70 lines
2.0 KiB
Go
70 lines
2.0 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package lib
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import (
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"math/rand"
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"time"
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)
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const (
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// minRate is the minimum rate at which we allow an action to be performed
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// across the whole cluster. The value is once a day: 1 / (1 * time.Day)
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minRate = 1.0 / 86400
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)
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// DurationMinusBuffer returns a duration, minus a buffer and jitter
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// subtracted from the duration. This function is used primarily for
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// servicing Consul TTL Checks in advance of the TTL.
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func DurationMinusBuffer(intv time.Duration, buffer time.Duration, jitter int64) time.Duration {
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d := intv - buffer
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if jitter == 0 {
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d -= RandomStagger(d)
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} else {
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d -= RandomStagger(time.Duration(int64(d) / jitter))
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}
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return d
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}
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// DurationMinusBufferDomain returns the domain of valid durations from a
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// call to DurationMinusBuffer. This function is used to check user
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// specified input values to DurationMinusBuffer.
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func DurationMinusBufferDomain(intv time.Duration, buffer time.Duration, jitter int64) (min time.Duration, max time.Duration) {
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max = intv - buffer
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if jitter == 0 {
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min = max
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} else {
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min = max - time.Duration(int64(max)/jitter)
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}
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return min, max
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}
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// RandomStagger returns an interval between 0 and the duration
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func RandomStagger(intv time.Duration) time.Duration {
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if intv == 0 {
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return 0
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}
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return time.Duration(uint64(rand.Int63()) % uint64(intv))
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}
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// RandomStaggerWithRange returns an interval between min and the max duration
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func RandomStaggerWithRange(min time.Duration, max time.Duration) time.Duration {
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return RandomStagger(max-min) + min
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}
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// RateScaledInterval is used to choose an interval to perform an action in
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// order to target an aggregate number of actions per second across the whole
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// cluster.
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func RateScaledInterval(rate float64, min time.Duration, n int) time.Duration {
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if rate <= minRate {
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return min
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}
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interval := time.Duration(float64(time.Second) * float64(n) / rate)
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if interval < min {
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return min
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}
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return interval
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}
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