RequestDispatch (jdisc_core 6.162.10 API)

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

Field Summary

Fields
Modifier and Type Field and Description

private FutureConjunction completions

private FutureResponse futureResponse

Fields
Modifier and Type	Field and Description
`private FutureConjunction`	`completions`
`private FutureResponse`	`futureResponse`

Constructor Summary

Constructors
Constructor and Description

RequestDispatch()

Constructors
Constructor and Description
`RequestDispatch()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
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

- Field Detail
  - completions
```
private final FutureConjunction completions
```
  - futureResponse
```
private final FutureResponse futureResponse
```
- 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.

Class RequestDispatch

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

completions

futureResponse

Constructor Detail

RequestDispatch

Method Detail

newRequest

requestContent

connect

connectFastWriter

dispatch

addListener

cancel

isCancelled

isDone

get

get

handleResponse