Module org.elasticsearch.server

Package org.elasticsearch.cluster.action.shard

Class ShardStateAction.ShardStartedClusterStateTaskExecutor

java.lang.Object

org.elasticsearch.cluster.action.shard.ShardStateAction.ShardStartedClusterStateTaskExecutor

All Implemented Interfaces:

ClusterStateTaskExecutor<ShardStateAction.StartedShardUpdateTask>

Enclosing class:

ShardStateAction

public static class ShardStateAction.ShardStartedClusterStateTaskExecutor
extends Object
implements ClusterStateTaskExecutor<ShardStateAction.StartedShardUpdateTask>

Nested Class Summary

Nested classes/interfaces inherited from interface org.elasticsearch.cluster.ClusterStateTaskExecutor

ClusterStateTaskExecutor.BatchExecutionContext<T extends ClusterStateTaskListener>, ClusterStateTaskExecutor.TaskContext<T extends ClusterStateTaskListener>

Constructor Summary

Constructors

Constructor	Description
ShardStartedClusterStateTaskExecutor(AllocationService allocationService, RerouteService rerouteService)

Method Summary

Modifier and Type	Method	Description
void	clusterStatePublished(ClusterState newClusterState)	Callback invoked after new cluster state is published.
ClusterState	execute(ClusterStateTaskExecutor.BatchExecutionContext<ShardStateAction.StartedShardUpdateTask> batchExecutionContext)	Update the cluster state based on the current state and the given tasks.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.elasticsearch.cluster.ClusterStateTaskExecutor

describeTasks, runOnlyOnMaster

Constructor Details

ShardStartedClusterStateTaskExecutor

public ShardStartedClusterStateTaskExecutor(AllocationService allocationService,
 RerouteService rerouteService)

Method Details

execute

public ClusterState execute(ClusterStateTaskExecutor.BatchExecutionContext<ShardStateAction.StartedShardUpdateTask> batchExecutionContext)
                     throws Exception

Description copied from interface: ClusterStateTaskExecutor

Update the cluster state based on the current state and the given tasks. Return batchExecutionContext.initialState() to avoid publishing any update.

If this method throws an exception then the cluster state is unchanged and every task's ClusterStateTaskListener.onFailure(java.lang.Exception) method is called.

A common implementation pattern is to iterate through the tasks, constructing a new and updated ClusterState for each one. This works ok but beware that constructing a whole new ClusterState can be somewhat expensive, and there may sometimes be surprisingly many tasks to process in the batch. If it's possible to accumulate the effects of the tasks at a lower level then you should do that instead.

Returning batchExecutionContext.initialState() is an important and useful optimisation in most cases, but note that this fast-path exposes APIs to the risk of stale reads in the vicinity of a master failover: a node N that handles such a no-op task batch does not verify with its peers that it's still the master, and if it's not the master then another node M may already have become master and updated the state in a way that would be inconsistent with the response that N sends back to clients.

Specified by:

execute in interface ClusterStateTaskExecutor<ShardStateAction.StartedShardUpdateTask>

Returns:

The resulting cluster state after executing all the tasks. If batchExecutionContext.initialState() is returned then no update is published.

Throws:

Exception

clusterStatePublished

public void clusterStatePublished(ClusterState newClusterState)

Description copied from interface: ClusterStateTaskExecutor

Callback invoked after new cluster state is published. Note that this method is not invoked if the cluster state was not updated. Note that this method will be executed using system context.

Specified by:

clusterStatePublished in interface ClusterStateTaskExecutor<ShardStateAction.StartedShardUpdateTask>

Parameters:

newClusterState - The new state which was published.