org.gridgain.grid.spi.collision.fifoqueue

Class GridFifoQueueCollisionSpi

java.lang.Object

org.gridgain.grid.spi.GridSpiAdapter

org.gridgain.grid.spi.collision.fifoqueue.GridFifoQueueCollisionSpi

All Implemented Interfaces:

GridFifoQueueCollisionSpiMBean, GridCollisionSpi, GridSpi, GridSpiManagementMBean

@GridSpiMultipleInstancesSupport(value=true)
public class GridFifoQueueCollisionSpi
extends GridSpiAdapter
implements GridCollisionSpi, GridFifoQueueCollisionSpiMBean

This class provides implementation for Collision SPI based on FIFO queue. Jobs are ordered as they arrived and only getParallelJobsNumber() number of jobs is allowed to execute in parallel. Other jobs will be buffered in the passive queue.

Configuration

Mandatory

This SPI has no mandatory configuration parameters.

Optional

This SPI has following optional configuration parameters:

• Number of jobs that can execute in parallel (see setParallelJobsNumber(int)). This number should usually be set to the number of threads in the execution thread pool.

Java Example

GridFifoQueueCollisionSpi can be configured as follows:

 GridFifoQueueCollisionSpi colSpi = new GridFifoQueueCollisionSpi();

 // Execute all jobs sequentially by setting parallel job number to 1.
 colSpi.setParallelJobsNumber(1);

 GridConfiguration cfg = new GridConfiguration();

 // Override default collision SPI.
 cfg.setCollisionSpi(colSpi);

 // Starts grid.
 G.start(cfg);
 

Spring Example

GridFifoQueueCollisionSpi can be configured from Spring XML configuration file:

 <bean id="grid.custom.cfg" class="org.gridgain.grid.GridConfiguration" singleton="true">
       ...
       <property name="collisionSpi">
           <bean class="org.gridgain.grid.spi.collision.fifoqueue.GridFifoQueueCollisionSpi">
               <property name="parallelJobsNumber" value="1"/>
           </bean>
       </property>
       ...
 </bean>
 

Field Summary

Fields

Modifier and Type	Field and Description
static int	DFLT_PARALLEL_JOBS_NUM Default number of parallel jobs allowed (value is 95 which is slightly less same as default value of threads in the execution thread pool to allow some extra threads for system processing).
static int	DFLT_WAIT_JOBS_NUM Default waiting jobs number.

Constructor Summary

Constructors

Constructor and Description
GridFifoQueueCollisionSpi()

Method Summary

Methods

Modifier and Type	Method and Description
int	getCurrentActiveJobsNumber() Gets current number of jobs that are active, i.e.
int	getCurrentHeldJobsNumber() Gets number of currently 'held' jobs.
int	getCurrentRunningJobsNumber()
int	getCurrentWaitJobsNumber() Gets current number of jobs that wait for the execution.
int	getParallelJobsNumber() Gets number of jobs that can be executed in parallel.
int	getWaitingJobsNumber() Maximum number of jobs that are allowed to wait in waiting queue.
void	onCollision(GridCollisionContext ctx) This is a callback called when either new grid job arrived or executing job finished its execution.
void	setExternalCollisionListener(GridCollisionExternalListener lsnr) Listener to be set for notification of external collision events (e.g.
void	setParallelJobsNumber(int parallelJobsNum) Sets number of jobs that can be executed in parallel.
void	setWaitingJobsNumber(int waitJobsNum) Sets maximum number of jobs that are allowed to wait in waiting queue.
void	spiStart(String gridName) This method is called to start SPI.
void	spiStop() This method is called to stop SPI.
String	toString()

Methods inherited from class org.gridgain.grid.spi.GridSpiAdapter

assertParameter, checkConfigurationConsistency0, configInfo, createSpiAttributeName, getConsistentAttributeNames, getGridGainHome, getLocalNodeId, getName, getNodeAttributes, getSpiContext, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted, injectables, onContextDestroyed, onContextDestroyed0, onContextInitialized, onContextInitialized0, registerMBean, setName, startInfo, startStopwatch, stopInfo, unregisterMBean

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.gridgain.grid.spi.GridSpi

getName, getNodeAttributes, onContextDestroyed, onContextInitialized

Methods inherited from interface org.gridgain.grid.spi.GridSpiManagementMBean

getGridGainHome, getLocalNodeId, getName, getStartTimestamp, getStartTimestampFormatted, getUpTime, getUpTimeFormatted

Field Detail

DFLT_PARALLEL_JOBS_NUM

public static final int DFLT_PARALLEL_JOBS_NUM

Default number of parallel jobs allowed (value is 95 which is slightly less same as default value of threads in the execution thread pool to allow some extra threads for system processing).

See Also:

Constant Field Values

DFLT_WAIT_JOBS_NUM

public static final int DFLT_WAIT_JOBS_NUM

Default waiting jobs number. If number of waiting jobs exceeds this number, jobs will be rejected. Default value is Integer.MAX_VALUE.

