62 lines
1.5 KiB
TypeScript
62 lines
1.5 KiB
TypeScript
import { Readable } from 'node:stream'
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export interface NodeReadableToWebStreamOptions {
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onCancel?: (reason?: unknown) => void | Promise<void>
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}
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/**
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* 将 Node.js Readable 转换为受 Web Stream 消费速度约束的流。
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*
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* 每次 pull 只向下游交付一个分块，避免 data 事件持续读取大文件、
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* 而浏览器或代理来不及接收时在 Node 进程内堆积大量内存。
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*/
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export function nodeReadableToWebStream(
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source: Readable,
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options: NodeReadableToWebStreamOptions = {},
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): ReadableStream<Uint8Array> {
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const iterator = source[Symbol.asyncIterator]()
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let finished = false
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return new ReadableStream<Uint8Array>(
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{
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async pull(controller) {
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if (finished) {
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return
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}
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try {
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const next = await iterator.next()
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if (next.done) {
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finished = true
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controller.close()
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return
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}
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const chunk = next.value
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controller.enqueue(chunk instanceof Uint8Array ? chunk : Buffer.from(chunk))
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} catch (error) {
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finished = true
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if (!source.destroyed) {
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source.destroy()
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}
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controller.error(error)
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}
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},
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async cancel(reason) {
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finished = true
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try {
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await options.onCancel?.(reason)
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} finally {
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if (!source.destroyed) {
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source.destroy()
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}
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}
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},
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},
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{
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highWaterMark: 1,
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size: () => 1,
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},
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)
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}
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