org.apache.camel.impl

Class ScheduledPollConsumer

java.lang.Object

org.apache.camel.support.ServiceSupport

org.apache.camel.impl.DefaultConsumer

org.apache.camel.impl.ScheduledPollConsumer

All Implemented Interfaces:

Runnable, Consumer, PollingConsumerPollingStrategy, Service, ShutdownableService, StatefulService, SuspendableService

Direct Known Subclasses:

DefaultScheduledPollConsumer, ScheduledBatchPollingConsumer

public abstract class ScheduledPollConsumer
extends DefaultConsumer
implements Runnable, SuspendableService, PollingConsumerPollingStrategy

A useful base class for any consumer which is polling based

Version:

Field Summary

Fields inherited from class org.apache.camel.impl.DefaultConsumer

log

Fields inherited from class org.apache.camel.support.ServiceSupport

shutdown, shuttingdown, started, starting, stopped, stopping, suspended, suspending

Constructor Summary

Constructors

Constructor and Description
ScheduledPollConsumer(Endpoint endpoint, Processor processor)
ScheduledPollConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService scheduledExecutorService)

Method Summary

Methods

Modifier and Type	Method and Description
void	afterPoll() Callback invoked after the poll.
long	beforePoll(long timeout) Callback invoked before the poll.
protected void	doShutdown() Implementations override this method to perform customized shutdown.
protected void	doStart() Implementations override this method to support customized start/stop.
protected void	doStop() Implementations override this method to support customized start/stop.
protected void	doSuspend() Implementations override this method to support customized suspend/resume.
long	getDelay()
long	getInitialDelay()
PollingConsumerPollStrategy	getPollStrategy()
LoggingLevel	getRunLoggingLevel()
ScheduledExecutorService	getScheduledExecutorService()
TimeUnit	getTimeUnit()
boolean	isGreedy()
protected boolean	isPollAllowed()
protected boolean	isPolling() Whether polling is currently in progress
boolean	isSchedulerStarted() Whether the scheduler has been started.
boolean	isSendEmptyMessageWhenIdle()
boolean	isStartScheduler()
boolean	isUseFixedDelay()
void	onInit() Callback invoked when the consumer is initialized such as when the PollingConsumer starts.
protected abstract int	poll() The polling method which is invoked periodically to poll this consumer
protected void	processEmptyMessage() No messages to poll so send an empty message instead.
void	run() Invoked whenever we should be polled
void	setDelay(long delay)
void	setGreedy(boolean greedy) If greedy then a poll is executed immediate after a previous poll that polled 1 or more messages.
void	setInitialDelay(long initialDelay)
void	setPollStrategy(PollingConsumerPollStrategy pollStrategy)
void	setRunLoggingLevel(LoggingLevel runLoggingLevel)
void	setScheduledExecutorService(ScheduledExecutorService scheduledExecutorService) Sets a custom shared ScheduledExecutorService to use as thread pool Notice: When using a custom thread pool, then the lifecycle of this thread pool is not controlled by this consumer (eg this consumer will not start/stop the thread pool when the consumer is started/stopped etc.)
void	setSendEmptyMessageWhenIdle(boolean sendEmptyMessageWhenIdle)
void	setStartScheduler(boolean startScheduler) Sets whether the scheduler should be started when this consumer starts.
void	setTimeUnit(TimeUnit timeUnit) Sets the time unit to use.
void	setUseFixedDelay(boolean useFixedDelay)
void	startScheduler() Starts the scheduler.

Methods inherited from class org.apache.camel.impl.DefaultConsumer

getAsyncProcessor, getEndpoint, getExceptionHandler, getProcessor, handleException, handleException, setExceptionHandler, toString

Methods inherited from class org.apache.camel.support.ServiceSupport

doResume, getStatus, getVersion, isRunAllowed, isStarted, isStarting, isStopped, isStopping, isStoppingOrStopped, isSuspended, isSuspending, resume, shutdown, start, stop, suspend

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.camel.SuspendableService

isSuspended, resume, suspend

Methods inherited from interface org.apache.camel.Service

start, stop

Constructor Detail

ScheduledPollConsumer

public ScheduledPollConsumer(Endpoint endpoint,
                     Processor processor)

ScheduledPollConsumer

public ScheduledPollConsumer(Endpoint endpoint,
                     Processor processor,
                     ScheduledExecutorService scheduledExecutorService)

Method Detail

run

public void run()

Invoked whenever we should be polled

Specified by:

run in interface Runnable

processEmptyMessage

protected void processEmptyMessage()
                            throws Exception

No messages to poll so send an empty message instead.

Throws:

Exception - is thrown if error processing the empty message.

isPollAllowed

protected boolean isPollAllowed()

isPolling

protected boolean isPolling()

Whether polling is currently in progress

getInitialDelay

public long getInitialDelay()

setInitialDelay

public void setInitialDelay(long initialDelay)

getDelay

public long getDelay()

setDelay

public void setDelay(long delay)

getTimeUnit

public TimeUnit getTimeUnit()

setTimeUnit

public void setTimeUnit(TimeUnit timeUnit)

Sets the time unit to use.

