src/share/vm/gc_implementation/shared/concurrentGCThread.hpp

/*
 * Copyright (c) 2001, 2013, 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
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#ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP
#define SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP

#include "utilities/macros.hpp"
#include "gc_implementation/shared/suspendibleThreadSet.hpp"
#include "runtime/thread.hpp"

class ConcurrentGCThread: public NamedThread {
  friend class VMStructs;

protected:
  bool _should_terminate;
  bool _has_terminated;

  enum CGC_flag_type {
    CGC_nil           = 0x0,
    CGC_dont_suspend  = 0x1,
    CGC_CGC_safepoint = 0x2,
    CGC_VM_safepoint  = 0x4
  };

  static int _CGC_flag;

  static bool CGC_flag_is_set(int b)       { return (_CGC_flag & b) != 0; }
  static int set_CGC_flag(int b)           { return _CGC_flag |= b; }
  static int reset_CGC_flag(int b)         { return _CGC_flag &= ~b; }

  // Create and start the thread (setting it's priority high.)
  void create_and_start();

  // Do initialization steps in the thread: record stack base and size,
  // init thread local storage, set JNI handle block.
  void initialize_in_thread();

  // Wait until Universe::is_fully_initialized();
  void wait_for_universe_init();

  // Record that the current thread is terminating, and will do more
  // concurrent work.
  void terminate();

public:
  // Constructor

  ConcurrentGCThread();
  ~ConcurrentGCThread() {} // Exists to call NamedThread destructor.

  // Tester
  bool is_ConcurrentGC_thread() const          { return true;       }
};

// The SurrogateLockerThread is used by concurrent GC threads for
// manipulating Java monitors, in particular, currently for
// manipulating the pending_list_lock. XXX
class SurrogateLockerThread: public JavaThread {
  friend class VMStructs;
 public:
  enum SLT_msg_type {
    empty = 0,           // no message
    acquirePLL,          // acquire pending list lock
    releaseAndNotifyPLL  // notify and release pending list lock
  };
 private:
  // the following are shared with the CMSThread
  SLT_msg_type  _buffer;  // communication buffer
  Monitor       _monitor; // monitor controlling buffer
  BasicLock     _basicLock; // used for PLL locking

 public:
  static SurrogateLockerThread* make(TRAPS);

  // Terminate VM with error message that SLT needed but not yet created.
  static void report_missing_slt();

  SurrogateLockerThread();

  bool is_hidden_from_external_view() const     { return true; }

  void loop(); // main method

  void manipulatePLL(SLT_msg_type msg);

};

#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP