File: FetchStream.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "FetchStream.h"
#include "mozilla/dom/DOMException.h"
#include "mozilla/dom/WorkerCommon.h"
#include "mozilla/dom/WorkerPrivate.h"
#include "nsProxyRelease.h"
#include "nsStreamUtils.h"

#define FETCH_STREAM_FLAG 0

static NS_DEFINE_CID(kStreamTransportServiceCID, NS_STREAMTRANSPORTSERVICE_CID);

namespace mozilla {
namespace dom {

namespace {

class FetchStreamWorkerHolder final : public WorkerHolder {
 public:
  explicit FetchStreamWorkerHolder(FetchStream* aStream)
      : WorkerHolder("FetchStreamWorkerHolder",
                     WorkerHolder::Behavior::AllowIdleShutdownStart),
        mStream(aStream),
        mWasNotified(false) {}

  bool Notify(WorkerStatus aStatus) override {
    if (!mWasNotified) {
      mWasNotified = true;
      mStream->Close();
    }

    return true;
  }

  WorkerPrivate* GetWorkerPrivate() const { return mWorkerPrivate; }

 private:
  RefPtr<FetchStream> mStream;
  bool mWasNotified;
};

class FetchStreamWorkerHolderShutdown final : public WorkerControlRunnable {
 public:
  FetchStreamWorkerHolderShutdown(WorkerPrivate* aWorkerPrivate,
                                  UniquePtr<WorkerHolder>&& aHolder,
                                  nsCOMPtr<nsIGlobalObject>&& aGlobal,
                                  RefPtr<FetchStreamHolder>&& aStreamHolder)
      : WorkerControlRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount),
        mHolder(Move(aHolder)),
        mGlobal(Move(aGlobal)),
        mStreamHolder(Move(aStreamHolder)) {}

  bool WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override {
    mHolder = nullptr;
    mGlobal = nullptr;

    mStreamHolder->NullifyStream();
    mStreamHolder = nullptr;

    return true;
  }

  // This runnable starts from a JS Thread. We need to disable a couple of
  // assertions overring the following methods.

  bool PreDispatch(WorkerPrivate* aWorkerPrivate) override { return true; }

  void PostDispatch(WorkerPrivate* aWorkerPrivate,
                    bool aDispatchResult) override {}

 private:
  UniquePtr<WorkerHolder> mHolder;
  nsCOMPtr<nsIGlobalObject> mGlobal;
  RefPtr<FetchStreamHolder> mStreamHolder;
};

}  // namespace

NS_IMPL_ISUPPORTS(FetchStream, nsIInputStreamCallback, nsIObserver,
                  nsISupportsWeakReference)

/* static */ void FetchStream::Create(JSContext* aCx,
                                      FetchStreamHolder* aStreamHolder,
                                      nsIGlobalObject* aGlobal,
                                      nsIInputStream* aInputStream,
                                      JS::MutableHandle<JSObject*> aStream,
                                      ErrorResult& aRv) {
  MOZ_DIAGNOSTIC_ASSERT(aCx);
  MOZ_DIAGNOSTIC_ASSERT(aStreamHolder);
  MOZ_DIAGNOSTIC_ASSERT(aInputStream);

  RefPtr<FetchStream> stream =
      new FetchStream(aGlobal, aStreamHolder, aInputStream);

  if (NS_IsMainThread()) {
    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
    if (NS_WARN_IF(!os)) {
      aRv.Throw(NS_ERROR_FAILURE);
      return;
    }

    aRv = os->AddObserver(stream, DOM_WINDOW_DESTROYED_TOPIC, true);
    if (NS_WARN_IF(aRv.Failed())) {
      return;
    }

  } else {
    WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(aCx);
    MOZ_ASSERT(workerPrivate);

    UniquePtr<FetchStreamWorkerHolder> holder(
        new FetchStreamWorkerHolder(stream));
    if (NS_WARN_IF(!holder->HoldWorker(workerPrivate, Closing))) {
      aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
      return;
    }

