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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.
+ */
+[builtinclass, 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 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() {
+ * 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.
+ */
+ void onDispatchedEvent();
+
+ /**
+ * 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);
+};