Package org.apache.camel.processor

Class ConcurrentRequestsThrottler

java.lang.Object

org.apache.camel.support.service.BaseService

org.apache.camel.support.service.ServiceSupport

org.apache.camel.support.AsyncProcessorSupport

org.apache.camel.processor.AbstractThrottler

org.apache.camel.processor.ConcurrentRequestsThrottler

All Implemented Interfaces:

AutoCloseable, org.apache.camel.AsyncProcessor, org.apache.camel.Processor, Throttler, 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 ConcurrentRequestsThrottler
extends AbstractThrottler

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

This pattern can be extremely useful if you have some external system which meters access; such as only allowing 10 concurrent requests; 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 Semaphore with maxConcurrentRequests permits on it. Callers trying to acquire a permit will block if necessary when maxConcurrentRequests permits have been acquired.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	ConcurrentRequestsThrottler.ThrottlingState

Field Summary

Fields inherited from class org.apache.camel.processor.AbstractThrottler

asyncDelayed, asyncExecutor, callerRunsWhenRejected, camelContext, correlationExpression, id, maxRequestsExpression, PROPERTY_EXCHANGE_QUEUED_TIMESTAMP, rejectExecution, routeId, shutdownAsyncExecutor

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

BUILT, FAILED, INITIALIZED, INITIALIZING, lock, NEW, SHUTDOWN, SHUTTING_DOWN, STARTED, STARTING, status, STOPPED, STOPPING, SUSPENDED, SUSPENDING

Constructor Summary

Constructors

Constructor	Description
ConcurrentRequestsThrottler(org.apache.camel.CamelContext camelContext, org.apache.camel.Expression maxRequestsExpression, ScheduledExecutorService asyncExecutor, boolean shutdownAsyncExecutor, boolean rejectExecution, org.apache.camel.Expression correlation)

Method Summary

Modifier and Type	Method	Description
protected void	doShutdown()
protected void	doStart()
int	getCurrentMaximumRequests()	Gets the current maximum request.
String	getMode()
String	getTraceLabel()
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, ConcurrentRequestsThrottler.ThrottlingState throttlingState)	Delegate blocking to an asyncExecutor.
String	toString()

Methods inherited from class org.apache.camel.processor.AbstractThrottler

getId, getMaximumRequestsExpression, getRouteId, handleException, handleInterrupt, isAsyncDelayed, isCallerRunsWhenRejected, isRejectExecution, setAsyncDelayed, setCallerRunsWhenRejected, setId, setMaximumRequestsExpression, setRejectExecution, setRouteId

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, doStop, doSuspend, fail, getInternalLock, 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.spi.IdAware

setGeneratedId

Methods inherited from interface org.apache.camel.Processor

process

Methods inherited from interface org.apache.camel.Service

build, close, init, start, stop

Methods inherited from interface org.apache.camel.ShutdownableService

shutdown

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

Constructor Details

ConcurrentRequestsThrottler

public ConcurrentRequestsThrottler(org.apache.camel.CamelContext camelContext,
 org.apache.camel.Expression maxRequestsExpression,
 ScheduledExecutorService asyncExecutor,
 boolean shutdownAsyncExecutor,
 boolean rejectExecution,
 org.apache.camel.Expression correlation)

Method Details

process

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

processAsynchronously

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

Delegate blocking 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.service.BaseService

Throws:

Exception

doShutdown

protected void doShutdown()
                   throws Exception

Overrides:

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

Throws:

Exception

getMode

public String getMode()

Specified by:

getMode in interface Throttler

Specified by:

getMode in class AbstractThrottler

getCurrentMaximumRequests

public int getCurrentMaximumRequests()

Gets the current maximum request. If it is grouped throttling applied with correlationExpression then the max within the group will return

getTraceLabel

public String getTraceLabel()

toString

public String toString()

Overrides:

toString in class Object