    // Note, this will create a ref-cycle between the holder and the stream.
    // The cycle is broken when the stream is closed or the worker begins
    // shutting down.
    stream->mWorkerHolder = Move(holder);
  }

  if (!JS::HasReadableStreamCallbacks(aCx)) {
    JS::SetReadableStreamCallbacks(
        aCx, &FetchStream::RequestDataCallback,
        &FetchStream::WriteIntoReadRequestCallback,
        &FetchStream::CancelCallback, &FetchStream::ClosedCallback,
        &FetchStream::ErroredCallback, &FetchStream::FinalizeCallback);
  }

  JS::Rooted<JSObject*> body(aCx, JS::NewReadableExternalSourceStreamObject(
                                      aCx, stream, FETCH_STREAM_FLAG));
  if (!body) {
    aRv.StealExceptionFromJSContext(aCx);
    return;
  }

  // This will be released in FetchStream::FinalizeCallback().  We are
  // guaranteed the jsapi will call FinalizeCallback when ReadableStream
  // js object is finalized.
  NS_ADDREF(stream.get());

  aStream.set(body);
}

/* static */ void FetchStream::RequestDataCallback(JSContext* aCx,
                                                   JS::HandleObject aStream,
                                                   void* aUnderlyingSource,
                                                   uint8_t aFlags,
                                                   size_t aDesiredSize) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);
  MOZ_DIAGNOSTIC_ASSERT(JS::ReadableStreamIsDisturbed(aStream));

  RefPtr<FetchStream> stream = static_cast<FetchStream*>(aUnderlyingSource);

  MOZ_DIAGNOSTIC_ASSERT(stream->mState == eWaiting ||
                        stream->mState == eChecking ||
                        stream->mState == eReading);

  if (stream->mState == eReading) {
    // We are already reading data.
    return;
  }

  if (stream->mState == eChecking) {
    // If we are looking for more data, there is nothing else we should do:
    // let's move this checking operation in a reading.
    MOZ_ASSERT(stream->mInputStream);
    stream->mState = eReading;
    return;
  }

  stream->mState = eReading;

  if (!stream->mInputStream) {
    // This is the first use of the stream. Let's convert the
    // mOriginalInputStream into an nsIAsyncInputStream.
    MOZ_ASSERT(stream->mOriginalInputStream);

    nsCOMPtr<nsIAsyncInputStream> asyncStream;
    nsresult rv = NS_MakeAsyncNonBlockingInputStream(
        stream->mOriginalInputStream.forget(), getter_AddRefs(asyncStream));
    if (NS_WARN_IF(NS_FAILED(rv))) {
      stream->ErrorPropagation(aCx, aStream, rv);
      return;
    }

    stream->mInputStream = asyncStream;
    stream->mOriginalInputStream = nullptr;
  }

  MOZ_DIAGNOSTIC_ASSERT(stream->mInputStream);
  MOZ_DIAGNOSTIC_ASSERT(!stream->mOriginalInputStream);

  nsresult rv =
      stream->mInputStream->AsyncWait(stream, 0, 0, stream->mOwningEventTarget);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    stream->ErrorPropagation(aCx, aStream, rv);
    return;
  }

  // All good.
}

/* static */ void FetchStream::WriteIntoReadRequestCallback(
    JSContext* aCx, JS::HandleObject aStream, void* aUnderlyingSource,
    uint8_t aFlags, void* aBuffer, size_t aLength, size_t* aByteWritten) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);
  MOZ_DIAGNOSTIC_ASSERT(aBuffer);
  MOZ_DIAGNOSTIC_ASSERT(aByteWritten);

  RefPtr<FetchStream> stream = static_cast<FetchStream*>(aUnderlyingSource);

  MOZ_DIAGNOSTIC_ASSERT(stream->mInputStream);
  MOZ_DIAGNOSTIC_ASSERT(stream->mState == eWriting);
  stream->mState = eChecking;

  uint32_t written;
  nsresult rv = stream->mInputStream->Read(static_cast<char*>(aBuffer), aLength,
                                           &written);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    stream->ErrorPropagation(aCx, aStream, rv);
    return;
  }

  *aByteWritten = written;

  if (written == 0) {
    stream->CloseAndReleaseObjects(aCx, aStream);
    return;
  }

  rv =
      stream->mInputStream->AsyncWait(stream, 0, 0, stream->mOwningEventTarget);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    stream->ErrorPropagation(aCx, aStream, rv);
    return;
  }

