Package org.apache.ignite.internal.processors.cache.persistence.snapshot

Class SnapshotMetadataVerificationTask

java.lang.Object

org.apache.ignite.compute.ComputeTaskAdapter<SnapshotMetadataVerificationTaskArg,SnapshotMetadataVerificationTaskResult>

org.apache.ignite.internal.processors.cache.persistence.snapshot.SnapshotMetadataVerificationTask

All Implemented Interfaces:

Serializable, ComputeTask<SnapshotMetadataVerificationTaskArg,SnapshotMetadataVerificationTaskResult>

@GridInternal
public class SnapshotMetadataVerificationTask
extends ComputeTaskAdapter<SnapshotMetadataVerificationTaskArg,SnapshotMetadataVerificationTaskResult>

Snapshot task to verify snapshot metadata on the baseline nodes for given snapshot name.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
SnapshotMetadataVerificationTask()

Method Summary

Modifier and Type	Method	Description
@NotNull Map<? extends ComputeJob,ClusterNode>	map(List<ClusterNode> subgrid, SnapshotMetadataVerificationTaskArg arg)	This method is called to map or split grid task into multiple grid jobs.
SnapshotMetadataVerificationTaskResult	reduce(List<ComputeJobResult> results)	Reduces (or aggregates) results received so far into one compound result to be returned to caller via ComputeTaskFuture.get() method.
ComputeJobResultPolicy	result(ComputeJobResult res, List<ComputeJobResult> rcvd)	Default implementation which will wait for all jobs to complete before calling ComputeTask.reduce(List) method.

Methods inherited from class java.lang.Object

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

Constructor Detail

SnapshotMetadataVerificationTask

public SnapshotMetadataVerificationTask()

Method Detail

map

@NotNull
public @NotNull Map<? extends ComputeJob,ClusterNode> map(List<ClusterNode> subgrid,
                                                                SnapshotMetadataVerificationTaskArg arg)
                                                         throws IgniteException

This method is called to map or split grid task into multiple grid jobs. This is the first method that gets called when task execution starts.

Parameters:

subgrid - Nodes available for this task execution. Note that order of nodes is guaranteed to be randomized by container. This ensures that every time you simply iterate through grid nodes, the order of nodes will be random which over time should result into all nodes being used equally.

arg - Task execution argument. Can be null. This is the same argument as the one passed into Grid#execute(...) methods.

Returns:

Map of grid jobs assigned to subgrid node. Unless ComputeTaskContinuousMapper is injected into task, if null or empty map is returned, exception will be thrown.

Throws:

IgniteException - If mapping could not complete successfully. This exception will be thrown out of ComputeTaskFuture.get() method.

reduce

public SnapshotMetadataVerificationTaskResult reduce(List<ComputeJobResult> results)
                                              throws IgniteException

Reduces (or aggregates) results received so far into one compound result to be returned to caller via ComputeTaskFuture.get() method.

Note, that if some jobs did not succeed and could not be failed over then the list of results passed into this method will include the failed results. Otherwise, failed results will not be in the list.

Parameters:

results - Received results of broadcasted remote executions. Note that if task class has ComputeTaskNoResultCache annotation, then this list will be empty.

Returns:

Grid job result constructed from results of remote executions.

Throws:

IgniteException - If reduction or results caused an error. This exception will be thrown out of ComputeTaskFuture.get() method.

result

public ComputeJobResultPolicy result(ComputeJobResult res,
                                     List<ComputeJobResult> rcvd)
                              throws IgniteException

Default implementation which will wait for all jobs to complete before calling ComputeTask.reduce(List) method.

If remote job resulted in exception (ComputeJobResult.getException() is not null), then ComputeJobResultPolicy.FAILOVER policy will be returned if the exception is instance of ClusterTopologyException or ComputeExecutionRejectedException, which means that remote node either failed or job execution was rejected before it got a chance to start. In all other cases the exception will be rethrown which will ultimately cause task to fail.

Specified by:

result in interface ComputeTask<SnapshotMetadataVerificationTaskArg,SnapshotMetadataVerificationTaskResult>

Overrides:

result in class ComputeTaskAdapter<SnapshotMetadataVerificationTaskArg,SnapshotMetadataVerificationTaskResult>

Parameters:

res - Received remote grid executable result.

rcvd - All previously received results.

Returns:

Result policy that dictates how to process further upcoming job results.

Throws:

IgniteException - If handling a job result caused an error effectively rejecting a failover. This exception will be thrown out of ComputeTaskFuture.get() method.