1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
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/. */
7 #include "mozilla/dom/AbortFollower.h"
8 #include "mozilla/dom/AbortSignal.h"
9 #include "mozilla/dom/ReadableStream.h"
10 #include "mozilla/dom/ReadableStreamDefaultReader.h"
11 #include "mozilla/dom/ReadableStreamPipeTo.h"
12 #include "mozilla/dom/WritableStream.h"
13 #include "mozilla/dom/WritableStreamDefaultWriter.h"
14 #include "mozilla/dom/Promise.h"
15 #include "mozilla/dom/PromiseNativeHandler.h"
16 #include "mozilla/AlreadyAddRefed.h"
17 #include "mozilla/ErrorResult.h"
18 #include "nsCycleCollectionParticipant.h"
19 #include "nsISupportsImpl.h"
21 #include "js/Exception.h"
23 namespace mozilla::dom
{
25 struct PipeToReadRequest
;
26 class WriteFinishedPromiseHandler
;
27 class ShutdownActionFinishedPromiseHandler
;
29 // https://streams.spec.whatwg.org/#readable-stream-pipe-to (Steps 14-15.)
31 // This class implements everything that is required to read all chunks from
32 // the reader (source) and write them to writer (destination), while
33 // following the constraints given in the spec using our implementation-defined
36 // The cycle-collected references look roughly like this:
39 // Closed promise <-- ReadableStreamDefaultReader <--> ReadableStream
41 // |(PromiseHandler) |(mReader) |(ReadRequest)
43 // |-------------> PipeToPump <-------
45 // |---------------| | |
46 // | | |-------(mLastWrite) -------->
47 // |(PromiseHandler) | |< ---- (PromiseHandler) ---- Promise
49 // | |(mWriter) |(mWriteRequests)
51 // Closed promise <-- WritableStreamDefaultWriter <--------> WritableStream
54 class PipeToPump final
: public AbortFollower
{
55 NS_DECL_CYCLE_COLLECTING_ISUPPORTS
56 NS_DECL_CYCLE_COLLECTION_CLASS(PipeToPump
)
58 friend struct PipeToReadRequest
;
59 friend class WriteFinishedPromiseHandler
;
60 friend class ShutdownActionFinishedPromiseHandler
;
62 PipeToPump(Promise
* aPromise
, ReadableStreamDefaultReader
* aReader
,
63 WritableStreamDefaultWriter
* aWriter
, bool aPreventClose
,
64 bool aPreventAbort
, bool aPreventCancel
)
68 mPreventClose(aPreventClose
),
69 mPreventAbort(aPreventAbort
),
70 mPreventCancel(aPreventCancel
) {}
72 MOZ_CAN_RUN_SCRIPT
void Start(JSContext
* aCx
, AbortSignal
* aSignal
);
74 MOZ_CAN_RUN_SCRIPT_BOUNDARY
void RunAbortAlgorithm() override
;
77 ~PipeToPump() override
= default;
79 MOZ_CAN_RUN_SCRIPT
void PerformAbortAlgorithm(JSContext
* aCx
,
80 AbortSignalImpl
* aSignal
);
82 MOZ_CAN_RUN_SCRIPT
bool SourceOrDestErroredOrClosed(JSContext
* aCx
);
84 using ShutdownAction
= already_AddRefed
<Promise
> (*)(
85 JSContext
*, PipeToPump
*, JS::Handle
<mozilla::Maybe
<JS::Value
>>,
88 MOZ_CAN_RUN_SCRIPT
void ShutdownWithAction(
89 JSContext
* aCx
, ShutdownAction aAction
,
90 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
);
91 MOZ_CAN_RUN_SCRIPT
void ShutdownWithActionAfterFinishedWrite(
92 JSContext
* aCx
, ShutdownAction aAction
,
93 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
);
95 MOZ_CAN_RUN_SCRIPT
void Shutdown(
96 JSContext
* aCx
, JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
);
98 void Finalize(JSContext
* aCx
, JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
);
100 MOZ_CAN_RUN_SCRIPT
void OnReadFulfilled(JSContext
* aCx
,
101 JS::Handle
<JS::Value
> aChunk
,
103 MOZ_CAN_RUN_SCRIPT
void OnWriterReady(JSContext
* aCx
, JS::Handle
<JS::Value
>);
104 MOZ_CAN_RUN_SCRIPT
void Read(JSContext
* aCx
);
106 MOZ_CAN_RUN_SCRIPT
void OnSourceClosed(JSContext
* aCx
, JS::Handle
<JS::Value
>);
107 MOZ_CAN_RUN_SCRIPT
void OnSourceErrored(JSContext
* aCx
,
108 JS::Handle
<JS::Value
> aError
);
110 MOZ_CAN_RUN_SCRIPT
void OnDestClosed(JSContext
* aCx
, JS::Handle
<JS::Value
>);
111 MOZ_CAN_RUN_SCRIPT
void OnDestErrored(JSContext
* aCx
,
112 JS::Handle
<JS::Value
> aError
);
114 RefPtr
<Promise
> mPromise
;
115 RefPtr
<ReadableStreamDefaultReader
> mReader
;
116 RefPtr
<WritableStreamDefaultWriter
> mWriter
;
117 RefPtr
<Promise
> mLastWritePromise
;
118 const bool mPreventClose
;
119 const bool mPreventAbort
;
120 const bool mPreventCancel
;
121 bool mShuttingDown
= false;
123 bool mReadChunk
= false;
127 // This is a helper class for PipeToPump that allows it to attach
128 // member functions as promise handlers.
