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Posted to common-commits@hadoop.apache.org by in...@apache.org on 2017/09/02 21:21:20 UTC
[36/48] hadoop git commit: HDFS-11546. Federation Router RPC server.
Contributed by Jason Kace and Inigo Goiri.
http://git-wip-us.apache.org/repos/asf/hadoop/blob/5da7d3f4/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java
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diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java
new file mode 100644
index 0000000..3a32be1
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java
@@ -0,0 +1,856 @@
+/**
+ * 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.server.federation.router;
+
+import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.net.InetSocketAddress;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.ThreadFactory;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
+import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.server.federation.resolver.ActiveNamenodeResolver;
+import org.apache.hadoop.hdfs.server.federation.resolver.FederationNamenodeContext;
+import org.apache.hadoop.hdfs.server.federation.resolver.RemoteLocation;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+import org.apache.hadoop.io.retry.RetryPolicy.RetryAction.RetryDecision;
+import org.apache.hadoop.ipc.RemoteException;
+import org.apache.hadoop.ipc.StandbyException;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+
+/**
+ * A client proxy for Router -> NN communication using the NN ClientProtocol.
+ * <p>
+ * Provides routers to invoke remote ClientProtocol methods and handle
+ * retries/failover.
+ * <ul>
+ * <li>invokeSingle Make a single request to a single namespace
+ * <li>invokeSequential Make a sequential series of requests to multiple
+ * ordered namespaces until a condition is met.
+ * <li>invokeConcurrent Make concurrent requests to multiple namespaces and
+ * return all of the results.
+ * </ul>
+ * Also maintains a cached pool of connections to NNs. Connections are managed
+ * by the ConnectionManager and are unique to each user + NN. The size of the
+ * connection pool can be configured. Larger pools allow for more simultaneous
+ * requests to a single NN from a single user.
+ */
+public class RouterRpcClient {
+
+ private static final Logger LOG =
+ LoggerFactory.getLogger(RouterRpcClient.class);
+
+
+ /** Router identifier. */
+ private final String routerId;
+
+ /** Interface to identify the active NN for a nameservice or blockpool ID. */
+ private final ActiveNamenodeResolver namenodeResolver;
+
+ /** Connection pool to the Namenodes per user for performance. */
+ private final ConnectionManager connectionManager;
+ /** Service to run asynchronous calls. */
+ private final ExecutorService executorService;
+ /** Retry policy for router -> NN communication. */
+ private final RetryPolicy retryPolicy;
+
+ /** Pattern to parse a stack trace line. */
+ private static final Pattern STACK_TRACE_PATTERN =
+ Pattern.compile("\\tat (.*)\\.(.*)\\((.*):(\\d*)\\)");
+
+
+ /**
+ * Create a router RPC client to manage remote procedure calls to NNs.
+ *
+ * @param conf Hdfs Configuation.
+ * @param resolver A NN resolver to determine the currently active NN in HA.
+ * @param monitor Optional performance monitor.
+ */
+ public RouterRpcClient(Configuration conf, String identifier,
+ ActiveNamenodeResolver resolver) {
+
+ this.routerId = identifier;
+
+ this.namenodeResolver = resolver;
+
+ this.connectionManager = new ConnectionManager(conf);
+ this.connectionManager.start();
+
+ ThreadFactory threadFactory = new ThreadFactoryBuilder()
+ .setNameFormat("RPC Router Client-%d")
+ .build();
+ this.executorService = Executors.newCachedThreadPool(threadFactory);
+
+ int maxFailoverAttempts = conf.getInt(
+ HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_KEY,
+ HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_DEFAULT);
+ int maxRetryAttempts = conf.getInt(
+ HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_KEY,
+ HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_DEFAULT);
+ int failoverSleepBaseMillis = conf.getInt(
+ HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_KEY,
+ HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_DEFAULT);
+ int failoverSleepMaxMillis = conf.getInt(
+ HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_KEY,
+ HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_DEFAULT);
+ this.retryPolicy = RetryPolicies.failoverOnNetworkException(
+ RetryPolicies.TRY_ONCE_THEN_FAIL, maxFailoverAttempts, maxRetryAttempts,
+ failoverSleepBaseMillis, failoverSleepMaxMillis);
+ }
+
+ /**
+ * Shutdown the client.
