com.hazelcast.cp.internal.IndeterminateOperationStateAware Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2021, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.cp.internal;
import com.hazelcast.config.cp.CPSubsystemConfig;
import com.hazelcast.core.IndeterminateOperationStateException;
/**
* When a {@link RaftOp} is replicated to the leader of a Raft group,
* but the leader fails before it sends any response, the caller has no idea
* about the status of its operation. The possible cases are:
* - the failed leader did not append the operation,
* - the failed leader appended the operation but not committed yet,
* - the failed leader committed the operation.
*
* In this case, we check if the operation is safe to retry. The operation is
* considered to be safe to retry only if it implements this interface and
* {@link #isRetryableOnIndeterminateOperationState()} method returns
* {@code true}. If this is the case, the operation will be retried. Otherwise,
* we do not know if the operation is safe or not. In this case, we make a
* decision between offering at-most-once and at-least-once execution
* semantics via the
* {@link CPSubsystemConfig#failOnIndeterminateOperationState} configuration.
* If this configuration is enabled, we do not retry the operation and fail
* with {@link IndeterminateOperationStateException}, hence offer at-most-once
* semantics. Otherwise, we retry the operation and we are fine with a possible
* duplicate commit of the operation.
*/
public interface IndeterminateOperationStateAware {
/**
* Returns true if duplicate commit of the operation is equivalent to
* committing it only once.
*/
boolean isRetryableOnIndeterminateOperationState();
}