129 class PipeToPumpHandler final
: public PromiseNativeHandler
{
130 virtual ~PipeToPumpHandler() = default;
132 using FunPtr
= void (PipeToPump::*)(JSContext
*, JS::Handle
<JS::Value
>);
134 RefPtr
<PipeToPump
> mPipeToPump
;
139 NS_DECL_CYCLE_COLLECTING_ISUPPORTS
140 NS_DECL_CYCLE_COLLECTION_CLASS(PipeToPumpHandler
)
142 explicit PipeToPumpHandler(PipeToPump
* aPipeToPump
, FunPtr aResolved
,
144 : mPipeToPump(aPipeToPump
), mResolved(aResolved
), mRejected(aRejected
) {}
146 void ResolvedCallback(JSContext
* aCx
, JS::Handle
<JS::Value
> aValue
,
147 ErrorResult
&) override
{
149 (mPipeToPump
->*mResolved
)(aCx
, aValue
);
153 void RejectedCallback(JSContext
* aCx
, JS::Handle
<JS::Value
> aReason
,
154 ErrorResult
&) override
{
156 (mPipeToPump
->*mRejected
)(aCx
, aReason
);
161 NS_IMPL_CYCLE_COLLECTION(PipeToPumpHandler
, mPipeToPump
)
162 NS_IMPL_CYCLE_COLLECTING_ADDREF(PipeToPumpHandler
)
163 NS_IMPL_CYCLE_COLLECTING_RELEASE(PipeToPumpHandler
)
164 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PipeToPumpHandler
)
165 NS_INTERFACE_MAP_ENTRY(nsISupports
)
168 void PipeToPump::RunAbortAlgorithm() {
170 if (!jsapi
.Init(mReader
->GetStream()->GetParentObject())) {
172 "Failed to initialize AutoJSAPI in PipeToPump::RunAbortAlgorithm");
175 JSContext
* cx
= jsapi
.cx();
177 RefPtr
<AbortSignalImpl
> signal
= Signal();
178 PerformAbortAlgorithm(cx
, signal
);
181 void PipeToPump::PerformAbortAlgorithm(JSContext
* aCx
,
182 AbortSignalImpl
* aSignal
) {
183 MOZ_ASSERT(aSignal
->Aborted());
185 // https://streams.spec.whatwg.org/#readable-stream-pipe-to
186 // Step 14.1. Let abortAlgorithm be the following steps:
187 // Note: All the following steps are 14.1.xx
189 // Step 1. Let error be signal’s abort reason.
190 JS::Rooted
<JS::Value
> error(aCx
);
191 aSignal
->GetReason(aCx
, &error
);
193 auto action
= [](JSContext
* aCx
, PipeToPump
* aPipeToPump
,
194 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
,
195 ErrorResult
& aRv
) MOZ_CAN_RUN_SCRIPT
{
196 JS::Rooted
<JS::Value
> error(aCx
, *aError
);
198 // Step 2. Let actions be an empty ordered set.
199 nsTArray
<RefPtr
<Promise
>> actions
;
201 // Step 3. If preventAbort is false, append the following action to actions:
202 if (!aPipeToPump
->mPreventAbort
) {
203 RefPtr
<WritableStream
> dest
= aPipeToPump
->mWriter
->GetStream();
205 // Step 3.1. If dest.[[state]] is "writable", return !
206 // WritableStreamAbort(dest, error).
207 if (dest
->State() == WritableStream::WriterState::Writable
) {
208 RefPtr
<Promise
> p
= WritableStreamAbort(aCx
, dest
, error
, aRv
);
210 return already_AddRefed
<Promise
>();
212 actions
.AppendElement(p
);
215 // Step 3.2. Otherwise, return a promise resolved with undefined.
216 // Note: This is basically a no-op.
219 // Step 4. If preventCancel is false, append the following action action to
221 if (!aPipeToPump
->mPreventCancel
) {
222 RefPtr
<ReadableStream
> source
= aPipeToPump
->mReader
->GetStream();
224 // Step 4.1. If source.[[state]] is "readable", return !
225 // ReadableStreamCancel(source, error).
226 if (source
->State() == ReadableStream::ReaderState::Readable
) {
227 RefPtr
<Promise
> p
= ReadableStreamCancel(aCx
, source
, error
, aRv
);
229 return already_AddRefed
<Promise
>();
231 actions
.AppendElement(p
);
234 // Step 4.2. Otherwise, return a promise resolved with undefined.
