| /** |
| * 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.io.IOException; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map.Entry; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.LinkedListMultimap; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.hdfs.net.Peer; |
| import org.apache.hadoop.hdfs.protocol.DatanodeID; |
| import org.apache.hadoop.hdfs.util.IOUtilsClient; |
| import org.apache.hadoop.util.Daemon; |
| import org.apache.hadoop.util.Time; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * A cache of input stream sockets to Data Node. |
| */ |
| @InterfaceStability.Unstable |
| @InterfaceAudience.Private |
| @VisibleForTesting |
| public class PeerCache { |
| private static final Logger LOG = LoggerFactory.getLogger(PeerCache.class); |
| |
| private static class Key { |
| final DatanodeID dnID; |
| final boolean isDomain; |
| |
| Key(DatanodeID dnID, boolean isDomain) { |
| this.dnID = dnID; |
| this.isDomain = isDomain; |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (!(o instanceof Key)) { |
| return false; |
| } |
| Key other = (Key)o; |
| return dnID.equals(other.dnID) && isDomain == other.isDomain; |
| } |
| |
| @Override |
| public int hashCode() { |
| return dnID.hashCode() ^ (isDomain ? 1 : 0); |
| } |
| } |
| |
| private static class Value { |
| private final Peer peer; |
| private final long time; |
| |
| Value(Peer peer, long time) { |
| this.peer = peer; |
| this.time = time; |
| } |
| |
| Peer getPeer() { |
| return peer; |
| } |
| |
| long getTime() { |
| return time; |
| } |
| } |
| |
| private Daemon daemon; |
| /** A map for per user per datanode. */ |
| private final LinkedListMultimap<Key, Value> multimap = |
| LinkedListMultimap.create(); |
| private final int capacity; |
| private final long expiryPeriod; |
| |
| public PeerCache(int c, long e) { |
| this.capacity = c; |
| this.expiryPeriod = e; |
| |
| if (capacity == 0 ) { |
| LOG.debug("SocketCache disabled."); |
| } else if (expiryPeriod == 0) { |
| throw new IllegalStateException("Cannot initialize expiryPeriod to " + |
| expiryPeriod + " when cache is enabled."); |
| } |
| } |
| |
| private boolean isDaemonStarted() { |
| return daemon != null; |
| } |
| |
| private synchronized void startExpiryDaemon() { |
| // start daemon only if not already started |
| if (isDaemonStarted()) { |
| return; |
| } |
| |
| daemon = new Daemon(new Runnable() { |
| @Override |
| public void run() { |
| try { |
| PeerCache.this.run(); |
| } catch(InterruptedException e) { |
| //noop |
| } finally { |
| PeerCache.this.clear(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return String.valueOf(PeerCache.this); |
| } |
| }); |
| daemon.start(); |
| } |
| |
| /** |
| * Get a cached peer connected to the given DataNode. |
| * @param dnId The DataNode to get a Peer for. |
| * @param isDomain Whether to retrieve a DomainPeer or not. |
| * |
| * @return An open Peer connected to the DN, or null if none |
| * was found. |
| */ |
| public Peer get(DatanodeID dnId, boolean isDomain) { |
| |
| if (capacity <= 0) { // disabled |
| return null; |
| } |
| return getInternal(dnId, isDomain); |
| } |
| |
| private synchronized Peer getInternal(DatanodeID dnId, boolean isDomain) { |
| List<Value> sockStreamList = multimap.get(new Key(dnId, isDomain)); |
| if (sockStreamList == null) { |
| return null; |
| } |
| |
| Iterator<Value> iter = sockStreamList.iterator(); |
| while (iter.hasNext()) { |
| Value candidate = iter.next(); |
| iter.remove(); |
| long ageMs = Time.monotonicNow() - candidate.getTime(); |
| Peer peer = candidate.getPeer(); |
| if (ageMs >= expiryPeriod) { |
| try { |
| peer.close(); |
| } catch (IOException e) { |
| LOG.warn("got IOException closing stale peer " + peer + |
| ", which is " + ageMs + " ms old"); |
| } |
| } else if (!peer.isClosed()) { |
| return peer; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Give an unused socket to the cache. |
| */ |
| public void put(DatanodeID dnId, Peer peer) { |
| Preconditions.checkNotNull(dnId); |
| Preconditions.checkNotNull(peer); |
| if (peer.isClosed()) return; |
| if (capacity <= 0) { |
| // Cache disabled. |
| IOUtilsClient.cleanup(LOG, peer); |
| return; |
| } |
| putInternal(dnId, peer); |
| } |
| |
| private synchronized void putInternal(DatanodeID dnId, Peer peer) { |
| startExpiryDaemon(); |
| |
| if (capacity == multimap.size()) { |
| evictOldest(); |
| } |
| multimap.put(new Key(dnId, peer.getDomainSocket() != null), |
| new Value(peer, Time.monotonicNow())); |
| } |
| |
| public synchronized int size() { |
| return multimap.size(); |
| } |
| |
| /** |
| * Evict and close sockets older than expiry period from the cache. |
| */ |
| private synchronized void evictExpired(long expiryPeriod) { |
| while (multimap.size() != 0) { |
| Iterator<Entry<Key, Value>> iter = |
| multimap.entries().iterator(); |
| Entry<Key, Value> entry = iter.next(); |
| // if oldest socket expired, remove it |
| if (entry == null || |
| Time.monotonicNow() - entry.getValue().getTime() < expiryPeriod) { |
| break; |
| } |
| IOUtilsClient.cleanup(LOG, entry.getValue().getPeer()); |
| iter.remove(); |
| } |
| } |
| |
| /** |
| * Evict the oldest entry in the cache. |
| */ |
| private synchronized void evictOldest() { |
| // We can get the oldest element immediately, because of an interesting |
| // property of LinkedListMultimap: its iterator traverses entries in the |
| // order that they were added. |
| Iterator<Entry<Key, Value>> iter = multimap.entries().iterator(); |
| if (!iter.hasNext()) { |
| throw new IllegalStateException("Cannot evict from empty cache! " + |
| "capacity: " + capacity); |
| } |
| Entry<Key, Value> entry = iter.next(); |
| IOUtilsClient.cleanup(LOG, entry.getValue().getPeer()); |
| iter.remove(); |
| } |
| |
| /** |
| * Periodically check in the cache and expire the entries older than |
| * expiryPeriod minutes. |
| */ |
| private void run() throws InterruptedException { |
| for(long lastExpiryTime = Time.monotonicNow(); |
| !Thread.interrupted(); |
| Thread.sleep(expiryPeriod)) { |
| final long elapsed = Time.monotonicNow() - lastExpiryTime; |
| if (elapsed >= expiryPeriod) { |
| evictExpired(expiryPeriod); |
| lastExpiryTime = Time.monotonicNow(); |
| } |
| } |
| clear(); |
| throw new InterruptedException("Daemon Interrupted"); |
| } |
| |
| /** |
| * Empty the cache, and close all sockets. |
| */ |
| @VisibleForTesting |
| synchronized void clear() { |
| for (Value value : multimap.values()) { |
| IOUtilsClient.cleanup(LOG, value.getPeer()); |
| } |
| multimap.clear(); |
| } |
| |
| @VisibleForTesting |
| void close() { |
| clear(); |
| if (daemon != null) { |
| daemon.interrupt(); |
| try { |
| daemon.join(); |
| } catch (InterruptedException e) { |
| throw new RuntimeException("failed to join thread"); |
| } |
| } |
| daemon = null; |
| } |
| } |