org.springframework.integration.util.CallerBlocksPolicy.java Source code

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Here is the source code for org.springframework.integration.util.CallerBlocksPolicy.java

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/*
 * Copyright 2014-2016 the original author or authors.
 *
 * Licensed 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.springframework.integration.util;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A {@link RejectedExecutionHandler} that blocks the caller until
 * the executor has room in its queue, or a timeout occurs (in which
 * case a {@link RejectedExecutionException} is thrown.
 *
 * @author Gary Russell
 * @since 3.0.3
 *
 */
public class CallerBlocksPolicy implements RejectedExecutionHandler {

    private static final Log logger = LogFactory.getLog(CallerBlocksPolicy.class);

    private final long maxWait;

    /**
     * @param maxWait The maximum time to wait for a queue slot to be
     * available, in milliseconds.
     */
    public CallerBlocksPolicy(long maxWait) {
        this.maxWait = maxWait;
    }

    @Override
    public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
        if (!executor.isShutdown()) {
            try {
                BlockingQueue<Runnable> queue = executor.getQueue();
                if (logger.isDebugEnabled()) {
                    logger.debug("Attempting to queue task execution for " + this.maxWait + " milliseconds");
                }
                if (!queue.offer(r, this.maxWait, TimeUnit.MILLISECONDS)) {
                    throw new RejectedExecutionException("Max wait time expired to queue task");
                }
                if (logger.isDebugEnabled()) {
                    logger.debug("Task execution queued");
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new RejectedExecutionException("Interrupted", e);
            }
        } else {
            throw new RejectedExecutionException("Executor has been shut down");
        }
    }

}