ceph/src/rocksdb/db/periodic_work_scheduler.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7
   8 #ifndef ROCKSDB_LITE
   9
  10 #include "db/db_impl/db_impl.h"
  11 #include "util/timer.h"
  12
  13 namespace ROCKSDB_NAMESPACE {
  14
  15 // PeriodicWorkScheduler is a singleton object, which is scheduling/running
  16 // DumpStats(), PersistStats(), and FlushInfoLog() for all DB instances. All DB
  17 // instances use the same object from `Default()`.
  18 //
  19 // Internally, it uses a single threaded timer object to run the periodic work
  20 // functions. Timer thread will always be started since the info log flushing
  21 // cannot be disabled.
  22 class PeriodicWorkScheduler {
  23  public:
  24   static PeriodicWorkScheduler* Default();
  25
  26   PeriodicWorkScheduler() = delete;
  27   PeriodicWorkScheduler(const PeriodicWorkScheduler&) = delete;
  28   PeriodicWorkScheduler(PeriodicWorkScheduler&&) = delete;
  29   PeriodicWorkScheduler& operator=(const PeriodicWorkScheduler&) = delete;
  30   PeriodicWorkScheduler& operator=(PeriodicWorkScheduler&&) = delete;
  31
  32   void Register(DBImpl* dbi, unsigned int stats_dump_period_sec,
  33                 unsigned int stats_persist_period_sec);
  34
  35   void Unregister(DBImpl* dbi);
  36
  37   // Periodically flush info log out of application buffer at a low frequency.
  38   // This improves debuggability in case of RocksDB hanging since it ensures the
  39   // log messages leading up to the hang will eventually become visible in the
  40   // log.
  41   static const uint64_t kDefaultFlushInfoLogPeriodSec = 10;
  42
  43  protected:
  44   std::unique_ptr<Timer> timer;
  45   // `timer_mu_` serves two purposes currently:
  46   // (1) to ensure calls to `Start()` and `Shutdown()` are serialized, as
  47   //     they are currently not implemented in a thread-safe way; and
  48   // (2) to ensure the `Timer::Add()`s and `Timer::Start()` run atomically, and
  49   //     the `Timer::Cancel()`s and `Timer::Shutdown()` run atomically.
  50   port::Mutex timer_mu_;
  51
  52   explicit PeriodicWorkScheduler(Env* env);
  53
  54  private:
  55   std::string GetTaskName(DBImpl* dbi, const std::string& func_name);
  56 };
  57
  58 #ifndef NDEBUG
  59 // PeriodicWorkTestScheduler is for unittest, which can specify the Env like
  60 // SafeMockTimeEnv. It also contains functions for unittest.
  61 class PeriodicWorkTestScheduler : public PeriodicWorkScheduler {
  62  public:
  63   static PeriodicWorkTestScheduler* Default(Env* env);
  64
  65   void TEST_WaitForRun(std::function<void()> callback) const;
  66
  67   size_t TEST_GetValidTaskNum() const;
  68
  69  private:
  70   explicit PeriodicWorkTestScheduler(Env* env);
  71 };
  72 #endif  // !NDEBUG
  73
  74 }  // namespace ROCKSDB_NAMESPACE
  75
  76 #endif  // ROCKSDB_LITE