// Copyright (c) 2006- Facebook
// Distributed under the Thrift Software License
//
// See accompanying file LICENSE or visit the Thrift site at:
// http://developers.facebook.com/thrift/

#include "Monitor.h"
#include "Exception.h"
#include "Util.h"

#include <assert.h>
#include <errno.h>

#include <iostream>

#include <pthread.h>

namespace facebook { namespace thrift { namespace concurrency {

/**
 * Monitor implementation using the POSIX pthread library
 *
 * @author marc
 * @version $Id:$
 */
class Monitor::Impl {

 public:

  Impl() :
    mutexInitialized_(false),
    condInitialized_(false) {

    if (pthread_mutex_init(&pthread_mutex_, NULL) == 0) {
      mutexInitialized_ = true;

      if (pthread_cond_init(&pthread_cond_, NULL) == 0) {
        condInitialized_ = true;
      }
    }

    if (!mutexInitialized_ || !condInitialized_) {
      cleanup();
      throw SystemResourceException();
    }
  }

  ~Impl() { cleanup(); }

  void lock() const { pthread_mutex_lock(&pthread_mutex_); }

  void unlock() const { pthread_mutex_unlock(&pthread_mutex_); }

  void wait(int64_t timeout) const {

    // XXX Need to assert that caller owns mutex
    assert(timeout >= 0LL);
    if (timeout == 0LL) {
      int iret = pthread_cond_wait(&pthread_cond_, &pthread_mutex_);
      assert(iret == 0);
    } else {
      struct timespec abstime;
      int64_t now = Util::currentTime();
      Util::toTimespec(abstime, now + timeout);
      int result = pthread_cond_timedwait(&pthread_cond_,
                                          &pthread_mutex_,
                                          &abstime);
      if (result == ETIMEDOUT) {
        // pthread_cond_timedwait has been observed to return early on
        // various platforms, so comment out this assert.
        //assert(Util::currentTime() >= (now + timeout));
        throw TimedOutException();
      }
    }
  }

  void notify() {
    // XXX Need to assert that caller owns mutex
    int iret = pthread_cond_signal(&pthread_cond_);
    assert(iret == 0);
  }

  void notifyAll() {
    // XXX Need to assert that caller owns mutex
    int iret = pthread_cond_broadcast(&pthread_cond_);
    assert(iret == 0);
  }

 private:

  void cleanup() {
    if (mutexInitialized_) {
      mutexInitialized_ = false;
      int iret = pthread_mutex_destroy(&pthread_mutex_);
      assert(iret == 0);
    }

    if (condInitialized_) {
      condInitialized_ = false;
      int iret = pthread_cond_destroy(&pthread_cond_);
      assert(iret == 0);
    }
  }

  mutable pthread_mutex_t pthread_mutex_;
  mutable bool mutexInitialized_;
  mutable pthread_cond_t pthread_cond_;
  mutable bool condInitialized_;
};

Monitor::Monitor() : impl_(new Monitor::Impl()) {}

Monitor::~Monitor() { delete impl_; }

void Monitor::lock() const { impl_->lock(); }

void Monitor::unlock() const { impl_->unlock(); }

void Monitor::wait(int64_t timeout) const { impl_->wait(timeout); }

void Monitor::notify() const { impl_->notify(); }

void Monitor::notifyAll() const { impl_->notifyAll(); }

}}} // facebook::thrift::concurrency