238 // Step 5. .. action consisting of getting a promise to wait for
239 // all of the actions in actions ...
240 return Promise::All(aCx
, actions
, aRv
);
243 // Step 5. Shutdown with an action consisting of getting a promise to wait for
244 // all of the actions in actions, and with error.
245 JS::Rooted
<Maybe
<JS::Value
>> someError(aCx
, Some(error
.get()));
246 ShutdownWithAction(aCx
, action
, someError
);
249 bool PipeToPump::SourceOrDestErroredOrClosed(JSContext
* aCx
) {
250 // (Constraint) Error and close states must be propagated:
251 // the following conditions must be applied in order.
252 RefPtr
<ReadableStream
> source
= mReader
->GetStream();
253 RefPtr
<WritableStream
> dest
= mWriter
->GetStream();
255 // Step 1. Errors must be propagated forward: if source.[[state]] is or
256 // becomes "errored", then
257 if (source
->State() == ReadableStream::ReaderState::Errored
) {
258 JS::Rooted
<JS::Value
> storedError(aCx
, source
->StoredError());
259 OnSourceErrored(aCx
, storedError
);
263 // Step 2. Errors must be propagated backward: if dest.[[state]] is or becomes
265 if (dest
->State() == WritableStream::WriterState::Errored
) {
266 JS::Rooted
<JS::Value
> storedError(aCx
, dest
->StoredError());
267 OnDestErrored(aCx
, storedError
);
271 // Step 3. Closing must be propagated forward: if source.[[state]] is or
272 // becomes "closed", then
273 if (source
->State() == ReadableStream::ReaderState::Closed
) {
274 OnSourceClosed(aCx
, JS::UndefinedHandleValue
);
278 // Step 4. Closing must be propagated backward:
279 // if ! WritableStreamCloseQueuedOrInFlight(dest) is true
280 // or dest.[[state]] is "closed", then
281 if (dest
->CloseQueuedOrInFlight() ||
282 dest
->State() == WritableStream::WriterState::Closed
) {
283 OnDestClosed(aCx
, JS::UndefinedHandleValue
);
290 // https://streams.spec.whatwg.org/#readable-stream-pipe-to
292 void PipeToPump::Start(JSContext
* aCx
, AbortSignal
* aSignal
) {
293 // Step 14. If signal is not undefined,
295 // Step 14.1. Let abortAlgorithm be the following steps:
296 // ... This is implemented by RunAbortAlgorithm.
298 // Step 14.2. If signal is aborted, perform abortAlgorithm and
300 if (aSignal
->Aborted()) {
301 PerformAbortAlgorithm(aCx
, aSignal
);
305 // Step 14.3. Add abortAlgorithm to signal.
309 // Step 15. In parallel but not really; see #905, using reader and writer,
310 // read all chunks from source and write them to dest.
311 // Due to the locking provided by the reader and writer,
312 // the exact manner in which this happens is not observable to author code,
313 // and so there is flexibility in how this is done.
315 // (Constraint) Error and close states must be propagated
317 // Before piping has started, we have to check for source/destination being
318 // errored/closed manually.
319 if (SourceOrDestErroredOrClosed(aCx
)) {
323 // We use the following two promises to propagate error and close states
325 RefPtr
<Promise
> readerClosed
= mReader
->ClosedPromise();
326 readerClosed
->AppendNativeHandler(new PipeToPumpHandler(
327 this, &PipeToPump::OnSourceClosed
, &PipeToPump::OnSourceErrored
));
329 // Note: Because we control the destination/writer it should never be closed
330 // after we did the initial check above with SourceOrDestErroredOrClosed.
331 RefPtr
<Promise
> writerClosed
= mWriter
->ClosedPromise();
332 writerClosed
->AppendNativeHandler(new PipeToPumpHandler(
333 this, &PipeToPump::OnDestClosed
, &PipeToPump::OnDestErrored
));
338 class WriteFinishedPromiseHandler final
: public PromiseNativeHandler
{
339 RefPtr
<PipeToPump
> mPipeToPump
;
340 PipeToPump::ShutdownAction mAction
;
342 JS::Heap
<JS::Value
> mError
;
344 virtual ~WriteFinishedPromiseHandler() { mozilla::DropJSObjects(this); };
347 NS_DECL_CYCLE_COLLECTING_ISUPPORTS
348 NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(WriteFinishedPromiseHandler
)
350 explicit WriteFinishedPromiseHandler(
351 JSContext
* aCx
, PipeToPump
* aPipeToPump
,
352 PipeToPump::ShutdownAction aAction
,
353 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
)
354 : mPipeToPump(aPipeToPump
), mAction(aAction
) {
355 mHasError
= aError
.isSome();
359 mozilla::HoldJSObjects(this);
362 MOZ_CAN_RUN_SCRIPT
void WriteFinished(JSContext
* aCx
) {
363 RefPtr
<PipeToPump
> pipeToPump
= mPipeToPump
; // XXX known-live?
