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/*
* Licensed to Metamarkets Group Inc. (Metamarkets) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Metamarkets 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 io.druid.java.util.common;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Throwables;
import io.druid.java.util.common.logger.Logger;
import java.util.concurrent.Callable;
import java.util.concurrent.ThreadLocalRandom;
public class RetryUtils
{
public static final Logger log = new Logger(RetryUtils.class);
/**
* Retry an operation using fuzzy exponentially increasing backoff. The wait time after the nth failed attempt is
* min(60000ms, 1000ms * pow(2, n - 1)), fuzzed by a number drawn from a Gaussian distribution with mean 0 and
* standard deviation 0.2.
*
* If maxTries is exhausted, or if shouldRetry returns false, the last exception thrown by "f" will be thrown
* by this function.
*
* @param f the operation
* @param shouldRetry predicate determining whether we should retry after a particular exception thrown by "f"
* @param quietTries first quietTries attempts will log exceptions at DEBUG level rather than WARN
* @param maxTries maximum number of attempts
*
* @return result of the first successful operation
*
* @throws Exception if maxTries is exhausted, or shouldRetry returns false
*/
public static T retry(
final Callable f,
Predicate shouldRetry,
final int quietTries,
final int maxTries
) throws Exception
{
Preconditions.checkArgument(maxTries > 0, "maxTries > 0");
int nTry = 0;
while (true) {
try {
nTry++;
return f.call();
}
catch (Throwable e) {
if (nTry < maxTries && shouldRetry.apply(e)) {
awaitNextRetry(e, nTry, nTry <= quietTries);
} else {
Throwables.propagateIfInstanceOf(e, Exception.class);
throw Throwables.propagate(e);
}
}
}
}
/**
* Same as {@link #retry(Callable, Predicate, int, int)} with quietTries = 0.
*/
public static T retry(final Callable f, Predicate shouldRetry, final int maxTries) throws Exception
{
return retry(f, shouldRetry, 0, maxTries);
}
private static void awaitNextRetry(final Throwable e, final int nTry, final boolean quiet) throws InterruptedException
{
final long baseSleepMillis = 1000;
final long maxSleepMillis = 60000;
final double fuzzyMultiplier = Math.min(Math.max(1 + 0.2 * ThreadLocalRandom.current().nextGaussian(), 0), 2);
final long sleepMillis = (long) (Math.min(maxSleepMillis, baseSleepMillis * Math.pow(2, nTry - 1))
* fuzzyMultiplier);
if (quiet) {
log.debug(e, "Failed on try %d, retrying in %,dms.", nTry, sleepMillis);
} else {
log.warn(e, "Failed on try %d, retrying in %,dms.", nTry, sleepMillis);
}
Thread.sleep(sleepMillis);
}
}
