/*

 * 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.

 *

 */

#ifndef SHARE_VM_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP

#define SHARE_VM_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP

#include "gc/shared/concurrentGCThread.hpp"

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

//

// The deduplication thread is where the actual deduplication occurs. It waits for

// deduplication candidates to appear on the deduplication queue, removes them from

// the queue and tries to deduplicate them. It uses the deduplication hashtable to

// find identical, already existing, character arrays on the heap. The thread runs

// concurrently with the Java application but participates in safepoints to allow

// the GC to adjust and unlink oops from the deduplication queue and table.

//

class StringDedupThread: public ConcurrentGCThread {

protected:

  static StringDedupThread* _thread;

  StringDedupThread();

  ~StringDedupThread();

  void print_start(const StringDedupStat* last_stat);

  void print_end(const StringDedupStat* last_stat, const StringDedupStat* total_stat);

  void run_service() { this->do_deduplication(); }

  void stop_service();

  void deduplicate_shared_strings(StringDedupStat* stat);

protected:

  virtual void do_deduplication() = 0;

public:

  static StringDedupThread* thread();

};

template <typename S>

class StringDedupThreadImpl : public StringDedupThread {

private:

  StringDedupThreadImpl() { }

protected:

  void do_deduplication();

public:

  static void create();

};

#endif // SHARE_VM_GC_SHARED_STRINGDEDUP_STRINGDEDUPTHREAD_HPP