org.apache.camel.processor

Class Throttler

java.lang.Object

org.apache.camel.support.service.BaseService

org.apache.camel.support.service.ServiceSupport

org.apache.camel.support.AsyncProcessorSupport

org.apache.camel.processor.Throttler

All Implemented Interfaces:

AutoCloseable, org.apache.camel.AsyncProcessor, org.apache.camel.Processor, org.apache.camel.Service, org.apache.camel.ShutdownableService, org.apache.camel.spi.HasId, org.apache.camel.spi.IdAware, org.apache.camel.spi.RouteIdAware, org.apache.camel.StatefulService, org.apache.camel.SuspendableService, org.apache.camel.Traceable

public class Throttler
extends org.apache.camel.support.AsyncProcessorSupport
implements org.apache.camel.Traceable, org.apache.camel.spi.IdAware, org.apache.camel.spi.RouteIdAware

A Throttler will set a limit on the maximum number of message exchanges which can be sent to a processor within a specific time period.

This pattern can be extremely useful if you have some external system which meters access; such as only allowing 100 requests per second; or if huge load can cause a particular system to malfunction or to reduce its throughput you might want to introduce some throttling. This throttle implementation is thread-safe and is therefore safe to be used by multiple concurrent threads in a single route. The throttling mechanism is a DelayQueue with maxRequestsPerPeriod permits on it. Each permit is set to be delayed by timePeriodMillis (except when the throttler is initialized or the throttle rate increased, then there is no delay for those permits). Callers trying to acquire a permit from the DelayQueue will block if necessary. The end result is a rolling window of time. Where from the callers point of view in the last timePeriodMillis no more than maxRequestsPerPeriod have been allowed to be acquired.

Field Summary

Fields inherited from class org.apache.camel.support.service.BaseService

BUILDED, FAILED, INITIALIZED, INITIALIZING, lock, NEW, SHUTDOWN, SHUTTINGDOWN, STARTED, STARTING, status, STOPPED, STOPPING, SUSPENDED, SUSPENDING

Constructor Summary

Constructors

Constructor and Description
Throttler(org.apache.camel.CamelContext camelContext, org.apache.camel.Expression maxRequestsPerPeriodExpression, long timePeriodMillis, ScheduledExecutorService asyncExecutor, boolean shutdownAsyncExecutor, boolean rejectExecution, org.apache.camel.Expression correlation)

Method Summary

Modifier and Type	Method and Description
protected void	doShutdown()
protected void	doStart()
protected void	doStop()
int	getCurrentMaximumRequestsPerPeriod() Gets the current maximum request per period value.
String	getId()
org.apache.camel.Expression	getMaximumRequestsPerPeriodExpression()
String	getRouteId()
long	getTimePeriodMillis()
String	getTraceLabel()
boolean	isAsyncDelayed()
boolean	isCallerRunsWhenRejected()
boolean	isRejectExecution()
boolean	process(org.apache.camel.Exchange exchange, org.apache.camel.AsyncCallback callback)
protected boolean	processAsynchronously(org.apache.camel.Exchange exchange, org.apache.camel.AsyncCallback callback, org.apache.camel.processor.Throttler.ThrottlingState throttlingState) Delegate blocking on the DelayQueue to an asyncExecutor.
void	setAsyncDelayed(boolean asyncDelayed)
void	setCallerRunsWhenRejected(boolean callerRunsWhenRejected)
void	setId(String id)
void	setMaximumRequestsPerPeriodExpression(org.apache.camel.Expression maxRequestsPerPeriodExpression) Sets the maximum number of requests per time period expression
void	setRejectExecution(boolean rejectExecution)
void	setRouteId(String routeId)
void	setTimePeriodMillis(long timePeriodMillis) Sets the time period during which the maximum number of requests apply
String	toString()

