44 lines
1.1 KiB
JavaScript
44 lines
1.1 KiB
JavaScript
/**
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* Token-bucket speed limiter for bandwidth throttling.
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* maxBytesPerSec = 0 means unlimited (passthrough).
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*/
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class Throttle {
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constructor(maxBytesPerSec) {
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this.maxBps = maxBytesPerSec || 0;
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this.tokens = this.maxBps;
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this.lastRefill = Date.now();
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}
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async consume(bytes, signal) {
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if (this.maxBps <= 0) return; // unlimited
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while (bytes > 0) {
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if (signal && signal.aborted) return;
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this._refill();
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const available = Math.min(bytes, Math.floor(this.tokens));
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if (available > 0) {
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this.tokens -= available;
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bytes -= available;
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}
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if (bytes > 0) {
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if (signal && signal.aborted) return;
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// Wait 50ms for tokens to refill
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await new Promise((r) => setTimeout(r, 50));
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}
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}
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}
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_refill() {
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const now = Date.now();
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const elapsed = (now - this.lastRefill) / 1000;
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this.tokens = Math.min(this.maxBps, this.tokens + elapsed * this.maxBps);
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this.lastRefill = now;
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}
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updateRate(maxBytesPerSec) {
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this.maxBps = maxBytesPerSec || 0;
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}
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}
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module.exports = Throttle;
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