| /* |
| * 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.flink.fs.s3.common.utils; |
| |
| import org.apache.flink.annotation.Internal; |
| import org.apache.flink.util.ExceptionUtils; |
| import org.apache.flink.util.FlinkRuntimeException; |
| |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.Semaphore; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| import static org.apache.flink.util.Preconditions.checkArgument; |
| import static org.apache.flink.util.Preconditions.checkNotNull; |
| |
| /** |
| * An executor decorator that allows only a certain number of concurrent executions. |
| * The {@link #execute(Runnable)} method blocks once that number of executions is exceeded. |
| */ |
| @Internal |
| public final class BackPressuringExecutor implements Executor { |
| |
| /** The executor for the actual execution. */ |
| private final Executor delegate; |
| |
| /** The semaphore to track permits and block until permits are available. */ |
| private final Semaphore permits; |
| |
| public BackPressuringExecutor(Executor delegate, int numConcurrentExecutions) { |
| checkArgument(numConcurrentExecutions > 0, "numConcurrentExecutions must be > 0"); |
| this.delegate = checkNotNull(delegate, "delegate"); |
| this.permits = new Semaphore(numConcurrentExecutions, true); |
| } |
| |
| @Override |
| public void execute(Runnable command) { |
| // To not block interrupts here (faster cancellation) we acquire interruptibly. |
| // Unfortunately, we need to rethrow this as a RuntimeException (suboptimal), because |
| // the method signature does not permit anything else, and we want to maintain the |
| // Executor interface for transparent drop-in. |
| try { |
| permits.acquire(); |
| } |
| catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| throw new FlinkRuntimeException("interrupted:", e); |
| } |
| |
| final SemaphoreReleasingRunnable runnable = new SemaphoreReleasingRunnable(command, permits); |
| try { |
| delegate.execute(runnable); |
| } catch (Throwable e) { |
| runnable.release(); |
| ExceptionUtils.rethrow(e, e.getMessage()); |
| } |
| } |
| |
| // ------------------------------------------------------------------------ |
| |
| private static class SemaphoreReleasingRunnable implements Runnable { |
| |
| private final Runnable delegate; |
| |
| private final Semaphore toRelease; |
| |
| private final AtomicBoolean released = new AtomicBoolean(); |
| |
| SemaphoreReleasingRunnable(Runnable delegate, Semaphore toRelease) { |
| this.delegate = delegate; |
| this.toRelease = toRelease; |
| } |
| |
| @Override |
| public void run() { |
| try { |
| delegate.run(); |
| } |
| finally { |
| release(); |
| } |
| } |
| |
| void release() { |
| if (released.compareAndSet(false, true)) { |
| toRelease.release(); |
| } |
| } |
| } |
| } |