Notice that both getDelay() and getInitialDelay() are using the same time unit. So if you change this value, then take into account that the default value of getInitialDelay() is 1000. So you may to adjust this value accordingly.

Parameters:

timeUnit - the time unit.

isUseFixedDelay

public boolean isUseFixedDelay()

setUseFixedDelay

public void setUseFixedDelay(boolean useFixedDelay)

getRunLoggingLevel

public LoggingLevel getRunLoggingLevel()

setRunLoggingLevel

public void setRunLoggingLevel(LoggingLevel runLoggingLevel)

getPollStrategy

public PollingConsumerPollStrategy getPollStrategy()

setPollStrategy

public void setPollStrategy(PollingConsumerPollStrategy pollStrategy)

isStartScheduler

public boolean isStartScheduler()

setStartScheduler

public void setStartScheduler(boolean startScheduler)

Sets whether the scheduler should be started when this consumer starts.

This option is default true.

Parameters:

startScheduler - whether to start scheduler

setSendEmptyMessageWhenIdle

public void setSendEmptyMessageWhenIdle(boolean sendEmptyMessageWhenIdle)

isSendEmptyMessageWhenIdle

public boolean isSendEmptyMessageWhenIdle()

isGreedy

public boolean isGreedy()

setGreedy

public void setGreedy(boolean greedy)

If greedy then a poll is executed immediate after a previous poll that polled 1 or more messages.

getScheduledExecutorService

public ScheduledExecutorService getScheduledExecutorService()

isSchedulerStarted

public boolean isSchedulerStarted()

Whether the scheduler has been started.

The scheduler can be started with the startScheduler() method.

Returns:

true if started, false if not.

setScheduledExecutorService

public void setScheduledExecutorService(ScheduledExecutorService scheduledExecutorService)

Sets a custom shared ScheduledExecutorService to use as thread pool

Notice: When using a custom thread pool, then the lifecycle of this thread pool is not controlled by this consumer (eg this consumer will not start/stop the thread pool when the consumer is started/stopped etc.)

Parameters:

scheduledExecutorService - the custom thread pool to use

poll

protected abstract int poll()
                     throws Exception

The polling method which is invoked periodically to poll this consumer

Returns:

number of messages polled, will be 0 if no message was polled at all.

Throws:

Exception - can be thrown if an exception occurred during polling

doStart

protected void doStart()
                throws Exception

Description copied from class: ServiceSupport

Implementations override this method to support customized start/stop.

Important: See ServiceSupport.doStop() for more details.

Overrides:

doStart in class DefaultConsumer

Throws:

Exception

See Also:

ServiceSupport.doStop()

startScheduler

public void startScheduler()

Starts the scheduler.

If the scheduler is already started, then this is a noop method call.

doStop

protected void doStop()
               throws Exception

Description copied from class: ServiceSupport

Implementations override this method to support customized start/stop.

Important: Camel will invoke this ServiceSupport.doStop() method when the service is being stopped. This method will also be invoked if the service is still in uninitialized state (eg has not been started). The method is always called to allow the service to do custom logic when the service is being stopped, such as when CamelContext is shutting down.

Overrides:

doStop in class DefaultConsumer

Throws:

Exception

See Also:

ServiceSupport.doStart()

doShutdown

protected void doShutdown()
                   throws Exception

Description copied from class: ServiceSupport

Implementations override this method to perform customized shutdown.

Overrides:

doShutdown in class ServiceSupport

Throws:

Exception

doSuspend

protected void doSuspend()
                  throws Exception

Description copied from class: ServiceSupport

Implementations override this method to support customized suspend/resume.

Overrides:

doSuspend in class ServiceSupport

Throws:

Exception

onInit

public void onInit()
            throws Exception

Description copied from interface: PollingConsumerPollingStrategy

Callback invoked when the consumer is initialized such as when the PollingConsumer starts.

Specified by:

onInit in interface PollingConsumerPollingStrategy

Throws:

Exception - can be thrown if error initializing.

beforePoll

public long beforePoll(long timeout)
                throws Exception

Description copied from interface: PollingConsumerPollingStrategy

Callback invoked before the poll.

Specified by:

beforePoll in interface PollingConsumerPollingStrategy

Parameters:

timeout - the timeout

Returns:

timeout to be used, this allows returning a higher timeout value to ensure at least one poll is being performed

Throws:

Exception - can be thrown if error occurred

afterPoll

public void afterPoll()
               throws Exception

Description copied from interface: PollingConsumerPollingStrategy

Callback invoked after the poll.

Specified by:

afterPoll in interface PollingConsumerPollingStrategy

Throws:

Exception - can be thrown if error occurred