Bug 1660555 - Split AbortFollower::Abort into AbortFollower::RunAbortAlgorithm and AbortSignalImpl::SignalAbort functions for readability. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D92321

dom/abort/AbortController.cpp

@@ -61,7 +61,7 @@ void AbortController::Abort() {
   mAborted = true;
 
   if (mSignal) {
-    mSignal->Abort();
+    mSignal->SignalAbort();
   }
 }
 

dom/abort/AbortSignal.cpp

@@ -19,7 +19,7 @@ AbortSignalImpl::AbortSignalImpl(bool aAborted) : mAborted(aAborted) {}
 
 bool AbortSignalImpl::Aborted() const { return mAborted; }
 
-void AbortSignalImpl::Abort() {
+void AbortSignalImpl::SignalAbort() {
   if (mAborted) {
     return;
   }
@@ -28,7 +28,7 @@ void AbortSignalImpl::Abort() {
 
   // Let's inform the followers.
   for (RefPtr<AbortFollower> follower : mFollowers.ForwardRange()) {
-    follower->Abort();
+    follower->RunAbortAlgorithm();
   }
 }
 
@@ -73,8 +73,8 @@ JSObject* AbortSignal::WrapObject(JSContext* aCx,
   return AbortSignal_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-void AbortSignal::Abort() {
-  AbortSignalImpl::Abort();
+void AbortSignal::SignalAbort() {
+  AbortSignalImpl::SignalAbort();
 
   EventInit init;
   init.mBubbles = false;

dom/abort/AbortSignal.h

@@ -23,7 +23,7 @@ class AbortFollower {
  public:
   NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
 
-  virtual void Abort() = 0;
+  virtual void RunAbortAlgorithm() = 0;
 
   void Follow(AbortSignalImpl* aSignal);
 
@@ -39,18 +39,13 @@ class AbortFollower {
   RefPtr<AbortSignalImpl> mFollowingSignal;
 };
 
-// Any subclass of this class must Traverse mFollowingSignal and call
-// Unfollow() when Unlinking.
-class AbortSignalImpl : public AbortFollower, public nsISupports {
+class AbortSignalImpl : public nsISupports {
  public:
-  using nsISupports::AddRef;
-  using nsISupports::Release;
-
   explicit AbortSignalImpl(bool aAborted);
 
   bool Aborted() const;
 
-  void Abort() override;
+  virtual void SignalAbort();
 
   void AddFollower(AbortFollower* aFollower);
 
@@ -66,7 +61,21 @@ class AbortSignalImpl : public AbortFollower, public nsISupports {
   bool mAborted;
 };
 
-class AbortSignal final : public DOMEventTargetHelper, public AbortSignalImpl {
+// AbortSignal the spec concept includes the concept of a child signal
+// "following" a parent signal -- internally, adding abort steps to the parent
+// signal that will then signal abort on the child signal -- to propagate
+// signaling abort from one signal to another.  See
+// <https://dom.spec.whatwg.org/#abortsignal-follow>.
+//
+// This requires that AbortSignal also inherit from AbortFollower.
+//
+// This ability to follow isn't directly exposed in the DOM; as of this writing
+// it appears only to be used internally in the Fetch API.  It might be a good
+// idea to split AbortSignal into an implementation that can follow, and an
+// implementation that can't, to provide this complexity only when it's needed.
+class AbortSignal final : public DOMEventTargetHelper,
+                          public AbortSignalImpl,
+                          public AbortFollower {
  public:
   NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(AbortSignal, DOMEventTargetHelper)
@@ -78,7 +87,11 @@ class AbortSignal final : public DOMEventTargetHelper, public AbortSignalImpl {
 
   IMPL_EVENT_HANDLER(abort);
 
-  void Abort() override;
+  // AbortSignalImpl
+  void SignalAbort() override;
+
+  // AbortFollower
+  void RunAbortAlgorithm() override { SignalAbort(); }
 
  private:
   ~AbortSignal() = default;

dom/base/BodyConsumer.cpp

@@ -803,7 +803,7 @@ NS_IMETHODIMP BodyConsumer::Observe(nsISupports* aSubject, const char* aTopic,
   return NS_OK;
 }
 
-void BodyConsumer::Abort() {
+void BodyConsumer::RunAbortAlgorithm() {
   AssertIsOnTargetThread();
   ShutDownMainThreadConsuming();
   ContinueConsumeBody(NS_ERROR_DOM_ABORT_ERR, 0, nullptr);

dom/base/BodyConsumer.h

@@ -90,7 +90,7 @@ class BodyConsumer final : public nsIObserver,
   }
 
   // AbortFollower
-  void Abort() override;
+  void RunAbortAlgorithm() override;
 