  // All good.
}

/* static */ JS::Value FetchStream::CancelCallback(JSContext* aCx,
                                                   JS::HandleObject aStream,
                                                   void* aUnderlyingSource,
                                                   uint8_t aFlags,
                                                   JS::HandleValue aReason) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);

  // This is safe because we created an extra reference in FetchStream::Create()
  // that won't be released until FetchStream::FinalizeCallback() is called.
  // We are guaranteed that won't happen until the js ReadableStream object
  // is finalized.
  FetchStream* stream = static_cast<FetchStream*>(aUnderlyingSource);

  if (stream->mInputStream) {
    stream->mInputStream->CloseWithStatus(NS_BASE_STREAM_CLOSED);
  }

  stream->ReleaseObjects();
  return JS::UndefinedValue();
}

/* static */ void FetchStream::ClosedCallback(JSContext* aCx,
                                              JS::HandleObject aStream,
                                              void* aUnderlyingSource,
                                              uint8_t aFlags) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);
}

/* static */ void FetchStream::ErroredCallback(JSContext* aCx,
                                               JS::HandleObject aStream,
                                               void* aUnderlyingSource,
                                               uint8_t aFlags,
                                               JS::HandleValue aReason) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);

  // This is safe because we created an extra reference in FetchStream::Create()
  // that won't be released until FetchStream::FinalizeCallback() is called.
  // We are guaranteed that won't happen until the js ReadableStream object
  // is finalized.
  FetchStream* stream = static_cast<FetchStream*>(aUnderlyingSource);

  if (stream->mInputStream) {
    stream->mInputStream->CloseWithStatus(NS_BASE_STREAM_CLOSED);
  }

  stream->ReleaseObjects();
}

void FetchStream::FinalizeCallback(void* aUnderlyingSource, uint8_t aFlags) {
  MOZ_DIAGNOSTIC_ASSERT(aUnderlyingSource);
  MOZ_DIAGNOSTIC_ASSERT(aFlags == FETCH_STREAM_FLAG);

  // This can be called in any thread.

  // This takes ownership of the ref created in FetchStream::Create().
  RefPtr<FetchStream> stream =
      dont_AddRef(static_cast<FetchStream*>(aUnderlyingSource));

  stream->ReleaseObjects();
}

FetchStream::FetchStream(nsIGlobalObject* aGlobal,
                         FetchStreamHolder* aStreamHolder,
                         nsIInputStream* aInputStream)
    : mState(eWaiting),
      mGlobal(aGlobal),
      mStreamHolder(aStreamHolder),
      mOwningEventTarget(aGlobal->EventTargetFor(TaskCategory::Other)),
      mOriginalInputStream(aInputStream) {
  MOZ_DIAGNOSTIC_ASSERT(aInputStream);
  MOZ_DIAGNOSTIC_ASSERT(aStreamHolder);
}

FetchStream::~FetchStream() {}

void FetchStream::ErrorPropagation(JSContext* aCx, JS::HandleObject aStream,
                                   nsresult aError) {
  // Nothing to do.
  if (mState == eClosed) {
    return;
  }

  // Let's close the stream.
  if (aError == NS_BASE_STREAM_CLOSED) {
    CloseAndReleaseObjects(aCx, aStream);
    return;
  }

  // Let's use a generic error.
  RefPtr<DOMException> error = DOMException::Create(NS_ERROR_DOM_TYPE_ERR);

  JS::Rooted<JS::Value> errorValue(aCx);
  if (ToJSValue(aCx, error, &errorValue)) {
    JS::ReadableStreamError(aCx, aStream, errorValue);
  }

  ReleaseObjects();
}

NS_IMETHODIMP
FetchStream::OnInputStreamReady(nsIAsyncInputStream* aStream) {
  MOZ_DIAGNOSTIC_ASSERT(aStream);

  // Already closed. We have nothing else to do here.
  if (mState == eClosed) {
    return NS_OK;
  }

  MOZ_DIAGNOSTIC_ASSERT(mInputStream);
  MOZ_DIAGNOSTIC_ASSERT(mState == eReading || mState == eChecking);

  AutoJSAPI jsapi;
  if (NS_WARN_IF(!jsapi.Init(mGlobal))) {
    // Without JSContext we are not able to close the stream or to propagate the
    // error.
    return NS_ERROR_FAILURE;
  }

