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 */ 017 package org.apache.activemq.broker.region; 018 019 import java.io.IOException; 020 import javax.jms.InvalidSelectorException; 021 import org.apache.activemq.broker.Broker; 022 import org.apache.activemq.broker.ConnectionContext; 023 import org.apache.activemq.command.ConsumerInfo; 024 import org.apache.activemq.command.MessageAck; 025 import org.apache.activemq.filter.MessageEvaluationContext; 026 import org.apache.activemq.usage.SystemUsage; 027 028 public class QueueBrowserSubscription extends QueueSubscription { 029 030 int queueRefs; 031 boolean browseDone; 032 boolean destinationsAdded; 033 034 public QueueBrowserSubscription(Broker broker,SystemUsage usageManager, ConnectionContext context, ConsumerInfo info) 035 throws InvalidSelectorException { 036 super(broker,usageManager, context, info); 037 } 038 039 protected boolean canDispatch(MessageReference node) { 040 return !((QueueMessageReference)node).isAcked(); 041 } 042 043 public synchronized String toString() { 044 return "QueueBrowserSubscription:" + " consumer=" + info.getConsumerId() + ", destinations=" 045 + destinations.size() + ", dispatched=" + dispatched.size() + ", delivered=" 046 + this.prefetchExtension + ", pending=" + getPendingQueueSize(); 047 } 048 049 synchronized public void destinationsAdded() throws Exception { 050 destinationsAdded = true; 051 checkDone(); 052 } 053 054 private void checkDone() throws Exception { 055 if( !browseDone && queueRefs == 0 && destinationsAdded) { 056 browseDone=true; 057 add(QueueMessageReference.NULL_MESSAGE); 058 } 059 } 060 061 public boolean matches(MessageReference node, MessageEvaluationContext context) throws IOException { 062 return !browseDone && super.matches(node, context); 063 } 064 065 /** 066 * Since we are a browser we don't really remove the message from the queue. 067 */ 068 protected void acknowledge(ConnectionContext context, final MessageAck ack, final MessageReference n) 069 throws IOException { 070 if (info.isNetworkSubscription()) { 071 super.acknowledge(context, ack, n); 072 } 073 } 074 075 synchronized public void incrementQueueRef() { 076 queueRefs++; 077 } 078 079 synchronized public void decrementQueueRef() throws Exception { 080 queueRefs--; 081 checkDone(); 082 } 083 084 }