| /* |
| * 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.ignite.spi.failover; |
| |
| import java.util.List; |
| import org.apache.ignite.cluster.ClusterNode; |
| import org.apache.ignite.spi.IgniteSpi; |
| |
| /** |
| * Failover SPI provides developer with ability to supply custom logic for handling |
| * failed execution of a grid job. Job execution can fail for a number of reasons: |
| * <ul> |
| * <li>Job execution threw an exception (runtime, assertion or error)</li> |
| * <li>Node on which job was execution left topology (crashed or stopped)</li> |
| * <li>Collision SPI on remote node cancelled a job before it got a chance to execute (job rejection).</li> |
| * </ul> |
| * In all cases failover SPI takes failed job (as failover context) and list of all |
| * grid nodes and provides another node on which the job execution will be retried. |
| * It is up to failover SPI to make sure that job is not mapped to the node it |
| * failed on. The failed node can be retrieved from |
| * {@link org.apache.ignite.compute.ComputeJobResult#getNode() GridFailoverContext.getJobResult().node()} |
| * method. |
| * <p> |
| * Ignite comes with the following built-in failover SPI implementations: |
| * <ul> |
| * <li>{@link org.apache.ignite.spi.failover.never.NeverFailoverSpi}</li> |
| * <li>{@link org.apache.ignite.spi.failover.always.AlwaysFailoverSpi}</li> |
| * <li>{@link org.apache.ignite.spi.failover.jobstealing.JobStealingFailoverSpi}</li> |
| * </ul> |
| * <b>NOTE:</b> this SPI (i.e. methods in this interface) should never be used directly. SPIs provide |
| * internal view on the subsystem and is used internally by Ignite kernal. In rare use cases when |
| * access to a specific implementation of this SPI is required - an instance of this SPI can be obtained |
| * via {@link org.apache.ignite.Ignite#configuration()} method to check its configuration properties or call other non-SPI |
| * methods. Note again that calling methods from this interface on the obtained instance can lead |
| * to undefined behavior and explicitly not supported. |
| */ |
| public interface FailoverSpi extends IgniteSpi { |
| /** |
| * This method is called when method {@link org.apache.ignite.compute.ComputeTask#result(org.apache.ignite.compute.ComputeJobResult, List)} returns |
| * value {@link org.apache.ignite.compute.ComputeJobResultPolicy#FAILOVER} policy indicating that the result of |
| * job execution must be failed over. Implementation of this method should examine failover |
| * context and choose one of the grid nodes from supplied {@code topology} to retry job execution |
| * on it. For best performance it is advised that {@link FailoverContext#getBalancedNode(List)} |
| * method is used to select node for execution of failed job. |
| * |
| * @param ctx Failover context. |
| * @param top Collection of all grid nodes within task topology (may include failed node). |
| * @return New node to route this job to or {@code null} if new node cannot be picked. |
| * If job failover fails (returns {@code null}) the whole task will be failed. |
| */ |
| public ClusterNode failover(FailoverContext ctx, List<ClusterNode> top); |
| } |