364 JS::Rooted
<Maybe
<JS::Value
>> error(aCx
);
366 error
= Some(mError
);
368 pipeToPump
->ShutdownWithActionAfterFinishedWrite(aCx
, mAction
, error
);
371 MOZ_CAN_RUN_SCRIPT
void ResolvedCallback(JSContext
* aCx
,
372 JS::Handle
<JS::Value
> aValue
,
373 ErrorResult
&) override
{
377 MOZ_CAN_RUN_SCRIPT
void RejectedCallback(JSContext
* aCx
,
378 JS::Handle
<JS::Value
> aReason
,
379 ErrorResult
&) override
{
384 NS_IMPL_CYCLE_COLLECTION_WITH_JS_MEMBERS(WriteFinishedPromiseHandler
,
385 (mPipeToPump
), (mError
))
386 NS_IMPL_CYCLE_COLLECTING_ADDREF(WriteFinishedPromiseHandler
)
387 NS_IMPL_CYCLE_COLLECTING_RELEASE(WriteFinishedPromiseHandler
)
388 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(WriteFinishedPromiseHandler
)
389 NS_INTERFACE_MAP_ENTRY(nsISupports
)
392 // https://streams.spec.whatwg.org/#rs-pipeTo-shutdown-with-action
393 // Shutdown with an action: if any of the above requirements ask to shutdown
394 // with an action action, optionally with an error originalError, then:
395 void PipeToPump::ShutdownWithAction(
396 JSContext
* aCx
, ShutdownAction aAction
,
397 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
) {
398 // Step 1. If shuttingDown is true, abort these substeps.
403 // Step 2. Set shuttingDown to true.
404 mShuttingDown
= true;
406 // Step 3. If dest.[[state]] is "writable" and !
407 // WritableStreamCloseQueuedOrInFlight(dest) is false,
408 RefPtr
<WritableStream
> dest
= mWriter
->GetStream();
409 if (dest
->State() == WritableStream::WriterState::Writable
&&
410 !dest
->CloseQueuedOrInFlight()) {
411 // Step 3.1. If any chunks have been read but not yet written, write them to
413 // Step 3.2. Wait until every chunk that has been read has been
414 // written (i.e. the corresponding promises have settled).
416 // Note: Write requests are processed in order, so when the promise
417 // for the last written chunk is settled all previous chunks have been
419 if (mLastWritePromise
) {
420 mLastWritePromise
->AppendNativeHandler(
421 new WriteFinishedPromiseHandler(aCx
, this, aAction
, aError
));
426 // Don't have to wait for last write, immediately continue.
427 ShutdownWithActionAfterFinishedWrite(aCx
, aAction
, aError
);
430 class ShutdownActionFinishedPromiseHandler final
: public PromiseNativeHandler
{
431 RefPtr
<PipeToPump
> mPipeToPump
;
433 JS::Heap
<JS::Value
> mError
;
435 virtual ~ShutdownActionFinishedPromiseHandler() {
436 mozilla::DropJSObjects(this);
440 NS_DECL_CYCLE_COLLECTING_ISUPPORTS
441 NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(
442 ShutdownActionFinishedPromiseHandler
)
444 explicit ShutdownActionFinishedPromiseHandler(
445 JSContext
* aCx
, PipeToPump
* aPipeToPump
,
446 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
)
447 : mPipeToPump(aPipeToPump
) {
448 mHasError
= aError
.isSome();
452 mozilla::HoldJSObjects(this);
455 void ResolvedCallback(JSContext
* aCx
, JS::Handle
<JS::Value
> aValue
,
456 ErrorResult
&) override
{
457 // https://streams.spec.whatwg.org/#rs-pipeTo-shutdown-with-action
458 // Step 5. Upon fulfillment of p, finalize, passing along originalError if
460 JS::Rooted
<Maybe
<JS::Value
>> error(aCx
);
462 error
= Some(mError
);
464 mPipeToPump
->Finalize(aCx
, error
);
467 void RejectedCallback(JSContext
* aCx
, JS::Handle
<JS::Value
> aReason
,
468 ErrorResult
&) override
{
469 // https://streams.spec.whatwg.org/#rs-pipeTo-shutdown-with-action
470 // Step 6. Upon rejection of p with reason newError, finalize with
472 JS::Rooted
<Maybe
<JS::Value
>> error(aCx
, Some(aReason
));
473 mPipeToPump
->Finalize(aCx
, error
);
477 NS_IMPL_CYCLE_COLLECTION_WITH_JS_MEMBERS(ShutdownActionFinishedPromiseHandler
,
478 (mPipeToPump
), (mError
))
479 NS_IMPL_CYCLE_COLLECTING_ADDREF(ShutdownActionFinishedPromiseHandler
)
480 NS_IMPL_CYCLE_COLLECTING_RELEASE(ShutdownActionFinishedPromiseHandler
)
481 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ShutdownActionFinishedPromiseHandler
)
482 NS_INTERFACE_MAP_ENTRY(nsISupports
)
485 // https://streams.spec.whatwg.org/#rs-pipeTo-shutdown-with-action
486 // Continuation after Step 3. triggered a promise resolution.
