Package org.eclipse.jetty.websocket.core.util

Class DemandingFlusher

java.lang.Object

org.eclipse.jetty.util.IteratingCallback

org.eclipse.jetty.websocket.core.util.DemandingFlusher

All Implemented Interfaces:

Callback, Invocable, DemandChain

Direct Known Subclasses:

FragmentExtension.FragmentingDemandingFlusher

public abstract class DemandingFlusher
extends IteratingCallback
implements DemandChain

This flusher can be used to mutated and fragment Frames and forwarded them on towards the application using the IncomingFrames provided in the constructor. This can split a single incoming frame into n Frames which are passed on to the IncomingFrames one at a time.

The asynchronous operation performed by this IteratingCallback is demanding from upper layer after which onFrame(Frame, Callback) will called with the new content.

This flusher relies on the interception of demand, and because of this it can only be used in an Extension which implements the DemandChain interface. The methods of DemandChain from the Extension must be forwarded to this flusher.

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.jetty.util.IteratingCallback

IteratingCallback.Action

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.Callback

Callback.Completable, Callback.Completing, Callback.Nested

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.thread.Invocable

Invocable.Callable, Invocable.InvocationType, Invocable.ReadyTask, Invocable.Task

Field Summary

Fields inherited from interface org.eclipse.jetty.util.Callback

NOOP

Fields inherited from interface org.eclipse.jetty.util.thread.Invocable

__nonBlocking

Constructor Summary

Constructors

Constructor	Description
DemandingFlusher(IncomingFrames emitFrame)

Method Summary

Modifier and Type	Method	Description
void	closeFlusher()	Used to close this flusher when there is no explicit failure.
void	demand()
void	emitFrame(Frame frame, Callback callback)	This is used within an implementation of handle(Frame, Callback, boolean) to forward a frame onto the next layer of processing.
void	failFlusher(Throwable t)	Used to fail this flusher possibly from an external event such as a callback.
protected abstract boolean	handle(Frame frame, Callback callback, boolean first)	Called when there is demand for a single frame to be produced.
protected void	onCompleteFailure(Throwable cause)	Invoked when the overall task has completed with a failure.
void	onFrame(Frame frame, Callback callback)	Used to supply the flusher with a new frame.
protected IteratingCallback.Action	process()	Method called by IteratingCallback.iterate() to process the asynchronous sub-task.
void	setNextDemand(DemandChain nextDemand)

Methods inherited from class org.eclipse.jetty.util.IteratingCallback

abort, close, failed, isAborted, isClosed, isFailed, isSucceeded, iterate, onCompleteSuccess, onSuccess, reset, succeeded, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.jetty.util.Callback

completeWith

Methods inherited from interface org.eclipse.jetty.util.thread.Invocable

getInvocationType

Constructor Details

DemandingFlusher

public DemandingFlusher(IncomingFrames emitFrame)

Parameters:

emitFrame - where frames generated by handle(Frame, Callback, boolean) are forwarded.

Method Details

handle

protected abstract boolean handle(Frame frame,
 Callback callback,
 boolean first)

Called when there is demand for a single frame to be produced. During this method a single call can be made to emitFrame(Frame, Callback) which will forward this frame towards the application. Returning true from this method signals that you are done processing the current Frame, and the next invocation of this method will have the next frame.

Note that the callback supplied here is specially wrapped so that you can call it multiple times and it will not be completed more than once. This simplifies the handling of failure cases.

Parameters:

frame - the original frame.

callback - to succeed to release the frame payload.

first - if this is the first time this method has been called for this frame.

Returns:

false to continue processing this frame, true to complete processing and get a new frame.

demand

public void demand()

Specified by:

demand in interface DemandChain

setNextDemand

public void setNextDemand(DemandChain nextDemand)

Specified by:

setNextDemand in interface DemandChain

onFrame

public void onFrame(Frame frame,
 Callback callback)

Used to supply the flusher with a new frame. This frame should only arrive if demanded through the DemandChain provided by setNextDemand(DemandChain).

Parameters:

frame - the WebSocket frame.

callback - to release frame payload.

closeFlusher

public void closeFlusher()

Used to close this flusher when there is no explicit failure.

failFlusher

public void failFlusher(Throwable t)

Used to fail this flusher possibly from an external event such as a callback.

Parameters:

t - the failure.

emitFrame

public void emitFrame(Frame frame,
 Callback callback)

This is used within an implementation of handle(Frame, Callback, boolean) to forward a frame onto the next layer of processing.

This method should only be called ONCE within each invocation of handle(Frame, Callback, boolean) otherwise

Parameters:

frame - the WebSocket frame.

callback - to release frame payload.

process

protected IteratingCallback.Action process()
                                    throws Throwable

Description copied from class: IteratingCallback

Method called by IteratingCallback.iterate() to process the asynchronous sub-task.

Implementations must initiate the asynchronous execution of the sub-task (if any) and return an appropriate action:

• IteratingCallback.Action.IDLE when no sub tasks are available for execution but the overall job is not completed yet
• IteratingCallback.Action.SCHEDULED when the sub task asynchronous execution has been started
• IteratingCallback.Action.SUCCEEDED when the overall job is completed

Specified by:

process in class IteratingCallback

Returns:

the appropriate Action

Throws:

Throwable - if the sub-task processing throws

onCompleteFailure

protected void onCompleteFailure(Throwable cause)

Description copied from class: IteratingCallback

Invoked when the overall task has completed with a failure.

Overrides:

onCompleteFailure in class IteratingCallback

Parameters:

cause - the throwable to indicate cause of failure

See Also:

• IteratingCallback.onCompleteSuccess()