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Diffstat (limited to 'xpcom/threads/nsIEventTarget.idl')
| -rw-r--r-- | xpcom/threads/nsIEventTarget.idl | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/xpcom/threads/nsIEventTarget.idl b/xpcom/threads/nsIEventTarget.idl new file mode 100644 index 0000000000..edd49f306d --- /dev/null +++ b/xpcom/threads/nsIEventTarget.idl @@ -0,0 +1,227 @@ +/* -*- 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 "nsISupports.idl" +#include "nsIRunnable.idl" +%{C++ +#include "nsCOMPtr.h" +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/Atomics.h" + +class nsITargetShutdownTask; +%} + +native alreadyAddRefed_nsIRunnable(already_AddRefed<nsIRunnable>); +[ptr] native nsITargetShutdownTask(nsITargetShutdownTask); + +[builtinclass, scriptable, rust_sync, uuid(a03b8b63-af8b-4164-b0e5-c41e8b2b7cfa)] +interface nsIEventTarget : nsISupports +{ + /* until we can get rid of all uses, keep the non-alreadyAddRefed<> version */ +%{C++ + nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) { + return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags); + } +%} + + /** + * This flag specifies the default mode of event dispatch, whereby the event + * is simply queued for later processing. When this flag is specified, + * dispatch returns immediately after the event is queued. + */ + const unsigned long DISPATCH_NORMAL = 0; + + // NOTE: 1 used to be DISPATCH_SYNC + + /** + * This flag specifies that the dispatch is occurring from a running event + * that was dispatched to the same event target, and that event is about to + * finish. + * + * A thread pool can use this as an optimization hint to not spin up + * another thread, since the current thread is about to become idle. + * + * These events are always async. + */ + const unsigned long DISPATCH_AT_END = 2; + + /** + * This flag specifies that the dispatched event may block the thread on + * which it executes, usually by doing some sort of I/O. This information + * may be used by the event target to execute the job on a thread + * specifically dedicated to doing I/O, leaving other threads available for + * CPU-intensive work. + */ + const unsigned long DISPATCH_EVENT_MAY_BLOCK = 4; + + /** + * This flag specifies that the dispatched event should be delivered to the + * target thread even if the thread has been configured to block dispatching + * of runnables. This is generally done for threads which have their own + * internal event loop, such as thread pools or the timer thread, and will not + * service runnables dispatched to them until shutdown. + */ + const unsigned long DISPATCH_IGNORE_BLOCK_DISPATCH = 8; + + /** + * IsOnCurrentThread() should return true if events dispatched to this target + * can possibly run on the current thread, and false otherwise. In the case + * of an nsIEventTarget for a thread pool, it should return true on all + * threads in the pool. In the case of a non-thread nsIEventTarget such as + * ThrottledEventQueue, it should return true on the thread where events are + * expected to be processed, even if no events from the queue are actually + * being processed right now. + * + * When called on an nsISerialEventTarget, IsOnCurrentThread can be used to + * ensure that no other thread has "ownership" of the event target. As such, + * it's useful for asserting that an object is only used on a particular + * thread. IsOnCurrentThread can't guarantee that the current event has been + * dispatched through a particular event target. + * + * The infallible version of IsOnCurrentThread() is optimized to avoid a + * virtual call for non-thread event targets. Thread targets should set + * mThread to their virtual PRThread. Non-thread targets should leave + * mThread null and implement IsOnCurrentThreadInfallible() to + * return the correct answer. + * + * The fallible version of IsOnCurrentThread may return errors, such as during + * shutdown. If it does not return an error, it should return the same result + * as the infallible version. The infallible method should return the correct + * result regardless of whether the fallible method returns an error. + */ + %{C++ +public: + // Infallible. Defined in nsThreadUtils.cpp. Delegates to + // IsOnCurrentThreadInfallible when mThread is null. + bool IsOnCurrentThread(); + +protected: + mozilla::Atomic<PRThread*> mThread; + + nsIEventTarget() : mThread(nullptr) {} + %} + // Note that this method is protected. We define it through IDL, rather than + // in a %{C++ block, to ensure that the correct method indices are