Bug 1824225: Add support for Implicit/Explicit to ReadableStream r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D173525

dom/streams/ReadableStream.cpp

@@ -82,17 +82,29 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ReadableStream)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
-ReadableStream::ReadableStream(nsIGlobalObject* aGlobal)
+ReadableStream::ReadableStream(nsIGlobalObject* aGlobal,
-    : mGlobal(aGlobal), mReader(nullptr) {
+                               HoldDropJSObjectsCaller aHoldDropCaller)
+    : mGlobal(aGlobal), mReader(nullptr), mHoldDropCaller(aHoldDropCaller) {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
     mozilla::HoldJSObjects(this);
   }
-
-ReadableStream::ReadableStream(const GlobalObject& aGlobal)
-    : mGlobal(do_QueryInterface(aGlobal.GetAsSupports())), mReader(nullptr) {
-  mozilla::HoldJSObjects(this);
 }
 
-ReadableStream::~ReadableStream() { mozilla::DropJSObjects(this); }
+ReadableStream::ReadableStream(const GlobalObject& aGlobal,
+                               HoldDropJSObjectsCaller aHoldDropCaller)
+    : mGlobal(do_QueryInterface(aGlobal.GetAsSupports())),
+      mReader(nullptr),
+      mHoldDropCaller(aHoldDropCaller) {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
+    mozilla::HoldJSObjects(this);
+  }
+}
+
+ReadableStream::~ReadableStream() {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
+    mozilla::DropJSObjects(this);
+  }
+}
 
 JSObject* ReadableStream::WrapObject(JSContext* aCx,
                                      JS::Handle<JSObject*> aGivenProto) {
@@ -167,7 +179,8 @@ already_AddRefed<ReadableStream> ReadableStream::Constructor(
   }
 
   // Step 3.
-  RefPtr<ReadableStream> readableStream = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> readableStream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
 
   // Step 4.
   if (underlyingSourceDict.mType.WasPassed()) {
@@ -264,7 +277,8 @@ already_AddRefed<ReadableStream> ReadableStream::CreateAbstract(
   // Step 3.
   MOZ_ASSERT(IsNonNegativeNumber(highWaterMark));
   // Step 4.
-  RefPtr<ReadableStream> stream = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
 
   // Step 5.
   InitializeReadableStream(stream);
@@ -1001,7 +1015,8 @@ already_AddRefed<ReadableStream> ReadableStream::CreateByteAbstract(
     JSContext* aCx, nsIGlobalObject* aGlobal,
     UnderlyingSourceAlgorithmsBase* aAlgorithms, ErrorResult& aRv) {
   // Step 1. Let stream be a new ReadableStream.
-  RefPtr<ReadableStream> stream = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
 
   // Step 2. Perform ! InitializeReadableStream(stream).
   InitializeReadableStream(stream);
@@ -1045,7 +1060,8 @@ already_AddRefed<ReadableStream> ReadableStream::CreateNative(
   // ReadableStream::Constructor for details)
 
   // Step 5: Perform ! InitializeReadableStream(stream).
-  RefPtr<ReadableStream> stream = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
 
   // Step 6: Let controller be a new ReadableStreamDefaultController.
   auto controller = MakeRefPtr<ReadableStreamDefaultController>(aGlobal);
@@ -1092,7 +1108,8 @@ already_AddRefed<ReadableStream> ReadableStream::CreateByteNative(
     JSContext* aCx, nsIGlobalObject* aGlobal,
     UnderlyingSourceAlgorithmsWrapper& aAlgorithms,
     mozilla::Maybe<double> aHighWaterMark, ErrorResult& aRv) {
-  RefPtr<ReadableStream> stream = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
   stream->SetUpByteNative(aCx, aAlgorithms, aHighWaterMark, aRv);
   if (aRv.Failed()) {
     return nullptr;

dom/streams/ReadableStream.h

@@ -53,8 +53,17 @@ class ReadableStream : public nsISupports, public nsWrapperCache {
 
   nsCOMPtr<nsIGlobalObject> mGlobal;
 
-  explicit ReadableStream(const GlobalObject& aGlobal);
+  // If one extends ReadableStream with another cycle collectable class,
-  explicit ReadableStream(nsIGlobalObject* aGlobal);
+  // calling HoldJSObjects and DropJSObjects should happen using 'this' of
+  // that extending class. And in that case Explicit should be passed to the
+  // constructor of ReadableStream so that it doesn't make those calls.
+  // See also https://bugzilla.mozilla.org/show_bug.cgi?id=1801214.
+  enum class HoldDropJSObjectsCaller { Implicit, Explicit };
+
+  explicit ReadableStream(const GlobalObject& aGlobal,
+                          HoldDropJSObjectsCaller aHoldDropCaller);
+  explicit ReadableStream(nsIGlobalObject* aGlobal,
+                          HoldDropJSObjectsCaller aHoldDropCaller);
 
  public:
   // Abstract algorithms
@@ -229,6 +238,8 @@ class ReadableStream : public nsISupports, public nsWrapperCache {
   RefPtr<ReadableStreamGenericReader> mReader;
   ReaderState mState = ReaderState::Readable;
   JS::Heap<JS::Value> mStoredError;
+
+  HoldDropJSObjectsCaller mHoldDropCaller;
 };
 
 namespace streams_abstract {

dom/streams/Transferable.cpp

@@ -863,7 +863,8 @@ ReadableStream::ReceiveTransferImpl(JSContext* aCx, nsIGlobalObject* aGlobal,
   // Step 2: Let port be deserializedRecord.[[Deserialized]].
 
   // Step 3: Perform ! SetUpCrossRealmTransformReadable(value, port).
-  RefPtr<ReadableStream> readable = new ReadableStream(aGlobal);
+  RefPtr<ReadableStream> readable =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
   ErrorResult rv;
   SetUpCrossRealmTransformReadable(readable, &aPort, rv);
   if (rv.MaybeSetPendingException(aCx)) {
@@ -910,7 +911,8 @@ bool WritableStream::Transfer(JSContext* aCx, UniqueMessagePortId& aPortId) {
   }
 
   // Step 5: Let readable be a new ReadableStream in the current Realm.
-  RefPtr<ReadableStream> readable = new ReadableStream(mGlobal);
+  RefPtr<ReadableStream> readable = new ReadableStream(
+      mGlobal, ReadableStream::HoldDropJSObjectsCaller::Implicit);
 
   // Step 6: Perform ! SetUpCrossRealmTransformReadable(readable, port1).
   // MOZ_KnownLive because Port1 never changes before CC

dom/webtransport/api/WebTransportReceiveStream.cpp

@@ -18,7 +18,7 @@ using namespace mozilla::ipc;
 namespace mozilla::dom {
 
 WebTransportReceiveStream::WebTransportReceiveStream(nsIGlobalObject* aGlobal)
-    : ReadableStream(aGlobal) {}
+    : ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit) {}
 
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