+ */
+ public void shutdown() {
+ if (this.connectionManager != null) {
+ this.connectionManager.close();
+ }
+ if (this.executorService != null) {
+ this.executorService.shutdownNow();
+ }
+ }
+
+ /**
+ * Total number of available sockets between the router and NNs.
+ *
+ * @return Number of namenode clients.
+ */
+ public int getNumConnections() {
+ return this.connectionManager.getNumConnections();
+ }
+
+ /**
+ * Total number of available sockets between the router and NNs.
+ *
+ * @return Number of namenode clients.
+ */
+ public int getNumActiveConnections() {
+ return this.connectionManager.getNumActiveConnections();
+ }
+
+ /**
+ * Total number of open connection pools to a NN. Each connection pool.
+ * represents one user + one NN.
+ *
+ * @return Number of connection pools.
+ */
+ public int getNumConnectionPools() {
+ return this.connectionManager.getNumConnectionPools();
+ }
+
+ /**
+ * Number of connections between the router and NNs being created sockets.
+ *
+ * @return Number of connections waiting to be created.
+ */
+ public int getNumCreatingConnections() {
+ return this.connectionManager.getNumCreatingConnections();
+ }
+
+ /**
+ * Get ClientProtocol proxy client for a NameNode. Each combination of user +
+ * NN must use a unique proxy client. Previously created clients are cached
+ * and stored in a connection pool by the ConnectionManager.
+ *
+ * @param ugi User group information.
+ * @param nsId Nameservice identifier.
+ * @param rpcAddress ClientProtocol RPC server address of the NN.
+ * @return ConnectionContext containing a ClientProtocol proxy client for the
+ * NN + current user.
+ * @throws IOException If we cannot get a connection to the NameNode.
+ */
+ private ConnectionContext getConnection(
+ UserGroupInformation ugi, String nsId, String rpcAddress)
+ throws IOException {
+ ConnectionContext connection = null;
+ try {
+ // Each proxy holds the UGI info for the current user when it is created.
+ // This cache does not scale very well, one entry per user per namenode,
+ // and may need to be adjusted and/or selectively pruned. The cache is
+ // important due to the excessive overhead of creating a new proxy wrapper
+ // for each individual request.
+
+ // TODO Add tokens from the federated UGI
+ connection = this.connectionManager.getConnection(ugi, rpcAddress);
+ LOG.debug("User {} NN {} is using connection {}",
+ ugi.getUserName(), rpcAddress, connection);
+ } catch (Exception ex) {
+ LOG.error("Cannot open NN client to address: {}", rpcAddress, ex);
+ }
+
+ if (connection == null) {
+ throw new IOException("Cannot get a connection to " + rpcAddress);
+ }
+ return connection;
+ }
+
+ /**
+ * Convert an exception to an IOException.
+ *
+ * For a non-IOException, wrap it with IOException. For a RemoteException,
+ * unwrap it. For an IOException which is not a RemoteException, return it.
+ *
+ * @param e Exception to convert into an exception.
+ * @return Created IO exception.
+ */
+ private static IOException toIOException(Exception e) {
+ if (e instanceof RemoteException) {
+ return ((RemoteException) e).unwrapRemoteException();
+ }
+ if (e instanceof IOException) {
+ return (IOException)e;
+ }
+ return new IOException(e);
+ }
+
+ /**
+ * If we should retry the RPC call.
+ *
+ * @param ex Exception reported.
+ * @param retryCount Number of retries.
+ * @return Retry decision.
+ * @throws IOException Original exception if the retry policy generates one.
+ */
+ private RetryDecision shouldRetry(final IOException ioe, final int retryCount)
+ throws IOException {
+ try {
+ final RetryPolicy.RetryAction a =
+ this.retryPolicy.shouldRetry(ioe, retryCount, 0, true);
+ return a.action;
+ } catch (Exception ex) {
+ LOG.error("Re-throwing API exception, no more retries", ex);
+ throw toIOException(ex);
+ }
+ }
+
+ /**
+ * Invokes a method against the ClientProtocol proxy server. If a standby
+ * exception is generated by the call to the client, retries using the
+ * alternate server.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param ugi User group information.
