/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2013 University of California, Los Angeles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *	   Zhenkai Zhu <zhenkai@cs.ucla.edu>
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#include "executor.h"

using namespace std;
using namespace boost;

Executor::Executor(int poolSize)
{
  for (int i = 0; i < poolSize; i++)
  {
    m_group.create_thread(bind(&Executor::run, this));
  }
}

Executor::~Executor()
{
  m_group.interrupt_all();
}

void
Executor::execute(const Job &job)
{
  Lock lock(m_mutex);
  bool queueWasEmpty = m_queue.empty();
  m_queue.push_back(job);

  // notify working threads if the queue was empty
  if (queueWasEmpty)
  {
    m_cond.notify_one();
  }
}

int
Executor::poolSize()
{
  return m_group.size();
}

int
Executor::jobQueueSize()
{
  Lock lock(m_mutex);
  return m_queue.size();
}

void
Executor::run()
{
  while(true)
  {
    Job job = waitForJob();

    job();
  }
}

Executor::Job
Executor::waitForJob()
{
  Lock lock(m_mutex);

  // wait until job queue is not empty
  while (m_queue.empty())
  {
    m_cond.wait(lock);
  }

  Job job = m_queue.front();
  m_queue.pop_front();
  return job;
}