/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef vm_Monitor_h
#define vm_Monitor_h

#include "mozilla/DebugOnly.h"

#include <stddef.h>

#include "js/Utility.h"

namespace js {

// A base class used for types intended to be used in a parallel
// fashion.  Combines a lock and a condition variable.  You can
// acquire the lock or signal the condition variable using the
// |AutoLockMonitor| type.

class Monitor
{
  protected:
    friend class AutoLockMonitor;
    friend class AutoUnlockMonitor;

    Mutex lock_;
    ConditionVariable condVar_;

  public:
    Monitor() { }
};

class AutoLockMonitor : public LockGuard<Mutex>
{
  private:
    using Base = LockGuard<Mutex>;
    Monitor& monitor;

  public:
    explicit AutoLockMonitor(Monitor& monitor)
      : Base(monitor.lock_)
      , monitor(monitor)
    { }

    bool isFor(Monitor& other) const {
        return monitor.lock_ == other.lock_;
    }

    void wait(ConditionVariable& condVar) {
        condVar.wait(*this);
    }

    void wait() {
        wait(monitor.condVar_);
    }

    void notify(ConditionVariable& condVar) {
        condVar.notify_one();
    }

    void notify() {
        notify(monitor.condVar_);
    }

    void notifyAll(ConditionVariable& condVar) {
        condVar.notify_all();
    }

    void notifyAll() {
        notifyAll(monitor.condVar_);
    }
};

class AutoUnlockMonitor
{
  private:
    Monitor& monitor;

  public:
    explicit AutoUnlockMonitor(Monitor& monitor)
      : monitor(monitor)
    {
        monitor.lock_.unlock();
    }

    ~AutoUnlockMonitor() {
        monitor.lock_.lock();
    }

    bool isFor(Monitor& other) const {
        return monitor.lock_ == other.lock_;
    }
};

} // namespace js

#endif /* vm_Monitor_h */
