Quelle  WritableStreamDefaultController.h

/* 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_WritableStreamDefaultController_h
#define mozilla_dom_WritableStreamDefaultController_h

#include "js/TypeDecls.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/Nullable.h"
#include "mozilla/dom/QueueWithSizes.h"
#include "mozilla/dom/QueuingStrategyBinding.h"
#include "mozilla/dom/ReadRequest.h"
#include "mozilla/dom/UnderlyingSinkCallbackHelpers.h"
#include "nsCycleCollectionParticipant.h"
#include "nsISupports.h"
#include "nsTArray.h"
#include "nsWrapperCache.h"

namespace mozilla::dom {

class AbortSignal;
class WritableStream;
struct UnderlyingSink;

class WritableStreamDefaultController final : public nsISupports,
                                              public nsWrapperCache {
 public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(WritableStreamDefaultController)

  explicit WritableStreamDefaultController(nsISupports* aGlobal,
                                           WritableStream& aStream);

 protected:
  ~WritableStreamDefaultController();

 public:
  nsIGlobalObject* GetParentObject() const { return mGlobal; }

  JSObject* WrapObject(JSContext* aCx,
                       JS::Handle<JSObject*> aGivenProto) override;

  // WebIDL methods/properties

  AbortSignal* Signal() { return mSignal; }

  MOZ_CAN_RUN_SCRIPT void Error(JSContext* aCx, JS::Handle<JS::Value> aError,
                                ErrorResult& aRv);

  // [[AbortSteps]]
  MOZ_CAN_RUN_SCRIPT virtual already_AddRefed<Promise> AbortSteps(
      JSContext* aCx, JS::Handle<JS::Value> aReason, ErrorResult& aRv);

  // [[ErrorSteps]]
  virtual void ErrorSteps();

  // Internal Slot Accessors

  QueueWithSizes& Queue() { return mQueue; }

  double QueueTotalSize() const { return mQueueTotalSize; }
  void SetQueueTotalSize(double aQueueTotalSize) {
    mQueueTotalSize = aQueueTotalSize;
  }

  void SetSignal(AbortSignal* aSignal);

  bool Started() const { return mStarted; }
  void SetStarted(bool aStarted) { mStarted = aStarted; }

  double StrategyHWM() const { return mStrategyHWM; }
  void SetStrategyHWM(double aStrategyHWM) { mStrategyHWM = aStrategyHWM; }

  QueuingStrategySize* StrategySizeAlgorithm() const {
    return mStrategySizeAlgorithm;
  }
  void SetStrategySizeAlgorithm(QueuingStrategySize* aStrategySizeAlgorithm) {
    mStrategySizeAlgorithm = aStrategySizeAlgorithm;
  }

  UnderlyingSinkAlgorithmsBase* GetAlgorithms() { return mAlgorithms; }
  void SetAlgorithms(UnderlyingSinkAlgorithmsBase& aAlgorithms) {
    mAlgorithms = &aAlgorithms;
  }

  WritableStream* Stream() { return mStream; }

  // WritableStreamDefaultControllerGetBackpressure
  // https://streams.spec.whatwg.org/#writable-stream-default-controller-get-backpressure
  bool GetBackpressure() const {
    // Step 1. Let desiredSize be !
    // WritableStreamDefaultControllerGetDesiredSize(controller).
    double desiredSize = GetDesiredSize();
    // Step 2. Return true if desiredSize ≤ 0, or false otherwise.
    return desiredSize <= 0;
  }

  // WritableStreamDefaultControllerGetDesiredSize
  // https://streams.spec.whatwg.org/#writable-stream-default-controller-get-desired-size
  double GetDesiredSize() const { return mStrategyHWM - mQueueTotalSize; }

  // WritableStreamDefaultControllerClearAlgorithms
  // https://streams.spec.whatwg.org/#writable-stream-default-controller-clear-algorithms
  void ClearAlgorithms() {
    // Step 1. Set controller.[[writeAlgorithm]] to undefined.
    // Step 2. Set controller.[[closeAlgorithm]] to undefined.
    // Step 3. Set controller.[[abortAlgorithm]] to undefined.
    // (As written in the spec, this can happen multiple time. Try running
    // wpt/streams/transform-streams/errors.any.js for example.)
    if (RefPtr<UnderlyingSinkAlgorithmsBase> algorithms =
            mAlgorithms.forget()) {
      algorithms->ReleaseObjects();
    }

    // Step 4. Set controller.[[strategySizeAlgorithm]] to undefined.
    mStrategySizeAlgorithm = nullptr;
  }

 private:
  nsCOMPtr<nsIGlobalObject> mGlobal;

  // Internal Slots
  QueueWithSizes mQueue = {};
  double mQueueTotalSize = 0.0;
  RefPtr<AbortSignal> mSignal;
  bool mStarted = false;
  double mStrategyHWM = 0.0;

  RefPtr<QueuingStrategySize> mStrategySizeAlgorithm;
  RefPtr<UnderlyingSinkAlgorithmsBase> mAlgorithms;
  RefPtr<WritableStream> mStream;
};

}  // namespace mozilla::dom

#endif  // mozilla_dom_WritableStreamDefaultController_h