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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "nsIThread.idl"
interface nsIRunnable;
interface nsIThreadObserver;
/**
* The XPCOM thread object implements this interface, which allows a consumer
* to observe dispatch activity on the thread.
*/
[scriptable, uuid(a3a72e5f-71d9-4add-8f30-59a78fb6d5eb)]
interface nsIThreadInternal : nsIThread
{
/**
* Get/set the current thread observer (may be null). This attribute may be
* read from any thread, but must only be set on the thread corresponding to
* this thread object. The observer will be released on the thread
* corresponding to this thread object after all other events have been
* processed during a call to Shutdown.
*/
attribute nsIThreadObserver observer;
/**
* Add an observer that will *only* receive onProcessNextEvent,
* beforeProcessNextEvent. and afterProcessNextEvent callbacks. Always called
* on the target thread, and the implementation does not have to be
* threadsafe. Order of callbacks is not guaranteed (i.e.
* afterProcessNextEvent may be called first depending on whether or not the
* observer is added in a nested loop). Holds a strong ref.
*/
void addObserver(in nsIThreadObserver observer);
/**
* Remove an observer added via the addObserver call. Once removed the
* observer will never be called again by the thread.
*/
void removeObserver(in nsIThreadObserver observer);
/**
* This method causes any events currently enqueued on the thread to be
* suppressed until PopEventQueue is called, and any event dispatched to this
* thread's nsIEventTarget will queue as well. Calls to PushEventQueue may be
* nested and must each be paired with a call to PopEventQueue in order to
* restore the original state of the thread. The returned nsIEventTarget may
* be used to push events onto the nested queue. Dispatching will be disabled
* once the event queue is popped. The thread will only ever process pending
* events for the innermost event queue. Must only be called on the target
* thread.
*/
[noscript] nsIEventTarget pushEventQueue();
/**
* Revert a call to PushEventQueue. When an event queue is popped, any events
* remaining in the queue are appended to the elder queue. This also causes
* the nsIEventTarget returned from PushEventQueue to stop dispatching events.
* Must only be called on the target thread, and with the innermost event
* queue.
*/
[noscript] void popEventQueue(in nsIEventTarget aInnermostTarget);
};
/**
* This interface provides the observer with hooks to implement a layered
* event queue. For example, it is possible to overlay processing events
* for a GUI toolkit on top of the events for a thread:
*
* var NativeQueue;
* Observer = {
* onDispatchedEvent(thread) {
* NativeQueue.signal();
* }
* onProcessNextEvent(thread, mayWait) {
* if (NativeQueue.hasNextEvent())
* NativeQueue.processNextEvent();
* while (mayWait && !thread.hasPendingEvent()) {
* NativeQueue.wait();
* NativeQueue.processNextEvent();
* }
* }
* };
*
* NOTE: The implementation of this interface must be threadsafe.
*
* NOTE: It is valid to change the thread's observer during a call to an
* observer method.
*
* NOTE: Will be split into two interfaces soon: one for onProcessNextEvent and
* afterProcessNextEvent, then another that inherits the first and adds
* onDispatchedEvent.
*/
[uuid(cc8da053-1776-44c2-9199-b5a629d0a19d)]
interface nsIThreadObserver : nsISupports
{
/**
* This method is called after an event has been dispatched to the thread.
* This method may be called from any thread.
*
* @param thread
* The thread where the event is being dispatched.
*/
void onDispatchedEvent(in nsIThreadInternal thread);
/**
* This method is called when nsIThread::ProcessNextEvent is called. It does
* not guarantee that an event is actually going to be processed. This method
* is only called on the target thread.
*
* @param thread
* The thread being asked to process another event.
* @param mayWait
* Indicates whether or not the method is allowed to block the calling
* thread. For example, this parameter is false during thread shutdown.
*/
void onProcessNextEvent(in nsIThreadInternal thread, in boolean mayWait);
/**
* This method is called (from nsIThread::ProcessNextEvent) after an event
* is processed. It does not guarantee that an event was actually processed
* (depends on the value of |eventWasProcessed|. This method is only called
* on the target thread. DO NOT EVER RUN SCRIPT FROM THIS CALLBACK!!!
*
* @param thread
* The thread that processed another event.
* @param eventWasProcessed
* Indicates whether an event was actually processed. May be false if the
* |mayWait| flag was false when calling nsIThread::ProcessNextEvent().
*/
void afterProcessNextEvent(in nsIThreadInternal thread,
in bool eventWasProcessed);
};
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