org.apache.catalina.valves
Class SemaphoreValve

java.lang.Object
  org.apache.catalina.util.LifecycleBase
      org.apache.catalina.util.LifecycleMBeanBase
          org.apache.catalina.valves.ValveBase
              org.apache.catalina.valves.SemaphoreValve

All Implemented Interfaces:

MBeanRegistration, Contained, Lifecycle, Valve

public class SemaphoreValve
extends ValveBase

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. Note that internally, some async requests may require multiple serial requests to complete what - to the user - appears as a single request.

Version:

$Id: SemaphoreValve.java 1187022 2011-10-20 19:55:37Z markt $

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 Semaphore	semaphore Semaphore.

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

asyncSupported, container, containerLog, next, sm

Fields inherited from class org.apache.catalina.util.LifecycleMBeanBase

mserver

Fields inherited from interface org.apache.catalina.Lifecycle

AFTER_DESTROY_EVENT, AFTER_INIT_EVENT, AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_DESTROY_EVENT, BEFORE_INIT_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, CONFIGURE_START_EVENT, CONFIGURE_STOP_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT

Constructor Summary

SemaphoreValve()

Method Summary

boolean	controlConcurrency(Request request, Response response) Subclass friendly method to add conditions.
boolean	getBlock()
int	getConcurrency()
boolean	getFairness()
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	setBlock(boolean block)
void	setConcurrency(int concurrency)
void	setFairness(boolean fairness)
void	setInterruptible(boolean interruptible)
protected void	startInternal() Start this component and implement the requirements of LifecycleBase.startInternal().
protected void	stopInternal() Stop this component and implement the requirements of LifecycleBase.stopInternal().

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

backgroundProcess, event, getContainer, getDomainInternal, getNext, getObjectNameKeyProperties, initInternal, isAsyncSupported, setAsyncSupported, setContainer, setNext, toString

Methods inherited from class org.apache.catalina.util.LifecycleMBeanBase

destroyInternal, getDomain, getObjectName, postDeregister, postRegister, preDeregister, preRegister, register, setDomain, unregister

Methods inherited from class org.apache.catalina.util.LifecycleBase

addLifecycleListener, destroy, findLifecycleListeners, fireLifecycleEvent, getState, getStateName, init, removeLifecycleListener, setState, setState, start, stop

Methods inherited from class java.lang.Object

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

Field Detail

semaphore

protected Semaphore semaphore

Semaphore.

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)

startInternal

protected void startInternal()
                      throws LifecycleException

Start this component and implement the requirements of LifecycleBase.startInternal().

Overrides:

startInternal in class ValveBase

Throws:

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

stopInternal

protected void stopInternal()
                     throws LifecycleException

Stop this component and implement the requirements of LifecycleBase.stopInternal().

Overrides:

stopInternal in class ValveBase

Throws:

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

getInfo

public 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 IOException,
                   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:

IOException - if an input/output error occurs

ServletException - if a servlet error occurs

controlConcurrency

public boolean controlConcurrency(Request request,
                                  Response response)

Subclass friendly method to add conditions.

Parameters:

request -

response -

permitDenied

public void permitDenied(Request request,
                         Response response)
                  throws IOException,
                         ServletException

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

Parameters:

request -

response -

Throws:

IOException

ServletException