Bug 1803386 - Part 1: Replace ReadableStream::mNativeUnderlyingSource with GetBodyStreamHolder() r=smaug

The underlying source algorithms class already has strong ref, so just use it.

Differential Revision: https://phabricator.services.mozilla.com/D166533

dom/fetch/Fetch.cpp

@@ -1194,7 +1194,7 @@ void FetchBody<Derived>::SetBodyUsed(JSContext* aCx, ErrorResult& aRv) {
   // If we already have a ReadableStreamBody and it has been created by DOM, we
   // have to lock it now because it can have been shared with other objects.
   if (mReadableStreamBody) {
-    if (mReadableStreamBody->HasNativeUnderlyingSource()) {
+    if (mReadableStreamBody->GetBodyStreamHolder()) {
       LockStream(aCx, mReadableStreamBody, aRv);
       if (NS_WARN_IF(aRv.Failed())) {
         return;
@@ -1500,7 +1500,7 @@ void FetchBody<Derived>::MaybeTeeReadableStreamBody(
   // If this is a ReadableStream with an native source, this has been
   // generated by a Fetch. In this case, Fetch will be able to recreate it
   // again when GetBody() is called.
-  if (mReadableStreamBody->HasNativeUnderlyingSource()) {
+  if (mReadableStreamBody->GetBodyStreamHolder()) {
     *aBodyOut = nullptr;
     return;
   }

dom/fetch/Response.cpp

@@ -293,11 +293,8 @@ already_AddRefed<Response> Response::Constructor(
 
       // If this is a DOM generated ReadableStream, we can extract the
       // inputStream directly.
-      if (readableStream.HasNativeUnderlyingSource()) {
-        BodyStreamHolder* underlyingSource =
-            readableStream.GetNativeUnderlyingSource();
-        MOZ_ASSERT(underlyingSource);
-
+      if (BodyStreamHolder* underlyingSource =
+              readableStream.GetBodyStreamHolder()) {
         aRv = BodyStream::RetrieveInputStream(underlyingSource,
                                               getter_AddRefs(bodyStream));
 

dom/streams/ByteStreamHelpers.cpp

@@ -140,6 +140,8 @@ class BodyStreamUnderlyingSourceAlgorithms final
     bodyStream->CloseInputAndReleaseObjects();
   }
 
+  BodyStreamHolder* GetBodyStreamHolder() override { return mUnderlyingSource; }
+
  protected:
   ~BodyStreamUnderlyingSourceAlgorithms() override = default;
 

dom/streams/ReadableStream.cpp

@@ -71,8 +71,7 @@ namespace mozilla::dom {
 
 // Only needed for refcounted objects.
 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_WITH_JS_MEMBERS(
-    ReadableStream, (mGlobal, mController, mReader, mNativeUnderlyingSource),
-    (mStoredError))
+    ReadableStream, (mGlobal, mController, mReader), (mStoredError))
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(ReadableStream)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(ReadableStream)
@@ -136,14 +135,7 @@ bool ReadableStreamHasDefaultReader(ReadableStream* aStream) {
   return reader->IsDefault();
 }
 
-void ReadableStream::SetNativeUnderlyingSource(
-    BodyStreamHolder* aUnderlyingSource) {
-  mNativeUnderlyingSource = aUnderlyingSource;
-}
-
 void ReadableStream::ReleaseObjectsFromBodyStream() {
-  SetNativeUnderlyingSource(nullptr);
-
   // XXX(krosylight): Hacky way to workaround the ownership issue between
   // BodyStream and ReadableStream trying to cleanup each other. See bug
   // 1803386.
@@ -1024,8 +1016,6 @@ already_AddRefed<ReadableStream> ReadableStream::Create(
     BodyStreamHolder* aUnderlyingSource, ErrorResult& aRv) {
   RefPtr<ReadableStream> stream = new ReadableStream(aGlobal);
 
-  stream->SetNativeUnderlyingSource(aUnderlyingSource);
-
   SetUpReadableByteStreamControllerFromBodyStreamUnderlyingSource(
       aCx, stream, aUnderlyingSource, aRv);
 

dom/streams/ReadableStream.h

@@ -86,11 +86,13 @@ class ReadableStream : public nsISupports, public nsWrapperCache {
     mStoredError = aStoredError;
   }
 
-  void SetNativeUnderlyingSource(BodyStreamHolder* aUnderlyingSource);
-  BodyStreamHolder* GetNativeUnderlyingSource() {
-    return mNativeUnderlyingSource;
+  BodyStreamHolder* GetBodyStreamHolder() {
+    if (UnderlyingSourceAlgorithmsBase* algorithms =
+            Controller()->GetAlgorithms()) {
+      return algorithms->GetBodyStreamHolder();
+    }
+    return nullptr;
   }
-  bool HasNativeUnderlyingSource() { return mNativeUnderlyingSource; }
 
   // XXX(krosylight): BodyStream should really be a subclass of ReadableStream
   // instead of owning ReadableStream this way. See bug 1803386.
@@ -168,23 +170,6 @@ class ReadableStream : public nsISupports, public nsWrapperCache {
   RefPtr<ReadableStreamGenericReader> mReader;
   ReaderState mState = ReaderState::Readable;
   JS::Heap<JS::Value> mStoredError;
-
-  // Optional strong reference to an Underlying Source; This
-  // exists because NativeUnderlyingSource callbacks don't hold
-  // a strong reference to the underlying source: So we need
-  // something else to hold onto that. As well, some of the integration
-  // desires the ability to extract the underlying source from the
-  // ReadableStream.
-  //
-  // While theoretically this ought to be some base class type to support
-  // multiple native underlying source types, I'm not sure what base class
-  // makes any sense for BodyStream, and given there's only body streams
-  // as the underlying source right now, I'm going to punt that problem to
-  // the future where we need to provide other native underlying sources
-  // (i.e. perhaps WebTransport.)
-  //
-  // See bug 1803386.
-  RefPtr<BodyStreamHolder> mNativeUnderlyingSource;
 };
 
 bool IsReadableStreamLocked(ReadableStream* aStream);

dom/streams/UnderlyingSourceCallbackHelpers.h

@@ -52,6 +52,9 @@ class UnderlyingSourceAlgorithmsBase : public nsISupports {
   // from closed(canceled)/errored streams, without waiting for GC.
   virtual void ReleaseObjects() {}
 
+  // Fetch wants to special-case BodyStream-based streams
+  virtual BodyStreamHolder* GetBodyStreamHolder() { return nullptr; }
+
  protected:
   virtual ~UnderlyingSourceAlgorithmsBase() = default;
 };