487 void PipeToPump::ShutdownWithActionAfterFinishedWrite(
488 JSContext
* aCx
, ShutdownAction aAction
,
489 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
) {
491 // Used to implement shutdown without action. Finalize immediately.
492 Finalize(aCx
, aError
);
496 // Step 4. Let p be the result of performing action.
497 RefPtr
<PipeToPump
> thisRefPtr
= this;
499 RefPtr
<Promise
> p
= aAction(aCx
, thisRefPtr
, aError
, rv
);
501 // Error while calling actions above, continue immediately with finalization.
502 if (rv
.MaybeSetPendingException(aCx
)) {
503 JS::Rooted
<Maybe
<JS::Value
>> someError(aCx
);
505 JS::Rooted
<JS::Value
> error(aCx
);
506 if (JS_GetPendingException(aCx
, &error
)) {
507 someError
= Some(error
.get());
510 JS_ClearPendingException(aCx
);
512 Finalize(aCx
, someError
);
517 p
->AppendNativeHandler(
518 new ShutdownActionFinishedPromiseHandler(aCx
, this, aError
));
521 // https://streams.spec.whatwg.org/#rs-pipeTo-shutdown
522 // Shutdown: if any of the above requirements or steps ask to shutdown,
523 // optionally with an error error, then:
524 void PipeToPump::Shutdown(JSContext
* aCx
,
525 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
) {
526 // Note: We implement "shutdown" in terms of "shutdown with action".
527 // We can observe that when passing along an action that always succeeds
528 // shutdown with action and shutdown have the same behavior, when
529 // Ignoring the potential micro task for the promise that we skip anyway.
530 ShutdownWithAction(aCx
, nullptr, aError
);
533 // https://streams.spec.whatwg.org/#rs-pipeTo-finalize
534 // Finalize: both forms of shutdown will eventually ask to finalize,
535 // optionally with an error error, which means to perform the following steps:
536 void PipeToPump::Finalize(JSContext
* aCx
,
537 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
) {
538 IgnoredErrorResult rv
;
539 // Step 1. Perform ! WritableStreamDefaultWriterRelease(writer).
540 WritableStreamDefaultWriterRelease(aCx
, mWriter
, rv
);
541 NS_WARNING_ASSERTION(!rv
.Failed(),
542 "WritableStreamDefaultWriterRelease should not fail.");
544 // Step 2. If reader implements ReadableStreamBYOBReader,
545 // perform ! ReadableStreamBYOBReaderRelease(reader).
546 // Note: We always use a default reader.
547 MOZ_ASSERT(!mReader
->IsBYOB());
549 // Step 3. Otherwise, perform ! ReadableStreamDefaultReaderRelease(reader).
550 ReadableStreamDefaultReaderRelease(aCx
, mReader
, rv
);
551 NS_WARNING_ASSERTION(!rv
.Failed(),
552 "ReadableStreamReaderGenericRelease should not fail.");
554 // Step 3. If signal is not undefined, remove abortAlgorithm from signal.
559 // Step 4. If error was given, reject promise with error.
560 if (aError
.isSome()) {
561 JS::Rooted
<JS::Value
> error(aCx
, *aError
);
562 mPromise
->MaybeReject(error
);
564 // Step 5. Otherwise, resolve promise with undefined.
565 mPromise
->MaybeResolveWithUndefined();
568 // Remove all references.
572 mLastWritePromise
= nullptr;
576 void PipeToPump::OnReadFulfilled(JSContext
* aCx
, JS::Handle
<JS::Value
> aChunk
,
578 // (Constraint) Shutdown must stop activity:
579 // if shuttingDown becomes true, the user agent must not initiate further
580 // reads from reader, and must only perform writes of already-read chunks ...
582 // We may reach this point after |On{Source,Dest}{Clos,Error}ed| has responded
583 // to an out-of-band change. Per the comment in |OnSourceErrored|, we want to
584 // allow the implicated shutdown to proceed, and we don't want to interfere
585 // with or additionally alter its operation. Particularly, we don't want to
586 // queue up the successfully-read chunk (if there was one, and this isn't just
587 // reporting "done") to be written: it wasn't "already-read" when that
588 // error/closure happened.
590 // All specified reactions to a closure/error invoke either the shutdown, or
591 // shutdown with an action, algorithms. Those algorithms each abort if either
592 // shutdown algorithm has already been invoked. So we check for shutdown here
593 // in case of asynchronous closure/error and abort if shutdown has already
594 // started (and possibly finished).
