groovyx.gpars.dataflow.operator
Interface DataflowEventListener

All Known Implementing Classes:

DataflowEventAdapter, GracefulShutdownListener, ProcessorPauseResume

public interface DataflowEventListener

Enables external entities to observe the state of dataflow selectors and operators

Author:

Vaclav Pech

Method Summary

void	afterRun(DataflowProcessor processor, java.util.List<java.lang.Object> messages) Invoked when the operator completes a single run When using maxForks, the method may be invoked from threads running the forks.
void	afterStart(DataflowProcessor processor) Invoked immediately after the operator starts by a pooled thread before the first message is obtained
void	afterStop(DataflowProcessor processor) Invoked immediately after the operator terminates
java.util.List<java.lang.Object>	beforeRun(DataflowProcessor processor, java.util.List<java.lang.Object> messages) Invoked when all messages required to trigger the operator become available in the input channels.
java.lang.Object	controlMessageArrived(DataflowProcessor processor, DataflowReadChannel<java.lang.Object> channel, int index, java.lang.Object message) Invoked when a control message (instances of ControlMessage) becomes available in an input channel.
java.lang.Object	customEvent(DataflowProcessor processor, java.lang.Object data) Invoked when the fireCustomEvent() method is triggered manually on a dataflow operator/selector When using maxForks, the method may be invoked from threads running the forks.
java.lang.Object	messageArrived(DataflowProcessor processor, DataflowReadChannel<java.lang.Object> channel, int index, java.lang.Object message) Invoked when a message becomes available in an input channel.
java.lang.Object	messageSentOut(DataflowProcessor processor, DataflowWriteChannel<java.lang.Object> channel, int index, java.lang.Object message) Invoked when a message is being bound to an output channel.
boolean	onException(DataflowProcessor processor, java.lang.Throwable e) Invoked if an exception occurs.
void	registered(DataflowProcessor processor) Invoked immediately after the listener has been attached to a dataflow processor.

Method Detail

registered

void registered(DataflowProcessor processor)

Invoked immediately after the listener has been attached to a dataflow processor.

Parameters:

processor - The reporting dataflow operator/selector

afterStart

void afterStart(DataflowProcessor processor)

Invoked immediately after the operator starts by a pooled thread before the first message is obtained

Parameters:

processor - The reporting dataflow operator/selector

afterStop

void afterStop(DataflowProcessor processor)

Invoked immediately after the operator terminates

Parameters:

processor - The reporting dataflow operator/selector

onException

boolean onException(DataflowProcessor processor,
                    java.lang.Throwable e)

Invoked if an exception occurs. If any of the listeners returns true, the operator will terminate. Exceptions outside of the operator's body or listeners' messageSentOut() handlers will terminate the operator irrespective of the listeners' votes. When using maxForks, the method may be invoked from threads running the forks.

Parameters:

processor - The reporting dataflow operator/selector

e - The thrown exception

Returns:

True, if the operator should terminate in response to the exception, false otherwise.

messageArrived

java.lang.Object messageArrived(DataflowProcessor processor,
                                DataflowReadChannel<java.lang.Object> channel,
                                int index,
                                java.lang.Object message)

Invoked when a message becomes available in an input channel.

Parameters:

processor - The reporting dataflow operator/selector

channel - The input channel holding the message

index - The index of the input channel within the operator

message - The incoming message

Returns:

The original message or a message that should be used instead

controlMessageArrived

java.lang.Object controlMessageArrived(DataflowProcessor processor,
                                       DataflowReadChannel<java.lang.Object> channel,
                                       int index,
                                       java.lang.Object message)

Invoked when a control message (instances of ControlMessage) becomes available in an input channel.

Parameters:

processor - The reporting dataflow operator/selector

channel - The input channel holding the message

index - The index of the input channel within the operator

message - The incoming message

Returns:

The original message or a message that should be used instead

messageSentOut

java.lang.Object messageSentOut(DataflowProcessor processor,
                                DataflowWriteChannel<java.lang.Object> channel,
                                int index,
                                java.lang.Object message)

Invoked when a message is being bound to an output channel. When using maxForks, the method may be invoked from threads running the forks.

Parameters:

processor - The reporting dataflow operator/selector

channel - The output channel to send the message to

index - The index of the output channel within the operator

message - The message to send

Returns:

The original message or a message that should be used instead

beforeRun

java.util.List<java.lang.Object> beforeRun(DataflowProcessor processor,
                                           java.util.List<java.lang.Object> messages)

Invoked when all messages required to trigger the operator become available in the input channels.

Parameters:

processor - The reporting dataflow operator/selector

messages - The incoming messages

Returns:

The original list of messages or a modified/new list of messages that should be used instead

afterRun

void afterRun(DataflowProcessor processor,
              java.util.List<java.lang.Object> messages)

Invoked when the operator completes a single run When using maxForks, the method may be invoked from threads running the forks.

Parameters:

processor - The reporting dataflow operator/selector

messages - The incoming messages that have been processed

customEvent

java.lang.Object customEvent(DataflowProcessor processor,
                             java.lang.Object data)

Invoked when the fireCustomEvent() method is triggered manually on a dataflow operator/selector When using maxForks, the method may be invoked from threads running the forks.

Parameters:

processor - The reporting dataflow operator/selector

data - The custom piece of data provided as part of the event

Returns:

A value to return from the fireCustomEvent() method to the caller (event initiator)