Package 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, JmxEnabled, 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.

Author:

Remy Maucherat

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.catalina.Lifecycle

Lifecycle.SingleUse

Field Summary

Fields

Modifier and Type	Field	Description
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 int	highConcurrencyStatus	High concurrency status.
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 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

Constructors

Constructor	Description
SemaphoreValve()

Method Summary

Modifier and Type	Method	Description
boolean	controlConcurrency(Request request, Response response)	Subclass friendly method to add conditions.
boolean	getBlock()
int	getConcurrency()
boolean	getFairness()
int	getHighConcurrencyStatus()
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	setHighConcurrencyStatus(int highConcurrencyStatus)
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, 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, unregister

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

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

Methods inherited from class java.lang.Object

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

Field Details

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.

highConcurrencyStatus

protected int highConcurrencyStatus

High concurrency status. This status code is returned as an error if concurrency is too high.

Constructor Details

SemaphoreValve

public SemaphoreValve()

Method Details

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)

getHighConcurrencyStatus

public int getHighConcurrencyStatus()

setHighConcurrencyStatus

public void setHighConcurrencyStatus(int highConcurrencyStatus)

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

invoke

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

Do concurrency control on the request using the semaphore.

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 - The Servlet request

response - The Servlet response

Returns:

true if the concurrency control should occur on this request

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 - The Servlet request

response - The Servlet response

Throws:

IOException - Error writing output

ServletException - Other error