org.gridgain.grid.spi.failover.always

Class GridAlwaysFailoverSpi

java.lang.Object

org.gridgain.grid.spi.GridSpiAdapter

org.gridgain.grid.spi.failover.always.GridAlwaysFailoverSpi

All Implemented Interfaces:

GridAlwaysFailoverSpiMBean, GridFailoverSpi, GridSpi, GridSpiManagementMBean

@GridSpiMultipleInstancesSupport(value=true)
@GridSpiConsistencyChecked(optional=true)
public class GridAlwaysFailoverSpi
extends GridSpiAdapter
implements GridFailoverSpi, GridAlwaysFailoverSpiMBean

Failover SPI that always reroutes a failed job to another node. Note, that at first an attempt will be made to reroute the failed job to a node that was not part of initial split for a better chance of success. If no such nodes are available, then an attempt will be made to reroute the failed job to the nodes in the initial split minus the node the job is failed on. If none of the above attempts succeeded, then the job will not be failed over and null will be returned.

Configuration

This SPI is default failover SPI and does not have to be explicitly configured unless configuration parameters need to be changed.

Mandatory

This SPI has no mandatory configuration parameters.

Optional

This SPI has following optional configuration parameters:

• Maximum failover attempts for a single job (see setMaximumFailoverAttempts(int)). If maximum failover attempts is reached, then job will not be failed-over and, hence, will fail.

Here is a Java example how to configure grid with GridAlwaysFailoverSpi failover SPI.

 GridAlwaysFailoverSpi spi = new GridAlwaysFailoverSpi();

 // Override maximum failover attempts.
 spi.setMaximumFailoverAttempts(5);

 GridConfiguration cfg = new GridConfiguration();

 // Override default failover SPI.
 cfg.setFailoverSpiSpi(spi);

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

Here is an example of how to configure GridAlwaysFailoverSpi from Spring XML configuration file.

 <property name="failoverSpi">
     <bean class="org.gridgain.grid.spi.failover.always.GridAlwaysFailoverSpi">
         <property name="maximumFailoverAttempts" value="5"/>
     </bean>
 </property>
 

For information about Spring framework visit www.springframework.org

See Also:

GridFailoverSpi

Field Summary

Fields

Modifier and Type	Field and Description
static int	DFLT_MAX_FAILOVER_ATTEMPTS Maximum number of attempts to execute a failed job on another node (default is 5).
static String	FAILED_NODE_LIST_ATTR Name of job context attribute containing all nodes a job failed on.
static String	MAX_FAILOVER_ATTEMPT_ATTR Maximum attempts attribute key should be the same on all nodes.

Constructor Summary

Constructors

Constructor and Description
GridAlwaysFailoverSpi()

Method Summary

Methods

Modifier and Type	Method and Description
GridNode	failover(GridFailoverContext ctx, List<GridNode> top) This method is called when method GridComputeTask.result(GridComputeJobResult, List) returns value GridComputeJobResultPolicy.FAILOVER policy indicating that the result of job execution must be failed over.
protected List<String>	getConsistentAttributeNames() Returns back a list of attributes that should be consistent for this SPI.
int	getMaximumFailoverAttempts() Gets maximum number of attempts to execute a failed job on another node.
Map<String,Object>	getNodeAttributes() This method is called before SPI starts (before method GridSpi.spiStart(String) is called).
int	getTotalFailoverJobsCount() Get total number of jobs that were failed over.
void	setMaximumFailoverAttempts(int maxFailoverAttempts) Sets maximum number of attempts to execute a failed job on another node.
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, getGridGainHome, getLocalNodeId, getName, 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, onContextDestroyed, onContextInitialized

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

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

Field Detail

DFLT_MAX_FAILOVER_ATTEMPTS

public static final int DFLT_MAX_FAILOVER_ATTEMPTS

Maximum number of attempts to execute a failed job on another node (default is 5).

See Also:

Constant Field Values

FAILED_NODE_LIST_ATTR

public static final String FAILED_NODE_LIST_ATTR

Name of job context attribute containing all nodes a job failed on.

See Also:

GridComputeJobContext, Constant Field Values

MAX_FAILOVER_ATTEMPT_ATTR

public static final String MAX_FAILOVER_ATTEMPT_ATTR

Maximum attempts attribute key should be the same on all nodes.

See Also:

Constant Field Values

Constructor Detail

GridAlwaysFailoverSpi

public GridAlwaysFailoverSpi()

Method Detail

getMaximumFailoverAttempts

public int getMaximumFailoverAttempts()

Gets maximum number of attempts to execute a failed job on another node. If not specified, DFLT_MAX_FAILOVER_ATTEMPTS value will be used.

Specified by:

getMaximumFailoverAttempts in interface GridAlwaysFailoverSpiMBean

Returns:

Maximum number of attempts to execute a failed job on another node.

setMaximumFailoverAttempts

@GridSpiConfiguration(optional=true)
public void setMaximumFailoverAttempts(int maxFailoverAttempts)

Sets maximum number of attempts to execute a failed job on another node. If not specified, DFLT_MAX_FAILOVER_ATTEMPTS value will be used.

Parameters:

maxFailoverAttempts - Maximum number of attempts to execute a failed job on another node.

getTotalFailoverJobsCount

public int getTotalFailoverJobsCount()

Get total number of jobs that were failed over.

Specified by:

getTotalFailoverJobsCount in interface GridAlwaysFailoverSpiMBean

Returns:

Total number of failed over jobs.

getNodeAttributes

public Map<String,Object> getNodeAttributes()
                                     throws GridSpiException

This method is called before SPI starts (before method GridSpi.spiStart(String) is called). It allows SPI implementation to add attributes to a local node. Kernal collects these attributes from all SPI implementations loaded up and then passes it to discovery SPI so that they can be exchanged with other nodes.

Specified by:

getNodeAttributes in interface GridSpi

Overrides:

getNodeAttributes in class GridSpiAdapter

Returns:

Map of local node attributes this SPI wants to add.

Throws:

GridSpiException - Throws in case of any error.

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.

failover

public GridNode failover(GridFailoverContext ctx,
                List<GridNode> top)

This method is called when method GridComputeTask.result(GridComputeJobResult, List) returns value GridComputeJobResultPolicy.FAILOVER policy indicating that the result of job execution must be failed over. Implementation of this method should examine failover context and choose one of the grid nodes from supplied topology to retry job execution on it. For best performance it is advised that GridFailoverContext.getBalancedNode(List) method is used to select node for execution of failed job.

Specified by:

failover in interface GridFailoverSpi

Parameters:

ctx - Failover context.

top - Collection of all grid nodes within task topology (may include failed node).

Returns:

New node to route this job to or null if new node cannot be picked. If job failover fails (returns null) the whole task will be failed.

getConsistentAttributeNames

protected List<String> getConsistentAttributeNames()

Returns back a list of attributes that should be consistent for this SPI. Consistency means that remote node has to have the same attribute with the same value.

Overrides:

getConsistentAttributeNames in class GridSpiAdapter

Returns:

List or attribute names.

toString

public String toString()

Overrides:

toString in class Object