org.apache.catalina.valves
Class SemaphoreValve

java.lang.Object
  org.apache.catalina.valves.ValveBase
      org.apache.catalina.valves.SemaphoreValve

All Implemented Interfaces:

javax.management.MBeanRegistration, Contained, Lifecycle, Valve

public class SemaphoreValve
extends ValveBase
implements Lifecycle

Implementation of a Valve that limits concurrency.

This Valve may be attached to any Container, depending on the granularity of the concurrency control you wish to perform.

Version:

$Revision: 515 $ $Date: 2008-03-17 22:02:23 +0100 (Mon, 17 Mar 2008) $

Author:

Remy Maucherat

Field Summary

protected boolean	block Block until a permit is available.
protected int	concurrency Concurrency level of the semaphore.
protected boolean	fairness Fairness of the semaphore.
protected boolean	interruptible Block interruptibly until a permit is available.
protected LifecycleSupport	lifecycle The lifecycle event support for this component.
protected java.util.concurrent.Semaphore	semaphore Semaphore.

Fields inherited from class org.apache.catalina.valves.ValveBase

container, containerLog, controller, domain, mserver, next, oname

Fields inherited from interface org.apache.catalina.Lifecycle

AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, DESTROY_EVENT, INIT_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT

Constructor Summary

SemaphoreValve()

Method Summary

void	addLifecycleListener(LifecycleListener listener) Add a lifecycle event listener to this component.
boolean	controlConcurrency(Request request, Response response) Subclass friendly method to add conditions.
LifecycleListener[]	findLifecycleListeners() Get the lifecycle listeners associated with this lifecycle.
boolean	getBlock()
int	getConcurrency()
boolean	getFairness()
java.lang.String	getInfo() Return descriptive information about this Valve implementation.
boolean	getInterruptible()
void	invoke(Request request, Response response) Do concurrency control on the request using the semaphore.
void	permitDenied(Request request, Response response) Subclass friendly method to add error handling when a permit isn't granted.
void	removeLifecycleListener(LifecycleListener listener) Remove a lifecycle event listener from this component.
void	setBlock(boolean block)
void	setConcurrency(int concurrency)
void	setFairness(boolean fairness)
void	setInterruptible(boolean interruptible)
void	start() Prepare for the beginning of active use of the public methods of this component.
void	stop() Gracefully terminate the active use of the public methods of this component.

Methods inherited from class org.apache.catalina.valves.ValveBase

backgroundProcess, createObjectName, event, getContainer, getContainerName, getController, getDomain, getNext, getObjectName, getParentName, postDeregister, postRegister, preDeregister, preRegister, setContainer, setController, setNext, setObjectName, toString

Methods inherited from class java.lang.Object

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

Field Detail

semaphore

protected java.util.concurrent.Semaphore semaphore

Semaphore.

lifecycle

protected LifecycleSupport lifecycle

The lifecycle event support for this component.

concurrency

protected int concurrency

Concurrency level of the semaphore.

fairness

protected boolean fairness

Fairness of the semaphore.

block

protected boolean block

Block until a permit is available.

interruptible

protected boolean interruptible

Block interruptibly until a permit is available.

Constructor Detail

SemaphoreValve

public SemaphoreValve()

Method Detail

getConcurrency

public int getConcurrency()

setConcurrency

public void setConcurrency(int concurrency)

getFairness

public boolean getFairness()

setFairness

public void setFairness(boolean fairness)

getBlock

public boolean getBlock()

setBlock

public void setBlock(boolean block)

getInterruptible

public boolean getInterruptible()

setInterruptible

public void setInterruptible(boolean interruptible)

addLifecycleListener

public void addLifecycleListener(LifecycleListener listener)

Add a lifecycle event listener to this component.

Specified by:

addLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to add

findLifecycleListeners

public LifecycleListener[] findLifecycleListeners()

Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned.

Specified by:

findLifecycleListeners in interface Lifecycle

removeLifecycleListener

public void removeLifecycleListener(LifecycleListener listener)

Remove a lifecycle event listener from this component.

Specified by:

removeLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to add

start

public void start()
           throws LifecycleException

Prepare for the beginning of active use of the public methods of this component. This method should be called after configure(), and before any of the public methods of the component are utilized.

Specified by:

start in interface Lifecycle

Throws:

LifecycleException - if this component detects a fatal error that prevents this component from being used

stop

public void stop()
          throws LifecycleException

Gracefully terminate the active use of the public methods of this component. This method should be the last one called on a given instance of this component.

Specified by:

stop in interface Lifecycle

Throws:

LifecycleException - if this component detects a fatal error that needs to be reported

getInfo

public java.lang.String getInfo()

Return descriptive information about this Valve implementation.

Specified by:

getInfo in interface Valve

Overrides:

getInfo in class ValveBase

invoke

public void invoke(Request request,
                   Response response)
            throws java.io.IOException,
                   javax.servlet.ServletException

Do concurrency control on the request using the semaphore.

Specified by:

invoke in interface Valve

Specified by:

invoke in class ValveBase

Parameters:

request - The servlet request to be processed

response - The servlet response to be created

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet error occurs

controlConcurrency

public boolean controlConcurrency(Request request,
                                  Response response)

Subclass friendly method to add conditions.

permitDenied

public void permitDenied(Request request,
                         Response response)
                  throws java.io.IOException,
                         javax.servlet.ServletException

Subclass friendly method to add error handling when a permit isn't granted.

Throws:

java.io.IOException

javax.servlet.ServletException