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| -rw-r--r-- | dom/streams/UnderlyingSourceCallbackHelpers.h | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/dom/streams/UnderlyingSourceCallbackHelpers.h b/dom/streams/UnderlyingSourceCallbackHelpers.h new file mode 100644 index 0000000000..1859204f32 --- /dev/null +++ b/dom/streams/UnderlyingSourceCallbackHelpers.h @@ -0,0 +1,318 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim:set ts=2 sw=2 sts=2 et cindent: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_dom_UnderlyingSourceCallbackHelpers_h +#define mozilla_dom_UnderlyingSourceCallbackHelpers_h + +#include "mozilla/DOMEventTargetHelper.h" +#include "mozilla/HoldDropJSObjects.h" +#include "mozilla/dom/Promise.h" +#include "mozilla/dom/UnderlyingSourceBinding.h" +#include "mozilla/WeakPtr.h" +#include "nsIAsyncInputStream.h" +#include "nsISupports.h" +#include "nsISupportsImpl.h" + +/* Since the streams specification has native descriptions of some callbacks + * (i.e. described in prose, rather than provided by user code), we need to be + * able to pass around native callbacks. To handle this, we define polymorphic + * classes That cover the difference between native callback and user-provided. + * + * The Streams specification wants us to invoke these callbacks, run through + * WebIDL as if they were methods. So we have to preserve the underlying object + * to use as the This value on invocation. + */ +enum class nsresult : uint32_t; + +namespace mozilla::dom { + +class StrongWorkerRef; +class BodyStreamHolder; +class ReadableStreamController; +class ReadableStream; + +class UnderlyingSourceAlgorithmsBase : public nsISupports { + public: + NS_DECL_CYCLE_COLLECTING_ISUPPORTS + NS_DECL_CYCLE_COLLECTION_CLASS(UnderlyingSourceAlgorithmsBase) + + MOZ_CAN_RUN_SCRIPT virtual void StartCallback( + JSContext* aCx, ReadableStreamController& aController, + JS::MutableHandle<JS::Value> aRetVal, ErrorResult& aRv) = 0; + + // A promise-returning algorithm that pulls data from the underlying byte + // source + MOZ_CAN_RUN_SCRIPT virtual already_AddRefed<Promise> PullCallback( + JSContext* aCx, ReadableStreamController& aController, + ErrorResult& aRv) = 0; + + // A promise-returning algorithm, taking one argument (the cancel reason), + // which communicates a requested cancelation to the underlying byte source + MOZ_CAN_RUN_SCRIPT virtual already_AddRefed<Promise> CancelCallback( + JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason, + ErrorResult& aRv) = 0; + + // Implement this when you need to release underlying resources immediately + // from closed(canceled)/errored streams, without waiting for GC. + virtual void ReleaseObjects() {} + + // Fetch wants to special-case nsIInputStream-based streams + virtual nsIInputStream* MaybeGetInputStreamIfUnread() { return nullptr; } + + // https://streams.spec.whatwg.org/#other-specs-rs-create + // By "native" we mean "instances initialized via the above set up or set up + // with byte reading support algorithms (not, e.g., on web-developer-created + // instances)" + virtual bool IsNative() { return true; } + + protected: + virtual ~UnderlyingSourceAlgorithmsBase() = default; +}; + +class UnderlyingSourceAlgorithms final : public UnderlyingSourceAlgorithmsBase { + public: + NS_DECL_ISUPPORTS_INHERITED + NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED( + UnderlyingSourceAlgorithms, UnderlyingSourceAlgorithmsBase) + + UnderlyingSourceAlgorithms(nsIGlobalObject* aGlobal, + JS::Handle<JSObject*> aUnderlyingSource, + UnderlyingSource& aUnderlyingSourceDict) + : mGlobal(aGlobal), mUnderlyingSource(aUnderlyingSource) { + // Step 6. (implicit Step 2.) + if (aUnderlyingSourceDict.mStart.WasPassed()) { + mStartCallback = aUnderlyingSourceDict.mStart.Value(); + } + + // Step 7. (implicit Step 3.) + if (aUnderlyingSourceDict.mPull.WasPassed()) { + mPullCallback = aUnderlyingSourceDict.mPull.Value(); + } + + // Step 8. (implicit Step 4.) + if (aUnderlyingSourceDict.mCancel.WasPassed()) { + mCancelCallback = aUnderlyingSourceDict.mCancel.Value(); + } + + mozilla::HoldJSObjects(this); + }; + + MOZ_CAN_RUN_SCRIPT void StartCallback(JSContext* aCx, + ReadableStreamController& aController, + JS::MutableHandle<JS::Value> aRetVal, + ErrorResult& aRv) override; + + MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> PullCallback( + JSContext* aCx, ReadableStreamController& aController, + ErrorResult& aRv) override; + + MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> CancelCallback( + JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason, + ErrorResult& aRv) override; + + bool IsNative() override { return false; } + + protected: + ~UnderlyingSourceAlgorithms() override { mozilla::DropJSObjects(this); }; + + private: + // Virtually const, but are cycle collected + nsCOMPtr<nsIGlobalObject> mGlobal; + JS::Heap<JSObject*> mUnderlyingSource; + MOZ_KNOWN_LIVE RefPtr<UnderlyingSourceStartCallback> mStartCallback; + MOZ_KNOWN_LIVE RefPtr<UnderlyingSourcePullCallback> mPullCallback; + MOZ_KNOWN_LIVE RefPtr<UnderlyingSourceCancelCallback> mCancelCallback; +}; + +// https://streams.spec.whatwg.org/#readablestream-set-up +// https://streams.spec.whatwg.org/#readablestream-set-up-with-byte-reading-support +// Wrappers defined by the "Set up" methods in the spec. This helps you just +// return nullptr when an error occurred as this wrapper converts it to a +// rejected promise. +// Note that StartCallback is only for JS consumers to access +// the controller, and thus is no-op here since native consumers can call +// `EnqueueNative()` etc. without direct controller access. +class UnderlyingSourceAlgorithmsWrapper + : public UnderlyingSourceAlgorithmsBase { + void StartCallback(JSContext*, ReadableStreamController&, + JS::MutableHandle<JS::Value> aRetVal, ErrorResult&) final; + + MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> PullCallback( + JSContext* aCx, ReadableStreamController& aController, + ErrorResult& aRv) final; + + MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> CancelCallback( + JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason, + ErrorResult& aRv) final; + + MOZ_CAN_RUN_SCRIPT virtual already_AddRefed<Promise> PullCallbackImpl( + JSContext* aCx, ReadableStreamController& aController, ErrorResult& aRv) { + // pullAlgorithm is optional, return null by default + return nullptr; + } + + virtual already_AddRefed<Promise> CancelCallbackImpl( + JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason, + ErrorResult& aRv) { + // cancelAlgorithm is optional, return null by default + return nullptr; + } +}; + +class InputToReadableStreamAlgorithms; + +// This class exists to isolate InputToReadableStreamAlgorithms from the +// nsIAsyncInputStream. If we call AsyncWait(this,...), it holds a +// reference to 'this' which can't be cc'd, and we can leak the stream, +// causing a Worker to assert with globalScopeAlive. By isolating +// ourselves from the inputstream, we can safely be CC'd if needed and +// will inform the inputstream to shut down. +class InputStreamHolder final : public nsIInputStreamCallback, + public GlobalTeardownObserver { + public: + NS_DECL_THREADSAFE_ISUPPORTS + NS_DECL_NSIINPUTSTREAMCALLBACK + + InputStreamHolder(nsIGlobalObject* aGlobal, + InputToReadableStreamAlgorithms* aCallback, + nsIAsyncInputStream* aInput); + + void Init(JSContext* aCx); + + void DisconnectFromOwner() override; + + // Used by global teardown + void Shutdown(); + + // These just proxy the calls to the nsIAsyncInputStream + nsresult AsyncWait(uint32_t aFlags, uint32_t aRequestedCount, + nsIEventTarget* aEventTarget); + nsresult Available(uint64_t* aSize) { return mInput->Available(aSize); } + nsresult Read(char* aBuffer, uint32_t aLength, uint32_t* aWritten) { + return