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68 lines
1.6 KiB
68 lines
1.6 KiB
2 years ago
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const events = require('events');
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// =============================================================================
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// StutteredPipe - Used to slow down streaming so GC can get a look in
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class StutteredPipe extends events.EventEmitter {
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constructor(readable, writable, options) {
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super();
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options = options || {};
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this.readable = readable;
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this.writable = writable;
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this.bufSize = options.bufSize || 16384;
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this.autoPause = options.autoPause || false;
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this.paused = false;
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this.eod = false;
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this.scheduled = null;
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readable.on('end', () => {
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this.eod = true;
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writable.end();
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});
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// need to have some way to communicate speed of stream
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// back from the consumer
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readable.on('readable', () => {
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if (!this.paused) {
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this.resume();
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}
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});
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this._schedule();
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}
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pause() {
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this.paused = true;
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}
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resume() {
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if (!this.eod) {
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if (this.scheduled !== null) {
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clearImmediate(this.scheduled);
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}
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this._schedule();
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}
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}
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_schedule() {
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this.scheduled = setImmediate(() => {
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this.scheduled = null;
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if (!this.eod && !this.paused) {
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const data = this.readable.read(this.bufSize);
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if (data && data.length) {
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this.writable.write(data);
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if (!this.paused && !this.autoPause) {
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this._schedule();
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}
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} else if (!this.paused) {
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this._schedule();
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}
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}
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});
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}
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}
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module.exports = StutteredPipe;
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