  private:
   BodyConsumer(nsIEventTarget* aMainThreadEventTarget,

dom/fetch/Fetch.cpp

@@ -94,11 +94,11 @@ class AbortSignalMainThread final : public AbortSignalImpl {
 NS_IMPL_CYCLE_COLLECTION_CLASS(AbortSignalMainThread)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(AbortSignalMainThread)
-  tmp->Unfollow();
+  // This is filled with new operations shortly.
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(AbortSignalMainThread)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFollowingSignal)
+  // This is filled with new operations shortly.
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(AbortSignalMainThread)
@@ -135,7 +135,7 @@ class AbortSignalProxy final : public AbortFollower {
       MOZ_ASSERT(NS_IsMainThread());
       AbortSignalImpl* signalImpl =
           mProxy->GetOrCreateSignalImplForMainThread();
-      signalImpl->Abort();
+      signalImpl->SignalAbort();
       return NS_OK;
     }
   };
@@ -151,7 +151,8 @@ class AbortSignalProxy final : public AbortFollower {
     Follow(aSignalImpl);
   }
 
-  void Abort() override {
+  // AbortFollower
+  void RunAbortAlgorithm() override {
     RefPtr<AbortSignalProxyRunnable> runnable =
         new AbortSignalProxyRunnable(this);
     mMainThreadEventTarget->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
@@ -1467,7 +1468,7 @@ template void FetchBody<Response>::MaybeTeeReadableStreamBody(
     ErrorResult& aRv);
 
 template <class Derived>
-void FetchBody<Derived>::Abort() {
+void FetchBody<Derived>::RunAbortAlgorithm() {
   if (!mReadableStreamBody) {
     return;
   }
@@ -1484,9 +1485,9 @@ void FetchBody<Derived>::Abort() {
   AbortStream(cx, body, result);
 }
 
-template void FetchBody<Request>::Abort();
+template void FetchBody<Request>::RunAbortAlgorithm();
 
-template void FetchBody<Response>::Abort();
+template void FetchBody<Response>::RunAbortAlgorithm();
 
 }  // namespace dom
 }  // namespace mozilla

dom/fetch/Fetch.h

@@ -210,7 +210,7 @@ class FetchBody : public BodyStreamHolder, public AbortFollower {
   virtual AbortSignalImpl* GetSignalImpl() const = 0;
 
   // AbortFollower
-  void Abort() override;
+  void RunAbortAlgorithm() override;
 
   already_AddRefed<Promise> ConsumeBody(JSContext* aCx,
                                         BodyConsumer::ConsumeType aType,

dom/fetch/FetchDriver.cpp

@@ -460,7 +460,7 @@ nsresult FetchDriver::Fetch(AbortSignalImpl* aSignalImpl,
   // the operation.
   if (aSignalImpl) {
     if (aSignalImpl->Aborted()) {
-      Abort();
+      RunAbortAlgorithm();
       return NS_OK;
     }
 
@@ -1579,7 +1579,7 @@ void FetchDriver::SetRequestHeaders(nsIHttpChannel* aChannel,
   }
 }
 
-void FetchDriver::Abort() {
+void FetchDriver::RunAbortAlgorithm() {
   MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
 
   if (mObserver) {

dom/fetch/FetchDriver.h

@@ -126,7 +126,7 @@ class FetchDriver final : public nsIStreamListener,
   }
 
   // AbortFollower
-  void Abort() override;
+  void RunAbortAlgorithm() override;
 
  private:
   nsCOMPtr<nsIPrincipal> mPrincipal;

dom/fetch/FetchObserver.cpp

@@ -43,7 +43,7 @@ JSObject* FetchObserver::WrapObject(JSContext* aCx,
 
 FetchState FetchObserver::State() const { return mState; }
 
-void FetchObserver::Abort() { SetState(FetchState::Aborted); }
+void FetchObserver::RunAbortAlgorithm() { SetState(FetchState::Aborted); }
 
 void FetchObserver::SetState(FetchState aState) {
   MOZ_ASSERT(mState < aState);

dom/fetch/FetchObserver.h

@@ -30,7 +30,8 @@ class FetchObserver final : public DOMEventTargetHelper, public AbortFollower {
   IMPL_EVENT_HANDLER(requestprogress);
   IMPL_EVENT_HANDLER(responseprogress);
 
-  void Abort() override;
+  // AbortFollower
+  void RunAbortAlgorithm() override;
 
   void SetState(FetchState aState);
 

dom/webauthn/WebAuthnManager.cpp

@@ -826,7 +826,9 @@ void WebAuthnManager::RequestAborted(const uint64_t& aTransactionId,
   }
 }
 
-void WebAuthnManager::Abort() { CancelTransaction(NS_ERROR_DOM_ABORT_ERR); }
+void WebAuthnManager::RunAbortAlgorithm() {
+  CancelTransaction(NS_ERROR_DOM_ABORT_ERR);
+}
 
 }  // namespace dom
 }  // namespace mozilla

dom/webauthn/WebAuthnManager.h

@@ -104,7 +104,7 @@ class WebAuthnManager final : public WebAuthnManagerBase, public AbortFollower {
 
   // AbortFollower
 
-  void Abort() override;
+  void RunAbortAlgorithm() override;
 
  protected:
   // Cancels the current transaction (by sending a Cancel message to the