| /** |
| * 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 |
| * <p> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p> |
| * 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.server.namenode.ha; |
| |
| import java.io.IOException; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| import java.net.URI; |
| import java.util.concurrent.TimeUnit; |
| import org.apache.hadoop.classification.VisibleForTesting; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hdfs.ClientGSIContext; |
| import org.apache.hadoop.hdfs.protocol.ClientProtocol; |
| import org.apache.hadoop.ipc.AlignmentContext; |
| import org.apache.hadoop.ipc.Client; |
| import org.apache.hadoop.ipc.RPC; |
| import org.apache.hadoop.ipc.RpcInvocationHandler; |
| import org.apache.hadoop.util.Time; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import static org.apache.hadoop.hdfs.server.namenode.ha.ObserverReadProxyProvider.AUTO_MSYNC_PERIOD_KEY_PREFIX; |
| import static org.apache.hadoop.hdfs.server.namenode.ha.ObserverReadProxyProvider.AUTO_MSYNC_PERIOD_DEFAULT; |
| |
| /** |
| * A {@link org.apache.hadoop.io.retry.FailoverProxyProvider} implementation |
| * to support automatic msync-ing when using routers. |
| * |
| * This constructs a wrapper proxy around an internal one, and |
| * injects msync calls when necessary via the InvocationHandler. |
| */ |
| public class RouterObserverReadProxyProvider<T> extends AbstractNNFailoverProxyProvider<T> { |
| @VisibleForTesting |
| static final Logger LOG = LoggerFactory.getLogger(ObserverReadProxyProvider.class); |
| |
| /** Client-side context for syncing with the NameNode server side. */ |
| private final AlignmentContext alignmentContext; |
| |
| /** The inner proxy provider used for active/standby failover. */ |
| private final AbstractNNFailoverProxyProvider<T> innerProxy; |
| |
| /** The proxy which redirects the internal one. */ |
| private final ProxyInfo<T> wrapperProxy; |
| |
| /** |
| * Whether reading from observer is enabled. If this is false, this proxy |
| * will not call msync. |
| */ |
| private final boolean observerReadEnabled; |
| |
| /** |
| * This adjusts how frequently this proxy provider should auto-msync to the |
| * Active NameNode, automatically performing an msync() call to the active |
| * to fetch the current transaction ID before submitting read requests to |
| * observer nodes. See HDFS-14211 for more description of this feature. |
| * If this is below 0, never auto-msync. If this is 0, perform an msync on |
| * every read operation. If this is above 0, perform an msync after this many |
| * ms have elapsed since the last msync. |
| */ |
| private final long autoMsyncPeriodMs; |
| |
| /** |
| * The time, in millisecond epoch, that the last msync operation was |
| * performed. This includes any implicit msync (any operation which is |
| * serviced by the Active NameNode). |
| */ |
| private volatile long lastMsyncTimeMs = -1; |
| |
| public RouterObserverReadProxyProvider(Configuration conf, URI uri, Class<T> xface, |
| HAProxyFactory<T> factory) { |
| this(conf, uri, xface, factory, new IPFailoverProxyProvider<>(conf, uri, xface, factory)); |
| } |
| |
| @SuppressWarnings("unchecked") |
| public RouterObserverReadProxyProvider(Configuration conf, URI uri, Class<T> xface, |
| HAProxyFactory<T> factory, AbstractNNFailoverProxyProvider<T> failoverProxy) { |
| super(conf, uri, xface, factory); |
| this.alignmentContext = new ClientGSIContext(); |
| factory.setAlignmentContext(alignmentContext); |
| this.innerProxy = failoverProxy; |
| |
| String proxyInfoString = "RouterObserverReadProxyProvider for " + innerProxy.getProxy(); |
| |
| T wrappedProxy = (T) Proxy.newProxyInstance( |
| RouterObserverReadInvocationHandler.class.getClassLoader(), |
