| /** |
| * 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.oncrpc; |
| |
| import java.net.InetAddress; |
| import java.util.Iterator; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| /** |
| * This class is used for handling the duplicate <em>non-idempotenty</em> Rpc |
| * calls. A non-idempotent request is processed as follows: |
| * <ul> |
| * <li>If the request is being processed for the first time, its state is |
| * in-progress in cache.</li> |
| * <li>If the request is retransimitted and is in-progress state, it is ignored. |
| * </li> |
| * <li>If the request is retransimitted and is completed, the previous response |
| * from the cache is sent back to the client.</li> |
| * </ul> |
| * <br> |
| * A request is identified by the client ID (address of the client) and |
| * transaction ID (xid) from the Rpc call. |
| * |
| */ |
| public class RpcCallCache { |
| |
| public static class CacheEntry { |
| private RpcResponse response; // null if no response has been sent |
| |
| public CacheEntry() { |
| response = null; |
| } |
| |
| public boolean isInProgress() { |
| return response == null; |
| } |
| |
| public boolean isCompleted() { |
| return response != null; |
| } |
| |
| public RpcResponse getResponse() { |
| return response; |
| } |
| |
| public void setResponse(RpcResponse response) { |
| this.response = response; |
| } |
| } |
| |
| /** |
| * Call that is used to track a client in the {@link RpcCallCache} |
| */ |
| public static class ClientRequest { |
| protected final InetAddress clientId; |
| protected final int xid; |
| |
| public InetAddress getClientId() { |
| return clientId; |
| } |
| |
| public ClientRequest(InetAddress clientId, int xid) { |
| this.clientId = clientId; |
| this.xid = xid; |
| } |
| |
| @Override |
| public int hashCode() { |
| return xid + clientId.hashCode() * 31; |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) { |
| return true; |
| } |
| if (obj == null || !(obj instanceof ClientRequest)) { |
| return false; |
| } |
| ClientRequest other = (ClientRequest) obj; |
| return clientId.equals(other.clientId) && (xid == other.xid); |
| } |
| } |
| |
| private final String program; |
| |
| private final Map<ClientRequest, CacheEntry> map; |
| |
| public RpcCallCache(final String program, final int maxEntries) { |
| if (maxEntries <= 0) { |
| throw new IllegalArgumentException("Cache size is " + maxEntries |
| + ". Should be > 0"); |
| } |
| this.program = program; |
| map = new LinkedHashMap<ClientRequest, CacheEntry>() { |
| private static final long serialVersionUID = 1L; |
| |
| @Override |
| protected boolean removeEldestEntry( |
| java.util.Map.Entry<ClientRequest, CacheEntry> eldest) { |
| return RpcCallCache.this.size() > maxEntries; |
| } |
| }; |
| } |
| |
| /** |
| * Return the program name. |
| * @return RPC program name |
| */ |
| public String getProgram() { |
| return program; |
| } |
| |
| /** |
| * Mark a request as completed and add corresponding response to the cache. |
| * @param clientId client IP address |
| * @param xid transaction id |
| * @param response RPC response |
| */ |
| public void callCompleted(InetAddress clientId, int xid, RpcResponse response) { |
| ClientRequest req = new ClientRequest(clientId, xid); |
| CacheEntry e; |
| synchronized(map) { |
| e = map.get(req); |
| } |
| e.response = response; |
| } |
| |
| /** |
| * Check the cache for an entry. If it does not exist, add the request |
| * as in progress. |
| * @param clientId client IP address |
| * @param xid transaction id |
| * @return cached entry |
| */ |
| public CacheEntry checkOrAddToCache(InetAddress clientId, int xid) { |
| ClientRequest req = new ClientRequest(clientId, xid); |
| CacheEntry e; |
| synchronized(map) { |
| e = map.get(req); |
| if (e == null) { |
| // Add an inprogress cache entry |
| map.put(req, new CacheEntry()); |
| } |
| } |
| return e; |
| } |
| |
| /** |
| * Return number of cached entries. |
| * @return cache size |
| */ |
| public int size() { |
| return map.size(); |
| } |
| |
| /** |
| * Iterator to the cache entries. |
| * @return iterator cache iterator |
| */ |
| @VisibleForTesting |
| public Iterator<Entry<ClientRequest, CacheEntry>> iterator() { |
| return map.entrySet().iterator(); |
| } |
| } |