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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2025 metamuffin <metamuffin.org>
*/
/// <reference lib="dom" />
import { OVar } from "../jshelper/mod.ts";
interface Measurement { time: number, duration: number, size: number }
export class SegmentDownloader {
private measurements: Measurement[] = []
public bandwidth_avail = new OVar(Infinity)
public bandwidth_used = new OVar(Infinity)
public total_downloaded = new OVar(0)
constructor() { }
async download(url: string): Promise<ArrayBuffer> {
const dl_start = performance.now();
const res = await fetch(url)
const dl_header = performance.now();
if (!res.ok) throw new Error("aaaaa");
const buf = await res.arrayBuffer()
const dl_body = performance.now();
this.total_downloaded.value += buf.byteLength
if (buf.byteLength > 100 * 1000) {
const m = {
time: dl_start,
duration: (dl_body - dl_header) / 1000,
size: buf.byteLength
}
this.measurements.push(m)
this.update_bandwidth()
}
return buf;
}
update_bandwidth() {
while (this.measurements.length > 32)
this.measurements.splice(0, 1)
const total_elapsed = (performance.now() - this.measurements.reduce((a, v) => Math.min(a, v.time), 0)) / 1000;
const total_size = this.measurements.reduce((a, v) => v.size + a, 0)
const total_duration = this.measurements.reduce((a, v) => v.duration + a, 0)
this.bandwidth_avail.value = total_size / total_duration
this.bandwidth_used.value = total_size / total_elapsed
}
}
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