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lens/src/renderer/utils/readableStream.ts
Sebastian Malton 972d2f9a01
Use type-fest's TypedArray for ReadableWebToNodeStream (#2899)
Signed-off-by: Sebastian Malton <sebastian@malton.name>
2021-05-28 09:38:59 -04:00

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TypeScript
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/**
* Copyright (c) 2021 OpenLens Authors
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
import { Readable } from "readable-stream";
import type { TypedArray } from "type-fest";
/**
* ReadableWebToNodeStream
*
* Copied from https://github.com/Borewit/readable-web-to-node-stream
*
* Adds read error handler
*
* */
export class ReadableWebToNodeStream<T extends TypedArray> extends Readable {
public bytesRead = 0;
public released = false;
/**
* Default web API stream reader
* https://developer.mozilla.org/en-US/docs/Web/API/ReadableStreamDefaultReader
*/
private reader: ReadableStreamReader<T>;
private pendingRead: Promise<ReadableStreamDefaultReadResult<T>>;
/**
*
* @param stream ReadableStream: https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream
*/
constructor(stream: ReadableStream<T>) {
super();
this.reader = stream.getReader();
}
/**
* Implementation of readable._read(size).
* When readable._read() is called, if data is available from the resource,
* the implementation should begin pushing that data into the read queue
* https://nodejs.org/api/stream.html#stream_readable_read_size_1
*/
public async _read() {
// Should start pushing data into the queue
// Read data from the underlying Web-API-readable-stream
if (this.released) {
this.push(null); // Signal EOF
return;
}
try {
this.pendingRead = this.reader.read();
const data = await this.pendingRead;
// clear the promise before pushing pushing new data to the queue and allow sequential calls to _read()
delete this.pendingRead;
if (data.done || this.released) {
this.push(null); // Signal EOF
} else {
this.bytesRead += data.value.length;
this.push(data.value); // Push new data to the queue
}
} catch (error) {
this.push(null); // Signal EOF
}
}
/**
* If there is no unresolved read call to Web-API ReadableStream immediately returns;
* otherwise will wait until the read is resolved.
*/
public async waitForReadToComplete() {
if (this.pendingRead) {
await this.pendingRead;
}
}
/**
* Close wrapper
*/
public async close(): Promise<void> {
await this.syncAndRelease();
}
private async syncAndRelease() {
this.released = true;
await this.waitForReadToComplete();
await this.reader.releaseLock();
}
}