d9c333199e
This uses the same mechanism as [large strings](https://github.com/facebook/react/pull/26932) to encode chunks of length based binary data in the RSC payload behind a flag. I introduce a new BinaryChunk type that's specific to each stream and ways to convert into it. That's because we sometimes need all chunks to be Uint8Array for the output, even if the source is another array buffer view, and sometimes we need to clone it before transferring. Each type of typed array is its own row tag. This lets us ensure that the instance is directly in the right format in the cached entry instead of creating a wrapper at each reference. Ideally this is also how Map/Set should work but those are lazy which complicates that approach a bit. We assume both server and client use little-endian for now. If we want to support other modes, we'd convert it to/from little-endian so that the transfer protocol is always little-endian. That way the common clients can be the fastest possible. So far this only implements Server to Client. Still need to implement Client to Server for parity. NOTE: This is the first time we make RSC effectively a binary format. This is not compatible with existing SSR techniques which serialize the stream as unicode in the HTML. To be compatible, those implementations would have to use base64 or something like that. Which is what we'll do when we move this technique to be built-in to Fizz.
99 lines
2.8 KiB
JavaScript
99 lines
2.8 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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*/
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type BunReadableStreamController = ReadableStreamController & {
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end(): mixed,
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write(data: Chunk | BinaryChunk): void,
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error(error: Error): void,
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};
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export type Destination = BunReadableStreamController;
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export type PrecomputedChunk = string;
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export opaque type Chunk = string;
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export type BinaryChunk = $ArrayBufferView;
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export function scheduleWork(callback: () => void) {
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callback();
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}
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export function flushBuffered(destination: Destination) {
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// WHATWG Streams do not yet have a way to flush the underlying
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// transform streams. https://github.com/whatwg/streams/issues/960
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}
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export function beginWriting(destination: Destination) {}
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export function writeChunk(
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destination: Destination,
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chunk: PrecomputedChunk | Chunk | BinaryChunk,
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): void {
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if (chunk.length === 0) {
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return;
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}
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destination.write(chunk);
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}
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export function writeChunkAndReturn(
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destination: Destination,
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chunk: PrecomputedChunk | Chunk | BinaryChunk,
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): boolean {
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return !!destination.write(chunk);
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}
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export function completeWriting(destination: Destination) {}
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export function close(destination: Destination) {
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destination.end();
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}
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export function stringToChunk(content: string): Chunk {
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return content;
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}
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export function stringToPrecomputedChunk(content: string): PrecomputedChunk {
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return content;
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}
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export function typedArrayToBinaryChunk(
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content: $ArrayBufferView,
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): BinaryChunk {
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// TODO: Does this needs to be cloned if it's transferred in enqueue()?
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return content;
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}
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export function clonePrecomputedChunk(
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chunk: PrecomputedChunk,
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): PrecomputedChunk {
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return chunk;
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}
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export function byteLengthOfChunk(chunk: Chunk | PrecomputedChunk): number {
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return Buffer.byteLength(chunk, 'utf8');
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}
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export function byteLengthOfBinaryChunk(chunk: BinaryChunk): number {
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return chunk.byteLength;
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}
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export function closeWithError(destination: Destination, error: mixed): void {
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if (typeof destination.error === 'function') {
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// $FlowFixMe[incompatible-call]: This is an Error object or the destination accepts other types.
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destination.error(error);
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} else {
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// Earlier implementations doesn't support this method. In that environment you're
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// supposed to throw from a promise returned but we don't return a promise in our
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// approach. We could fork this implementation but this is environment is an edge
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// case to begin with. It's even less common to run this in an older environment.
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// Even then, this is not where errors are supposed to happen and they get reported
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// to a global callback in addition to this anyway. So it's fine just to close this.
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destination.close();
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}
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}
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