com.yahoo.jdisc.handler

Class RequestDispatch

java.lang.Object

com.yahoo.jdisc.handler.RequestDispatch

All Implemented Interfaces:

com.google.common.util.concurrent.ListenableFuture<Response>, ResponseHandler, Future<Response>

Direct Known Subclasses:

CallableRequestDispatch

public abstract class RequestDispatch
extends Object
implements com.google.common.util.concurrent.ListenableFuture<Response>, ResponseHandler

This class provides a convenient way of safely dispatching a Request. Using this class you do not have to worry about the exception safety surrounding the SharedResource logic. The internal mechanics of this class will ensure that anything that goes wrong during dispatch is safely handled according to jDISC contracts.

It also provides a default implementation of the ResponseHandler interface that returns a NullContent. If you want to return a different ContentChannel, you need to override handleResponse(Response).

The following is a simple example on how to use this class:

 public void handleRequest(final Request parent, final ResponseHandler handler) {
     new RequestDispatch() {
         @Override
         protected Request newRequest() {
             return new Request(parent, URI.create("http://remotehost/"));
         }
         @Override
         protected Iterable<ByteBuffer> requestContent() {
             return Collections.singleton(ByteBuffer.wrap(new byte[] { 6, 9 }));
         }
         @Override
         public ContentChannel handleResponse(Response response) {
             return handler.handleResponse(response);
         }
     }.dispatch();
 }
 

Author:

Simon Thoresen Hult

Constructor Summary

Constructors

Constructor and Description
RequestDispatch()

Method Summary

Modifier and Type	Method and Description
void	addListener(Runnable listener, Executor executor)
boolean	cancel(boolean mayInterruptIfRunning)
ContentChannel	connect() This methods calls newRequest() to create a new Request, and then calls Request.connect(ResponseHandler) on that.
FastContentWriter	connectFastWriter() This is a convenient method to construct a FastContentWriter over the ContentChannel returned by calling connect().
com.google.common.util.concurrent.ListenableFuture<Response>	dispatch() This method calls connect() to establish a ContentChannel for the Request, and then iterates through all the ByteBuffers returned by requestContent() and writes them to that ContentChannel.
Response	get()
Response	get(long timeout, TimeUnit unit)
ContentChannel	handleResponse(Response response) This method will process the given Response and return a ContentChannel into which the caller can write the Response's content.
boolean	isCancelled()
boolean	isDone()
protected abstract Request	newRequest() Creates and returns the Request to dispatch.
protected Iterable<ByteBuffer>	requestContent() Returns an Iterable for the ByteBuffers that the dispatch() method should write to the Request once it has connected.

Methods inherited from class java.lang.Object

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

Constructor Detail

RequestDispatch

public RequestDispatch()

Method Detail

newRequest

protected abstract Request newRequest()

Creates and returns the Request to dispatch. The internal code that calls this method takes care of the necessary exception safety of connecting the Request.

Returns:

The Request to dispatch.

requestContent

protected Iterable<ByteBuffer> requestContent()

Returns an Iterable for the ByteBuffers that the dispatch() method should write to the Request once it has connected. The default implementation returns an empty list. Because this method uses the Iterable interface, you can create the ByteBuffers lazily, or provide them as they become available.

Returns:

The ByteBuffers to write to the Request's ContentChannel.

connect

public final ContentChannel connect()

This methods calls newRequest() to create a new Request, and then calls Request.connect(ResponseHandler) on that. This method uses a finally block to make sure that the Request is always released.

Returns:

The ContentChannel to write the Request's content to.

connectFastWriter

public final FastContentWriter connectFastWriter()

This is a convenient method to construct a FastContentWriter over the ContentChannel returned by calling connect().

Returns:

The ContentWriter for the connected Request.

dispatch

public final com.google.common.util.concurrent.ListenableFuture<Response> dispatch()

This method calls connect() to establish a ContentChannel for the Request, and then iterates through all the ByteBuffers returned by requestContent() and writes them to that ContentChannel. This method uses a finally block to make sure that the ContentChannel is always closed.

The returned Future will wait for all CompletionHandlers associated with the Request have been completed, and a Response has been received.

Returns:

A Future that can be waited for.

addListener

public void addListener(Runnable listener,
                        Executor executor)

Specified by:

addListener in interface com.google.common.util.concurrent.ListenableFuture<Response>

cancel

public final boolean cancel(boolean mayInterruptIfRunning)

Specified by:

cancel in interface Future<Response>

isCancelled

public final boolean isCancelled()

Specified by:

isCancelled in interface Future<Response>

isDone

public final boolean isDone()

Specified by:

isDone in interface Future<Response>

get

public final Response get()
                   throws InterruptedException,
                          ExecutionException

Specified by:

get in interface Future<Response>

Throws:

InterruptedException

ExecutionException

get

public final Response get(long timeout,
                          TimeUnit unit)
                   throws InterruptedException,
                          ExecutionException,
                          TimeoutException

Specified by:

get in interface Future<Response>

Throws:

InterruptedException

ExecutionException

TimeoutException

handleResponse

public ContentChannel handleResponse(Response response)

Description copied from interface: ResponseHandler

This method will process the given Response and return a ContentChannel into which the caller can write the Response's content.

Specified by:

handleResponse in interface ResponseHandler

Parameters:

response - The Response to handle.

Returns:

The ContentChannel to write the Response content to. Notice that the ContentChannel holds a Container reference, so failure to close this will prevent the Container from ever shutting down.