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/*
 * 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.hbase.client;

import java.util.ArrayList;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A completion service for the RpcRetryingCallerFactory. Keeps the list of the futures, and allows
 * to cancel them all. This means as well that it can be used for a small set of tasks only. 
* Implementation is not Thread safe. CompletedTasks is implemented as a queue, the entry is added * based on the time order. I.e, when the first task completes (whether it is a success or failure), * it is added as a first entry in the queue, the next completed task is added as a second entry in * the queue, ... When iterating through the queue, we know it is based on time order. If the first * completed task succeeds, it is returned. If it is failure, the iteration goes on until it finds a * success. */ @InterfaceAudience.Private public class ResultBoundedCompletionService { private static final Logger LOG = LoggerFactory.getLogger(ResultBoundedCompletionService.class); private final RpcRetryingCallerFactory retryingCallerFactory; private final Executor executor; private final QueueingFuture[] tasks; // all the tasks private final ArrayList completedTasks; // completed tasks private volatile boolean cancelled = false; class QueueingFuture implements RunnableFuture { private final RetryingCallable future; private T result = null; private ExecutionException exeEx = null; private volatile boolean cancelled = false; private final int operationTimeout; private final RpcRetryingCaller retryingCaller; private boolean resultObtained = false; private final int replicaId; // replica id public QueueingFuture(RetryingCallable future, int rpcTimeout, int operationTimeout, int id) { this.future = future; this.operationTimeout = operationTimeout; this.retryingCaller = retryingCallerFactory. newCaller(rpcTimeout); this.replicaId = id; } @SuppressWarnings("unchecked") @Override public void run() { try { if (!cancelled) { result = this.retryingCaller.callWithRetries(future, operationTimeout); resultObtained = true; } } catch (Throwable t) { exeEx = new ExecutionException(t); } finally { synchronized (tasks) { // If this wasn't canceled then store the result. if (!cancelled) { completedTasks.add(QueueingFuture.this); } // Notify just in case there was someone waiting and this was canceled. // That shouldn't happen but better safe than sorry. tasks.notify(); } } } @Override public boolean cancel(boolean mayInterruptIfRunning) { if (resultObtained || exeEx != null) return false; retryingCaller.cancel(); if (future instanceof Cancellable) ((Cancellable) future).cancel(); cancelled = true; return true; } @Override public boolean isCancelled() { return cancelled; } @Override public boolean isDone() { return resultObtained || exeEx != null; } @Override public T get() throws InterruptedException, ExecutionException { try { return get(1000, TimeUnit.DAYS); } catch (TimeoutException e) { throw new RuntimeException("You did wait for 1000 days here?", e); } } @Override public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { synchronized (tasks) { if (resultObtained) { return result; } if (exeEx != null) { throw exeEx; } unit.timedWait(tasks, timeout); } if (resultObtained) { return result; } if (exeEx != null) { throw exeEx; } throw new TimeoutException("timeout=" + timeout + ", " + unit); } public int getReplicaId() { return replicaId; } public ExecutionException getExeEx() { return exeEx; } } @SuppressWarnings("unchecked") public ResultBoundedCompletionService(RpcRetryingCallerFactory retryingCallerFactory, Executor executor, int maxTasks) { this.retryingCallerFactory = retryingCallerFactory; this.executor = executor; this.tasks = new QueueingFuture[maxTasks]; this.completedTasks = new ArrayList<>(maxTasks); } public void submit(RetryingCallable task, int rpcTimeout, int operationTimeout, int id) { QueueingFuture newFuture = new QueueingFuture<>(task, rpcTimeout, operationTimeout, id); // remove trace for runnable because HBASE-25373 and OpenTelemetry do not cover TraceRunnable executor.execute(newFuture); tasks[id] = newFuture; } public QueueingFuture take() throws InterruptedException { synchronized (tasks) { while (!cancelled && (completedTasks.size() < 1)) tasks.wait(); } return completedTasks.get(0); } /** * Poll for the first completed task whether it is a success or execution exception. * @param timeout - time to wait before it times out * @param unit - time unit for timeout */ public QueueingFuture poll(long timeout, TimeUnit unit) throws InterruptedException { return pollForSpecificCompletedTask(timeout, unit, 0); } /** * Poll for the first successfully completed task whose completed order is in startIndex, * endIndex(exclusive) range * @param timeout - time to wait before it times out * @param unit - time unit for timeout * @param startIndex - start index, starting from 0, inclusive * @param endIndex - end index, exclusive * @return If within timeout time, there is no successfully completed task, return null; If all * tasks get execution exception, it will throw out the last execution exception, * otherwise return the first successfully completed task's result. */ public QueueingFuture pollForFirstSuccessfullyCompletedTask(long timeout, TimeUnit unit, int startIndex, int endIndex) throws InterruptedException, CancellationException, ExecutionException { QueueingFuture f; long start, duration; for (int i = startIndex; i < endIndex; i++) { start = EnvironmentEdgeManager.currentTime(); f = pollForSpecificCompletedTask(timeout, unit, i); duration = EnvironmentEdgeManager.currentTime() - start; // Even with operationTimeout less than 0, still loop through the rest as there could // be other completed tasks before operationTimeout. timeout -= duration; if (f == null) { return null; } else if (f.getExeEx() != null) { // we continue here as we need to loop through all the results. if (LOG.isDebugEnabled()) { LOG.debug("Replica " + ((f == null) ? 0 : f.getReplicaId()) + " returns " + f.getExeEx().getCause()); } if (i == (endIndex - 1)) { // Rethrow this exception throw f.getExeEx(); } continue; } return f; } return null; } /** * Poll for the Nth completed task (index starts from 0 (the 1st), 1 (the second)...) * @param timeout - time to wait before it times out * @param unit - time unit for timeout * @param index - the index(th) completed task, index starting from 0 */ private QueueingFuture pollForSpecificCompletedTask(long timeout, TimeUnit unit, int index) throws InterruptedException { if (index < 0) { return null; } synchronized (tasks) { if (!cancelled && (completedTasks.size() <= index)) unit.timedWait(tasks, timeout); if (completedTasks.size() <= index) return null; } return completedTasks.get(index); } public void cancelAll() { // Grab the lock on tasks so that cancelled is visible everywhere synchronized (tasks) { cancelled = true; } for (QueueingFuture future : tasks) { if (future != null) future.cancel(true); } } }




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