/*

 * Copyright (c) 2017, 2019, Red Hat, Inc. All rights reserved.

 *

 * 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 "gc/shared/stringdedup/stringDedup.hpp"

#include "gc/shared/stringdedup/stringDedupThread.hpp"

#include "gc/shenandoah/shenandoahHeap.inline.hpp"

#include "gc/shenandoah/shenandoahStrDedupQueue.inline.hpp"

#include "gc/shenandoah/shenandoahStringDedup.inline.hpp"

#include "logging/log.hpp"

#include "runtime/mutex.hpp"

#include "runtime/mutexLocker.hpp"

ShenandoahStrDedupQueue::ShenandoahStrDedupQueue() :

  _consumer_queue(NULL),

  _num_producer_queue(ShenandoahHeap::heap()->max_workers()),

  _published_queues(NULL),

  _free_list(NULL),

  _num_free_buffer(0),

  _max_free_buffer(ShenandoahHeap::heap()->max_workers() * 2),

  _cancel(false),

  _total_buffers(0) {

  _producer_queues = NEW_C_HEAP_ARRAY(ShenandoahQueueBuffer*, _num_producer_queue, mtGC);

  for (size_t index = 0; index < _num_producer_queue; index ++) {

    _producer_queues[index] = NULL;

  }

}

ShenandoahStrDedupQueue::~ShenandoahStrDedupQueue() {

  MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

  for (size_t index = 0; index < num_queues(); index ++) {

    release_buffers(queue_at(index));

  }

  release_buffers(_free_list);

  FREE_C_HEAP_ARRAY(ShenandoahQueueBuffer*, _producer_queues);

}

void ShenandoahStrDedupQueue::wait_impl() {

  MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

  while (_consumer_queue == NULL && !_cancel) {

    ml.wait();

    assert(_consumer_queue == NULL, "Why wait?");

    _consumer_queue = _published_queues;

    _published_queues = NULL;

  }

}

void ShenandoahStrDedupQueue::cancel_wait_impl() {

  MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

  _cancel = true;

  ml.notify();

}

void ShenandoahStrDedupQueue::unlink_or_oops_do_impl(StringDedupUnlinkOrOopsDoClosure* cl, size_t queue) {

  ShenandoahQueueBuffer* q = queue_at(queue);

  while (q != NULL) {

    q->unlink_or_oops_do(cl);

    q = q->next();

  }

}

ShenandoahQueueBuffer* ShenandoahStrDedupQueue::queue_at(size_t queue_id) const {

  assert(queue_id <= num_queues(), "Invalid queue id");

  if (queue_id < _num_producer_queue) {

    return _producer_queues[queue_id];

  } else if (queue_id == _num_producer_queue) {

    return _consumer_queue;

  } else {

    assert(queue_id == _num_producer_queue + 1, "Must be");

    return _published_queues;

  }

}

void ShenandoahStrDedupQueue::set_producer_buffer(ShenandoahQueueBuffer* buf, size_t queue_id) {

  assert(queue_id < _num_producer_queue, "Not a producer queue id");

  _producer_queues[queue_id] = buf;

}

void ShenandoahStrDedupQueue::push_impl(uint worker_id, oop string_oop) {

  assert(worker_id < _num_producer_queue, "Invalid queue id. Can only push to producer queue");

  assert(ShenandoahStringDedup::is_candidate(string_oop), "Not a candidate");

  ShenandoahQueueBuffer* buf = queue_at((size_t)worker_id);

  if (buf == NULL) {

    MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

    buf = new_buffer();

    set_producer_buffer(buf, worker_id);

  } else if (buf->is_full()) {

    MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

    buf->set_next(_published_queues);

    _published_queues = buf;

    buf = new_buffer();

    set_producer_buffer(buf, worker_id);

    ml.notify();

  }

  assert(!buf->is_full(), "Sanity");

  buf->push(string_oop);

}

oop ShenandoahStrDedupQueue::pop_impl() {

  assert(Thread::current() == StringDedupThread::thread(), "Must be dedup thread");

  while (true) {

    if (_consumer_queue == NULL) {

      MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

      _consumer_queue = _published_queues;

      _published_queues = NULL;

    }

    // there is nothing

    if (_consumer_queue == NULL) {

      return NULL;

    }

    oop obj = NULL;

    if (pop_candidate(obj)) {

      assert(ShenandoahStringDedup::is_candidate(obj), "Must be a candidate");

      return obj;

    }

    assert(obj == NULL, "No more candidate");

  }

}

bool ShenandoahStrDedupQueue::pop_candidate(oop& obj) {

  ShenandoahQueueBuffer* to_release = NULL;

  bool suc = true;

  do {

    if (_consumer_queue->is_empty()) {

      ShenandoahQueueBuffer* buf = _consumer_queue;

      _consumer_queue = _consumer_queue->next();

      buf->set_next(to_release);

      to_release = buf;

      if (_consumer_queue == NULL) {

        suc = false;

        break;

      }

    }

    obj = _consumer_queue->pop();

  } while (obj == NULL);

  if (to_release != NULL) {

    MonitorLocker ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);

    release_buffers(to_release);

  }

  return suc;

}

ShenandoahQueueBuffer* ShenandoahStrDedupQueue::new_buffer() {

  assert_lock_strong(StringDedupQueue_lock);

  if (_free_list != NULL) {

    assert(_num_free_buffer > 0, "Sanity");

    ShenandoahQueueBuffer* buf = _free_list;

    _free_list = _free_list->next();

    _num_free_buffer --;

    buf->reset();

    return buf;

  } else {

    assert(_num_free_buffer == 0, "Sanity");

    _total_buffers ++;

    return new ShenandoahQueueBuffer;

  }

}

void ShenandoahStrDedupQueue::release_buffers(ShenandoahQueueBuffer* list) {

  assert_lock_strong(StringDedupQueue_lock);

  while (list != NULL) {

    ShenandoahQueueBuffer* tmp = list;

    list = list->next();

    if (_num_free_buffer < _max_free_buffer) {

      tmp->set_next(_free_list);

      _free_list = tmp;

      _num_free_buffer ++;

    } else {

      _total_buffers --;

      delete tmp;

    }

  }

}

void ShenandoahStrDedupQueue::print_statistics_impl() {

  Log(gc, stringdedup) log;

  log.debug("  Queue:");

}

class VerifyQueueClosure : public OopClosure {

private:

  ShenandoahHeap* _heap;

public:

  VerifyQueueClosure();

  void do_oop(oop* o);

  void do_oop(narrowOop* o) {

    ShouldNotCallThis();

  }

};

VerifyQueueClosure::VerifyQueueClosure() :

  _heap(ShenandoahHeap::heap()) {

}

void VerifyQueueClosure::do_oop(oop* o) {

  if (*o != NULL) {

    oop obj = *o;

    shenandoah_assert_correct(o, obj);

    assert(java_lang_String::is_instance(obj), "Object must be a String");

  }

}

void ShenandoahStrDedupQueue::verify_impl() {

  VerifyQueueClosure vcl;

  for (size_t index = 0; index < num_queues(); index ++) {

    ShenandoahQueueBuffer* buf = queue_at(index);

    while (buf != NULL) {

      buf->oops_do(&vcl);

      buf = buf->next();

    }

  }

}