szetszwo commented on code in PR #9641: URL: https://github.com/apache/ozone/pull/9641#discussion_r2718160144
########## hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/ha/HadoopRpcOMFollowerReadFailoverProxyProvider.java: ########## @@ -0,0 +1,414 @@ +/* + * 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.ozone.om.ha; + +import static org.apache.hadoop.ozone.om.ha.OMFailoverProxyProviderBase.getLeaderNotReadyException; +import static org.apache.hadoop.ozone.om.ha.OMFailoverProxyProviderBase.getNotLeaderException; + +import com.google.common.annotations.VisibleForTesting; +import com.google.protobuf.Message; +import com.google.protobuf.RpcController; +import com.google.protobuf.ServiceException; +import java.io.IOException; +import java.io.InterruptedIOException; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.lang.reflect.Proxy; +import java.util.List; +import org.apache.hadoop.hdds.conf.ConfigurationSource; +import org.apache.hadoop.io.retry.FailoverProxyProvider; +import org.apache.hadoop.io.retry.RetryPolicy; +import org.apache.hadoop.ipc_.Client.ConnectionId; +import org.apache.hadoop.ipc_.RPC; +import org.apache.hadoop.ipc_.RpcInvocationHandler; +import org.apache.hadoop.ipc_.RpcNoSuchProtocolException; +import org.apache.hadoop.ozone.OmUtils; +import org.apache.hadoop.ozone.om.exceptions.OMLeaderNotReadyException; +import org.apache.hadoop.ozone.om.exceptions.OMNotLeaderException; +import org.apache.hadoop.ozone.om.protocolPB.OzoneManagerProtocolPB; +import org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.OMRequest; +import org.apache.hadoop.security.UserGroupInformation; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A {@link org.apache.hadoop.io.retry.FailoverProxyProvider} implementation + * that supports reading from follower OM(s) (i.e. non-leader OMs also includes + * OM listeners). + * <p> + * This constructs a wrapper proxy might send the read request to follower + * OM(s), if follower read is enabled. It will try to send read requests + * to the first OM node. If RPC failed, it will try to failover to the next OM node. + * It will fail back to the leader OM after it has exhausted all the OMs. + * TODO: Currently the logic does not prioritize forwarding to followers since + * it requires an extra RPC latency to check the OM role info. + * In the future, we can try to try to pick the followers before forwarding + * the request to the leader (similar to ObserverReadProxyProvider). + * <p> + * Read and write requests will still be sent to leader OM if reading from + * follower is disabled. + */ +public class HadoopRpcOMFollowerReadFailoverProxyProvider<T> implements FailoverProxyProvider<T> { + @VisibleForTesting + public static final Logger LOG = LoggerFactory.getLogger(HadoopRpcOMFollowerReadFailoverProxyProvider.class); + + private final Class<T> protocolClass; + + /** The inner proxy provider used for leader-based failover. */ + private final HadoopRpcOMFailoverProxyProvider<T> failoverProxy; + + /** The combined proxy which redirects to other proxies as necessary. */ + private final ProxyInfo<T> combinedProxy; + + /** + * Whether reading from follower is enabled. If this is false, all read + * requests will still go to OM leader. + */ + private volatile boolean followerReadEnabled; + + /** + * The current index of the underlying leader-based proxy provider's omNodesInOrder currently being used. + * Should only be accessed in synchronized methods. + */ + private int currentIndex = -1; + + /** + * The proxy currently being used to send the read request. + * Should only be accessed in synchronized methods. + */ + private OMProxyInfo<T> currentProxy; + + /** The last proxy that has been used. Only used for testing. */ + private volatile OMProxyInfo<T> lastProxy = null; + + public HadoopRpcOMFollowerReadFailoverProxyProvider( + ConfigurationSource configuration, UserGroupInformation ugi, String omServiceId, Class<T> protocol) + throws IOException { + this(omServiceId, protocol, + new HadoopRpcOMFailoverProxyProvider<>(configuration, ugi, omServiceId, protocol)); + } + + @SuppressWarnings("unchecked") + public HadoopRpcOMFollowerReadFailoverProxyProvider(String omServiceId, Class<T> protocol, Review Comment: Is it the case that it uses follower read only if protocol == OzoneManagerProtocolPB.class? If yes, we don't pass the `protocol` parameter. ########## hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/ha/HadoopRpcOMFailoverProxyProvider.java: ########## @@ -123,7 +123,7 @@ public synchronized ProxyInfo<T> getProxy() { /** * Creates proxy object. */ - protected ProxyInfo<T> createOMProxyIfNeeded(OMProxyInfo<T> omProxyInfo) { + protected synchronized