view src/share/vm/memory/referencePolicy.hpp @ 2753:d1bdeef3e3e2

7098282: G1: assert(interval >= 0) failed: Sanity check, referencePolicy.cpp: 76 Summary: There is a race between one thread successfully forwarding and copying the klass mirror for the SoftReference class (including the static master clock) and another thread attempting to use the master clock while attempting to discover a soft reference object. Maintain a shadow copy of the soft reference master clock and use the shadow during reference discovery and reference processing. Reviewed-by: tonyp, brutisso, ysr
author johnc
date Wed, 12 Oct 2011 10:25:51 -0700
parents f95d63e2154a
children d2a62e0f25eb
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/*
 * Copyright (c) 2000, 2011, 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_MEMORY_REFERENCEPOLICY_HPP
#define SHARE_VM_MEMORY_REFERENCEPOLICY_HPP

// referencePolicy is used to determine when soft reference objects
// should be cleared.


class ReferencePolicy : public CHeapObj {
 public:
  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
    ShouldNotReachHere();
    return true;
  }

  // Capture state (of-the-VM) information needed to evaluate the policy
  virtual void setup() { /* do nothing */ }
};

class NeverClearPolicy : public ReferencePolicy {
 public:
  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
    return false;
  }
};

class AlwaysClearPolicy : public ReferencePolicy {
 public:
  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
    return true;
  }
};

class LRUCurrentHeapPolicy : public ReferencePolicy {
 private:
  jlong _max_interval;

 public:
  LRUCurrentHeapPolicy();

  // Capture state (of-the-VM) information needed to evaluate the policy
  void setup();
  virtual bool should_clear_reference(oop p, jlong timestamp_clock);
};

class LRUMaxHeapPolicy : public ReferencePolicy {
 private:
  jlong _max_interval;

 public:
  LRUMaxHeapPolicy();

  // Capture state (of-the-VM) information needed to evaluate the policy
  void setup();
  virtual bool should_clear_reference(oop p, jlong timestamp_clock);
};

#endif // SHARE_VM_MEMORY_REFERENCEPOLICY_HPP