| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.hdfs; |
| |
| import java.net.Socket; |
| import java.net.SocketAddress; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map.Entry; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.LinkedListMultimap; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.io.IOUtils; |
| |
| /** |
| * A cache of sockets. |
| */ |
| class SocketCache { |
| static final Log LOG = LogFactory.getLog(SocketCache.class); |
| |
| private final LinkedListMultimap<SocketAddress, Socket> multimap; |
| private final int capacity; |
| |
| /** |
| * Create a SocketCache with the given capacity. |
| * @param capacity Max cache size. |
| */ |
| public SocketCache(int capacity) { |
| multimap = LinkedListMultimap.create(); |
| this.capacity = capacity; |
| } |
| |
| /** |
| * Get a cached socket to the given address. |
| * @param remote Remote address the socket is connected to. |
| * @return A socket with unknown state, possibly closed underneath. Or null. |
| */ |
| public synchronized Socket get(SocketAddress remote) { |
| List<Socket> socklist = multimap.get(remote); |
| if (socklist == null) { |
| return null; |
| } |
| |
| Iterator<Socket> iter = socklist.iterator(); |
| while (iter.hasNext()) { |
| Socket candidate = iter.next(); |
| iter.remove(); |
| if (!candidate.isClosed()) { |
| return candidate; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Give an unused socket to the cache. |
| * @param sock socket not used by anyone. |
| */ |
| public synchronized void put(Socket sock) { |
| Preconditions.checkNotNull(sock); |
| |
| SocketAddress remoteAddr = sock.getRemoteSocketAddress(); |
| if (remoteAddr == null) { |
| LOG.warn("Cannot cache (unconnected) socket with no remote address: " + |
| sock); |
| IOUtils.closeSocket(sock); |
| return; |
| } |
| |
| if (capacity == multimap.size()) { |
| evictOldest(); |
| } |
| multimap.put(remoteAddr, sock); |
| } |
| |
| public synchronized int size() { |
| return multimap.size(); |
| } |
| |
| /** |
| * Evict the oldest entry in the cache. |
| */ |
| private synchronized void evictOldest() { |
| Iterator<Entry<SocketAddress, Socket>> iter = |
| multimap.entries().iterator(); |
| if (!iter.hasNext()) { |
| throw new IllegalStateException("Cannot evict from empty cache!"); |
| } |
| Entry<SocketAddress, Socket> entry = iter.next(); |
| iter.remove(); |
| Socket sock = entry.getValue(); |
| IOUtils.closeSocket(sock); |
| } |
| |
| /** |
| * Empty the cache, and close all sockets. |
| */ |
| public synchronized void clear() { |
| for (Socket sock : multimap.values()) { |
| IOUtils.closeSocket(sock); |
| } |
| multimap.clear(); |
| } |
| |
| protected void finalize() { |
| clear(); |
| } |
| |
| } |