LibWeb: Add ReadableStreamByteController interface

Author: https://github.com/mattco98
Commit: https://github.com/SerenityOS/serenity/commit/819b6332d1
Pull-request: https://github.com/SerenityOS/serenity/pull/18283
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -464,6 +464,7 @@ set(SOURCES
     ResizeObserver/ResizeObserver.cpp
     SecureContexts/AbstractOperations.cpp
     Streams/AbstractOperations.cpp
+    Streams/ReadableByteStreamController.cpp
     Streams/ReadableStream.cpp
     Streams/ReadableStreamBYOBRequest.cpp
     Streams/ReadableStreamDefaultController.cpp

Userland/Libraries/LibWeb/Forward.h

@@ -426,6 +426,7 @@ class Selection;
 
 namespace Web::Streams {
 class ReadableStream;
+class ReadableByteStreamController;
 class ReadableStreamBYOBRequest;
 class ReadableStreamDefaultController;
 class ReadableStreamDefaultReader;

Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp

@@ -10,6 +10,7 @@
 #include <LibWeb/Bindings/ExceptionOrUtils.h>
 #include <LibWeb/DOM/AbortSignal.h>
 #include <LibWeb/Streams/AbstractOperations.h>
+#include <LibWeb/Streams/ReadableByteStreamController.h>
 #include <LibWeb/Streams/ReadableStream.h>
 #include <LibWeb/Streams/ReadableStreamDefaultController.h>
 #include <LibWeb/Streams/ReadableStreamDefaultReader.h>
@@ -739,6 +740,24 @@ WebIDL::ExceptionOr<void> set_up_readable_stream_default_controller_from_underly
     return set_up_readable_stream_default_controller(stream, controller, move(start_algorithm), move(pull_algorithm), move(cancel_algorithm), high_water_mark, move(size_algorithm));
 }
 
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-get-desired-size
+Optional<double> readable_byte_stream_controller_get_desired_size(ReadableByteStreamController const& controller)
+{
+    auto stream = controller.stream();
+
+    // 1. Let state be controller.[[stream]].[[state]].
+    // 2. If state is "errored", return null.
+    if (stream->is_errored())
+        return {};
+
+    // 3. If state is "closed", return 0.
+    if (stream->is_closed())
+        return 0.0;
+
+    // 4. Return controller.[[strategyHWM]] − controller.[[queueTotalSize]].
+    return controller.strategy_hwm() - controller.queue_total_size();
+}
+
 // https://streams.spec.whatwg.org/#acquire-writable-stream-default-writer
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WritableStreamDefaultWriter>> acquire_writable_stream_default_writer(WritableStream& stream)
 {

Userland/Libraries/LibWeb/Streams/AbstractOperations.h

@@ -53,6 +53,8 @@ bool readable_stream_default_controller_can_close_or_enqueue(ReadableStreamDefau
 WebIDL::ExceptionOr<void> set_up_readable_stream_default_controller(ReadableStream&, ReadableStreamDefaultController&, StartAlgorithm&&, PullAlgorithm&&, CancelAlgorithm&&, double high_water_mark, SizeAlgorithm&&);
 WebIDL::ExceptionOr<void> set_up_readable_stream_default_controller_from_underlying_source(ReadableStream&, JS::Value underlying_source_value, UnderlyingSource, double high_water_mark, SizeAlgorithm&&);
 
+Optional<double> readable_byte_stream_controller_get_desired_size(ReadableByteStreamController const&);
+
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WritableStreamDefaultWriter>> acquire_writable_stream_default_writer(WritableStream&);
 bool is_writable_stream_locked(WritableStream const&);
 WebIDL::ExceptionOr<void> set_up_writable_stream_default_writer(WritableStreamDefaultWriter&, WritableStream&);

Userland/Libraries/LibWeb/Streams/ReadableByteStreamController.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2023, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Streams/ReadableByteStreamController.h>
+#include <LibWeb/Streams/ReadableStream.h>
+#include <LibWeb/Streams/ReadableStreamBYOBRequest.h>
+
+namespace Web::Streams {
+
+// https://streams.spec.whatwg.org/#rbs-controller-desired-size
+Optional<double> ReadableByteStreamController::desired_size() const
+{
+    // 1. Return ! ReadableByteStreamControllerGetDesiredSize(this).
+    return readable_byte_stream_controller_get_desired_size(*this);
+}
+
+ReadableByteStreamController::ReadableByteStreamController(JS::Realm& realm)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+void ReadableByteStreamController::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_byob_request);
+    for (auto const& pending_pull_into : m_pending_pull_intos) {
+        visitor.visit(pending_pull_into.buffer);
+        visitor.visit(pending_pull_into.view_constructor);
+    }
+    for (auto const& item : m_queue)
+        visitor.visit(item.buffer);
+    visitor.visit(m_stream);
+}
+
+}