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

process, processAsync

Methods inherited from class org.apache.camel.support.service.BaseService

build, doBuild, doFail, doInit, doLifecycleChange, doResume, doSuspend, fail, getStatus, init, isBuild, isInit, isNew, isRunAllowed, isShutdown, isStarted, isStarting, isStartingOrStarted, isStopped, isStopping, isStoppingOrStopped, isSuspended, isSuspending, isSuspendingOrSuspended, 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.StatefulService

getStatus, isRunAllowed, isStarted, isStarting, isStopped, isStopping, isSuspending

Methods inherited from interface org.apache.camel.SuspendableService

isSuspended, resume, suspend

Methods inherited from interface org.apache.camel.ShutdownableService

shutdown

Methods inherited from interface org.apache.camel.Service

build, close, init, start, stop

Constructor Detail

Throttler

public Throttler(org.apache.camel.CamelContext camelContext,
                 org.apache.camel.Expression maxRequestsPerPeriodExpression,
                 long timePeriodMillis,
                 ScheduledExecutorService asyncExecutor,
                 boolean shutdownAsyncExecutor,
                 boolean rejectExecution,
                 org.apache.camel.Expression correlation)

Method Detail

process

public boolean process(org.apache.camel.Exchange exchange,
                       org.apache.camel.AsyncCallback callback)

Specified by:

process in interface org.apache.camel.AsyncProcessor

processAsynchronously

protected boolean processAsynchronously(org.apache.camel.Exchange exchange,
                                        org.apache.camel.AsyncCallback callback,
                                        org.apache.camel.processor.Throttler.ThrottlingState throttlingState)

Delegate blocking on the DelayQueue to an asyncExecutor. Except if the executor rejects the submission and isCallerRunsWhenRejected() is enabled, then this method will delegate back to process(), but not before changing the exchange state to stop any recursion.

doStart

protected void doStart()
                throws Exception

Overrides:

doStart in class org.apache.camel.support.AsyncProcessorSupport

Throws:

Exception

doStop

protected void doStop()
               throws Exception

Overrides:

doStop in class org.apache.camel.support.AsyncProcessorSupport

Throws:

Exception

doShutdown

protected void doShutdown()
                   throws Exception

Overrides:

doShutdown in class org.apache.camel.support.service.BaseService

Throws:

Exception

isRejectExecution

public boolean isRejectExecution()

setRejectExecution

public void setRejectExecution(boolean rejectExecution)

isAsyncDelayed

public boolean isAsyncDelayed()

setAsyncDelayed

public void setAsyncDelayed(boolean asyncDelayed)

isCallerRunsWhenRejected

public boolean isCallerRunsWhenRejected()

setCallerRunsWhenRejected

public void setCallerRunsWhenRejected(boolean callerRunsWhenRejected)

getId

public String getId()

Specified by:

getId in interface org.apache.camel.spi.HasId

setId

public void setId(String id)

Specified by:

setId in interface org.apache.camel.spi.IdAware

getRouteId

public String getRouteId()

Specified by:

getRouteId in interface org.apache.camel.spi.RouteIdAware

setRouteId

public void setRouteId(String routeId)

Specified by:

setRouteId in interface org.apache.camel.spi.RouteIdAware

setMaximumRequestsPerPeriodExpression

public void setMaximumRequestsPerPeriodExpression(org.apache.camel.Expression maxRequestsPerPeriodExpression)

Sets the maximum number of requests per time period expression

getMaximumRequestsPerPeriodExpression

public org.apache.camel.Expression getMaximumRequestsPerPeriodExpression()

getCurrentMaximumRequestsPerPeriod

public int getCurrentMaximumRequestsPerPeriod()

Gets the current maximum request per period value. If it is grouped throttling applied with correlationExpression than the max per period within the group will return

setTimePeriodMillis

public void setTimePeriodMillis(long timePeriodMillis)

Sets the time period during which the maximum number of requests apply

getTimePeriodMillis

public long getTimePeriodMillis()

getTraceLabel

public String getTraceLabel()

Specified by:

getTraceLabel in interface org.apache.camel.Traceable

toString

public String toString()

Overrides:

toString in class Object