+ * @param namenodes A prioritized list of namenodes within the same
+ * nameservice.
+ * @param method Remote ClientProtcol method to invoke.
+ * @param params Variable list of parameters matching the method.
+ * @return The result of invoking the method.
+ * @throws IOException
+ */
+ private Object invokeMethod(
+ final UserGroupInformation ugi,
+ final List<? extends FederationNamenodeContext> namenodes,
+ final Method method, final Object... params) throws IOException {
+
+ if (namenodes == null || namenodes.isEmpty()) {
+ throw new IOException("No namenodes to invoke " + method.getName() +
+ " with params " + Arrays.toString(params) + " from " + this.routerId);
+ }
+
+ Object ret = null;
+ boolean failover = false;
+ Map<FederationNamenodeContext, IOException> ioes = new LinkedHashMap<>();
+ for (FederationNamenodeContext namenode : namenodes) {
+ ConnectionContext connection = null;
+ try {
+ String nsId = namenode.getNameserviceId();
+ String rpcAddress = namenode.getRpcAddress();
+ connection = this.getConnection(ugi, nsId, rpcAddress);
+ ProxyAndInfo<ClientProtocol> client = connection.getClient();
+ ClientProtocol proxy = client.getProxy();
+ ret = invoke(0, method, proxy, params);
+ if (failover) {
+ // Success on alternate server, update
+ InetSocketAddress address = client.getAddress();
+ namenodeResolver.updateActiveNamenode(nsId, address);
+ }
+ return ret;
+ } catch (IOException ioe) {
+ ioes.put(namenode, ioe);
+ if (ioe instanceof StandbyException) {
+ // Fail over indicated by retry policy and/or NN
+ failover = true;
+ } else if (ioe instanceof RemoteException) {
+ // RemoteException returned by NN
+ throw (RemoteException) ioe;
+ } else {
+ // Other communication error, this is a failure
+ // Communication retries are handled by the retry policy
+ throw ioe;
+ }
+ } finally {
+ if (connection != null) {
+ connection.release();
+ }
+ }
+ }
+
+ // All namenodes were unavailable or in standby
+ String msg = "No namenode available to invoke " + method.getName() + " " +
+ Arrays.toString(params);
+ LOG.error(msg);
+ for (Entry<FederationNamenodeContext, IOException> entry :
+ ioes.entrySet()) {
+ FederationNamenodeContext namenode = entry.getKey();
+ String nsId = namenode.getNameserviceId();
+ String nnId = namenode.getNamenodeId();
+ String addr = namenode.getRpcAddress();
+ IOException ioe = entry.getValue();
+ if (ioe instanceof StandbyException) {
+ LOG.error("{} {} at {} is in Standby", nsId, nnId, addr);
+ } else {
+ LOG.error("{} {} at {} error: \"{}\"",
+ nsId, nnId, addr, ioe.getMessage());
+ }
+ }
+ throw new StandbyException(msg);
+ }
+
+ /**
+ * Invokes a method on the designated object. Catches exceptions specific to
+ * the invocation.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param method Method to invoke
+ * @param obj Target object for the method
+ * @param params Variable parameters
+ * @return Response from the remote server
+ * @throws IOException
+ * @throws InterruptedException
+ */
+ private Object invoke(int retryCount, final Method method, final Object obj,
+ final Object... params) throws IOException {
+ try {
+ return method.invoke(obj, params);
+ } catch (IllegalAccessException e) {
+ LOG.error("Unexpected exception while proxying API", e);
+ return null;
+ } catch (IllegalArgumentException e) {
+ LOG.error("Unexpected exception while proxying API", e);
+ return null;
+ } catch (InvocationTargetException e) {
+ Throwable cause = e.getCause();
+ if (cause instanceof IOException) {
+ IOException ioe = (IOException) cause;
+ // Check if we should retry.
+ RetryDecision decision = shouldRetry(ioe, retryCount);
+ if (decision == RetryDecision.RETRY) {
+ // retry
+ return invoke(++retryCount, method, obj, params);
+ } else if (decision == RetryDecision.FAILOVER_AND_RETRY) {
+ // failover, invoker looks for standby exceptions for failover.