ProxyInfo<T> createOMProxyIfNeeded(OMProxyInfo<T> omProxyInfo) { if (omProxyInfo.proxy == null) { Review Comment: Let merge this first if it is ready. I can update the change for HDDS-14470. ########## hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/ha/HadoopRpcOMFollowerReadFailoverProxyProvider.java: ########## @@ -0,0 +1,414 @@ +/* + * 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.ozone.om.ha; + +import static org.apache.hadoop.ozone.om.ha.OMFailoverProxyProviderBase.getLeaderNotReadyException; +import static org.apache.hadoop.ozone.om.ha.OMFailoverProxyProviderBase.getNotLeaderException; + +import com.google.common.annotations.VisibleForTesting; +import com.google.protobuf.Message; +import com.google.protobuf.RpcController; +import com.google.protobuf.ServiceException; +import java.io.IOException; +import java.io.InterruptedIOException; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.lang.reflect.Proxy; +import java.util.List; +import org.apache.hadoop.hdds.conf.ConfigurationSource; +import org.apache.hadoop.io.retry.FailoverProxyProvider; +import org.apache.hadoop.io.retry.RetryPolicy; +import org.apache.hadoop.ipc_.Client.ConnectionId; +import org.apache.hadoop.ipc_.RPC; +import org.apache.hadoop.ipc_.RpcInvocationHandler; +import org.apache.hadoop.ipc_.RpcNoSuchProtocolException; +import org.apache.hadoop.ozone.OmUtils; +import org.apache.hadoop.ozone.om.exceptions.OMLeaderNotReadyException; +import org.apache.hadoop.ozone.om.exceptions.OMNotLeaderException; +import org.apache.hadoop.ozone.om.protocolPB.OzoneManagerProtocolPB; +import org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.OMRequest; +import org.apache.hadoop.security.UserGroupInformation; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A {@link org.apache.hadoop.io.retry.FailoverProxyProvider} implementation + * that supports reading from follower OM(s) (i.e. non-leader OMs also includes + * OM listeners). + * <p> + * This constructs a wrapper proxy might send the read request to follower + * OM(s), if follower read is enabled. It will try to send read requests + * to the first OM node. If RPC failed, it will try to failover to the next OM node. + * It will fail back to the leader OM after it has exhausted all the OMs. + * TODO: Currently the logic does not prioritize forwarding to followers since + * it requires an extra RPC latency to check the OM role info. + * In the future, we can try to try to pick the followers before forwarding + * the request to the leader (similar to ObserverReadProxyProvider). + * <p> + * Read and write requests will still be sent to leader OM if reading from + * follower is disabled. + */ +public class HadoopRpcOMFollowerReadFailoverProxyProvider<T> implements FailoverProxyProvider<T> { + @VisibleForTesting + public static final Logger LOG = LoggerFactory.getLogger(HadoopRpcOMFollowerReadFailoverProxyProvider.class); + + private final Class<T> protocolClass; + + /** The inner proxy provider used for leader-based failover. */ + private final HadoopRpcOMFailoverProxyProvider<T> failoverProxy; + + /** The combined proxy which redirects to other proxies as necessary. */ + private final ProxyInfo<T> combinedProxy; + + /** + * Whether reading from follower is enabled. If this is false, all read + * requests will still go to OM leader. + */ + private volatile boolean followerReadEnabled; + + /** + * The current index of the underlying leader-based proxy provider's omNodesInOrder currently being used. + * Should only be accessed in synchronized methods. + */ + private int currentIndex = -1; + + /** + * The proxy currently being used to send the read request. + * Should only be accessed in synchronized methods. + */ + private OMProxyInfo<T> currentProxy; + + /** The last proxy that has been used. Only used for testing. */ + private volatile OMProxyInfo<T> lastProxy = null; + + public HadoopRpcOMFollowerReadFailoverProxyProvider( + ConfigurationSource configuration, UserGroupInformation ugi, String omServiceId, Class<T> protocol) + throws IOException { + this(omServiceId, protocol, + new HadoopRpcOMFailoverProxyProvider<>(configuration, ugi, omServiceId, protocol)); + } + + @SuppressWarnings("unchecked") + public HadoopRpcOMFollowerReadFailoverProxyProvider(String omServiceId, Class<T> protocol, + HadoopRpcOMFailoverProxyProvider<T> failoverProxy) throws IOException { + this.protocolClass = protocol; + this.failoverProxy = failoverProxy; + + // Create a wrapped proxy containing all the proxies. Since this combined + // proxy is just redirecting to other proxies, all invocations can share it. + StringBuilder combinedInfo = new StringBuilder("["); + for (int i = 0; i < failoverProxy.getOMProxies().size(); i++) { + if (i > 0) { + combinedInfo.append(','); + } + combinedInfo.append(failoverProxy.getOMProxies().get(i).proxyInfo); + } + combinedInfo.append(']'); + T wrappedProxy = (T) Proxy.newProxyInstance( + FollowerReadInvocationHandler.class.getClassLoader(), + new Class<?