596 // TODO: Implement the eventual resolution from
597 // https://github.com/whatwg/streams/issues/1207
602 RefPtr
<WritableStreamDefaultWriter
> writer
= mWriter
;
604 WritableStreamDefaultWriterWrite(aCx
, writer
, aChunk
, aRv
);
606 mLastWritePromise
= nullptr;
610 mLastWritePromise
->AppendNativeHandler(
611 new PipeToPumpHandler(this, nullptr, &PipeToPump::OnDestErrored
));
613 // Last read has finished, so it's time to start reading again.
617 void PipeToPump::OnWriterReady(JSContext
* aCx
, JS::Handle
<JS::Value
>) {
618 // Writer is ready again (i.e. backpressure was resolved), so read.
622 struct PipeToReadRequest
: public ReadRequest
{
624 NS_DECL_ISUPPORTS_INHERITED
625 NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(PipeToReadRequest
, ReadRequest
)
627 RefPtr
<PipeToPump
> mPipeToPump
;
629 explicit PipeToReadRequest(PipeToPump
* aPipeToPump
)
630 : mPipeToPump(aPipeToPump
) {}
632 MOZ_CAN_RUN_SCRIPT_BOUNDARY
void ChunkSteps(JSContext
* aCx
,
633 JS::Handle
<JS::Value
> aChunk
,
634 ErrorResult
& aRv
) override
{
635 RefPtr
<PipeToPump
> pipeToPump
= mPipeToPump
; // XXX known live?
636 pipeToPump
->OnReadFulfilled(aCx
, aChunk
, aRv
);
639 // The reader's closed promise handlers will already call OnSourceClosed/
640 // OnSourceErrored, so these steps can just be ignored.
641 void CloseSteps(JSContext
* aCx
, ErrorResult
& aRv
) override
{}
642 void ErrorSteps(JSContext
* aCx
, JS::Handle
<JS::Value
> aError
,
643 ErrorResult
& aRv
) override
{}
646 virtual ~PipeToReadRequest() = default;
649 NS_IMPL_CYCLE_COLLECTION_INHERITED(PipeToReadRequest
, ReadRequest
, mPipeToPump
)
651 NS_IMPL_ADDREF_INHERITED(PipeToReadRequest
, ReadRequest
)
652 NS_IMPL_RELEASE_INHERITED(PipeToReadRequest
, ReadRequest
)
654 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PipeToReadRequest
)
655 NS_INTERFACE_MAP_END_INHERITING(ReadRequest
)
657 void PipeToPump::Read(JSContext
* aCx
) {
662 // (Constraint) Shutdown must stop activity:
663 // If shuttingDown becomes true, the user agent must not initiate
664 // further reads from reader
669 // (Constraint) Backpressure must be enforced:
670 // While WritableStreamDefaultWriterGetDesiredSize(writer) is ≤ 0 or is null,
671 // the user agent must not read from reader.
672 Nullable
<double> desiredSize
=
673 WritableStreamDefaultWriterGetDesiredSize(mWriter
);
674 if (desiredSize
.IsNull()) {
675 // This means the writer has errored. This is going to be handled
676 // by the writer closed promise.
680 if (desiredSize
.Value() <= 0) {
681 // Wait for the writer to become ready before reading more data from
682 // the reader. We don't care about rejections here, because those are
683 // already handled by the writer closed promise.
684 RefPtr
<Promise
> readyPromise
= mWriter
->Ready();
685 readyPromise
->AppendNativeHandler(
686 new PipeToPumpHandler(this, &PipeToPump::OnWriterReady
, nullptr));
690 RefPtr
<ReadableStreamDefaultReader
> reader
= mReader
;
691 RefPtr
<ReadRequest
> request
= new PipeToReadRequest(this);
693 ReadableStreamDefaultReaderRead(aCx
, reader
, request
, rv
);
694 if (rv
.MaybeSetPendingException(aCx
)) {
695 // XXX It's actually not quite obvious what we should do here.
696 // We've got an error during reading, so on the surface it seems logical
697 // to invoke `OnSourceErrored`. However in certain cases the required
698 // condition > source.[[state]] is or becomes "errored" < won't actually
699 // happen i.e. when `WritableStreamDefaultWriterWrite` called from
700 // `OnReadFulfilled` (via PipeToReadRequest::ChunkSteps) fails in
701 // a synchronous fashion.
702 JS::Rooted
<JS::Value
> error(aCx
);
703 JS::Rooted
<Maybe
<JS::Value
>> someError(aCx
);
705 // The error was moved to the JSContext by MaybeSetPendingException.
706 if (JS_GetPendingException(aCx
, &error
)) {
707 someError
= Some(error
.get());
710 JS_ClearPendingException(aCx
);
712 Shutdown(aCx
, someError
);
716 // Step 3. Closing must be propagated forward: if source.[[state]] is or
717 // becomes "closed", then
718 void PipeToPump::OnSourceClosed(JSContext
* aCx
, JS::Handle
<JS::Value
>) {
719 // Step 3.1. If preventClose is false, shutdown with an action of
720 // ! WritableStreamDefaultWriterCloseWithErrorPropagation(writer).
