| /** |
| * 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.util; |
| |
| import com.google.common.util.concurrent.ForwardingListeningExecutorService; |
| import com.google.common.util.concurrent.Futures; |
| import com.google.common.util.concurrent.ListenableFuture; |
| import com.google.common.util.concurrent.ListeningExecutorService; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.Semaphore; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| |
| /** |
| * This ExecutorService blocks the submission of new tasks when its queue is |
| * already full by using a semaphore. Task submissions require permits, task |
| * completions release permits. |
| * <p> |
| * This is a refactoring of {@link BlockingThreadPoolExecutorService}; that code |
| * contains the thread pool logic, whereas this isolates the semaphore |
| * and submit logic for use with other thread pools and delegation models. |
| * <p> |
| * This is inspired by <a href="https://github.com/apache/incubator-s4/blob/master/subprojects/s4-comm/src/main/java/org/apache/s4/comm/staging/BlockingThreadPoolExecutorService.java"> |
| * this s4 threadpool</a> |
| */ |
| @SuppressWarnings("NullableProblems") |
| @InterfaceAudience.Private |
| public class SemaphoredDelegatingExecutor extends |
| ForwardingListeningExecutorService { |
| |
| private final Semaphore queueingPermits; |
| private final ListeningExecutorService executorDelegatee; |
| private final int permitCount; |
| |
| /** |
| * Instantiate. |
| * @param executorDelegatee Executor to delegate to |
| * @param permitCount number of permits into the queue permitted |
| * @param fair should the semaphore be "fair" |
| */ |
| public SemaphoredDelegatingExecutor( |
| ListeningExecutorService executorDelegatee, |
| int permitCount, |
| boolean fair) { |
| this.permitCount = permitCount; |
| queueingPermits = new Semaphore(permitCount, fair); |
| this.executorDelegatee = executorDelegatee; |
| } |
| |
| @Override |
| protected ListeningExecutorService delegate() { |
| return executorDelegatee; |
| } |
| |
| |
| @Override |
| public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) |
| throws InterruptedException { |
| throw new RuntimeException("Not implemented"); |
| } |
| |
| @Override |
| public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, |
| long timeout, TimeUnit unit) throws InterruptedException { |
| throw new RuntimeException("Not implemented"); |
| } |
| |
| @Override |
| public <T> T invokeAny(Collection<? extends Callable<T>> tasks) |
| throws InterruptedException, ExecutionException { |
| throw new RuntimeException("Not implemented"); |
| } |
| |
| @Override |
| public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, |
| TimeUnit unit) |
| throws InterruptedException, ExecutionException, TimeoutException { |
| throw new RuntimeException("Not implemented"); |
| } |
| |
| @Override |
| public <T> ListenableFuture<T> submit(Callable<T> task) { |
| try { |
| queueingPermits.acquire(); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| return Futures.immediateFailedCheckedFuture(e); |
| } |
| return super.submit(new CallableWithPermitRelease<>(task)); |
| } |
| |
| @Override |
| public <T> ListenableFuture<T> submit(Runnable task, T result) { |
| try { |
| queueingPermits.acquire(); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| return Futures.immediateFailedCheckedFuture(e); |
| } |
| return super.submit(new RunnableWithPermitRelease(task), result); |
| } |
| |
| @Override |
| public ListenableFuture<?> submit(Runnable task) { |
| try { |
| queueingPermits.acquire(); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| return Futures.immediateFailedCheckedFuture(e); |
| } |
| return super.submit(new RunnableWithPermitRelease(task)); |
| } |
| |
| @Override |
| public void execute(Runnable command) { |
| try { |
| queueingPermits.acquire(); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| } |
| super.execute(new RunnableWithPermitRelease(command)); |
| } |
| |
| /** |
| * Get the number of permits available; guaranteed to be |
| * {@code 0 <= availablePermits <= size}. |
| * @return the number of permits available at the time of invocation. |
| */ |
| public int getAvailablePermits() { |
| return queueingPermits.availablePermits(); |
| } |
| |
| /** |
| * Get the number of threads waiting to acquire a permit. |
| * @return snapshot of the length of the queue of blocked threads. |
| */ |
| public int getWaitingCount() { |
| return queueingPermits.getQueueLength(); |
| } |
| |
| /** |
| * Total number of permits. |
| * @return the number of permits as set in the constructor |
| */ |
| public int getPermitCount() { |
| return permitCount; |
| } |
| |
| @Override |
| public String toString() { |
| final StringBuilder sb = new StringBuilder( |
| "SemaphoredDelegatingExecutor{"); |
| sb.append("permitCount=").append(getPermitCount()); |
| sb.append(", available=").append(getAvailablePermits()); |
| sb.append(", waiting=").append(getWaitingCount()); |
| sb.append('}'); |
| return sb.toString(); |
| } |
| |
| /** |
| * Releases a permit after the task is executed. |
| */ |
| class RunnableWithPermitRelease implements Runnable { |
| |
| private Runnable delegatee; |
| |
| RunnableWithPermitRelease(Runnable delegatee) { |
| this.delegatee = delegatee; |
| } |
| |
| @Override |
| public void run() { |
| try { |
| delegatee.run(); |
| } finally { |
| queueingPermits.release(); |
| } |
| |
| } |
| } |
| |
| /** |
| * Releases a permit after the task is completed. |
| */ |
| class CallableWithPermitRelease<T> implements Callable<T> { |
| |
| private Callable<T> delegatee; |
| |
| CallableWithPermitRelease(Callable<T> delegatee) { |
| this.delegatee = delegatee; |
| } |
| |
| @Override |
| public T call() throws Exception { |
| try { |
| return delegatee.call(); |
| } finally { |
| queueingPermits.release(); |
| } |
| } |
| |
| } |
| |
| } |