mInput->Read(aBuffer, aLength, aWritten); + } + nsresult CloseWithStatus(nsresult aStatus) { + return mInput->CloseWithStatus(aStatus); + } + + private: + ~InputStreamHolder(); + + // WeakPtr to avoid cycles + WeakPtr<InputToReadableStreamAlgorithms> mCallback; + // To ensure the worker sticks around + RefPtr<StrongWorkerRef> mAsyncWaitWorkerRef; + RefPtr<StrongWorkerRef> mWorkerRef; + nsCOMPtr<nsIAsyncInputStream> mInput; + + // To ensure the underlying source sticks around during an ongoing read + // operation. mAlgorithms is not cycle collected on purpose, and this holder + // is responsible to keep the underlying source algorithms until + // nsIAsyncInputStream responds. + // + // This is done because otherwise the whole stream objects may be cycle + // collected, including the promises created from read(), as our JS engine may + // throw unsettled promises away for optimization. See bug 1849860. + RefPtr<InputToReadableStreamAlgorithms> mAsyncWaitAlgorithms; +}; + +// Using this class means you are also passing the lifetime control of your +// nsIAsyncInputStream, as it will be closed when this class tears down. +class InputToReadableStreamAlgorithms final + : public UnderlyingSourceAlgorithmsWrapper, + public nsIInputStreamCallback, + public SupportsWeakPtr { + NS_DECL_ISUPPORTS_INHERITED + NS_DECL_NSIINPUTSTREAMCALLBACK + NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(InputToReadableStreamAlgorithms, + UnderlyingSourceAlgorithmsWrapper) + + InputToReadableStreamAlgorithms(JSContext* aCx, nsIAsyncInputStream* aInput, + ReadableStream* aStream); + + // Streams algorithms + + already_AddRefed<Promise> PullCallbackImpl( + JSContext* aCx, ReadableStreamController& aController, + ErrorResult& aRv) override; + + void ReleaseObjects() override; + + private: + ~InputToReadableStreamAlgorithms() { + if (mInput) { + mInput->Shutdown(); + } + } + + MOZ_CAN_RUN_SCRIPT_BOUNDARY void CloseAndReleaseObjects( + JSContext* aCx, ReadableStream* aStream); + + void WriteIntoReadRequestBuffer(JSContext* aCx, ReadableStream* aStream, + JS::Handle<JSObject*> aBuffer, + uint32_t aLength, uint32_t* aByteWritten); + + MOZ_CAN_RUN_SCRIPT_BOUNDARY void EnqueueChunkWithSizeIntoStream( + JSContext* aCx, ReadableStream* aStream, uint64_t aAvailableData, + ErrorResult& aRv); + void ErrorPropagation(JSContext* aCx, ReadableStream* aStream, + nsresult aError); + + // Common methods + + bool IsClosed() { return !mInput; } + + nsCOMPtr<nsIEventTarget> mOwningEventTarget; + + // This promise is created by PullCallback and resolved when + // OnInputStreamReady succeeds. No need to try hard to settle it though, see + // also ReleaseObjects() for the reason. + RefPtr<Promise> mPullPromise; + + RefPtr<InputStreamHolder> mInput; + RefPtr<ReadableStream> mStream; +}; + +class NonAsyncInputToReadableStreamAlgorithms + : public UnderlyingSourceAlgorithmsWrapper { + public: + NS_DECL_ISUPPORTS_INHERITED + NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED( + NonAsyncInputToReadableStreamAlgorithms, + UnderlyingSourceAlgorithmsWrapper) + + explicit NonAsyncInputToReadableStreamAlgorithms(nsIInputStream& aInput) + : mInput(&aInput) {} + + already_AddRefed<Promise> PullCallbackImpl( + JSContext* aCx, ReadableStreamController& aController, + ErrorResult& aRv) override; + + void ReleaseObjects() override { + if (RefPtr<InputToReadableStreamAlgorithms> algorithms = + mAsyncAlgorithms.forget()) { + algorithms->ReleaseObjects(); + } + if (nsCOMPtr<nsIInputStream> input = mInput.forget()) { + input->Close(); + } + } + + nsIInputStream* MaybeGetInputStreamIfUnread() override { + MOZ_ASSERT(mInput, "Should be only called on non-disturbed streams"); + return mInput; + } + + private: + ~NonAsyncInputToReadableStreamAlgorithms() = default; + + nsCOMPtr<nsIInputStream> mInput; + RefPtr<InputToReadableStreamAlgorithms> mAsyncAlgorithms; +}; + +} // namespace mozilla::dom + +#endif |