recorded + // for XPConnect purposes. + [noscript,notxpcom] boolean isOnCurrentThreadInfallible(); + %{C++ +public: + %} + + // Fallible version of IsOnCurrentThread. + boolean isOnCurrentThread(); + + /** + * Dispatch an event to this event target. This function may be called from + * any thread, and it may be called re-entrantly. + * + * @param event + * The alreadyAddRefed<> event to dispatch. + * NOTE that the event will be leaked if it fails to dispatch. + * @param flags + * The flags modifying event dispatch. The flags are described in detail + * below. + * + * @throws NS_ERROR_INVALID_ARG + * Indicates that event is null. + * @throws NS_ERROR_UNEXPECTED + * Indicates that the thread is shutting down and has finished processing + * events, so this event would never run and has not been dispatched. + */ + [noscript, binaryname(Dispatch)] void dispatchFromC(in alreadyAddRefed_nsIRunnable event, + [default(DISPATCH_NORMAL)] in unsigned long flags); + /** + * Version of Dispatch to expose to JS, which doesn't require an alreadyAddRefed<> + * (it will be converted to that internally) + * + * @param event + * The (raw) event to dispatch. + * @param flags + * The flags modifying event dispatch. The flags are described in detail + * below. + * + * @throws NS_ERROR_INVALID_ARG + * Indicates that event is null. + * @throws NS_ERROR_UNEXPECTED + * Indicates that the thread is shutting down and has finished processing + * events, so this event would never run and has not been dispatched. + */ + [binaryname(DispatchFromScript)] void dispatch(in nsIRunnable event, in unsigned long flags); + /** + * Dispatch an event to this event target, but do not run it before delay + * milliseconds have passed. This function may be called from any thread. + * + * @param event + * The alreadyAddrefed<> event to dispatch. + * @param delay + * The delay (in ms) before running the event. If event does not rise to + * the top of the event queue before the delay has passed, it will be set + * aside to execute once the delay has passed. Otherwise, it will be + * executed immediately. + * + * @throws NS_ERROR_INVALID_ARG + * Indicates that event is null. + * @throws NS_ERROR_UNEXPECTED + * Indicates that the thread is shutting down and has finished processing + * events, so this event would never run and has not been dispatched, or + * that delay is zero. + */ + [noscript] void delayedDispatch(in alreadyAddRefed_nsIRunnable event, in unsigned long delay); + + /** + * Register an task to be run on this event target when it begins shutting + * down. Shutdown tasks may be run in any order, and this function may be + * called from any thread. + * + * The event target may or may not continue accepting events during or after + * the shutdown task. The precise behaviour here depends on the event target. + * + * @param task + * The task to be registered to the target thread. + * NOTE that unlike `dispatch`, this will not leak the task if it fails. + * + * @throws NS_ERROR_INVALID_ARG + * Indicates that task is null. + * @throws NS_ERROR_NOT_IMPLEMENTED + * Indicates that this event target doesn't support shutdown tasks. + * @throws NS_ERROR_UNEXPECTED + * Indicates that the thread is already shutting down, and no longer + * accepting events. + */ + [noscript] void registerShutdownTask(in nsITargetShutdownTask task); + + /** + * Unregisters an task previously registered with registerShutdownTask. This + * function may be called from any thread. + * + * @param task + * The task previously registered with registerShutdownTask + * + * @throws NS_ERROR_INVALID_ARG + * Indicates that task is null. + * @throws NS_ERROR_NOT_IMPLEMENTED + * Indicates that this event target doesn't support shutdown tasks. + * @throws NS_ERROR_UNEXPECTED + * Indicates that the thread is already shutting down, and no longer + * accepting events, or that the shutdown task cannot be found. + */ + [noscript] void unregisterShutdownTask(in nsITargetShutdownTask task); +}; + +%{C++ +// convenient aliases: +#define NS_DISPATCH_NORMAL nsIEventTarget::DISPATCH_NORMAL +#define NS_DISPATCH_AT_END nsIEventTarget::DISPATCH_AT_END +#define NS_DISPATCH_EVENT_MAY_BLOCK nsIEventTarget::DISPATCH_EVENT_MAY_BLOCK +#define NS_DISPATCH_IGNORE_BLOCK_DISPATCH nsIEventTarget::DISPATCH_IGNORE_BLOCK_DISPATCH + +// Convenient NS_DECL variant that includes some C++-only methods. +#define NS_DECL_NSIEVENTTARGET_FULL \ + NS_DECL_NSIEVENTTARGET \ + /* Avoid hiding these methods */ \ + using nsIEventTarget::Dispatch; \ + using nsIEventTarget::IsOnCurrentThread; +%} |