+ if (ioe instanceof StandbyException) {
+ throw ioe;
+ } else {
+ throw new StandbyException(ioe.getMessage());
+ }
+ } else {
+ if (ioe instanceof RemoteException) {
+ RemoteException re = (RemoteException) ioe;
+ ioe = re.unwrapRemoteException();
+ ioe = getCleanException(ioe);
+ }
+ throw ioe;
+ }
+ } else {
+ throw new IOException(e);
+ }
+ }
+ }
+
+ /**
+ * Get a clean copy of the exception. Sometimes the exceptions returned by the
+ * server contain the full stack trace in the message.
+ *
+ * @param ioe Exception to clean up.
+ * @return Copy of the original exception with a clean message.
+ */
+ private static IOException getCleanException(IOException ioe) {
+ IOException ret = null;
+
+ String msg = ioe.getMessage();
+ Throwable cause = ioe.getCause();
+ StackTraceElement[] stackTrace = ioe.getStackTrace();
+
+ // Clean the message by removing the stack trace
+ int index = msg.indexOf("\n");
+ if (index > 0) {
+ String[] msgSplit = msg.split("\n");
+ msg = msgSplit[0];
+
+ // Parse stack trace from the message
+ List<StackTraceElement> elements = new LinkedList<>();
+ for (int i=1; i<msgSplit.length; i++) {
+ String line = msgSplit[i];
+ Matcher matcher = STACK_TRACE_PATTERN.matcher(line);
+ if (matcher.find()) {
+ String declaringClass = matcher.group(1);
+ String methodName = matcher.group(2);
+ String fileName = matcher.group(3);
+ int lineNumber = Integer.parseInt(matcher.group(4));
+ StackTraceElement element = new StackTraceElement(
+ declaringClass, methodName, fileName, lineNumber);
+ elements.add(element);
+ }
+ }
+ stackTrace = elements.toArray(new StackTraceElement[elements.size()]);
+ }
+
+ // Create the new output exception
+ if (ioe instanceof RemoteException) {
+ RemoteException re = (RemoteException)ioe;
+ ret = new RemoteException(re.getClassName(), msg);
+ } else {
+ // Try the simple constructor and initialize the fields
+ Class<? extends IOException> ioeClass = ioe.getClass();
+ try {
+ Constructor<? extends IOException> constructor =
+ ioeClass.getDeclaredConstructor(String.class);
+ ret = constructor.newInstance(msg);
+ } catch (ReflectiveOperationException e) {
+ // If there are errors, just use the input one
+ LOG.error("Could not create exception {}", ioeClass.getSimpleName(), e);
+ ret = ioe;
+ }
+ }
+ if (ret != null) {
+ ret.initCause(cause);
+ ret.setStackTrace(stackTrace);
+ }
+
+ return ret;
+ }
+
+ /**
+ * Invokes a ClientProtocol method. Determines the target nameservice via a
+ * provided block.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param block Block used to determine appropriate nameservice.
+ * @param method The remote method and parameters to invoke.
+ * @return The result of invoking the method.
+ * @throws IOException
+ */
+ public Object invokeSingle(final ExtendedBlock block, RemoteMethod method)
+ throws IOException {
+ String bpId = block.getBlockPoolId();
+ return invokeSingleBlockPool(bpId, method);
+ }
+
+ /**
+ * Invokes a ClientProtocol method. Determines the target nameservice using
+ * the block pool id.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param bpId Block pool identifier.
+ * @param method The remote method and parameters to invoke.
+ * @return The result of invoking the method.
+ * @throws IOException
+ */
+ public Object invokeSingleBlockPool(final String bpId, RemoteMethod method)
+ throws IOException {
+ String nsId = getNameserviceForBlockPoolId(bpId);
+ return invokeSingle(nsId, method);
+ }
+
+ /**
+ * Invokes a ClientProtocol method against the specified namespace.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param nsId Target namespace for the method.
+ * @param method The remote method and parameters to invoke.
+ * @return The result of invoking the method.
