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-rw-r--r--src/cmd/godoc/throttle.go88
1 files changed, 0 insertions, 88 deletions
diff --git a/src/cmd/godoc/throttle.go b/src/cmd/godoc/throttle.go
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--- a/src/cmd/godoc/throttle.go
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-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package main
-
-import "time"
-
-// A Throttle permits throttling of a goroutine by
-// calling the Throttle method repeatedly.
-//
-type Throttle struct {
- f float64 // f = (1-r)/r for 0 < r < 1
- dt time.Duration // minimum run time slice; >= 0
- tr time.Duration // accumulated time running
- ts time.Duration // accumulated time stopped
- tt time.Time // earliest throttle time (= time Throttle returned + tm)
-}
-
-// NewThrottle creates a new Throttle with a throttle value r and
-// a minimum allocated run time slice of dt:
-//
-// r == 0: "empty" throttle; the goroutine is always sleeping
-// r == 1: full throttle; the goroutine is never sleeping
-//
-// A value of r == 0.6 throttles a goroutine such that it runs
-// approx. 60% of the time, and sleeps approx. 40% of the time.
-// Values of r < 0 or r > 1 are clamped down to values between 0 and 1.
-// Values of dt < 0 are set to 0.
-//
-func NewThrottle(r float64, dt time.Duration) *Throttle {
- var f float64
- switch {
- case r <= 0:
- f = -1 // indicates always sleep
- case r >= 1:
- f = 0 // assume r == 1 (never sleep)
- default:
- // 0 < r < 1
- f = (1 - r) / r
- }
- if dt < 0 {
- dt = 0
- }
- return &Throttle{f: f, dt: dt, tt: time.Now().Add(dt)}
-}
-
-// Throttle calls time.Sleep such that over time the ratio tr/ts between
-// accumulated run (tr) and sleep times (ts) approximates the value 1/(1-r)
-// where r is the throttle value. Throttle returns immediately (w/o sleeping)
-// if less than tm ns have passed since the last call to Throttle.
-//
-func (p *Throttle) Throttle() {
- if p.f < 0 {
- select {} // always sleep
- }
-
- t0 := time.Now()
- if t0.Before(p.tt) {
- return // keep running (minimum time slice not exhausted yet)
- }
-
- // accumulate running time
- p.tr += t0.Sub(p.tt) + p.dt
-
- // compute sleep time
- // Over time we want:
- //
- // tr/ts = r/(1-r)
- //
- // Thus:
- //
- // ts = tr*f with f = (1-r)/r
- //
- // After some incremental run time δr added to the total run time
- // tr, the incremental sleep-time δs to get to the same ratio again
- // after waking up from time.Sleep is:
- if δs := time.Duration(float64(p.tr)*p.f) - p.ts; δs > 0 {
- time.Sleep(δs)
- }
-
- // accumulate (actual) sleep time
- t1 := time.Now()
- p.ts += t1.Sub(t0)
-
- // set earliest next throttle time
- p.tt = t1.Add(p.dt)
-}