::string path);
// Map from filenames to MemFile objects, representing a simple file system.
typedef std::map<std::string, MemFile*> FileSystem;
port::Mutex mutex_;
FileSystem file_map_; // Protected by mutex_.
std::atomic<int64_t> fake_sleep_micros_;
};
} // namespace ROCKSDB_NAMESPACE