org.apache.ignite.compute

Interface ComputeJobContext

All Superinterfaces:

ComputeJobContinuation

public interface ComputeJobContext
extends ComputeJobContinuation

Context attached to every job executed on the grid. Note that unlike ComputeTaskSession, which distributes all attributes to all jobs in the task including the task itself, job context attributes belong to a job and do not get sent over network unless a job moves from one node to another.

In most cases a job, once assigned to a node, will never move to another node. However, it is possible that collision SPI rejects a job before it ever got a chance to execute (job rejection) which will cause fail-over to another node. Or user is not satisfied with the outcome of a job and fails it over to another node by returning ComputeJobResultPolicy.FAILOVER policy from ComputeTask.result(ComputeJobResult, List) method. In this case all context attributes set on one node will be available on any other node this job travels to.

You can also use ComputeJobContext to communicate between SPI's and jobs. For example, if you need to cancel an actively running job from CollisionSpi you may choose to set some context attribute on the job to mark the fact that a job was cancelled by grid and not by a user. Context attributes can also be assigned in FailoverSpi prior to failing over a job.

From within ComputeTask.result(ComputeJobResult, List) or ComputeTask.reduce(List) methods, job context is available via ComputeJobResult.getJobContext() method which gives user the ability to check context attributes from within grid task implementation for every job returned from remote nodes.

Job context can be injected into ComputeJob via JobContextResource annotation. Refer to the JobContextResource documentation for coding examples on how to inject job context.

Attribute names that start with "apache.ignite:" are reserved for internal system use.

Method Summary

Modifier and Type	Method and Description
<K,V> V	getAttribute(K key) Gets attribute from this job context.
Map<?,?>	getAttributes() Gets all attributes present in this job context.
IgniteUuid	getJobId() Gets ID of the job this context belongs to.
void	setAttribute(Object key, Object val) Sets an attribute into this job context.
void	setAttributes(Map<?,?> attrs) Sets map of attributes into this job context.

Methods inherited from interface org.apache.ignite.compute.ComputeJobContinuation

callcc, heldcc, holdcc, holdcc

Method Detail

getJobId

IgniteUuid getJobId()

Gets ID of the job this context belongs to.

Returns:

ID of the job this context belongs to.

setAttribute

void setAttribute(Object key,
                  Object val)

Sets an attribute into this job context.

Parameters:

key - Attribute key.

val - Attribute value, may be null.

setAttributes

void setAttributes(Map<?,?> attrs)

Sets map of attributes into this job context.

Parameters:

attrs - Local attributes.

getAttribute

<K,V> V getAttribute(K key)

Gets attribute from this job context.

Type Parameters:

K - Type of the attribute key.

V - Type of the attribute value.

Parameters:

key - Attribute key.

Returns:

Attribute value (possibly null).

getAttributes

Map<?,?> getAttributes()

Gets all attributes present in this job context.

Returns:

All attributes.