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rocksdb/db/periodic_work_scheduler.h

93 lines
3.3 KiB

// 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).
#pragma once
#ifndef ROCKSDB_LITE
#include "db/db_impl/db_impl.h"
#include "util/timer.h"
namespace ROCKSDB_NAMESPACE {
class SystemClock;
// PeriodicWorkScheduler is a singleton object, which is scheduling/running
// DumpStats(), PersistStats(), and FlushInfoLog() for all DB instances. All DB
// instances use the same object from `Default()`.
//
// Internally, it uses a single threaded timer object to run the periodic work
// functions. Timer thread will always be started since the info log flushing
// cannot be disabled.
class PeriodicWorkScheduler {
public:
static PeriodicWorkScheduler* Default();
PeriodicWorkScheduler() = delete;
PeriodicWorkScheduler(const PeriodicWorkScheduler&) = delete;
PeriodicWorkScheduler(PeriodicWorkScheduler&&) = delete;
PeriodicWorkScheduler& operator=(const PeriodicWorkScheduler&) = delete;
PeriodicWorkScheduler& operator=(PeriodicWorkScheduler&&) = delete;
Status Register(DBImpl* dbi, unsigned int stats_dump_period_sec,
unsigned int stats_persist_period_sec);
Status RegisterRecordSeqnoTimeWorker(DBImpl* dbi, uint64_t record_cadence);
void Unregister(DBImpl* dbi);
void UnregisterRecordSeqnoTimeWorker(DBImpl* dbi);
// Periodically flush info log out of application buffer at a low frequency.
// This improves debuggability in case of RocksDB hanging since it ensures the
// log messages leading up to the hang will eventually become visible in the
// log.
static const uint64_t kDefaultFlushInfoLogPeriodSec = 10;
protected:
std::unique_ptr<Timer> timer;
// `timer_mu_` serves two purposes currently:
// (1) to ensure calls to `Start()` and `Shutdown()` are serialized, as
// they are currently not implemented in a thread-safe way; and
// (2) to ensure the `Timer::Add()`s and `Timer::Start()` run atomically, and
// the `Timer::Cancel()`s and `Timer::Shutdown()` run atomically.
port::Mutex timer_mu_;
explicit PeriodicWorkScheduler(const std::shared_ptr<SystemClock>& clock);
// Get the unique task name (prefix with db session id)
std::string GetTaskName(const DBImpl* dbi,
const std::string& func_name) const;
private:
uint64_t record_seqno_time_cadence_ = 0;
};
#ifndef NDEBUG
// PeriodicWorkTestScheduler is for unittest, which can specify the SystemClock
// It also contains functions for unittest.
class PeriodicWorkTestScheduler : public PeriodicWorkScheduler {
public:
static PeriodicWorkTestScheduler* Default(
const std::shared_ptr<SystemClock>& clock);
void TEST_WaitForRun(std::function<void()> callback) const;
size_t TEST_GetValidTaskNum() const;
bool TEST_HasValidTask(const DBImpl* dbi, const std::string& func_name) const;
private:
explicit PeriodicWorkTestScheduler(const std::shared_ptr<SystemClock>& clock);
};
#endif // !NDEBUG
struct PeriodicWorkTaskNames {
static const std::string kDumpStats;
static const std::string kPersistStats;
static const std::string kFlushInfoLog;
static const std::string kRecordSeqnoTime;
};
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE