| /* |
| * 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.io.retry; |
| |
| import java.io.IOException; |
| import java.lang.reflect.InvocationHandler; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| import java.util.Collections; |
| import java.util.Map; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.io.retry.FailoverProxyProvider.ProxyInfo; |
| import org.apache.hadoop.io.retry.RetryPolicy.RetryAction; |
| import org.apache.hadoop.ipc.Client; |
| import org.apache.hadoop.ipc.Client.ConnectionId; |
| import org.apache.hadoop.ipc.ProtocolTranslator; |
| import org.apache.hadoop.ipc.RPC; |
| import org.apache.hadoop.ipc.RpcConstants; |
| import org.apache.hadoop.ipc.RpcInvocationHandler; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| /** |
| * This class implements RpcInvocationHandler and supports retry on the client |
| * side. |
| */ |
| @InterfaceAudience.Private |
| public class RetryInvocationHandler<T> implements RpcInvocationHandler { |
| public static final Log LOG = LogFactory.getLog(RetryInvocationHandler.class); |
| private final FailoverProxyProvider<T> proxyProvider; |
| |
| /** |
| * The number of times the associated proxyProvider has ever been failed over. |
| */ |
| private long proxyProviderFailoverCount = 0; |
| private volatile boolean hasMadeASuccessfulCall = false; |
| |
| private final RetryPolicy defaultPolicy; |
| private final Map<String,RetryPolicy> methodNameToPolicyMap; |
| private ProxyInfo<T> currentProxy; |
| |
| protected RetryInvocationHandler(FailoverProxyProvider<T> proxyProvider, |
| RetryPolicy retryPolicy) { |
| this(proxyProvider, retryPolicy, Collections.<String, RetryPolicy>emptyMap()); |
| } |
| |
| protected RetryInvocationHandler(FailoverProxyProvider<T> proxyProvider, |
| RetryPolicy defaultPolicy, |
| Map<String, RetryPolicy> methodNameToPolicyMap) { |
| this.proxyProvider = proxyProvider; |
| this.defaultPolicy = defaultPolicy; |
| this.methodNameToPolicyMap = methodNameToPolicyMap; |
| this.currentProxy = proxyProvider.getProxy(); |
| } |
| |
| @Override |
| public Object invoke(Object proxy, Method method, Object[] args) |
| throws Throwable { |
| RetryPolicy policy = methodNameToPolicyMap.get(method.getName()); |
| if (policy == null) { |
| policy = defaultPolicy; |
| } |
| |
| // The number of times this method invocation has been failed over. |
| int invocationFailoverCount = 0; |
| final boolean isRpc = isRpcInvocation(currentProxy.proxy); |
| final int callId = isRpc? Client.nextCallId(): RpcConstants.INVALID_CALL_ID; |
| int retries = 0; |
| while (true) { |
| // The number of times this invocation handler has ever been failed over, |
| // before this method invocation attempt. Used to prevent concurrent |
| // failed method invocations from triggering multiple failover attempts. |
| long invocationAttemptFailoverCount; |
| synchronized (proxyProvider) { |
| invocationAttemptFailoverCount = proxyProviderFailoverCount; |
| } |
| |
| if (isRpc) { |
| Client.setCallIdAndRetryCount(callId, retries); |
| } |
| try { |
| Object ret = invokeMethod(method, args); |
| hasMadeASuccessfulCall = true; |
| return ret; |
| } catch (Exception e) { |
| boolean isIdempotentOrAtMostOnce = proxyProvider.getInterface() |
| .getMethod(method.getName(), method.getParameterTypes()) |
| .isAnnotationPresent(Idempotent.class); |
| if (!isIdempotentOrAtMostOnce) { |
| isIdempotentOrAtMostOnce = proxyProvider.getInterface() |
| .getMethod(method.getName(), method.getParameterTypes()) |
| .isAnnotationPresent(AtMostOnce.class); |
| } |
| RetryAction action = policy.shouldRetry(e, retries++, |
| invocationFailoverCount, isIdempotentOrAtMostOnce); |
| if (action.action == RetryAction.RetryDecision.FAIL) { |
| if (action.reason != null) { |
| LOG.warn("Exception while invoking " + currentProxy.proxy.getClass() |
| + "." + method.getName() + " over " + currentProxy.proxyInfo |
| + ". Not retrying because " + action.reason, e); |
| } |
| throw e; |
| } else { // retry or failover |
| // avoid logging the failover if this is the first call on this |
| // proxy object, and we successfully achieve the failover without |
| // any flip-flopping |
| boolean worthLogging = |
| !(invocationFailoverCount == 0 && !hasMadeASuccessfulCall); |
| worthLogging |= LOG.isDebugEnabled(); |
| if (action.action == RetryAction.RetryDecision.FAILOVER_AND_RETRY && |
| worthLogging) { |
| String msg = "Exception while invoking " + method.getName() |
| + " of class " + currentProxy.proxy.getClass().getSimpleName() |
| + " over " + currentProxy.proxyInfo; |
| |
| if (invocationFailoverCount > 0) { |
| msg += " after " + invocationFailoverCount + " fail over attempts"; |
| } |
| msg += ". Trying to fail over " + formatSleepMessage(action.delayMillis); |
| LOG.info(msg, e); |
| } else { |
| if(LOG.isDebugEnabled()) { |
| LOG.debug("Exception while invoking " + method.getName() |
| + " of class " + currentProxy.proxy.getClass().getSimpleName() |
| + " over " + currentProxy.proxyInfo + ". Retrying " |
| + formatSleepMessage(action.delayMillis), e); |
| } |
| } |
| |
| if (action.delayMillis > 0) { |
| Thread.sleep(action.delayMillis); |
| } |
| |
| if (action.action == RetryAction.RetryDecision.FAILOVER_AND_RETRY) { |
| // Make sure that concurrent failed method invocations only cause a |
| // single actual fail over. |
| synchronized (proxyProvider) { |
| if (invocationAttemptFailoverCount == proxyProviderFailoverCount) { |
| proxyProvider.performFailover(currentProxy.proxy); |
| proxyProviderFailoverCount++; |
| } else { |
| LOG.warn("A failover has occurred since the start of this method" |
| + " invocation attempt."); |
| } |
| currentProxy = proxyProvider.getProxy(); |
| } |
| invocationFailoverCount++; |
| } |
| } |
| } |
| } |
| } |
| |
| private static String formatSleepMessage(long millis) { |
| if (millis > 0) { |
| return "after sleeping for " + millis + "ms."; |
| } else { |
| return "immediately."; |
| } |
| } |
| |
| protected Object invokeMethod(Method method, Object[] args) throws Throwable { |
| try { |
| if (!method.isAccessible()) { |
| method.setAccessible(true); |
| } |
| return method.invoke(currentProxy.proxy, args); |
| } catch (InvocationTargetException e) { |
| throw e.getCause(); |
| } |
| } |
| |
| @VisibleForTesting |
| static boolean isRpcInvocation(Object proxy) { |
| if (proxy instanceof ProtocolTranslator) { |
| proxy = ((ProtocolTranslator) proxy).getUnderlyingProxyObject(); |
| } |
| if (!Proxy.isProxyClass(proxy.getClass())) { |
| return false; |
| } |
| final InvocationHandler ih = Proxy.getInvocationHandler(proxy); |
| return ih instanceof RpcInvocationHandler; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| proxyProvider.close(); |
| } |
| |
| @Override //RpcInvocationHandler |
| public ConnectionId getConnectionId() { |
| return RPC.getConnectionIdForProxy(currentProxy.proxy); |
| } |
| |
| } |