721 if (!mPreventClose
) {
724 [](JSContext
* aCx
, PipeToPump
* aPipeToPump
,
725 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
, ErrorResult
& aRv
)
727 RefPtr
<WritableStreamDefaultWriter
> writer
= aPipeToPump
->mWriter
;
728 return WritableStreamDefaultWriterCloseWithErrorPropagation(
731 JS::NothingHandleValue
);
733 // Step 3.2 Otherwise, shutdown.
734 Shutdown(aCx
, JS::NothingHandleValue
);
738 // Step 1. Errors must be propagated forward: if source.[[state]] is or
739 // becomes "errored", then
740 void PipeToPump::OnSourceErrored(JSContext
* aCx
,
741 JS::Handle
<JS::Value
> aSourceStoredError
) {
742 // If |source| becomes errored not during a pending read, it's clear we must
743 // react immediately.
745 // But what if |source| becomes errored *during* a pending read? Should this
746 // first error, or the pending-read second error, predominate? Two semantics
747 // are possible when |source|/|dest| become closed or errored while there's a
750 // 1. Wait until the read fulfills or rejects, then respond to the
751 // closure/error without regard to the read having fulfilled or rejected.
752 // (This will simply not react to the read being rejected, or it will
753 // queue up the read chunk to be written during shutdown.)
754 // 2. React to the closure/error immediately per "Error and close states
755 // must be propagated". Then when the read fulfills or rejects later, do
758 // The spec doesn't clearly require either semantics. It requires that
759 // *already-read* chunks be written (at least if |dest| didn't become errored
760 // or closed such that no further writes can occur). But it's silent as to
761 // not-fully-read chunks. (These semantic differences may only be observable
762 // with very carefully constructed readable/writable streams.)
764 // It seems best, generally, to react to the temporally-earliest problem that
765 // arises, so we implement option #2. (Blink, in contrast, currently
766 // implements option #1.)
768 // All specified reactions to a closure/error invoke either the shutdown, or
769 // shutdown with an action, algorithms. Those algorithms each abort if either
770 // shutdown algorithm has already been invoked. So we don't need to do
771 // anything special here to deal with a pending read.
773 // TODO: Implement the eventual resolution from
774 // https://github.com/whatwg/streams/issues/1207
776 // Step 1.1 If preventAbort is false, shutdown with an action of
777 // ! WritableStreamAbort(dest, source.[[storedError]])
778 // and with source.[[storedError]].
779 JS::Rooted
<Maybe
<JS::Value
>> error(aCx
, Some(aSourceStoredError
));
780 if (!mPreventAbort
) {
783 [](JSContext
* aCx
, PipeToPump
* aPipeToPump
,
784 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
, ErrorResult
& aRv
)
786 JS::Rooted
<JS::Value
> error(aCx
, *aError
);
787 RefPtr
<WritableStream
> dest
= aPipeToPump
->mWriter
->GetStream();
788 return WritableStreamAbort(aCx
, dest
, error
, aRv
);
792 // Step 1.1. Otherwise, shutdown with source.[[storedError]].
793 Shutdown(aCx
, error
);
797 // Step 4. Closing must be propagated backward:
798 // if ! WritableStreamCloseQueuedOrInFlight(dest) is true
799 // or dest.[[state]] is "closed", then
800 void PipeToPump::OnDestClosed(JSContext
* aCx
, JS::Handle
<JS::Value
>) {
801 // Step 4.1. Assert: no chunks have been read or written.
802 // Note: No reading automatically implies no writing.
803 // In a perfect world OnDestClosed would only be called before we start
804 // piping, because afterwards the writer has an exclusive lock on the stream.
805 // In reality the closed promise can still be resolved after we release
806 // the lock on the writer in Finalize.
810 MOZ_ASSERT(!mReadChunk
);
812 // Step 4.2. Let destClosed be a new TypeError.
813 JS::Rooted
<Maybe
<JS::Value
>> destClosed(aCx
, Nothing());
816 rv
.ThrowTypeError("Cannot pipe to closed stream");
817 JS::Rooted
<JS::Value
> error(aCx
);
818 bool ok
= ToJSValue(aCx
, std::move(rv
), &error
);
819 MOZ_RELEASE_ASSERT(ok
, "must be ok");
820 destClosed
= Some(error
.get());
823 // Step 4.3. If preventCancel is false, shutdown with an action of
824 // ! ReadableStreamCancel(source, destClosed) and with destClosed.
825 if (!mPreventCancel
) {
828 [](JSContext
* aCx
, PipeToPump
* aPipeToPump
,
829 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
, ErrorResult
& aRv
)
831 JS::Rooted
<JS::Value
> error(aCx
, *aError
);
832 RefPtr
<ReadableStream
> dest
= aPipeToPump
->mReader
->GetStream();
833 return ReadableStreamCancel(aCx
, dest
, error
, aRv
);
837 // Step 4.4. Otherwise, shutdown with destClosed.
