/*

 * Copyright (c) 2014, 2018, 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/javaClasses.inline.hpp"

#include "gc/g1/g1CollectedHeap.inline.hpp"

#include "gc/g1/g1GCPhaseTimes.hpp"

#include "gc/g1/g1StringDedup.hpp"

#include "gc/g1/g1StringDedupQueue.hpp"

#include "gc/g1/g1StringDedupStat.hpp"

#include "gc/shared/stringdedup/stringDedup.inline.hpp"

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

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

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

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

void G1StringDedup::initialize() {

  assert(UseG1GC, "String deduplication available with G1");

  StringDedup::initialize_impl<G1StringDedupQueue, G1StringDedupStat>();

}

bool G1StringDedup::is_candidate_from_mark(oop obj) {

  if (java_lang_String::is_instance_inlined(obj)) {

    bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young();

    if (from_young && obj->age() < StringDeduplicationAgeThreshold) {

      // Candidate found. String is being evacuated from young to old but has not

      // reached the deduplication age threshold, i.e. has not previously been a

      // candidate during its life in the young generation.

      return true;

    }

  }

  // Not a candidate

  return false;

}

void G1StringDedup::enqueue_from_mark(oop java_string, uint worker_id) {

  assert(is_enabled(), "String deduplication not enabled");

  if (is_candidate_from_mark(java_string)) {

    G1StringDedupQueue::push(worker_id, java_string);

  }

}

bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {

  if (from_young && java_lang_String::is_instance_inlined(obj)) {

    if (to_young && obj->age() == StringDeduplicationAgeThreshold) {

      // Candidate found. String is being evacuated from young to young and just

      // reached the deduplication age threshold.

      return true;

    }

    if (!to_young && obj->age() < StringDeduplicationAgeThreshold) {

      // Candidate found. String is being evacuated from young to old but has not

      // reached the deduplication age threshold, i.e. has not previously been a

      // candidate during its life in the young generation.

      return true;

    }

  }

  // Not a candidate

  return false;

}

void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) {

  assert(is_enabled(), "String deduplication not enabled");

  if (is_candidate_from_evacuation(from_young, to_young, java_string)) {

    G1StringDedupQueue::push(worker_id, java_string);

  }

}

void G1StringDedup::oops_do(OopClosure* keep_alive) {

  assert(is_enabled(), "String deduplication not enabled");

  unlink_or_oops_do(NULL, keep_alive, true /* allow_resize_and_rehash */);

}

void G1StringDedup::parallel_unlink(G1StringDedupUnlinkOrOopsDoClosure* unlink, uint worker_id) {

  assert(is_enabled(), "String deduplication not enabled");

  StringDedupQueue::unlink_or_oops_do(unlink);

  StringDedupTable::unlink_or_oops_do(unlink, worker_id);

}

//

// Task for parallel unlink_or_oops_do() operation on the deduplication queue

// and table.

//

class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask {

private:

  G1StringDedupUnlinkOrOopsDoClosure _cl;

  G1GCPhaseTimes* _phase_times;

public:

  G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive,

                                  OopClosure* keep_alive,

                                  bool allow_resize_and_rehash,

                                  G1GCPhaseTimes* phase_times) :

    AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"),

    _cl(is_alive, keep_alive, allow_resize_and_rehash), _phase_times(phase_times) { }

  virtual void work(uint worker_id) {

    {

      G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);

      StringDedupQueue::unlink_or_oops_do(&_cl);

    }

    {

      G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);

      StringDedupTable::unlink_or_oops_do(&_cl, worker_id);

    }

  }

};

void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive,

                                      OopClosure* keep_alive,

                                      bool allow_resize_and_rehash,

                                      G1GCPhaseTimes* phase_times) {

  assert(is_enabled(), "String deduplication not enabled");

  G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash, phase_times);

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  g1h->workers()->run_task(&task);

}