Userland/Libraries/LibWeb/Streams/ReadableByteStreamController.h

@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2023, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <AK/SinglyLinkedList.h>
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/Streams/AbstractOperations.h>
+
+namespace Web::Streams {
+
+enum class ReaderType {
+    Default,
+    Byob,
+    None,
+};
+
+// https://streams.spec.whatwg.org/#pull-into-descriptor
+struct PullIntoDescriptor {
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-buffer
+    // An ArrayBuffer
+    JS::NonnullGCPtr<JS::ArrayBuffer> buffer;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-buffer-byte-length
+    // A positive integer representing the initial byte length of buffer
+    u32 buffer_byte_length;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-byte-offset
+    // A nonnegative integer byte offset into the buffer where the underlying byte source will start writing
+    u32 byte_offset;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-byte-length
+    // A positive integer number of bytes which can be written into the buffer
+    u32 byte_length;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-bytes-filled
+    // A nonnegative integer number of bytes that have been written into the buffer so far
+    u32 bytes_filled;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-element-size
+    // A positive integer representing the number of bytes that can be written into the buffer at a time, using views of the type described by the view constructor
+    u32 element_size;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-view-constructor
+    // A typed array constructor or %DataView%, which will be used for constructing a view with which to write into the buffer
+    JS::NonnullGCPtr<JS::NativeFunction> view_constructor;
+
+    // https://streams.spec.whatwg.org/#pull-into-descriptor-reader-type
+    // Either "default" or "byob", indicating what type of readable stream reader initiated this request, or "none" if the initiating reader was released
+    ReaderType reader_type;
+};
+
+// https://streams.spec.whatwg.org/#readable-byte-stream-queue-entry
+struct ReadableByteStreamQueueEntry {
+    // https://streams.spec.whatwg.org/#readable-byte-stream-queue-entry-buffer
+    // An ArrayBuffer, which will be a transferred version of the one originally supplied by the underlying byte source
+    JS::NonnullGCPtr<JS::ArrayBuffer> buffer;
+
+    // https://streams.spec.whatwg.org/#readable-byte-stream-queue-entry-byte-offset
+    // A nonnegative integer number giving the byte offset derived from the view originally supplied by the underlying byte source
+    u32 byte_offset;
+
+    // https://streams.spec.whatwg.org/#readable-byte-stream-queue-entry-byte-length
+    // A nonnegative integer number giving the byte length derived from the view originally supplied by the underlying byte source
+    u32 byte_length;
+};
+
+// https://streams.spec.whatwg.org/#readablebytestreamcontroller
+class ReadableByteStreamController : public Bindings::PlatformObject {
+    WEB_PLATFORM_OBJECT(ReadableByteStreamController, Bindings::PlatformObject);
+
+public:
+    virtual ~ReadableByteStreamController() override = default;
+
+    JS::GCPtr<ReadableStreamBYOBRequest> byob_request() { return m_byob_request; }
+    void set_byob_request(JS::GCPtr<ReadableStreamBYOBRequest> request) { m_byob_request = request; }
+
+    Optional<double> desired_size() const;
+
+    Optional<u32> const& auto_allocate_chunk_size() { return m_auto_allocate_chunk_size; }
+    void set_auto_allocate_chunk_size(Optional<u32> value) { m_auto_allocate_chunk_size = value; }
+
+    auto& cancel_algorithm() { return m_cancel_algorithm; }
+    void set_cancel_algorithm(Optional<CancelAlgorithm> value) { m_cancel_algorithm = move(value); }
+
+    bool close_requested() const { return m_close_requested; }
+    void set_close_requested(bool value) { m_close_requested = value; }
+
+    bool pull_again() const { return m_pull_again; }
+    void set_pull_again(bool value) { m_pull_again = value; }
+
+    auto& pull_algorithm() { return m_pull_algorithm; }
+    void set_pull_algorithm(Optional<PullAlgorithm> value) { m_pull_algorithm = move(value); }
+
+    bool pulling() const { return m_pulling; }
+    void set_pulling(bool value) { m_pulling = value; }
+
+    SinglyLinkedList<PullIntoDescriptor>& pending_pull_intos() { return m_pending_pull_intos; }
+
+    SinglyLinkedList<ReadableByteStreamQueueEntry>& queue() { return m_queue; }
+
+    u32 queue_total_size() const { return m_queue_total_size; }
+    void set_queue_total_size(u32 size) { m_queue_total_size = size; }
+
+    bool started() const { return m_started; }
+    void set_started(bool value) { m_started = value; }
+
+    u32 strategy_hwm() const { return m_strategy_hwm; }
+    void set_strategy_hwm(u32 value) { m_strategy_hwm = value; }
+
+    JS::GCPtr<ReadableStream const> stream() const { return m_stream; }
+    JS::GCPtr<ReadableStream> stream() { return m_stream; }
+    void set_stream(JS::GCPtr<ReadableStream> stream) { m_stream = stream; }
+
+private:
+    explicit ReadableByteStreamController(JS::Realm&);
+
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    // https://streams.spec.whatwg.org/#readablebytestreamcontroller-autoallocatechunksize
+    // A positive integer, when the automatic buffer allocation feature is enabled. In that case, this value specifies the size of buffer to allocate. It is undefined otherwise.
+    Optional<u32> m_auto_allocate_chunk_size;
+
+    // https://streams.spec.whatwg.org/#readablebytestreamcontroller-byobrequest
+    // A ReadableStreamBYOBRequest instance representing the current BYOB pull request, or null if there are no pending requests
+    JS::GCPtr<ReadableStreamBYOBRequest> m_byob_request;
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-cancelalgorithm
+    // A promise-returning algorithm, taking one argument (the cancel reason), which communicates a requested cancelation to the underlying source
+    Optional<CancelAlgorithm> m_cancel_algorithm;
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-closerequested
+    // A boolean flag indicating whether the stream has been closed by its underlying source, but still has chunks in its internal queue that have not yet been read
+    bool m_close_requested { false };
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-pullagain
+    // A boolean flag set to true if the stream’s mechanisms requested a call to the underlying source's pull algorithm to pull more data, but the pull could not yet be done since a previous call is still executing
+    bool m_pull_again { false };
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-pullalgorithm
+    // A promise-returning algorithm that pulls data from the underlying source
+    Optional<PullAlgorithm> m_pull_algorithm;
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-pulling
+    // A boolean flag set to true while the underlying source's pull algorithm is executing and the returned promise has not yet fulfilled, used to prevent reentrant calls
+    bool m_pulling { false };
+
+    // https://streams.spec.whatwg.org/#readablebytestreamcontroller-pendingpullintos
+    // A list of pull-into descriptors
+    SinglyLinkedList<PullIntoDescriptor> m_pending_pull_intos;
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-queue
+    // A list representing the stream’s internal queue of chunks
+    SinglyLinkedList<ReadableByteStreamQueueEntry> m_queue;
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-queuetotalsize
+    // The total size of all the chunks stored in [[queue]]
+    u32 m_queue_total_size { 0 };
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-started
+    // A boolean flag indicating whether the underlying source has finished starting
+    bool m_started { false };
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-strategyhwm
+    // A number supplied to the constructor as part of the stream’s queuing strategy, indicating the point at which the stream will apply backpressure to its underlying source
+    u32 m_strategy_hwm { 0 };
+
+    // https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-stream
+    // The ReadableStream instance controlled
+    JS::GCPtr<ReadableStream> m_stream;
+};
+
+}

