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AbortFollower.h (3305B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef mozilla_dom_AbortFollower_h
      8 #define mozilla_dom_AbortFollower_h
      9 
     10 #include "jsapi.h"
     11 #include "mozilla/WeakPtr.h"
     12 #include "nsISupportsImpl.h"
     13 #include "nsTObserverArray.h"
     14 
     15 namespace mozilla::dom {
     16 
     17 enum class SignalAborted { No, Yes };
     18 
     19 class AbortSignal;
     20 class AbortSignalImpl;
     21 
     22 // This class must be implemented by objects who want to follow an
     23 // AbortSignalImpl.
     24 class AbortFollower : public nsISupports {
     25 public:
     26  virtual void RunAbortAlgorithm() = 0;
     27 
     28  // This adds strong reference to this follower on the signal, which means
     29  // you'll need to call Unfollow() to prevent your object from living
     30  // needlessly longer.
     31  void Follow(AbortSignalImpl* aSignal);
     32 
     33  // Explicitly call this to let garbage collection happen sooner when the
     34  // follower finished its work and cannot be aborted anymore.
     35  void Unfollow();
     36 
     37  bool IsFollowing() const;
     38 
     39  AbortSignalImpl* Signal() const { return mFollowingSignal; }
     40 
     41 protected:
     42  virtual ~AbortFollower();
     43 
     44  friend class AbortSignalImpl;
     45 
     46  WeakPtr<AbortSignalImpl> mFollowingSignal;
     47 };
     48 
     49 /*
     50 * TODO(krosylight): The only consumer of this is Fetch. It would be nice to
     51 * merge this back to AbortSignal as it's quite a duplication right now.
     52 *
     53 * AbortSignalImpl is a minimal implementation without an associated global
     54 * and without event dispatching, those are added in AbortSignal.
     55 * See Bug 1478101
     56 */
     57 class AbortSignalImpl : public nsISupports, public SupportsWeakPtr {
     58 public:
     59  explicit AbortSignalImpl(SignalAborted aAborted,
     60                           JS::Handle<JS::Value> aReason);
     61 
     62  bool Aborted() const;
     63 
     64  // Web IDL Layer
     65  void GetReason(JSContext* aCx, JS::MutableHandle<JS::Value> aReason);
     66  // Helper for other DOM code
     67  JS::Value RawReason() const;
     68 
     69  void SignalAbort(JS::Handle<JS::Value> aReason);
     70 
     71 protected:
     72  // Subclasses of this class must call these Traverse and Unlink functions
     73  // during corresponding cycle collection operations.
     74  static void Traverse(AbortSignalImpl* aSignal,
     75                       nsCycleCollectionTraversalCallback& cb);
     76 
     77  static void Unlink(AbortSignalImpl* aSignal);
     78 
     79  virtual ~AbortSignalImpl() { UnlinkFollowers(); }
     80 
     81  virtual void SignalAbortWithDependents();
     82 
     83  virtual void RunAbortSteps();
     84 
     85  void SetAborted(JS::Handle<JS::Value> aReason);
     86 
     87  JS::Heap<JS::Value> mReason;
     88 
     89 private:
     90  friend class AbortFollower;
     91 
     92  void MaybeAssignAbortError(JSContext* aCx);
     93 
     94  void UnlinkFollowers();
     95 
     96  // TODO(krosylight): We should rename all names around the term "Follow". See
     97  // bug 1873648.
     98  //
     99  // |AbortFollower::Follow| adds to this array, and
    100  // |AbortFollower::Unfollow| (also called by the destructor) will remove
    101  // from this array.  Finally, calling |SignalAbort()| will (after running all
    102  // abort algorithms) empty this and make all contained followers |Unfollow()|.
    103  nsTObserverArray<RefPtr<AbortFollower>> mFollowers;
    104 
    105  SignalAborted mAborted;
    106 };
    107 
    108 }  // namespace mozilla::dom
    109 
    110 #endif  // mozilla_dom_AbortFollower_h