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package com.sun.xml.ws.api.pipe;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Interception for {@link Fiber} context switch.
*
*
* Even though pipeline runs asynchronously, sometimes it's desirable
* to bind some state to the current thread running a fiber. Such state
* may include security subject (in terms of {@link AccessController#doPrivileged}),
* or a transaction.
*
*
* This mechanism makes it possible to do such things, by allowing
* some code to be executed before and after a thread executes a fiber.
*
*
* The design also encapsulates the entire fiber execution in a single
* opaque method invocation {@link Work#execute}, allowing the use of
* finally block.
*
*
* @author Kohsuke Kawaguchi
*/
public interface FiberContextSwitchInterceptor {
/**
* Allows the interception of the fiber execution.
*
*
* This method needs to be implemented like this:
*
*
* <R,P> R execute( Fiber f, P p, Work<R,P> work ) {
* // do some preparation work
* ...
* try {
* // invoke
* return work.execute(p);
* } finally {
* // do some clean up work
* ...
* }
* }
*
*
*
* While somewhat unintuitive,
* this interception mechanism enables the interceptor to wrap
* the whole fiber execution into a {@link AccessController#doPrivileged(PrivilegedAction)},
* for example.
*
* @param f
* {@link Fiber} to be executed.
* @param p
* The opaque parameter value for {@link Work}. Simply pass this value to
* {@link Work#execute(Object)}.
* @return
* The opaque return value from the the {@link Work}. Simply return
* the value from {@link Work#execute(Object)}.
*/
R execute( Fiber f, P p, Work work );
/**
* Abstraction of the execution that happens inside the interceptor.
*/
interface Work {
/**
* Have the current thread executes the current fiber,
* and returns when it stops doing so.
*
*
* The parameter and the return value is controlled by the
* JAX-WS runtime, and interceptors should simply treat
* them as opaque values.
*/
R execute(P param);
}
}