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products/sources/formale Sprachen/Java/Openjdk/src/hotspot/share/gc/shared/ (Sun/Oracle ^©) Datei vom 13.11.2022 mit Größe 2 kB

Quelle referencePolicy.cpp Sprache: C

/*
* Copyright (c) 2000, 2021, 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.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/gc_globals.hpp"
#include "gc/shared/referencePolicy.hpp"
#include "memory/universe.hpp"
#include "runtime/globals.hpp"

LRUCurrentHeapPolicy::LRUCurrentHeapPolicy() {
  setup();
}

// Capture state (of-the-VM) information needed to evaluate the policy
void LRUCurrentHeapPolicy::setup() {
  _max_interval = (Universe::heap()->free_at_last_gc() / M) * SoftRefLRUPolicyMSPerMB;
  assert(_max_interval >= 0,"Sanity check");
}

// The oop passed in is the SoftReference object, and not
// the object the SoftReference points to.
bool LRUCurrentHeapPolicy::should_clear_reference(oop p,
                                                  jlong timestamp_clock) {
  jlong interval = timestamp_clock - java_lang_ref_SoftReference::timestamp(p);
  assert(interval >= 0, "Sanity check");

  // The interval will be zero if the ref was accessed since the last scavenge/gc.
  if(interval <= _max_interval) {
    return false;
  }

  return true;
}

/////////////////////// MaxHeap //////////////////////

LRUMaxHeapPolicy::LRUMaxHeapPolicy() {
  setup();
}

// Capture state (of-the-VM) information needed to evaluate the policy
void LRUMaxHeapPolicy::setup() {
  size_t max_heap = MaxHeapSize;
  max_heap -= Universe::heap()->used_at_last_gc();
  max_heap /= M;

  _max_interval = max_heap * SoftRefLRUPolicyMSPerMB;
  assert(_max_interval >= 0,"Sanity check");
}

// The oop passed in is the SoftReference object, and not
// the object the SoftReference points to.
bool LRUMaxHeapPolicy::should_clear_reference(oop p,
                                             jlong timestamp_clock) {
  jlong interval = timestamp_clock - java_lang_ref_SoftReference::timestamp(p);
  assert(interval >= 0, "Sanity check");

  // The interval will be zero if the ref was accessed since the last scavenge/gc.
  if(interval <= _max_interval) {
    return false;
  }

  return true;
}

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