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.transport.discovery.zeroconf; 018 019import java.io.IOException; 020import java.net.InetAddress; 021import java.util.HashMap; 022import java.util.Map; 023import java.util.concurrent.atomic.AtomicInteger; 024import javax.jmdns.JmDNS; 025 026public final class JmDNSFactory { 027 028 static Map<InetAddress, UsageTracker> registry = new HashMap<InetAddress, UsageTracker>(); 029 030 static class UsageTracker { 031 AtomicInteger count = new AtomicInteger(0); 032 JmDNS jmDNS; 033 } 034 035 private JmDNSFactory() { 036 } 037 038 static synchronized JmDNS create(final InetAddress address) throws IOException { 039 UsageTracker tracker = registry.get(address); 040 if (tracker == null) { 041 tracker = new UsageTracker(); 042 tracker.jmDNS = JmDNS.create(address); 043 registry.put(address, tracker); 044 } 045 tracker.count.incrementAndGet(); 046 return tracker.jmDNS; 047 } 048 049 static synchronized boolean onClose(InetAddress address) { 050 UsageTracker tracker = registry.get(address); 051 if (tracker != null) { 052 if (tracker.count.decrementAndGet() == 0) { 053 registry.remove(address); 054 return true; 055 } 056 } 057 return false; 058 } 059}