Package org.apache.ignite.internal

Class GridJobContextImpl

java.lang.Object

org.apache.ignite.internal.GridJobContextImpl

All Implemented Interfaces:

Externalizable, Serializable, ComputeJobContext, ComputeJobContinuation

public class GridJobContextImpl
extends Object
implements ComputeJobContext, Externalizable

Remote job context implementation.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
GridJobContextImpl()	Empty constructor required by Externalizable.
GridJobContextImpl(@Nullable GridKernalContext ctx, IgniteUuid jobId)
GridJobContextImpl(GridKernalContext ctx, IgniteUuid jobId, Map<? extends Serializable,? extends Serializable> attrs)

Method Summary

Modifier and Type	Method	Description
void	callcc()	Resumes job if it was held by ComputeJobContinuation.holdcc() method.
<K,V> V	getAttribute(K key)	Gets attribute from this job context.
Map<Object,Object>	getAttributes()	Gets all attributes present in this job context.
IgniteUuid	getJobId()	Gets ID of the job this context belongs to.
boolean	heldcc()	Checks if job execution has been temporarily held (suspended).
<T> T	holdcc()	Holds (suspends) a given job indefinitely until ComputeJobContinuation.callcc() is called.
<T> T	holdcc(long timeout)	Holds (suspends) a given job for specified timeout or until ComputeJobContinuation.callcc() is called.
void	job(GridJobWorker job)
void	readExternal(ObjectInput in)
void	setAttribute(Object key, @Nullable Object val)	Sets an attribute into this job context.
void	setAttributes(Map<?,?> attrs)	Sets map of attributes into this job context.
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class java.lang.Object

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

Constructor Detail

GridJobContextImpl

public GridJobContextImpl()

Empty constructor required by Externalizable.

GridJobContextImpl

public GridJobContextImpl(@Nullable
                          @Nullable GridKernalContext ctx,
                          IgniteUuid jobId)

Parameters:

ctx - Kernal context.

jobId - Job ID.

GridJobContextImpl

public GridJobContextImpl(GridKernalContext ctx,
                          IgniteUuid jobId,
                          Map<? extends Serializable,? extends Serializable> attrs)

Parameters:

ctx - Kernal context.

jobId - Job ID.

attrs - Job attributes.

Method Detail

job

public void job(GridJobWorker job)

Parameters:

job - Job worker.

getJobId

public IgniteUuid getJobId()

Gets ID of the job this context belongs to.

Specified by:

getJobId in interface ComputeJobContext

Returns:

ID of the job this context belongs to.

setAttribute

public void setAttribute(Object key,
                         @Nullable
                         @Nullable Object val)

Sets an attribute into this job context.

Specified by:

setAttribute in interface ComputeJobContext

Parameters:

key - Attribute key.

val - Attribute value.

setAttributes

public void setAttributes(Map<?,?> attrs)

Sets map of attributes into this job context.

Specified by:

setAttributes in interface ComputeJobContext

Parameters:

attrs - Local attributes.

getAttribute

public <K,V> V getAttribute(K key)

Gets attribute from this job context.

Specified by:

getAttribute in interface ComputeJobContext

Type Parameters:

K - Type of the attribute key.

V - Type of the attribute value.

Parameters:

key - Attribute key.

Returns:

Attribute value (possibly null).

getAttributes

public Map<Object,Object> getAttributes()

Gets all attributes present in this job context.

Specified by:

getAttributes in interface ComputeJobContext

Returns:

All attributes.

heldcc

public boolean heldcc()

Checks if job execution has been temporarily held (suspended).

If job has completed its execution, then false is always returned.

Specified by:

heldcc in interface ComputeJobContinuation

Returns:

True if job has been held.

holdcc

public <T> T holdcc()

Holds (suspends) a given job indefinitely until ComputeJobContinuation.callcc() is called. Job will remain in active queue, but its ComputeJobContinuation.heldcc() method will return true. Implementations of CollisionSpi should check if jobs are held or not as needed.

All jobs should stop their execution and return right after calling 'holdcc(..)' method. For convenience, this method always returns null, so you can hold and return in one line by calling 'return holdcc()' method.

If job is not running or has completed its execution, then no-op.

The 'cc' suffix stands for 'current-continuation' which is a pretty standard notation for this concept that originated from Scheme programming language. Basically, the job is held to be continued later, hence the name of the method.

Specified by:

holdcc in interface ComputeJobContinuation

Type Parameters:

T - Type of the job execution result.

Returns:

Always returns null for convenience to be used in code with return statement.

holdcc

public <T> T holdcc(long timeout)

Holds (suspends) a given job for specified timeout or until ComputeJobContinuation.callcc() is called. Holds (suspends) a given job for specified timeout or until ComputeJobContinuation.callcc() is called. Job will remain in active queue, but its ComputeJobContinuation.heldcc() method will return true. Implementations of CollisionSpi should check if jobs are held or not as needed.

All jobs should stop their execution and return right after calling 'holdcc(..)' method. For convenience, this method always returns null, so you can hold and return in one line by calling 'return holdcc()'.

If job is not running or has completed its execution, then no-op.

The 'cc' suffix stands for 'current-continuation' which is a fairly standard notation for this concept. Basically, the job is held to be continued later, hence the name of the method.

Specified by:

holdcc in interface ComputeJobContinuation

Type Parameters:

T - Type of the job execution result.

Parameters:

timeout - Timeout in milliseconds after which job will be automatically resumed.

Returns:

Always returns null for convenience to be used in code with return statement.

callcc

public void callcc()

Resumes job if it was held by ComputeJobContinuation.holdcc() method. Resuming job means that ComputeJob.execute() method will be called again. It is user's responsibility to check, as needed, whether job is executing from scratch and has been resumed.

Note that the job is resumed with exactly the same state as of when it was 'held' via the ComputeJobContinuation.holdcc() method.

If job is not running, has not been suspended, or has completed its execution, then no-op.

The method is named after 'call-with-current-continuation' design pattern, commonly abbreviated as 'call/cc', which originated in Scheme programming language.

Specified by:

callcc in interface ComputeJobContinuation

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

toString

public String toString()

Overrides:

toString in class Object