See Also:

Constant Field Values

Constructor Detail

GridFifoQueueCollisionSpi

public GridFifoQueueCollisionSpi()

Method Detail

getParallelJobsNumber

public int getParallelJobsNumber()

Gets number of jobs that can be executed in parallel.

Specified by:

getParallelJobsNumber in interface GridFifoQueueCollisionSpiMBean

Returns:

Number of jobs that can be executed in parallel.

setParallelJobsNumber

@GridSpiConfiguration(optional=true)
public void setParallelJobsNumber(int parallelJobsNum)

Sets number of jobs that can be executed in parallel.

Specified by:

setParallelJobsNumber in interface GridFifoQueueCollisionSpiMBean

Parameters:

parallelJobsNum - Parallel jobs number.

getWaitingJobsNumber

public int getWaitingJobsNumber()

Maximum number of jobs that are allowed to wait in waiting queue. If number of waiting jobs ever exceeds this number, excessive jobs will be rejected.

Specified by:

getWaitingJobsNumber in interface GridFifoQueueCollisionSpiMBean

Returns:

Maximum allowed number of waiting jobs.

setWaitingJobsNumber

@GridSpiConfiguration(optional=true)
public void setWaitingJobsNumber(int waitJobsNum)

Sets maximum number of jobs that are allowed to wait in waiting queue. If number of waiting jobs ever exceeds this number, excessive jobs will be rejected.

Specified by:

setWaitingJobsNumber in interface GridFifoQueueCollisionSpiMBean

Parameters:

waitJobsNum - Waiting jobs number.

getCurrentWaitJobsNumber

public int getCurrentWaitJobsNumber()

Gets current number of jobs that wait for the execution.

Specified by:

getCurrentWaitJobsNumber in interface GridFifoQueueCollisionSpiMBean

Returns:

Number of jobs that wait for execution.

getCurrentActiveJobsNumber

public int getCurrentActiveJobsNumber()

Gets current number of jobs that are active, i.e. 'running + held' jobs.

Specified by:

getCurrentActiveJobsNumber in interface GridFifoQueueCollisionSpiMBean

Returns:

Number of active jobs.

getCurrentRunningJobsNumber

public int getCurrentRunningJobsNumber()

Specified by:

getCurrentRunningJobsNumber in interface GridFifoQueueCollisionSpiMBean

getCurrentHeldJobsNumber

public int getCurrentHeldJobsNumber()

Gets number of currently 'held' jobs.

Specified by:

getCurrentHeldJobsNumber in interface GridFifoQueueCollisionSpiMBean

Returns:

Number of currently 'held' jobs.

spiStart

public void spiStart(String gridName)
              throws GridSpiException

This method is called to start SPI. After this method returns successfully kernel assumes that SPI is fully operational.

Specified by:

spiStart in interface GridSpi

Parameters:

gridName - Name of grid instance this SPI is being started for (null for default grid).

Throws:

GridSpiException - Throws in case of any error during SPI start.

spiStop

public void spiStop()
             throws GridSpiException

This method is called to stop SPI. After this method returns kernel assumes that this SPI is finished and all resources acquired by it are released.

Note that this method can be called at any point including during recovery of failed start. It should make no assumptions on what state SPI will be in when this method is called.

Specified by:

spiStop in interface GridSpi

Throws:

GridSpiException - Thrown in case of any error during SPI stop.

setExternalCollisionListener

public void setExternalCollisionListener(GridCollisionExternalListener lsnr)

Listener to be set for notification of external collision events (e.g. job stealing). Once grid receives such notification, it will immediately invoke collision SPI.

GridGain uses this listener to enable job stealing from overloaded to underloaded nodes. However, you can also utilize it, for instance, to provide time based collision resolution. To achieve this, you most likely would mark some job by setting a certain attribute in job context (see GridComputeJobContext) for a job that requires time-based scheduling and set some timer in your SPI implementation that would wake up after a certain period of time. Once this period is reached, you would notify this listener that a collision resolution should take place. Then inside of your collision resolution logic, you would find the marked waiting job and activate it.

Note that most collision SPI's might not have external collisions. In that case, they should simply ignore this method and do nothing when listener is set.

Specified by:

setExternalCollisionListener in interface GridCollisionSpi

Parameters:

lsnr - Listener for external collision events.

onCollision

public void onCollision(GridCollisionContext ctx)

This is a callback called when either new grid job arrived or executing job finished its execution. When new job arrives it is added to the end of the wait list and this method is called. When job finished its execution, it is removed from the active list and this method is called (i.e., when grid job is finished it will not appear in any list in collision resolution).

Implementation of this method should act on all lists, each of which contains collision job contexts that define a set of operations available during collision resolution. Refer to GridCollisionContext and GridCollisionJobContext documentation for more information.

Specified by:

onCollision in interface GridCollisionSpi

Parameters:

ctx - Collision context which contains all collision lists.

toString

public String toString()

Overrides:

toString in class Object