//  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

#include "monitoring/statistics_impl.h"

#include "port/port.h"

#include "rocksdb/statistics.h"

#include "rocksdb/system_clock.h"

#include "rocksdb/thread_status.h"

#include "util/stop_watch.h"

namespace ROCKSDB_NAMESPACE {

class InstrumentedCondVar;

// A wrapper class for port::Mutex that provides additional layer

// for collecting stats and instrumentation.

class InstrumentedMutex {

 public:

  explicit InstrumentedMutex(bool adaptive = false)

      : mutex_(adaptive), stats_(nullptr), clock_(nullptr), stats_code_(0) {}

  explicit InstrumentedMutex(SystemClock* clock, bool adaptive = false)

      : mutex_(adaptive), stats_(nullptr), clock_(clock), stats_code_(0) {}

  InstrumentedMutex(Statistics* stats, SystemClock* clock, int stats_code,

                    bool adaptive = false)

      : mutex_(adaptive),

        stats_(stats),

        clock_(clock),

        stats_code_(stats_code) {}

#ifdef COERCE_CONTEXT_SWITCH

  InstrumentedMutex(Statistics* stats, SystemClock* clock, int stats_code,

                    InstrumentedCondVar* bg_cv, bool adaptive = false)

      : mutex_(adaptive),

        stats_(stats),

        clock_(clock),

        stats_code_(stats_code),

        bg_cv_(bg_cv) {}

#endif

  void Lock();

  void Unlock() { mutex_.Unlock(); }

  void AssertHeld() const { mutex_.AssertHeld(); }

 private:

  void LockInternal();

  friend class InstrumentedCondVar;

  port::Mutex mutex_;

  Statistics* stats_;

  SystemClock* clock_;

  int stats_code_;

#ifdef COERCE_CONTEXT_SWITCH

  InstrumentedCondVar* bg_cv_ = nullptr;

#endif

};

class ALIGN_AS(CACHE_LINE_SIZE) CacheAlignedInstrumentedMutex

    : public InstrumentedMutex {

  using InstrumentedMutex::InstrumentedMutex;

};

static_assert(alignof(CacheAlignedInstrumentedMutex) != CACHE_LINE_SIZE ||

              sizeof(CacheAlignedInstrumentedMutex) % CACHE_LINE_SIZE == 0);

// RAII wrapper for InstrumentedMutex

class InstrumentedMutexLock {

 public:

  explicit InstrumentedMutexLock(InstrumentedMutex* mutex) : mutex_(mutex) {

    mutex_->Lock();

  }

  ~InstrumentedMutexLock() { mutex_->Unlock(); }

 private:

  InstrumentedMutex* const mutex_;

  InstrumentedMutexLock(const InstrumentedMutexLock&) = delete;

  void operator=(const InstrumentedMutexLock&) = delete;

};

// RAII wrapper for temporary releasing InstrumentedMutex inside

// InstrumentedMutexLock

class InstrumentedMutexUnlock {

 public:

  explicit InstrumentedMutexUnlock(InstrumentedMutex* mutex) : mutex_(mutex) {

    mutex_->Unlock();

  }

  ~InstrumentedMutexUnlock() { mutex_->Lock(); }

 private:

  InstrumentedMutex* const mutex_;

  InstrumentedMutexUnlock(const InstrumentedMutexUnlock&) = delete;

  void operator=(const InstrumentedMutexUnlock&) = delete;

};

class InstrumentedCondVar {

 public:

  explicit InstrumentedCondVar(InstrumentedMutex* instrumented_mutex)

      : cond_(&(instrumented_mutex->mutex_)),

        stats_(instrumented_mutex->stats_),

        clock_(instrumented_mutex->clock_),

        stats_code_(instrumented_mutex->stats_code_) {}

  void Wait();

  bool TimedWait(uint64_t abs_time_us);

  void Signal() { cond_.Signal(); }

  void SignalAll() { cond_.SignalAll(); }

 private:

  void WaitInternal();

  bool TimedWaitInternal(uint64_t abs_time_us);

  port::CondVar cond_;

  Statistics* stats_;

  SystemClock* clock_;

  int stats_code_;

};

}  // namespace ROCKSDB_NAMESPACE