+ * @throws IOException
+ */
+ public Object invokeSingle(final String nsId, RemoteMethod method)
+ throws IOException {
+ UserGroupInformation ugi = RouterRpcServer.getRemoteUser();
+ List<? extends FederationNamenodeContext> nns =
+ getNamenodesForNameservice(nsId);
+ RemoteLocationContext loc = new RemoteLocation(nsId, "/");
+ return invokeMethod(ugi, nns, method.getMethod(), method.getParams(loc));
+ }
+
+ /**
+ * Invokes a single proxy call for a single location.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param location RemoteLocation to invoke.
+ * @param remoteMethod The remote method and parameters to invoke.
+ * @return The result of invoking the method if successful.
+ * @throws IOException
+ */
+ public Object invokeSingle(final RemoteLocationContext location,
+ RemoteMethod remoteMethod) throws IOException {
+ List<RemoteLocationContext> locations = Collections.singletonList(location);
+ return invokeSequential(locations, remoteMethod);
+ }
+
+ /**
+ * Invokes sequential proxy calls to different locations. Continues to invoke
+ * calls until a call returns without throwing a remote exception.
+ *
+ * @param locations List of locations/nameservices to call concurrently.
+ * @param remoteMethod The remote method and parameters to invoke.
+ * @return The result of the first successful call, or if no calls are
+ * successful, the result of the last RPC call executed.
+ * @throws IOException if the success condition is not met and one of the RPC
+ * calls generated a remote exception.
+ */
+ public Object invokeSequential(
+ final List<? extends RemoteLocationContext> locations,
+ final RemoteMethod remoteMethod) throws IOException {
+ return invokeSequential(locations, remoteMethod, null, null);
+ }
+
+ /**
+ * Invokes sequential proxy calls to different locations. Continues to invoke
+ * calls until the success condition is met, or until all locations have been
+ * attempted.
+ *
+ * The success condition may be specified by:
+ * <ul>
+ * <li>An expected result class
+ * <li>An expected result value
+ * </ul>
+ *
+ * If no expected result class/values are specified, the success condition is
+ * a call that does not throw a remote exception.
+ *
+ * @param locations List of locations/nameservices to call concurrently.
+ * @param remoteMethod The remote method and parameters to invoke.
+ * @param expectedResultClass In order to be considered a positive result, the
+ * return type must be of this class.
+ * @param expectedResultValue In order to be considered a positive result, the
+ * return value must equal the value of this object.
+ * @return The result of the first successful call, or if no calls are
+ * successful, the result of the first RPC call executed.
+ * @throws IOException if the success condition is not met, return the first
+ * remote exception generated.
+ */
+ public Object invokeSequential(
+ final List<? extends RemoteLocationContext> locations,
+ final RemoteMethod remoteMethod, Class<?> expectedResultClass,
+ Object expectedResultValue) throws IOException {
+
+ final UserGroupInformation ugi = RouterRpcServer.getRemoteUser();
+ final Method m = remoteMethod.getMethod();
+ IOException firstThrownException = null;
+ IOException lastThrownException = null;
+ Object firstResult = null;
+ // Invoke in priority order
+ for (final RemoteLocationContext loc : locations) {
+ String ns = loc.getNameserviceId();
+ List<? extends FederationNamenodeContext> namenodes =
+ getNamenodesForNameservice(ns);
+ try {
+ Object[] params = remoteMethod.getParams(loc);
+ Object result = invokeMethod(ugi, namenodes, m, params);
+ // Check if the result is what we expected
+ if (isExpectedClass(expectedResultClass, result) &&
+ isExpectedValue(expectedResultValue, result)) {
+ // Valid result, stop here
+ return result;
+ }
+ if (firstResult == null) {
+ firstResult = result;
+ }
+ } catch (IOException ioe) {
+ // Record it and move on
+ lastThrownException = (IOException) ioe;
+ if (firstThrownException == null) {
+ firstThrownException = lastThrownException;
+ }
+ } catch (Exception e) {
+ // Unusual error, ClientProtocol calls always use IOException (or
+ // RemoteException). Re-wrap in IOException for compatibility with
+ // ClientProtcol.
