1import * as _ from 'lodash-es'
2import { assertDefined } from '../sharedF/assertsF/assertDefinedF.mts'
3
4type RlHistRec = {lastRunAtMs: number, backoffNo: number, numSilenced: number, silencedSamples?: unknown[]}
5
6export const getExpBackoffLimited = ({
7  cache_key, rlHistH, backoffBaseMs=60 * 1000,
8  recoveryPeriodMs=1000 * 60 * 60 * 24,
9  backoffCapMs=recoveryPeriodMs,
10  silencedSample, maxSilencedSamples=10,
11}: {cache_key: string, rlHistH: Record<string, RlHistRec>, backoffBaseMs?: number, recoveryPeriodMs?: number, backoffCapMs?: number, silencedSample?: unknown, maxSilencedSamples?: number}) => {
12  assertDefined(rlHistH)
13
14  let rec: RlHistRec | undefined = rlHistH[cache_key]
15
16  const now = _.now()
17
18  let backoffNo = -1
19  let numSilenced = 0
20  let lastRunAtMs = 0
21
22  if (rec) {
23    ;({lastRunAtMs, backoffNo, numSilenced} = rec)
24
25    const minRecovResetMs = now - recoveryPeriodMs
26    if (lastRunAtMs < minRecovResetMs) {
27      delete rlHistH[cache_key]
28      rec = undefined
29    }
30  }
31
32  if (rec) {
33    // cap the exponential at backoffCapMs (default = recoveryPeriodMs, ~daily) so a PERSISTENT error
34    // keeps reminding once/day instead of fading below daily as 2^backoffNo grows unbounded.
35    const backoffWaitMs = Math.min(backoffBaseMs * Math.pow(2, backoffNo), backoffCapMs)
36
37    const mustWaitUntilMs = lastRunAtMs + backoffWaitMs
38    const silencedForMs = mustWaitUntilMs - now
39    const isLimited = silencedForMs > 0
40
41    if (isLimited) {
42      numSilenced += 1
43      rec.numSilenced += 1
44      if (silencedSample !== undefined) {
45        ;(rec.silencedSamples ||= []).push(silencedSample)
46        if (rec.silencedSamples.length > maxSilencedSamples) rec.silencedSamples.length = maxSilencedSamples
47      }
48      return {isLimited, backoffNo, numSilenced}
49    }
50  }
51
52  const prevSilencedSamples = rec?.silencedSamples
53
54  backoffNo += 1
55
56  rlHistH[cache_key] = {
57    numSilenced: 0,
58    lastRunAtMs: now,
59    backoffNo,
60  }
61
62  return {isLimited: false, backoffNo, numSilenced, silencedSamples: prevSilencedSamples}
63}