  JSContext* cx = jsapi.cx();
  JS::Rooted<JSObject*> stream(cx, mStreamHolder->ReadableStreamBody());

  uint64_t size = 0;
  nsresult rv = mInputStream->Available(&size);
  if (NS_SUCCEEDED(rv) && size == 0) {
    // In theory this should not happen. If size is 0, the stream should be
    // considered closed.
    rv = NS_BASE_STREAM_CLOSED;
  }

  // No warning for stream closed.
  if (rv == NS_BASE_STREAM_CLOSED || NS_WARN_IF(NS_FAILED(rv))) {
    ErrorPropagation(cx, stream, rv);
    return NS_OK;
  }

  // This extra checking is completed. Let's wait for the next read request.
  if (mState == eChecking) {
    mState = eWaiting;
    return NS_OK;
  }

  mState = eWriting;
  JS::ReadableStreamUpdateDataAvailableFromSource(cx, stream, size);

  // The WriteInto callback changes mState to eChecking.
  MOZ_DIAGNOSTIC_ASSERT(mState == eChecking);

  return NS_OK;
}

/* static */ nsresult FetchStream::RetrieveInputStream(
    void* aUnderlyingReadableStreamSource, nsIInputStream** aInputStream) {
  MOZ_ASSERT(aUnderlyingReadableStreamSource);
  MOZ_ASSERT(aInputStream);

  RefPtr<FetchStream> stream =
      static_cast<FetchStream*>(aUnderlyingReadableStreamSource);

  // if mOriginalInputStream is null, the reading already started. We don't want
  // to expose the internal inputStream.
  if (NS_WARN_IF(!stream->mOriginalInputStream)) {
    return NS_ERROR_DOM_INVALID_STATE_ERR;
  }

  nsCOMPtr<nsIInputStream> inputStream = stream->mOriginalInputStream;
  inputStream.forget(aInputStream);
  return NS_OK;
}

void FetchStream::Close() {
  if (mState == eClosed) {
    return;
  }

  AutoJSAPI jsapi;
  if (NS_WARN_IF(!jsapi.Init(mGlobal))) {
    ReleaseObjects();
    return;
  }

  JSContext* cx = jsapi.cx();
  JS::Rooted<JSObject*> stream(cx, mStreamHolder->ReadableStreamBody());
  CloseAndReleaseObjects(cx, stream);
}

void FetchStream::CloseAndReleaseObjects(JSContext* aCx,
                                         JS::HandleObject aStream) {
  MOZ_DIAGNOSTIC_ASSERT(mState != eClosed);

  ReleaseObjects();

  if (JS::ReadableStreamIsReadable(aStream)) {
    JS::ReadableStreamClose(aCx, aStream);
  }
}

void FetchStream::ReleaseObjects() {
  if (mState == eClosed) {
    return;
  }

  mState = eClosed;

  if (mWorkerHolder) {
    RefPtr<FetchStreamWorkerHolderShutdown> r =
        new FetchStreamWorkerHolderShutdown(
            static_cast<FetchStreamWorkerHolder*>(mWorkerHolder.get())
                ->GetWorkerPrivate(),
            Move(mWorkerHolder), Move(mGlobal), Move(mStreamHolder));
    r->Dispatch();
  } else {
    RefPtr<FetchStream> self = this;
    RefPtr<Runnable> r =
        NS_NewRunnableFunction("FetchStream::ReleaseObjects", [self]() {
          nsCOMPtr<nsIObserverService> obs =
              mozilla::services::GetObserverService();
          if (obs) {
            obs->RemoveObserver(self, DOM_WINDOW_DESTROYED_TOPIC);
          }
          self->mGlobal = nullptr;

          self->mStreamHolder->NullifyStream();
          self->mStreamHolder = nullptr;
        });

    mOwningEventTarget->Dispatch(r.forget());
  }
}

// nsIObserver
// -----------

NS_IMETHODIMP
FetchStream::Observe(nsISupports* aSubject, const char* aTopic,
                     const char16_t* aData) {
  AssertIsOnMainThread();

  MOZ_ASSERT(strcmp(aTopic, DOM_WINDOW_DESTROYED_TOPIC) == 0);

  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(mGlobal);
  if (SameCOMIdentity(aSubject, window)) {
    Close();
  }

  return NS_OK;
}

}  // namespace dom
}  // namespace mozilla