dom/webscheduling/WebTaskScheduler.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:expandtab:shiftwidth=2:tabstop=2:
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #ifndef mozilla_dom_WebTaskScheduler_h
   9 #define mozilla_dom_WebTaskScheduler_h
  10
  11 #include "nsThreadUtils.h"
  12 #include "nsPIDOMWindow.h"
  13 #include "nsWrapperCache.h"
  14 #include "nsClassHashtable.h"
  15
  16 #include "mozilla/dom/Promise.h"
  17 #include "mozilla/dom/AbortFollower.h"
  18 #include "mozilla/dom/TimeoutHandler.h"
  19 #include "mozilla/dom/WebTaskSchedulingBinding.h"
  20
  21 namespace mozilla::dom {
  22 class WebTask : public LinkedListElement<RefPtr<WebTask>>,
  23                 public AbortFollower,
  24                 public SupportsWeakPtr {
  25   friend class WebTaskScheduler;
  26
  27  public:
  28   MOZ_CAN_RUN_SCRIPT bool Run();
  29
  30   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  31
  32   NS_DECL_CYCLE_COLLECTION_CLASS(WebTask)
  33   WebTask(uint32_t aEnqueueOrder, SchedulerPostTaskCallback& aCallback,
  34           Promise* aPromise)
  35       : mEnqueueOrder(aEnqueueOrder),
  36         mCallback(&aCallback),
  37         mPromise(aPromise),
  38         mHasScheduled(false) {}
  39
  40   void RunAbortAlgorithm() override;
  41
  42   bool HasScheduled() const { return mHasScheduled; }
  43
  44   uint32_t EnqueueOrder() const { return mEnqueueOrder; }
  45
  46  private:
  47   void SetHasScheduled(bool aHasScheduled) { mHasScheduled = aHasScheduled; }
  48
  49   uint32_t mEnqueueOrder;
  50
  51   RefPtr<SchedulerPostTaskCallback> mCallback;
  52   RefPtr<Promise> mPromise;
  53
  54   bool mHasScheduled;
  55
  56   ~WebTask() = default;
  57 };
  58
  59 class WebTaskQueue {
  60  public:
  61   WebTaskQueue() = default;
  62
  63   TaskPriority Priority() const { return mPriority; }
  64   void SetPriority(TaskPriority aNewPriority) { mPriority = aNewPriority; }
  65
  66   LinkedList<RefPtr<WebTask>>& Tasks() { return mTasks; }
  67
  68   void AddTask(WebTask* aTask) { mTasks.insertBack(aTask); }
  69
  70   // TODO: To optimize it, we could have the scheduled and unscheduled
  71   // tasks stored separately.
  72   WebTask* GetFirstScheduledTask() {
  73     for (const auto& task : mTasks) {
  74       if (task->HasScheduled()) {
  75         return task;
  76       }
  77     }
  78     return nullptr;
  79   }
  80
  81   ~WebTaskQueue() { mTasks.clear(); }
  82
  83  private:
  84   TaskPriority mPriority = TaskPriority::User_visible;
  85   LinkedList<RefPtr<WebTask>> mTasks;
  86 };
  87
  88 class WebTaskSchedulerMainThread;
  89 class WebTaskSchedulerWorker;
  90
  91 class WebTaskScheduler : public nsWrapperCache, public SupportsWeakPtr {
  92   friend class DelayedWebTaskHandler;
  93
  94  public:
  95   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(WebTaskScheduler)
  96   NS_DECL_CYCLE_COLLECTION_NATIVE_WRAPPERCACHE_CLASS(WebTaskScheduler)
  97
  98   static already_AddRefed<WebTaskSchedulerMainThread> CreateForMainThread(
  99       nsGlobalWindowInner* aWindow);
 100
 101   static already_AddRefed<WebTaskSchedulerWorker> CreateForWorker(
 102       WorkerPrivate* aWorkerPrivate);
 103
 104   explicit WebTaskScheduler(nsIGlobalObject* aParent);
 105
 106   already_AddRefed<Promise> PostTask(SchedulerPostTaskCallback& aCallback,
 107                                      const SchedulerPostTaskOptions& aOptions);
 108
 109   nsIGlobalObject* GetParentObject() const { return mParent; }
 110
 111   virtual JSObject* WrapObject(JSContext* cx,
 112                                JS::Handle<JSObject*> aGivenProto) override;
 113
 114   WebTask* GetNextTask() const;
 115
 116   void Disconnect();
 117
 118   void RunTaskSignalPriorityChange(TaskSignal* aTaskSignal);
 119
 120  protected:
 121   virtual ~WebTaskScheduler() = default;
 122   nsCOMPtr<nsIGlobalObject> mParent;
 123
 124   uint32_t mNextEnqueueOrder;
 125
 126  private:
 127   already_AddRefed<WebTask> CreateTask(
 128       WebTaskQueue& aQueue, const Optional<OwningNonNull<AbortSignal>>& aSignal,
 129       SchedulerPostTaskCallback& aCallback, Promise* aPromise);
 130
 131   bool QueueTask(WebTask* aTask);
 132
 133   WebTaskQueue& SelectTaskQueue(
 134       const Optional<OwningNonNull<AbortSignal>>& aSignal,
 135       const Optional<TaskPriority>& aPriority);
 136
 137   virtual nsresult SetTimeoutForDelayedTask(WebTask* aTask,
 138                                             uint64_t aDelay) = 0;
 139   virtual bool DispatchEventLoopRunnable() = 0;
 140
 141   nsClassHashtable<nsUint32HashKey, WebTaskQueue> mStaticPriorityTaskQueues;
 142   nsClassHashtable<nsPtrHashKey<TaskSignal>, WebTaskQueue>
 143       mDynamicPriorityTaskQueues;
 144 };
 145
 146 class DelayedWebTaskHandler final : public TimeoutHandler {
 147  public:
 148   DelayedWebTaskHandler(JSContext* aCx, WebTaskScheduler* aScheduler,
 149                         WebTask* aTask)
 150       : TimeoutHandler(aCx), mScheduler(aScheduler), mWebTask(aTask) {}
 151
 152   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
 153   NS_DECL_CYCLE_COLLECTION_CLASS(DelayedWebTaskHandler)
 154
 155   MOZ_CAN_RUN_SCRIPT bool Call(const char* /* unused */) override {
 156     if (mScheduler && mWebTask) {
 157       MOZ_ASSERT(!mWebTask->HasScheduled());
 158       if (!mScheduler->QueueTask(mWebTask)) {
 159         return false;
 160       }
 161     }
 162     return true;
 163   }
 164
 165  private:
 166   ~DelayedWebTaskHandler() override = default;
 167   WeakPtr<WebTaskScheduler> mScheduler;
 168   // WebTask gets added to WebTaskQueue, and WebTaskQueue keeps its alive.
 169   WeakPtr<WebTask> mWebTask;
 170 };
 171 }  // namespace mozilla::dom
 172 #endif