1 /*** 2 * 3 * Copyright 2004 Hiram Chirino 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 **/ 18 package org.activeio.packet; 19 20 import java.util.ArrayList; 21 22 import org.activeio.Packet; 23 24 import EDU.oswego.cs.dl.util.concurrent.SynchronizedInt; 25 26 /*** 27 * Provides a simple pool of Packet objects. When the packets that this pool produces are disposed, 28 * they are returned to the pool. 29 * 30 * @version $Revision: 1.1 $ 31 */ 32 abstract public class PacketPool { 33 34 public static final int DEFAULT_POOL_SIZE = Integer.parseInt(System.getProperty("org.activeio.journal.active.DefaultPoolSize", ""+(5))); 35 public static final int DEFAULT_PACKET_SIZE = Integer.parseInt(System.getProperty("org.activeio.journal.active.DefaultPacketSize", ""+(1024*1024*4))); 36 37 private final ArrayList pool = new ArrayList(); 38 private final int maxPackets; 39 private int currentPoolSize; 40 41 public class PooledPacket extends FilterPacket { 42 private final SynchronizedInt referenceCounter; 43 44 public PooledPacket(Packet next) { 45 this(next, new SynchronizedInt(0)); 46 } 47 48 private PooledPacket(Packet next, SynchronizedInt referenceCounter) { 49 super(next); 50 this.referenceCounter=referenceCounter; 51 this.referenceCounter.increment(); 52 } 53 54 public Packet filter(Packet packet) { 55 return new PooledPacket(next, referenceCounter); 56 } 57 58 int getReferenceCounter() { 59 return referenceCounter.get(); 60 } 61 62 public void dispose() { 63 if( referenceCounter.decrement()==0 ) { 64 returnPacket(next); 65 } 66 } 67 } 68 69 /*** 70 * @param maxPackets the number of buffers that will be in the pool. 71 */ 72 public PacketPool(int maxPackets) { 73 this.maxPackets = maxPackets; 74 } 75 76 /*** 77 * Blocks until a ByteBuffer can be retreived from the pool. 78 * 79 * @return 80 * @throws InterruptedException 81 */ 82 public Packet getPacket() throws InterruptedException { 83 Packet answer=null; 84 synchronized(this) { 85 while(answer==null) { 86 if( pool.size()>0) { 87 answer = (Packet) pool.remove(pool.size()-1); 88 } else if( currentPoolSize < maxPackets ) { 89 answer = allocateNewPacket(); 90 currentPoolSize++; 91 } 92 if( answer==null ) { 93 this.wait(); 94 } 95 } 96 } 97 return new PooledPacket(answer); 98 } 99 100 /*** 101 * Returns a ByteBuffer to the pool. 102 * 103 * @param packet 104 */ 105 private void returnPacket(Packet packet) { 106 packet.clear(); 107 synchronized(this) { 108 pool.add(packet); 109 this.notify(); 110 } 111 } 112 113 /*** 114 * @return 115 */ 116 abstract protected Packet allocateNewPacket(); 117 118 }