| new Class<?>[]{xface}, new RouterObserverReadInvocationHandler()); |
| this.wrapperProxy = new ProxyInfo<>(wrappedProxy, proxyInfoString); |
| |
| autoMsyncPeriodMs = conf.getTimeDuration( |
| // The host of the URI is the name service ID |
| AUTO_MSYNC_PERIOD_KEY_PREFIX + "." + uri.getHost(), |
| AUTO_MSYNC_PERIOD_DEFAULT, TimeUnit.MILLISECONDS); |
| |
| if (wrappedProxy instanceof ClientProtocol) { |
| this.observerReadEnabled = true; |
| } else { |
| LOG.info("Disabling observer reads for {} because the requested proxy " |
| + "class does not implement {}", uri, ClientProtocol.class.getName()); |
| this.observerReadEnabled = false; |
| } |
| } |
| |
| |
| public AlignmentContext getAlignmentContext() { |
| return alignmentContext; |
| } |
| |
| @Override |
| public ProxyInfo<T> getProxy() { |
| return wrapperProxy; |
| } |
| |
| @Override |
| public void performFailover(T currentProxy) { |
| innerProxy.performFailover(currentProxy); |
| } |
| |
| @Override |
| public boolean useLogicalURI() { |
| return innerProxy.useLogicalURI(); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| innerProxy.close(); |
| } |
| |
| /** |
| * Return the input proxy, cast as a {@link ClientProtocol}. This catches any |
| * {@link ClassCastException} and wraps it in a more helpful message. This |
| * should ONLY be called if the caller is certain that the proxy is, in fact, |
| * a {@link ClientProtocol}. |
| */ |
| private ClientProtocol getProxyAsClientProtocol(T proxy) { |
| assert proxy instanceof ClientProtocol : "BUG: Attempted to use proxy of class " |
| + proxy.getClass() |
| + " as if it was a ClientProtocol."; |
| return (ClientProtocol) proxy; |
| } |
| |
| /** |
| * This will call {@link ClientProtocol#msync()} on the active NameNode |
| * (via the {@link #innerProxy}) to update the state of this client, only |
| * if at least {@link #autoMsyncPeriodMs} ms has elapsed since the last time |
| * an msync was performed. |
| * |
| * @see #autoMsyncPeriodMs |
| */ |
| private void autoMsyncIfNecessary() throws IOException { |
| if (autoMsyncPeriodMs == 0) { |
| // Always msync |
| getProxyAsClientProtocol(innerProxy.getProxy().proxy).msync(); |
| } else if (autoMsyncPeriodMs > 0) { |
| if (Time.monotonicNow() - lastMsyncTimeMs > autoMsyncPeriodMs) { |
| synchronized (this) { |
| // Use a synchronized block so that only one thread will msync |
| // if many operations are submitted around the same time. |
| // Re-check the entry criterion since the status may have changed |
| // while waiting for the lock. |
| if (Time.monotonicNow() - lastMsyncTimeMs > autoMsyncPeriodMs) { |
| getProxyAsClientProtocol(innerProxy.getProxy().proxy).msync(); |
| lastMsyncTimeMs = Time.monotonicNow(); |
| } |
| } |
| } |
| } |
| } |
| |
| /** |
| * Check if a method is read-only. |
| * |
| * @return whether the 'method' is a read-only operation. |
| */ |
| private static boolean isRead(Method method) { |
| if (!method.isAnnotationPresent(ReadOnly.class)) { |
| return false; |
| } |
| return !method.getAnnotationsByType(ReadOnly.class)[0].activeOnly(); |
| } |
| |
| private class RouterObserverReadInvocationHandler implements RpcInvocationHandler { |
| |
| @Override |
| public Client.ConnectionId getConnectionId() { |
| return RPC.getConnectionIdForProxy(innerProxy.getProxy().proxy); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| innerProxy.close(); |
| } |
| |
| @Override |
| public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { |
| if (observerReadEnabled && isRead(method)) { |
| autoMsyncIfNecessary(); |
| } |
| |
| try { |
| return method.invoke(innerProxy.getProxy().proxy, args); |
| } catch (InvocationTargetException e) { |
| // This exception will be handled by higher layers |
| throw e.getCause(); |
| } |
| } |
| } |
| } |