gecko/dom/promise/PromiseWorkerProxy.h

121 lines
4.1 KiB
C++

/* 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/. */
#ifndef mozilla_dom_PromiseWorkerProxy_h
#define mozilla_dom_PromiseWorkerProxy_h
// Required for Promise::PromiseTaskSync.
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/PromiseNativeHandler.h"
#include "mozilla/dom/workers/bindings/WorkerFeature.h"
#include "nsProxyRelease.h"
namespace mozilla {
namespace dom {
class Promise;
namespace workers {
class WorkerPrivate;
}
// A proxy to catch the resolved/rejected Promise's result from the main thread
// and resolve/reject that on the worker thread eventually.
//
// How to use:
//
// 1. Create a Promise on the worker thread and return it to the content
// script:
//
// nsRefPtr<Promise> promise = Promise::Create(workerPrivate->GlobalScope(), aRv);
// if (aRv.Failed()) {
// return nullptr;
// }
// // Pass |promise| around to the WorkerMainThreadRunnable
// return promise.forget();
//
// 2. In your WorkerMainThreadRunnable's ctor, create a PromiseWorkerProxy
// which holds a nsRefPtr<Promise> to the Promise created at #1.
//
// 3. In your WorkerMainThreadRunnable::MainThreadRun(), obtain a Promise on
// the main thread and call its AppendNativeHandler(PromiseNativeHandler*)
// to bind the PromiseWorkerProxy created at #2.
//
// 4. Then the Promise results returned by ResolvedCallback/RejectedCallback
// will be dispatched as a WorkerRunnable to the worker thread to
// resolve/reject the Promise created at #1.
//
// PromiseWorkerProxy can also be used in situations where there is no main
// thread Promise, or where special handling is required on the worker thread
// for promise resolution. Create a PromiseWorkerProxy as in steps 1 and
// 2 above. When the main thread is ready to resolve the worker thread promise,
// dispatch a runnable to the worker. Use GetWorkerPrivate() to acquire the
// worker. This might be null! In the WorkerRunnable's WorkerRun() use
// GetWorkerPromise() to access the Promise and resolve/reject it. Then call
// CleanUp() on the worker
// thread.
class PromiseWorkerProxy : public PromiseNativeHandler,
public workers::WorkerFeature
{
friend class PromiseWorkerProxyRunnable;
// This overrides the non-threadsafe refcounting in PromiseNativeHandler.
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(PromiseWorkerProxy)
public:
PromiseWorkerProxy(workers::WorkerPrivate* aWorkerPrivate,
Promise* aWorkerPromise,
JSStructuredCloneCallbacks* aCallbacks = nullptr);
workers::WorkerPrivate* GetWorkerPrivate() const;
Promise* GetWorkerPromise() const;
void StoreISupports(nsISupports* aSupports);
void CleanUp(JSContext* aCx);
protected:
virtual void ResolvedCallback(JSContext* aCx,
JS::Handle<JS::Value> aValue) MOZ_OVERRIDE;
virtual void RejectedCallback(JSContext* aCx,
JS::Handle<JS::Value> aValue) MOZ_OVERRIDE;
virtual bool Notify(JSContext* aCx, workers::Status aStatus) MOZ_OVERRIDE;
private:
virtual ~PromiseWorkerProxy();
// Function pointer for calling Promise::{ResolveInternal,RejectInternal}.
typedef void (Promise::*RunCallbackFunc)(JSContext*,
JS::Handle<JS::Value>);
void RunCallback(JSContext* aCx,
JS::Handle<JS::Value> aValue,
RunCallbackFunc aFunc);
workers::WorkerPrivate* mWorkerPrivate;
// This lives on the worker thread.
nsRefPtr<Promise> mWorkerPromise;
bool mCleanedUp; // To specify if the cleanUp() has been done.
JSStructuredCloneCallbacks* mCallbacks;
// Aimed to keep objects alive when doing the structured-clone read/write,
// which can be added by calling StoreISupports() on the main thread.
nsTArray<nsMainThreadPtrHandle<nsISupports>> mSupportsArray;
// Ensure the worker and the main thread won't race to access |mCleanedUp|.
Mutex mCleanUpLock;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_PromiseWorkerProxy_h