>[] {protocol}, new FollowerReadInvocationHandler()); + combinedProxy = new ProxyInfo<>(wrappedProxy, combinedInfo.toString()); + + if (wrappedProxy instanceof OzoneManagerProtocolPB) { + this.followerReadEnabled = true; + } else { + LOG.debug("Disabling follower reads for {} because the requested proxy " + + "class does not implement {}", omServiceId, OzoneManagerProtocolPB.class.getName()); + this.followerReadEnabled = false; + } + } + + @Override + public Class<T> getInterface() { + return protocolClass; + } + + @Override + public ProxyInfo<T> getProxy() { + return combinedProxy; + } + + @Override + public void performFailover(T currProxy) { + // Since FollowerReadInvocationHandler might user or fallback to leader-based failover logic, + // we should delegate the failover logic to the leader's failover. + failoverProxy.performFailover(currProxy); + } + + public RetryPolicy getRetryPolicy(int maxFailovers) { + // We use the OMFailoverProxyProviderBase's RetryPolicy instead of using our own retry policy + // for a few reasons + // 1. We want to ensure that the retry policy behavior remains the same when we use the leader proxy + // (when follower read is disabled or using write request) + // 2. The FollowerInvocationHandler is also written so that the thrown exception is handled by the + // OMFailoverProxyProviderbase's RetryPolicy + return failoverProxy.getRetryPolicy(maxFailovers); + } + + /** + * Parse the OM request from the request args. + * + * @return parsed OM request. + */ + private static OMRequest parseOMRequest(Object[] args) throws Throwable { + if (args == null || args.length < 2 || !(args[1] instanceof Message)) { + LOG.error("Request failed since OM request is null and cannot be parsed"); + // Throws a non-retriable exception to prevent retry and failover + // See the HddsUtils#shouldNotFailoverOnRpcException used in + // OMFailoverProxyProviderBase#shouldFailover + throw wrapInServiceException( + new RpcNoSuchProtocolException("OM request is null and cannot be parsed")); + } + final Message theRequest = (Message) args[1]; + return (OMRequest) theRequest; + } + + @VisibleForTesting + void setFollowerReadEnabled(boolean flag) { + this.followerReadEnabled = flag; + } + + @VisibleForTesting + public ProxyInfo<T> getLastProxy() { + return lastProxy; + } + + /** + * Return the currently used proxy. If there is none, first calls + * {@link #changeProxy(OMProxyInfo)} to initialize one. + */ + @VisibleForTesting + public OMProxyInfo<T> getCurrentProxy() { + return changeProxy(null); + } + + /** + * Move to the next proxy in the proxy list. If the OMProxyInfo supplied by + * the caller does not match the current proxy, the call is ignored; this is + * to handle concurrent calls (to avoid changing the proxy multiple times). + * The service state of the newly selected proxy will be updated before + * returning. + * + * @param initial The expected current proxy + * @return The new proxy that should be used. + */ + private synchronized OMProxyInfo<T> changeProxy(OMProxyInfo<T> initial) { + if (currentProxy != initial) { + // Must have been a concurrent modification; ignore the move request + return currentProxy; + } + currentIndex = (currentIndex + 1) % failoverProxy.getOmNodesInOrder().size(); + String currentOmNodeId = failoverProxy.getOmNodesInOrder().get(currentIndex); + currentProxy = (OMProxyInfo<T>) failoverProxy.createOMProxyIfNeeded(currentOmNodeId); + LOG.debug("Changed current proxy from {} to {}", + initial == null ? "none" : initial.proxyInfo, + currentProxy.proxyInfo); + return currentProxy; + } + + /** + * An InvocationHandler to handle incoming requests. This class's invoke + * method contains the primary logic for redirecting to followers. + * <p> + * If follower reads are enabled, attempt to send read operations to the + * current proxy which can be either a leader or follower. If the current + * proxy's OM node fails, adjust the current proxy and return on the next one. + * <p> + * Write requests are always forwarded to the leader. + */ + private class FollowerReadInvocationHandler implements RpcInvocationHandler { + + @Override + public Object invoke(Object proxy, final Method method, final Object[] args) + throws Throwable { + lastProxy = null; + if (method.getDeclaringClass() == Object.class) { Review Comment: Thanks for trying it! Let's keep using Object.class. -- This is an automated message from the Apache Git Service. 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