1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. 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 libcore.net.http; 19 20 import dalvik.system.SocketTagger; 21 import java.io.IOException; 22 import java.net.Socket; 23 import java.net.SocketException; 24 import java.util.ArrayList; 25 import java.util.HashMap; 26 import java.util.List; 27 28 /** 29 * A pool of HTTP connections. This class exposes its tuning parameters as 30 * system properties: 31 * <ul> 32 * <li>{@code http.keepAlive} true if HTTP connections should be pooled at 33 * all. Default is true. 34 * <li>{@code http.maxConnections} maximum number of connections to each URI. 35 * Default is 5. 36 * </ul> 37 * 38 * <p>This class <i>doesn't</i> adjust its configuration as system properties 39 * are changed. This assumes that the applications that set these parameters do 40 * so before making HTTP connections, and that this class is initialized lazily. 41 */ 42 final class HttpConnectionPool { 43 44 public static final HttpConnectionPool INSTANCE = new HttpConnectionPool(); 45 46 private final int maxConnections; 47 private final HashMap<HttpConnection.Address, List<HttpConnection>> connectionPool 48 = new HashMap<HttpConnection.Address, List<HttpConnection>>(); 49 50 private HttpConnectionPool() { 51 String keepAlive = System.getProperty("http.keepAlive"); 52 if (keepAlive != null && !Boolean.parseBoolean(keepAlive)) { 53 maxConnections = 0; 54 return; 55 } 56 57 String maxConnectionsString = System.getProperty("http.maxConnections"); 58 this.maxConnections = maxConnectionsString != null 59 ? Integer.parseInt(maxConnectionsString) 60 : 5; 61 } 62 63 public HttpConnection get(HttpConnection.Address address, int connectTimeout) 64 throws IOException { 65 // First try to reuse an existing HTTP connection. 66 synchronized (connectionPool) { 67 List<HttpConnection> connections = connectionPool.get(address); 68 while (connections != null) { 69 HttpConnection connection = connections.remove(connections.size() - 1); 70 if (connections.isEmpty()) { 71 connectionPool.remove(address); 72 connections = null; 73 } 74 if (connection.isEligibleForRecycling()) { 75 // Since Socket is recycled, re-tag before using 76 Socket socket = connection.getSocket(); 77 SocketTagger.get().tag(socket); 78 return connection; 79 } 80 } 81 } 82 83 /* 84 * We couldn't find a reusable connection, so we need to create a new 85 * connection. We're careful not to do so while holding a lock! 86 */ 87 return address.connect(connectTimeout); 88 } 89 90 public void recycle(HttpConnection connection) { 91 Socket socket = connection.getSocket(); 92 try { 93 SocketTagger.get().untag(socket); 94 } catch (SocketException e) { 95 // When unable to remove tagging, skip recycling and close 96 System.logW("Unable to untagSocket(): " + e); 97 connection.closeSocketAndStreams(); 98 return; 99 } 100 101 if (maxConnections > 0 && connection.isEligibleForRecycling()) { 102 HttpConnection.Address address = connection.getAddress(); 103 synchronized (connectionPool) { 104 List<HttpConnection> connections = connectionPool.get(address); 105 if (connections == null) { 106 connections = new ArrayList<HttpConnection>(); 107 connectionPool.put(address, connections); 108 } 109 if (connections.size() < maxConnections) { 110 connection.setRecycled(); 111 connections.add(connection); 112 return; // keep the connection open 113 } 114 } 115 } 116 117 // don't close streams while holding a lock! 118 connection.closeSocketAndStreams(); 119 } 120 } 121