+ LOG.error("Unexpected exception {} proxying {} to {}",
+ e.getClass(), m.getName(), ns, e);
+ lastThrownException = new IOException(
+ "Unexpected exception proxying API " + e.getMessage(), e);
+ if (firstThrownException == null) {
+ firstThrownException = lastThrownException;
+ }
+ }
+ }
+
+ if (firstThrownException != null) {
+ // re-throw the last exception thrown for compatibility
+ throw firstThrownException;
+ }
+ // Return the last result, whether it is the value we are looking for or a
+ return firstResult;
+ }
+
+ /**
+ * Checks if a result matches the required result class.
+ *
+ * @param expectedResultClass Required result class, null to skip the check.
+ * @param result The result to check.
+ * @return True if the result is an instance of the required class or if the
+ * expected class is null.
+ */
+ private static boolean isExpectedClass(Class<?> expectedClass, Object clazz) {
+ if (expectedClass == null) {
+ return true;
+ } else if (clazz == null) {
+ return false;
+ } else {
+ return expectedClass.isInstance(clazz);
+ }
+ }
+
+ /**
+ * Checks if a result matches the expected value.
+ *
+ * @param expectedResultValue The expected value, null to skip the check.
+ * @param result The result to check.
+ * @return True if the result is equals to the expected value or if the
+ * expected value is null.
+ */
+ private static boolean isExpectedValue(Object expectedValue, Object value) {
+ if (expectedValue == null) {
+ return true;
+ } else if (value == null) {
+ return false;
+ } else {
+ return value.equals(expectedValue);
+ }
+ }
+
+ /**
+ * Invokes multiple concurrent proxy calls to different clients. Returns an
+ * array of results.
+ *
+ * Re-throws exceptions generated by the remote RPC call as either
+ * RemoteException or IOException.
+ *
+ * @param locations List of remote locations to call concurrently.
+ * @param remoteMethod The remote method and parameters to invoke.
+ * @param requireResponse If true an exception will be thrown if all calls do
+ * not complete. If false exceptions are ignored and all data results
+ * successfully received are returned.
+ * @param standby If the requests should go to the standby namenodes too.
+ * @return Result of invoking the method per subcluster: nsId -> result.
+ * @throws IOException If requiredResponse=true and any of the calls throw an
+ * exception.
+ */
+ @SuppressWarnings("unchecked")
+ public <T extends RemoteLocationContext> Map<T, Object> invokeConcurrent(
+ final Collection<T> locations, final RemoteMethod method,
+ boolean requireResponse, boolean standby) throws IOException {
+
+ final UserGroupInformation ugi = RouterRpcServer.getRemoteUser();
+ final Method m = method.getMethod();
+
+ if (locations.size() == 1) {
+ // Shortcut, just one call
+ T location = locations.iterator().next();
+ String ns = location.getNameserviceId();
+ final List<? extends FederationNamenodeContext> namenodes =
+ getNamenodesForNameservice(ns);
+ Object[] paramList = method.getParams(location);
+ Object result = invokeMethod(ugi, namenodes, m, paramList);
+ return Collections.singletonMap(location, result);
+ }
+
+ List<T> orderedLocations = new LinkedList<>();
+ Set<Callable<Object>> callables = new HashSet<>();
+ for (final T location : locations) {
+ String nsId = location.getNameserviceId();
+ final List<? extends FederationNamenodeContext> namenodes =
+ getNamenodesForNameservice(nsId);
+ final Object[] paramList = method.getParams(location);
+ if (standby) {
+ // Call the objectGetter to all NNs (including standby)
+ for (final FederationNamenodeContext nn : namenodes) {
+ String nnId = nn.getNamenodeId();
+ final List<FederationNamenodeContext> nnList =
+ Collections.singletonList(nn);
+ T nnLocation = location;
+ if (location instanceof RemoteLocation) {
+ nnLocation = (T)new RemoteLocation(nsId, nnId, location.getDest());
+ }
+ orderedLocations.add(nnLocation);
+ callables.add(new Callable<Object>() {
+ public Object call() throws Exception {
+ return invokeMethod(ugi, nnList, m, paramList);
+ }
+ });
+ }
+ } else {
+ // Call the objectGetter in order of nameservices in the NS list
+ orderedLocations.add(location);
+ callables.add(new Callable<Object>() {
+ public Object call() throws Exception {
+ return invokeMethod(ugi, namenodes, m, paramList);
+ }
+ });
+ }
+ }
+
+ try {
+ List<Future<Object>> futures = executorService.invokeAll(callables);
+ Map<T, Object> results = new TreeMap<>();
+ Map<T, IOException> exceptions = new TreeMap<>();
+ for (int i=0; i<futures.size(); i++) {
+ T location = orderedLocations.get(i);
+ try {
+ Future<Object> future = futures.get(i);
+ Object result = future.get();
+ results.put(location, result);
+ } catch (ExecutionException ex) {
+ Throwable cause = ex.getCause();
+ LOG.debug("Canot execute {} in {}: {}",
+ m.getName(), location, cause.getMessage());
+
+ // Convert into IOException if needed
+ IOException ioe = null;
+ if (cause instanceof IOException) {
+ ioe = (IOException) cause;
+ } else {
+ ioe = new IOException("Unhandled exception while proxying API " +
+ m.getName() + ": " + cause.getMessage(), cause);
+ }
+
+ // Response from all servers required, use this error.
