File	Doc	Category	Size	Date	Package
SemaphoreValve.java	API Doc	Apache Tomcat 6.0.14	8273	Fri Jul 20 04:20:32 BST 2007	org.apache.catalina.valves

SemaphoreValve

• java.lang.Object
  • ValveBase

Fields Summary
private static final String	info The descriptive information related to this implementation.
private org.apache.catalina.util.StringManager	sm The string manager for this package.
protected Semaphore	semaphore Semaphore.
protected org.apache.catalina.util.LifecycleSupport	lifecycle The lifecycle event support for this component.
private boolean	started Has this component been started yet?
protected int	concurrency Concurrency level of the semaphore.
protected boolean	fairness Fairness of the semaphore.
protected boolean	block Block until a permit is available.
protected boolean	interruptible Block interruptibly until a permit is available.

Constructors Summary

Methods Summary
public void	addLifecycleListener(org.apache.catalina.LifecycleListener listener) Add a lifecycle event listener to this component. param listener The listener to add lifecycle.addLifecycleListener(listener);
public boolean	controlConcurrency(org.apache.catalina.connector.Request request, org.apache.catalina.connector.Response response) Subclass friendly method to add conditions. return true;
public org.apache.catalina.LifecycleListener[]	findLifecycleListeners() Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned. return lifecycle.findLifecycleListeners();
public boolean	getBlock() return block;
public int	getConcurrency() return concurrency;
public boolean	getFairness() return fairness;
public java.lang.String	getInfo() Return descriptive information about this Valve implementation. return (info);
public boolean	getInterruptible() return interruptible;
public void	invoke(org.apache.catalina.connector.Request request, org.apache.catalina.connector.Response response) Do concurrency control on the request using the semaphore. param request The servlet request to be processed param response The servlet response to be created exception IOException if an input/output error occurs exception ServletException if a servlet error occurs if (controlConcurrency(request, response)) { boolean shouldRelease = true; try { if (block) { if (interruptible) { try { semaphore.acquire(); } catch (InterruptedException e) { shouldRelease = false; permitDenied(request, response); return; } } else { semaphore.acquireUninterruptibly(); } } else { if (!semaphore.tryAcquire()) { shouldRelease = false; permitDenied(request, response); return; } } getNext().invoke(request, response); } finally { if (shouldRelease) { semaphore.release(); } } } else { getNext().invoke(request, response); }
public void	permitDenied(org.apache.catalina.connector.Request request, org.apache.catalina.connector.Response response) Subclass friendly method to add error handling when a permit isn't granted.
public void	removeLifecycleListener(org.apache.catalina.LifecycleListener listener) Remove a lifecycle event listener from this component. param listener The listener to add lifecycle.removeLifecycleListener(listener);
public void	setBlock(boolean block) this.block = block;
public void	setConcurrency(int concurrency) this.concurrency = concurrency;
public void	setFairness(boolean fairness) this.fairness = fairness;
public void	setInterruptible(boolean interruptible) this.interruptible = interruptible;
public void	start() 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. exception LifecycleException if this component detects a fatal error that prevents this component from being used // Validate and update our current component state if (started) throw new LifecycleException (sm.getString("semaphoreValve.alreadyStarted")); lifecycle.fireLifecycleEvent(START_EVENT, null); started = true; semaphore = new Semaphore(concurrency, fairness);
public void	stop() 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. exception LifecycleException if this component detects a fatal error that needs to be reported // Validate and update our current component state if (!started) throw new LifecycleException (sm.getString("semaphoreValve.notStarted")); lifecycle.fireLifecycleEvent(STOP_EVENT, null); started = false; semaphore = null;