org.apache.hadoop.io.retry.RetryPolicy Maven / Gradle / Ivy
/*
* 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.io.retry;
import org.apache.hadoop.classification.InterfaceStability;
/**
*
* Specifies a policy for retrying method failures.
* Implementations of this interface should be immutable.
*
*/
@InterfaceStability.Evolving
public interface RetryPolicy {
/**
* Returned by {@link RetryPolicy#shouldRetry(Exception, int, int, boolean)}.
*/
@InterfaceStability.Evolving
public static class RetryAction {
// A few common retry policies, with no delays.
public static final RetryAction FAIL =
new RetryAction(RetryDecision.FAIL);
public static final RetryAction RETRY =
new RetryAction(RetryDecision.RETRY);
public static final RetryAction FAILOVER_AND_RETRY =
new RetryAction(RetryDecision.FAILOVER_AND_RETRY);
public final RetryDecision action;
public final long delayMillis;
public final String reason;
public RetryAction(RetryDecision action) {
this(action, 0, null);
}
public RetryAction(RetryDecision action, long delayTime) {
this(action, delayTime, null);
}
public RetryAction(RetryDecision action, long delayTime, String reason) {
this.action = action;
this.delayMillis = delayTime;
this.reason = reason;
}
@Override
public String toString() {
return getClass().getSimpleName() + "(action=" + action
+ ", delayMillis=" + delayMillis + ", reason=" + reason + ")";
}
public enum RetryDecision {
// Ordering: FAIL < RETRY < FAILOVER_AND_RETRY.
FAIL,
RETRY,
FAILOVER_AND_RETRY
}
}
/**
*
* Determines whether the framework should retry a method for the given
* exception, and the number of retries that have been made for that operation
* so far.
*
*
* @param e The exception that caused the method to fail
* @param retries The number of times the method has been retried
* @param failovers The number of times the method has failed over to a
* different backend implementation
* @param isIdempotentOrAtMostOnce true if the method is
* {@link Idempotent} or {@link AtMostOnce} and so can reasonably be
* retried on failover when we don't know if the previous attempt
* reached the server or not
* @return {@link RetryAction} with {@code RetryDecision.FAIL} if the method
* should not be retried, {@code RetryDecision.RETRY} if the method
* should be retried or {@code RetryDecision.FAILOVER_AND_RETRY}
* if failover has to be performed before retry.
* @throws Exception The re-thrown exception e indicating that
* the method failed and should not be retried further
*/
public RetryAction shouldRetry(Exception e, int retries, int failovers,
boolean isIdempotentOrAtMostOnce) throws Exception;
}