org.eclipse.jetty.continuation

Class Servlet3Continuation

java.lang.Object

org.eclipse.jetty.continuation.Servlet3Continuation

All Implemented Interfaces:

EventListener, AsyncListener, Continuation

public class Servlet3Continuation
extends Object
implements Continuation, AsyncListener

This implementation of Continuation is used by ContinuationSupport when it detects that the application has been deployed in a Servlet 3 server.

Field Summary

Fields inherited from interface org.eclipse.jetty.continuation.Continuation

ATTRIBUTE

Constructor Summary

Constructors

Constructor and Description
Servlet3Continuation(ServletRequest request)

Method Summary

Modifier and Type	Method and Description
void	addContinuationListener(ContinuationListener listener) Add a ContinuationListener.
void	complete() Complete a suspended request.
Object	getAttribute(String name) Get a request attribute.
ServletResponse	getServletResponse() Get the suspended response.
boolean	isExpired()
boolean	isInitial()
boolean	isResponseWrapped() Is the suspended response wrapped.
boolean	isResumed()
boolean	isSuspended()
void	keepWrappers()
void	onComplete(AsyncEvent event)
void	onError(AsyncEvent event)
void	onStartAsync(AsyncEvent event)
void	onTimeout(AsyncEvent event)
void	removeAttribute(String name) Remove a request attribute.
void	resume() Resume a suspended request.
void	setAttribute(String name, Object attribute) Set a request attribute.
void	setTimeout(long timeoutMs) Set the continuation timeout.
void	suspend() Suspend the processing of the request and associated ServletResponse.
void	suspend(ServletResponse response) Suspend the processing of the request and associated ServletResponse.
void	undispatch() Undispatch the request.

Methods inherited from class java.lang.Object

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

Constructor Detail

Servlet3Continuation

public Servlet3Continuation(ServletRequest request)

Method Detail

addContinuationListener

public void addContinuationListener(ContinuationListener listener)

Description copied from interface: Continuation

Add a ContinuationListener.

Specified by:

addContinuationListener in interface Continuation

Parameters:

listener - the listener

complete

public void complete()

Description copied from interface: Continuation

Complete a suspended request.

This method can be called by any thread that has been passed a reference to a suspended request. When a request is completed, the associated response object committed and flushed. The request is not redispatched.

If complete is called before a suspended request is returned to the container (ie the thread that called Continuation.suspend() is still within the filter chain and/or servlet service method), then the complete does not take effect until the call to the filter chain and/or servlet returns to the container. In this case both Continuation.isSuspended() and Continuation.isResumed() return true.

Typically resume() is used after a call to Continuation.suspend(ServletResponse) with a possibly wrapped response. The async handler should use the response provided by Continuation.getServletResponse() to write the response before calling Continuation.complete(). If the request was suspended with a call to Continuation.suspend() then no response object will be available via Continuation.getServletResponse().

Once complete has been called and any thread calling the filter chain and/or servlet chain has returned to the container, the request lifecycle is complete. The container is able to recycle request objects, so it is not valid hold a request or continuation reference after the end of the life cycle.

Specified by:

complete in interface Continuation

See Also:

Continuation.suspend()

getServletResponse

public ServletResponse getServletResponse()

Description copied from interface: Continuation

Get the suspended response.

Specified by:

getServletResponse in interface Continuation

Returns:

the ServletResponse passed to Continuation.suspend(ServletResponse).

isExpired

public boolean isExpired()

Specified by:

isExpired in interface Continuation

Returns:

true after a request has been redispatched as the result of a timeout. Returns false after any subsequent call to suspend.

isInitial

public boolean isInitial()

Specified by:

isInitial in interface Continuation

Returns:

true while the request is within the initial dispatch to the filter chain and/or servlet. Will return false once the calling thread has returned to the container after suspend has been called and during any subsequent redispatch.

isResumed

public boolean isResumed()

Specified by:

isResumed in interface Continuation

Returns:

true if the request has been redispatched by a call to Continuation.resume(). Returns false after any subsequent call to suspend

isSuspended

public boolean isSuspended()

Specified by:

isSuspended in interface Continuation

Returns:

true after Continuation.suspend() has been called and before the request has been redispatched due to being resumed, completed or timed out.

keepWrappers

public void keepWrappers()

resume

public void resume()

Description copied from interface: Continuation

Resume a suspended request.

This method can be called by any thread that has been passed a reference to a continuation. When called the request is redispatched to the normal filter chain and servlet processing with Continuation.isInitial() false.

If resume is called before a suspended request is returned to the container (ie the thread that called Continuation.suspend() is still within the filter chain and/or servlet service method), then the resume does not take effect until the call to the filter chain and/or servlet returns to the container. In this case both Continuation.isSuspended() and Continuation.isResumed() return true. Multiple calls to resume are ignored.

Typically resume() is used after a call to Continuation.suspend() with no arguments. The dispatch after a resume call will use the original request and response objects, even if Continuation.suspend(ServletResponse) had been passed a wrapped response.

Specified by:

resume in interface Continuation

See Also:

Continuation.suspend()

setTimeout

public void setTimeout(long timeoutMs)

Description copied from interface: Continuation

Set the continuation timeout.

