66 lines
2.1 KiB
TypeScript
66 lines
2.1 KiB
TypeScript
import { findClosestSnapshot, getLatestSnapshot, hasAtLeast2Snapshots } from "db/snapshotSchedule.ts";
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import { truncate } from "utils/truncate.ts";
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import { closetMilestone } from "./exec/snapshotTick.ts";
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import { HOUR, MINUTE } from "@core/const/time.ts";
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import type { Psql } from "@core/db/psql.d.ts";
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const log = (value: number, base: number = 10) => Math.log(value) / Math.log(base);
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const getFactor = (x: number) => {
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const a = 1.054;
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const b = 4.5;
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const c = 100;
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const u = 0.601;
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const g = 455;
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if (x>g) {
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return log(b/log(x+1),a);
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}
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else {
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return log(b/log(x+c),a)+u;
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}
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}
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/*
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* Returns the minimum ETA in hours for the next snapshot
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* @param client - Postgres client
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* @param aid - aid of the video
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* @returns ETA in hours
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*/
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export const getAdjustedShortTermETA = async (sql: Psql, aid: number) => {
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const latestSnapshot = await getLatestSnapshot(sql, aid);
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// Immediately dispatch a snapshot if there is no snapshot yet
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if (!latestSnapshot) return 0;
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const snapshotsEnough = await hasAtLeast2Snapshots(sql, aid);
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if (!snapshotsEnough) return 0;
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const currentTimestamp = new Date().getTime();
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const timeIntervals = [3 * MINUTE, 20 * MINUTE, HOUR, 3 * HOUR, 6 * HOUR, 72 * HOUR];
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const DELTA = 0.00001;
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let minETAHours = Infinity;
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for (const timeInterval of timeIntervals) {
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const date = new Date(currentTimestamp - timeInterval);
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const snapshot = await findClosestSnapshot(sql, aid, date);
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if (!snapshot) continue;
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const hoursDiff = (latestSnapshot.created_at - snapshot.created_at) / HOUR;
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const viewsDiff = latestSnapshot.views - snapshot.views;
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if (viewsDiff <= 0) continue;
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const speed = viewsDiff / (hoursDiff + DELTA);
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const target = closetMilestone(latestSnapshot.views);
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const viewsToIncrease = target - latestSnapshot.views;
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const eta = viewsToIncrease / (speed + DELTA);
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let factor = getFactor(viewsToIncrease);
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factor = truncate(factor, 4.5, 100);
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const adjustedETA = eta / factor;
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if (adjustedETA < minETAHours) {
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minETAHours = adjustedETA;
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}
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}
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if (isNaN(minETAHours)) {
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minETAHours = Infinity;
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}
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return minETAHours;
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};
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