dom/fetch/FetchStreamReader.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_FetchStreamReader_h
   8 #define mozilla_dom_FetchStreamReader_h
   9
  10 #include "js/RootingAPI.h"
  11 #include "js/TypeDecls.h"
  12 #include "mozilla/Attributes.h"
  13 #include "mozilla/dom/FetchBinding.h"
  14 #include "mozilla/dom/PromiseNativeHandler.h"
  15 #include "nsIAsyncOutputStream.h"
  16 #include "nsIGlobalObject.h"
  17
  18 namespace mozilla::dom {
  19
  20 class ReadableStream;
  21 class ReadableStreamDefaultReader;
  22 class StrongWorkerRef;
  23
  24 class FetchStreamReader final : public nsIOutputStreamCallback {
  25  public:
  26   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  27   NS_DECL_CYCLE_COLLECTION_CLASS(FetchStreamReader)
  28   NS_DECL_NSIOUTPUTSTREAMCALLBACK
  29
  30   // This creates a nsIInputStream able to retrieve data from the ReadableStream
  31   // object. The reading starts when StartConsuming() is called.
  32   static nsresult Create(JSContext* aCx, nsIGlobalObject* aGlobal,
  33                          FetchStreamReader** aStreamReader,
  34                          nsIInputStream** aInputStream);
  35
  36   MOZ_CAN_RUN_SCRIPT
  37   void ChunkSteps(JSContext* aCx, JS::Handle<JS::Value> aChunk,
  38                   ErrorResult& aRv);
  39   MOZ_CAN_RUN_SCRIPT
  40   void CloseSteps(JSContext* aCx, ErrorResult& aRv);
  41   MOZ_CAN_RUN_SCRIPT
  42   void ErrorSteps(JSContext* aCx, JS::Handle<JS::Value> aError,
  43                   ErrorResult& aRv);
  44
  45   // Idempotently close the output stream and null out all state. If aCx is
  46   // provided, the reader will also be canceled.  aStatus must be a DOM error
  47   // as understood by DOMException because it will be provided as the
  48   // cancellation reason.
  49   //
  50   // This is a script boundary minimize annotation changes required while
  51   // we figure out how to handle some more tricky annotation cases (for
  52   // example, the destructor of this class. Tracking under Bug 1750656)
  53   MOZ_CAN_RUN_SCRIPT_BOUNDARY
  54   void CloseAndRelease(JSContext* aCx, nsresult aStatus);
  55
  56   void StartConsuming(JSContext* aCx, ReadableStream* aStream,
  57                       ErrorResult& aRv);
  58
  59  private:
  60   explicit FetchStreamReader(nsIGlobalObject* aGlobal);
  61   ~FetchStreamReader();
  62
  63   nsresult MaybeGrabStrongWorkerRef(JSContext* aCx);
  64
  65   nsresult WriteBuffer();
  66
  67   // Attempt to copy data from mBuffer into mPipeOut. Returns `true` if data was
  68   // written, and AsyncWait callbacks or FetchReadRequest calls have been set up
  69   // to write more data in the future, and `false` otherwise.
  70   MOZ_CAN_RUN_SCRIPT
  71   bool Process(JSContext* aCx);
  72
  73   void ReportErrorToConsole(JSContext* aCx, JS::Handle<JS::Value> aValue);
  74
  75   nsCOMPtr<nsIGlobalObject> mGlobal;
  76   nsCOMPtr<nsIEventTarget> mOwningEventTarget;
  77
  78   nsCOMPtr<nsIAsyncOutputStream> mPipeOut;
  79
  80   RefPtr<StrongWorkerRef> mWorkerRef;
  81   // This is an additional refcount we add to `mWorkerRef` when we have a
  82   // pending callback from mPipeOut.AsyncWait() which is guaranteed to fire when
  83   // either we can write to the pipe or the stream has been closed.  Because
  84   // this callback must run on our owning worker thread, we must ensure that the
  85   // worker thread lives long enough to process the runnable (and potentially
  86   // release the last reference to this non-thread-safe object on this thread).
  87   //
  88   // By holding an additional refcount we can avoid creating a mini state
  89   // machine around mWorkerRef which hopefully improves clarity.
  90   RefPtr<StrongWorkerRef> mAsyncWaitWorkerRef;
  91
  92   RefPtr<ReadableStreamDefaultReader> mReader;
  93
  94   nsTArray<uint8_t> mBuffer;
  95   uint32_t mBufferRemaining = 0;
  96   uint32_t mBufferOffset = 0;
  97
  98   bool mHasOutstandingReadRequest = false;
  99   bool mStreamClosed = false;
 100 };
 101
 102 }  // namespace mozilla::dom
 103
 104 #endif  // mozilla_dom_FetchStreamReader_h