org.gridgain.grid
Interface GridJobContext

@Apache20LicenseCompatible
public interface GridJobContext

Context attached to every job executed on the grid. Note that unlike GridTaskSession, 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 GridJobResultPolicy.FAILOVER policy from GridTask.result(GridJobResult, 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 GridJobContext to communicate between SPI's and jobs. For example, if you need to cancel an actively running job from GridCollisionSpi 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 GridFailoverSpi prior to failing over a job.

From within GridTask.result(GridJobResult, List) or GridTask.reduce(List) methods, job context is available via GridJobResult.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 GridJob via @GridJobContextResource annotation. Refer to the @GridJobContextResource documentation for coding examples on how to inject job context.

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



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Author: 2005-2008 Copyright © GridGain Systems. All Rights Reserved. ver. 2.1.0

	Nikita Ivanov, GridGain Systems nivanov@gridgain.com
	Dmitriy Setrakyan, GridGain Systems dsetrakyan@gridgain.com
	Alexander Magdenko, GridGain Systems amagdenko@gridgain.com
	Boris Suchodoev, GridGain Systems bsuchodoev@gridgain.com
	Denis Kharlamov, GridGain Systems dkharlamov@gridgain.com
	close

Method Summary

Serializable	getAttribute(Serializable key) Gets attribute from this job context.
Map<? extends Serializable,? extends Serializable>	getAttributes() Gets all attributes present in this job context.
UUID	getJobId() Gets ID of the job this context belongs to.
void	setAttribute(Serializable key, Serializable val) Sets an attribute into this job context.
void	setAttributes(Map<? extends Serializable,? extends Serializable> attrs) Sets map of attributes into this job context.

Method Detail

getJobId

UUID getJobId()

Gets ID of the job this context belongs to.

Returns:

ID of the job this context belongs to.

setAttribute

void setAttribute(Serializable key,
                  @Nullable
                  Serializable val)

Sets an attribute into this job context.

Parameters:

key - Attribute key.

val - Attribute value.

setAttributes

void setAttributes(Map<? extends Serializable,? extends Serializable> attrs)

Sets map of attributes into this job context.

Parameters:

attrs - Local attributes.

getAttribute

Serializable getAttribute(Serializable key)

Gets attribute from this job context.

Parameters:

key - Attribute key.

Returns:

Attribute value (possibly null).

getAttributes

Map<? extends Serializable,? extends Serializable> getAttributes()

Gets all attributes present in this job context.

Returns:

All attributes.