838 Shutdown(aCx
, destClosed
);
842 // Step 2. Errors must be propagated backward: if dest.[[state]] is or becomes
844 void PipeToPump::OnDestErrored(JSContext
* aCx
,
845 JS::Handle
<JS::Value
> aDestStoredError
) {
846 // Step 2.1. If preventCancel is false, shutdown with an action of
847 // ! ReadableStreamCancel(source, dest.[[storedError]])
848 // and with dest.[[storedError]].
849 JS::Rooted
<Maybe
<JS::Value
>> error(aCx
, Some(aDestStoredError
));
850 if (!mPreventCancel
) {
853 [](JSContext
* aCx
, PipeToPump
* aPipeToPump
,
854 JS::Handle
<mozilla::Maybe
<JS::Value
>> aError
, ErrorResult
& aRv
)
856 JS::Rooted
<JS::Value
> error(aCx
, *aError
);
857 RefPtr
<ReadableStream
> dest
= aPipeToPump
->mReader
->GetStream();
858 return ReadableStreamCancel(aCx
, dest
, error
, aRv
);
862 // Step 2.1. Otherwise, shutdown with dest.[[storedError]].
863 Shutdown(aCx
, error
);
867 NS_IMPL_CYCLE_COLLECTION_CLASS(PipeToPump
)
868 NS_IMPL_CYCLE_COLLECTING_ADDREF(PipeToPump
)
869 NS_IMPL_CYCLE_COLLECTING_RELEASE(PipeToPump
)
870 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PipeToPump
)
871 NS_INTERFACE_MAP_ENTRY(nsISupports
)
874 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(PipeToPump
)
875 NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPromise
)
876 NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mReader
)
877 NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWriter
)
878 NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mLastWritePromise
)
879 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
881 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(PipeToPump
)
882 NS_IMPL_CYCLE_COLLECTION_UNLINK(mPromise
)
883 NS_IMPL_CYCLE_COLLECTION_UNLINK(mReader
)
884 NS_IMPL_CYCLE_COLLECTION_UNLINK(mWriter
)
885 NS_IMPL_CYCLE_COLLECTION_UNLINK(mLastWritePromise
)
886 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
888 // https://streams.spec.whatwg.org/#readable-stream-pipe-to
889 already_AddRefed
<Promise
> ReadableStreamPipeTo(
890 ReadableStream
* aSource
, WritableStream
* aDest
, bool aPreventClose
,
891 bool aPreventAbort
, bool aPreventCancel
, AbortSignal
* aSignal
,
892 mozilla::ErrorResult
& aRv
) {
893 // Step 1. Assert: source implements ReadableStream. (Implicit)
894 // Step 2. Assert: dest implements WritableStream. (Implicit)
895 // Step 3. Assert: preventClose, preventAbort, and preventCancel are all
896 // booleans (Implicit)
897 // Step 4. If signal was not given, let signal be
898 // undefined. (Implicit)
899 // Step 5. Assert: either signal is undefined, or signal
900 // implements AbortSignal. (Implicit)
901 // Step 6. Assert: !IsReadableStreamLocked(source) is false.
902 MOZ_ASSERT(!IsReadableStreamLocked(aSource
));
904 // Step 7. Assert: !IsWritableStreamLocked(dest) is false.
905 MOZ_ASSERT(!IsWritableStreamLocked(aDest
));
908 if (!jsapi
.Init(aSource
->GetParentObject())) {
909 aRv
.ThrowUnknownError("Internal error");
912 JSContext
* cx
= jsapi
.cx();
914 // Step 8. If source.[[controller]] implements ReadableByteStreamController,
915 // let reader be either !AcquireReadableStreamBYOBReader(source) or
916 // !AcquireReadableStreamDefaultReader(source), at the user agent’s
918 // Step 9. Otherwise, let reader be
919 // !AcquireReadableStreamDefaultReader(source).
921 // Note: In the interests of simplicity, we choose here to always acquire
923 RefPtr
<ReadableStreamDefaultReader
> reader
=
924 AcquireReadableStreamDefaultReader(aSource
, aRv
);
929 // Step 10. Let writer be ! AcquireWritableStreamDefaultWriter(dest).
930 RefPtr
<WritableStreamDefaultWriter
> writer
=
931 AcquireWritableStreamDefaultWriter(aDest
, aRv
);
936 // Step 11. Set source.[[disturbed]] to true.
937 aSource
->SetDisturbed(true);
939 // Step 12. Let shuttingDown be false.
940 // Note: PipeToPump ensures this by construction.
942 // Step 13. Let promise be a new promise.
943 RefPtr
<Promise
> promise
= Promise::Create(aSource
->GetParentObject(), aRv
);
949 RefPtr
<PipeToPump
> pump
= new PipeToPump(
950 promise
, reader
, writer
, aPreventClose
, aPreventAbort
, aPreventCancel
);
951 pump
->Start(cx
, aSignal
);
953 // Step 16. Return promise.
954 return promise
.forget();
957 } // namespace mozilla::dom