Specified by:

setTimeout in interface Continuation

Parameters:

timeoutMs - The time in milliseconds to wait before expiring this continuation after a call to Continuation.suspend() or Continuation.suspend(ServletResponse). A timeout of <=0 means the continuation will never expire.

suspend

public void suspend(ServletResponse response)

Description copied from interface: Continuation

Suspend the processing of the request and associated ServletResponse.

After this method has been called, the lifecycle of the request will be extended beyond the return to the container from the Servlet.service(ServletRequest, ServletResponse) method and Filter.doFilter(ServletRequest, ServletResponse, FilterChain) calls. When a suspended request is returned to the container after a dispatch, then the container will not commit the associated response (unless an exception other than ContinuationThrowable is thrown).

When the thread calling the filter chain and/or servlet has returned to the container with a suspended request, the thread is freed for other tasks and the request is held until either:

• a call to Continuation.resume().
• a call to Continuation.complete().
• the timeout expires.

Typically suspend with a response argument is uses when a call to Continuation.complete() is expected. If a call to Continuation.resume() is expected, then the Continuation.suspend() method should be used instead of this method.

Filters that may wrap the response object should check Continuation.isResponseWrapped() to decide if they should destroy/finish the wrapper. If Continuation.isResponseWrapped() returns true, then the wrapped request has been passed to the asynchronous handler and the wrapper should not be destroyed/finished until after a call to Continuation.complete() (potentially using a ContinuationListener.onComplete(Continuation) listener).

Specified by:

suspend in interface Continuation

Parameters:

response - The response to return via a call to Continuation.getServletResponse()

suspend

public void suspend()

Description copied from interface: Continuation

Suspend the processing of the request and associated ServletResponse.

After this method has been called, the lifecycle of the request will be extended beyond the return to the container from the Servlet.service(ServletRequest, ServletResponse) method and Filter.doFilter(ServletRequest, ServletResponse, FilterChain) calls. When a suspended request is returned to the container after a dispatch, then the container will not commit the associated response (unless an exception other than ContinuationThrowable is thrown).

When the thread calling the filter chain and/or servlet has returned to the container with a suspended request, the thread is freed for other tasks and the request is held until either:

• a call to Continuation.resume().
• a call to Continuation.complete().
• the timeout expires.

Typically suspend with no arguments is uses when a call to Continuation.resume() is expected. If a call to Continuation.complete() is expected, then the Continuation.suspend(ServletResponse) method should be used instead of this method.

Specified by:

suspend in interface Continuation

isResponseWrapped

public boolean isResponseWrapped()

Description copied from interface: Continuation

Is the suspended response wrapped.

Filters that wrap the response object should check this method to determine if they should destroy/finish the wrapped response. If the request was suspended with a call to Continuation.suspend(ServletResponse) that passed the wrapped response, then the filter should register a ContinuationListener to destroy/finish the wrapped response during a call to ContinuationListener.onComplete(Continuation).

Specified by:

isResponseWrapped in interface Continuation

Returns:

True if Continuation.suspend(ServletResponse) has been passed a ServletResponseWrapper instance.

getAttribute

public Object getAttribute(String name)

Description copied from interface: Continuation

Get a request attribute. This method is a convenience method to call the ServletRequest.getAttribute(String) method on the associated request object. This is a thread safe call and may be called by any thread.

Specified by:

getAttribute in interface Continuation

Parameters:

name - the attribute name

Returns:

the attribute value

See Also:

Continuation.getAttribute(java.lang.String)

removeAttribute

public void removeAttribute(String name)

Description copied from interface: Continuation

Remove a request attribute. This method is a convenience method to call the ServletRequest.removeAttribute(String) method on the associated request object. This is a thread safe call and may be called by any thread.

Specified by:

removeAttribute in interface Continuation

Parameters:

name - the attribute name

See Also:

Continuation.removeAttribute(java.lang.String)

setAttribute

public void setAttribute(String name,
                         Object attribute)

Description copied from interface: Continuation

Set a request attribute. This method is a convenience method to call the ServletRequest.setAttribute(String, Object) method on the associated request object. This is a thread safe call and may be called by any thread.

Specified by:

setAttribute in interface Continuation

Parameters:

name - the attribute name

attribute - the attribute value

See Also:

Continuation.setAttribute(java.lang.String, java.lang.Object)

undispatch

public void undispatch()

Description copied from interface: Continuation

Undispatch the request.

This method can be called on a suspended continuation in order to exit the dispatch to the filter/servlet by throwing a ContinuationThrowable which is caught either by the container or the ContinuationFilter. This is an alternative to simply returning from the dispatch in the case where filters in the filter chain may not be prepared to handle a suspended request.

This method should only be used as a last resort and a normal return is a prefereable solution if filters can be updated to handle that case.

Specified by:

undispatch in interface Continuation

See Also:

Continuation.undispatch()

onComplete

public void onComplete(AsyncEvent event)
                throws IOException

Specified by:

onComplete in interface AsyncListener

Throws:

IOException

onError

public void onError(AsyncEvent event)
             throws IOException

Specified by:

onError in interface AsyncListener

Throws:

IOException

onStartAsync

public void onStartAsync(AsyncEvent event)
                  throws IOException

Specified by:

onStartAsync in interface AsyncListener

Throws:

IOException

onTimeout

public void onTimeout(AsyncEvent event)
               throws IOException

Specified by:

onTimeout in interface AsyncListener

Throws:

IOException