Userland/Libraries/LibWeb/Streams/ReadableByteStreamController.idl

@@ -0,0 +1,12 @@
+#import <Streams/ReadableStreamBYOBRequest.idl>
+
+[Exposed=*]
+interface ReadableByteStreamController {
+    readonly attribute ReadableStreamBYOBRequest? byobRequest;
+    readonly attribute unrestricted double? desiredSize;
+
+    // FIXME: Implement
+    // undefined close();
+    // undefined enqueue(ArrayBufferView chunk);
+    // undefined error(optional any e);
+};

Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibWeb/Streams/ReadableByteStreamController.h>
 #include <LibWeb/Streams/ReadableStreamBYOBRequest.h>
 
 namespace Web::Streams {

Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBRequest.h

@@ -27,7 +27,7 @@ private:
 
     // https://streams.spec.whatwg.org/#readablestreambyobrequest-controller
     // The parent ReadableByteStreamController instance
-    JS::GCPtr<JS::Object> m_controller;
+    JS::GCPtr<ReadableByteStreamController> m_controller;
 
     // https://streams.spec.whatwg.org/#readablestreambyobrequest-view
     // A typed array representing the destination region to which the controller can write generated data, or null after the BYOB request has been invalidated.

Userland/Libraries/LibWeb/idl_files.cmake

@@ -179,6 +179,7 @@ libweb_js_bindings(NavigationTiming/PerformanceTiming)
 libweb_js_bindings(PerformanceTimeline/PerformanceEntry)
 libweb_js_bindings(RequestIdleCallback/IdleDeadline)
 libweb_js_bindings(ResizeObserver/ResizeObserver)
+libweb_js_bindings(Streams/ReadableByteStreamController)
 libweb_js_bindings(Streams/ReadableStream)
 libweb_js_bindings(Streams/ReadableStreamBYOBRequest)
 libweb_js_bindings(Streams/ReadableStreamDefaultController)