com.twitter.common.util.RetryingRunnable.java Source code

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Here is the source code for com.twitter.common.util.RetryingRunnable.java

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// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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 com.twitter.common.util;

import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.common.base.Throwables;

import org.apache.commons.lang.builder.ToStringBuilder;

import com.twitter.common.base.ExceptionalCommand;
import com.twitter.common.quantity.Amount;
import com.twitter.common.quantity.Time;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

/**
 * A runnable task that is retried in a user-configurable fashion.
 *
 * @param <E> The type of exception that the ExceptionalCommand throws.
 *
 * @author Utkarsh Srivastava
 */
public class RetryingRunnable<E extends Exception> implements Runnable {
    private final String name;
    private final int tryNum;
    private final int numTries;
    private final Amount<Long, Time> retryDelay;
    private final ExceptionalCommand<E> task;
    private final CommandExecutor commandExecutor;
    private final Class<E> exceptionClass;

    private static final Logger LOG = Logger.getLogger(RetryingRunnable.class.getName());

    /**
     * Create a Task with name {@code name} that executes at most {@code  numTries}
     * in case of failure with an interval of {@code retryDelay} between attempts.
     *
     * @param name Human readable name for this task.
     * @param task the task to execute.
     * @param exceptionClass class of the exception thrown by the task.
     * @param numTries the total number of times to try.
     * @param retryDelay the delay between successive tries.
     * @param commandExecutor Executor to resubmit retries to.
     * @param tryNum the seq number of this try.
     */
    public RetryingRunnable(String name, ExceptionalCommand<E> task, Class<E> exceptionClass, int numTries,
            Amount<Long, Time> retryDelay, CommandExecutor commandExecutor, int tryNum) {

        this.name = checkNotNull(name);
        this.task = checkNotNull(task);
        this.exceptionClass = checkNotNull(exceptionClass);
        this.retryDelay = checkNotNull(retryDelay);
        this.commandExecutor = checkNotNull(commandExecutor);
        checkArgument(numTries > 0);
        this.tryNum = tryNum;
        this.numTries = numTries;
    }

    /**
     * Create a Task with name {@code name} that executes at most {@code numTries}
     * in case of failure with an interval of {@code retryDelay} between attempts
     *  and sets tryNum to be the first (=1).
     *
     * @param name Human readable name for this task.
     * @param task the task to execute.
     * @param exceptionClass class of the exception thrown by the task.
     * @param numTries the total number of times to try.
     * @param retryDelay the delay between successive tries.
     * @param commandExecutor Executor to resubmit retries to.
     */
    public RetryingRunnable(String name, ExceptionalCommand<E> task, Class<E> exceptionClass, int numTries,
            Amount<Long, Time> retryDelay, CommandExecutor commandExecutor) {

        this(name, task, exceptionClass, numTries, retryDelay, commandExecutor, /*tryNum=*/ 1);
    }

    @Override
    public void run() {
        try {
            task.execute();
        } catch (Exception e) {
            if (e.getClass().isAssignableFrom(exceptionClass)) {
                if (tryNum < numTries) {
                    commandExecutor.execute(name, task, exceptionClass, numTries - 1, retryDelay);
                } else {
                    LOG.log(Level.INFO,
                            "Giving up on task: " + name + " " + "after " + "trying " + numTries + " times" + ".",
                            e);
                }
            } else {
                LOG.log(Level.INFO, "Giving up on task: " + name + " after trying " + numTries + " times. "
                        + "due to unhandled exception ", e);
                throw Throwables.propagate(e);
            }
        }
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this).append("name", name).append("tryNum", tryNum).append("numTries", numTries)
                .append("retryDelay", retryDelay).toString();
    }
}