001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.activemq.memory; 018 019import java.util.Iterator; 020import java.util.LinkedList; 021import java.util.List; 022import java.util.concurrent.CopyOnWriteArrayList; 023 024import org.apache.activemq.thread.Task; 025import org.apache.activemq.thread.TaskRunner; 026import org.apache.activemq.thread.TaskRunnerFactory; 027import org.apache.activemq.usage.Usage; 028import org.apache.activemq.usage.UsageListener; 029import org.slf4j.Logger; 030import org.slf4j.LoggerFactory; 031 032public class CacheEvictionUsageListener implements UsageListener { 033 034 private static final Logger LOG = LoggerFactory.getLogger(CacheEvictionUsageListener.class); 035 036 private final List<CacheEvictor> evictors = new CopyOnWriteArrayList<CacheEvictor>(); 037 private final int usageHighMark; 038 private final int usageLowMark; 039 040 private final TaskRunner evictionTask; 041 private final Usage usage; 042 043 public CacheEvictionUsageListener(Usage usage, int usageHighMark, int usageLowMark, TaskRunnerFactory taskRunnerFactory) { 044 this.usage = usage; 045 this.usageHighMark = usageHighMark; 046 this.usageLowMark = usageLowMark; 047 evictionTask = taskRunnerFactory.createTaskRunner(new Task() { 048 public boolean iterate() { 049 return evictMessages(); 050 } 051 }, "Cache Evictor: " + System.identityHashCode(this)); 052 } 053 054 boolean evictMessages() { 055 // Try to take the memory usage down below the low mark. 056 LOG.debug("Evicting cache memory usage: {}", usage.getPercentUsage()); 057 058 List<CacheEvictor> list = new LinkedList<CacheEvictor>(evictors); 059 while (list.size() > 0 && usage.getPercentUsage() > usageLowMark) { 060 061 // Evenly evict messages from all evictors 062 for (Iterator<CacheEvictor> iter = list.iterator(); iter.hasNext();) { 063 CacheEvictor evictor = iter.next(); 064 if (evictor.evictCacheEntry() == null) { 065 iter.remove(); 066 } 067 } 068 } 069 return false; 070 } 071 072 public void onUsageChanged(Usage usage, int oldPercentUsage, int newPercentUsage) { 073 // Do we need to start evicting cache entries? Usage > than the 074 // high mark 075 if (oldPercentUsage < newPercentUsage && usage.getPercentUsage() >= usageHighMark) { 076 try { 077 evictionTask.wakeup(); 078 } catch (InterruptedException e) { 079 Thread.currentThread().interrupt(); 080 } 081 } 082 } 083 084 public void add(CacheEvictor evictor) { 085 evictors.add(evictor); 086 } 087 088 public void remove(CacheEvictor evictor) { 089 evictors.remove(evictor); 090 } 091}