+ if (requireResponse) {
+ throw ioe;
+ }
+
+ // Store the exceptions
+ exceptions.put(location, ioe);
+ }
+ }
+
+ // Throw the exception for the first location if there are no results
+ if (results.isEmpty()) {
+ T location = orderedLocations.get(0);
+ IOException ioe = exceptions.get(location);
+ if (ioe != null) {
+ throw ioe;
+ }
+ }
+
+ return results;
+ } catch (InterruptedException ex) {
+ LOG.error("Unexpected error while invoking API: {}", ex.getMessage());
+ throw new IOException(
+ "Unexpected error while invoking API " + ex.getMessage(), ex);
+ }
+ }
+
+ /**
+ * Get a prioritized list of NNs that share the same nameservice ID (in the
+ * same namespace). NNs that are reported as ACTIVE will be first in the list.
+ *
+ * @param nameserviceId The nameservice ID for the namespace.
+ * @return A prioritized list of NNs to use for communication.
+ * @throws IOException If a NN cannot be located for the nameservice ID.
+ */
+ private List<? extends FederationNamenodeContext> getNamenodesForNameservice(
+ final String nsId) throws IOException {
+
+ final List<? extends FederationNamenodeContext> namenodes =
+ namenodeResolver.getNamenodesForNameserviceId(nsId);
+
+ if (namenodes == null || namenodes.isEmpty()) {
+ throw new IOException("Cannot locate a registered namenode for " + nsId +
+ " from " + this.routerId);
+ }
+ return namenodes;
+ }
+
+ /**
+ * Get a prioritized list of NNs that share the same block pool ID (in the
+ * same namespace). NNs that are reported as ACTIVE will be first in the list.
+ *
+ * @param blockPoolId The blockpool ID for the namespace.
+ * @return A prioritized list of NNs to use for communication.
+ * @throws IOException If a NN cannot be located for the block pool ID.
+ */
+ private List<? extends FederationNamenodeContext> getNamenodesForBlockPoolId(
+ final String bpId) throws IOException {
+
+ List<? extends FederationNamenodeContext> namenodes =
+ namenodeResolver.getNamenodesForBlockPoolId(bpId);
+
+ if (namenodes == null || namenodes.isEmpty()) {
+ throw new IOException("Cannot locate a registered namenode for " + bpId +
+ " from " + this.routerId);
+ }
+ return namenodes;
+ }
+
+ /**
+ * Get the nameservice identifier for a block pool.
+ *
+ * @param bpId Identifier of the block pool.
+ * @return Nameservice identifier.
+ * @throws IOException If a NN cannot be located for the block pool ID.
+ */
+ private String getNameserviceForBlockPoolId(final String bpId)
+ throws IOException {
+ List<? extends FederationNamenodeContext> namenodes =
+ getNamenodesForBlockPoolId(bpId);
+ FederationNamenodeContext namenode = namenodes.get(0);
+ return namenode.getNameserviceId();
+ }
+}
\ No newline at end of file
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