/*

 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "classfile/systemDictionary.hpp"

#include "gc/shared/concurrentGCThread.hpp"

#include "oops/instanceRefKlass.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/init.hpp"

#include "runtime/java.hpp"

#include "runtime/javaCalls.hpp"

#include "runtime/os.hpp"

ConcurrentGCThread::ConcurrentGCThread() :

  _should_terminate(false), _has_terminated(false) {

};

void ConcurrentGCThread::create_and_start(ThreadPriority prio) {

  if (os::create_thread(this, os::cgc_thread)) {

    // XXX: need to set this to low priority

    // unless "aggressive mode" set; priority

    // should be just less than that of VMThread.

    os::set_priority(this, prio);

    if (!_should_terminate) {

      os::start_thread(this);

    }

  }

}

void ConcurrentGCThread::initialize_in_thread() {

  this->initialize_named_thread();

  this->set_active_handles(JNIHandleBlock::allocate_block());

  // From this time Thread::current() should be working.

  assert(this == Thread::current(), "just checking");

}

void ConcurrentGCThread::wait_for_universe_init() {

  MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);

  while (!is_init_completed() && !_should_terminate) {

    CGC_lock->wait(Mutex::_no_safepoint_check_flag, 1);

  }

}

void ConcurrentGCThread::terminate() {

  assert(_should_terminate, "Should only be called on terminate request.");

  // Signal that it is terminated

  {

    MutexLockerEx mu(Terminator_lock,

                     Mutex::_no_safepoint_check_flag);

    _has_terminated = true;

    Terminator_lock->notify();

  }

}

void ConcurrentGCThread::run() {

  initialize_in_thread();

  wait_for_universe_init();

  run_service();

  terminate();

}

void ConcurrentGCThread::stop() {

  // it is ok to take late safepoints here, if needed

  {

    MutexLockerEx mu(Terminator_lock);

    assert(!_has_terminated,   "stop should only be called once");

    assert(!_should_terminate, "stop should only be called once");

    _should_terminate = true;

  }

  stop_service();

  {

    MutexLockerEx mu(Terminator_lock);

    while (!_has_terminated) {

      Terminator_lock->wait();

    }

  }

}