parReg.wbcl.newWan

Class MyAsyncEventListener

java.lang.Object

parReg.wbcl.newWan.MyAsyncEventListener

All Implemented Interfaces:

com.gemstone.gemfire.cache.asyncqueue.AsyncEventListener<Object,Object>, com.gemstone.gemfire.cache.CacheCallback, com.gemstone.gemfire.cache.Declarable

Direct Known Subclasses:

WBCLOrderPolicyListener

public class MyAsyncEventListener
extends Object
implements com.gemstone.gemfire.cache.asyncqueue.AsyncEventListener<Object,Object>, com.gemstone.gemfire.cache.Declarable

MyAsyncEventListener (AsyncEventListener) Following steps are done: 1) Used separate replicated region "dupEventPRegion" to track sequenceID per DistributedMembershipID + ThreadID. 2) For each event's DistributedMembershipID_ThreadID, if current_SequenceID > last_SequenceId then proceed, else ignore as event is duplicate. 3) Provide key level synchronisation while processing duplicated keys. I.e. if event k1v1 is received by two vms vm1 and vm2, we want only one to be processed and other to be ignore. We are using transaction to achieve this. Tx provides key level isolation and makes processing event and updating sequenceID as atomic operation, so if vm1 is processing k1v1, vm2 will get CommitConflictException 4) We should hold on processing the subsequent events till duplicate event is successfully processed i.e. say vm1 received (and processing) k1v1, whereas vm2 received events k1v1(duplicate) followed by k1v2; then vm2 should ignore k1v1 and wait till vm1 process k1v1. To achieve this, we loops on CommitConflictException in vm2 till vm1 successfully processed k1v1 and updated SequenceID in dupEventPRegion.

Since:

7.0

Field Summary

Fields

Modifier and Type	Field and Description
static int	lastEventTime
int	whereIWasRegistered The process ID of the VM that created this listener

Constructor Summary

Constructors

Constructor and Description
MyAsyncEventListener() noArg constructor

Method Summary

Modifier and Type	Method and Description
void	close()
boolean	hasSeenEvent(com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event) Return boolean value to validate duplicity of event.
void	init(Properties prop)
String	logCall(String methodName, com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event) Log that a gateway event occurred.
boolean	processEvents(List<com.gemstone.gemfire.cache.asyncqueue.AsyncEvent<Object,Object>> events) process events
protected void	throwException(String errStr) Utility method to write an Exception string to the Event Blackboard and to also throw an exception containing the same string.
String	toString(String methodName, com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event) Return a string description of the GatewayEvent.
void	updateSeenEvent(com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event)
static void	waitForSilence(long desiredSilenceSec, long sleepMS) Return when no events have been invoked for the given number of seconds.

Methods inherited from class java.lang.Object

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

Field Detail

lastEventTime

public static int lastEventTime

whereIWasRegistered

public int whereIWasRegistered

The process ID of the VM that created this listener

Constructor Detail

MyAsyncEventListener

public MyAsyncEventListener()

noArg constructor

Method Detail

processEvents

public boolean processEvents(List<com.gemstone.gemfire.cache.asyncqueue.AsyncEvent<Object,Object>> events)

process events

Specified by:

processEvents in interface com.gemstone.gemfire.cache.asyncqueue.AsyncEventListener<Object,Object>

init

public void init(Properties prop)

Specified by:

init in interface com.gemstone.gemfire.cache.Declarable

close

public void close()

Specified by:

close in interface com.gemstone.gemfire.cache.CacheCallback

hasSeenEvent

public boolean hasSeenEvent(com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event)

Return boolean value to validate duplicity of event.

Parameters:

event - The event object that was passed to the event.

updateSeenEvent

public void updateSeenEvent(com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event)

throwException

protected void throwException(String errStr)

Utility method to write an Exception string to the Event Blackboard and to also throw an exception containing the same string.

Parameters:

errStr - String to log, post to EventBB and throw

Throws:

TestException - containing the passed in String

See Also:

util.TestHelper.checkForEventError

logCall

public String logCall(String methodName,
                      com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event)

Log that a gateway event occurred.

Parameters:

event - The event object that was passed to the event.

toString

public String toString(String methodName,
                       com.gemstone.gemfire.cache.asyncqueue.AsyncEvent event)

Return a string description of the GatewayEvent.

Parameters:

event - The AsyncEvent object that was passed to the CqListener

Returns:

A String description of the invoked GatewayEvent

waitForSilence

public static void waitForSilence(long desiredSilenceSec,
                                  long sleepMS)

Return when no events have been invoked for the given number of seconds.

Parameters:

sleepMS - The number of milliseonds to sleep between checks for silence.