90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 234.
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// Package cake provides a simulation of
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// a concurrent cake shop with numerous parameters.
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//
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// Use this command to run the benchmarks:
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// $ go test -bench=. gopl.io/ch8/cake
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package cake
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import (
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"fmt"
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"math/rand"
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"time"
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)
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type Shop struct {
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Verbose bool
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Cakes int // number of cakes to bake
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BakeTime time.Duration // time to bake one cake
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BakeStdDev time.Duration // standard deviation of baking time
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BakeBuf int // buffer slots between baking and icing
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NumIcers int // number of cooks doing icing
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IceTime time.Duration // time to ice one cake
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IceStdDev time.Duration // standard deviation of icing time
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IceBuf int // buffer slots between icing and inscribing
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InscribeTime time.Duration // time to inscribe one cake
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InscribeStdDev time.Duration // standard deviation of inscribing time
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}
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type cake int
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func (s *Shop) baker(baked chan<- cake) {
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for i := 0; i < s.Cakes; i++ {
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c := cake(i)
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if s.Verbose {
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fmt.Println("baking", c)
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}
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work(s.BakeTime, s.BakeStdDev)
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baked <- c
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}
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close(baked)
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}
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func (s *Shop) icer(iced chan<- cake, baked <-chan cake) {
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for c := range baked {
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if s.Verbose {
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fmt.Println("icing", c)
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}
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work(s.IceTime, s.IceStdDev)
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iced <- c
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}
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}
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func (s *Shop) inscriber(iced <-chan cake) {
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for i := 0; i < s.Cakes; i++ {
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c := <-iced
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if s.Verbose {
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fmt.Println("inscribing", c)
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}
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work(s.InscribeTime, s.InscribeStdDev)
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if s.Verbose {
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fmt.Println("finished", c)
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}
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}
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}
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// Work runs the simulation 'runs' times.
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func (s *Shop) Work(runs int) {
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for run := 0; run < runs; run++ {
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baked := make(chan cake, s.BakeBuf)
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iced := make(chan cake, s.IceBuf)
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go s.baker(baked)
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for i := 0; i < s.NumIcers; i++ {
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go s.icer(iced, baked)
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}
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s.inscriber(iced)
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}
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}
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// work blocks the calling goroutine for a period of time
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// that is normally distributed around d
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// with a standard deviation of stddev.
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func work(d, stddev time.Duration) {
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delay := d + time.Duration(rand.NormFloat64()*float64(stddev))
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time.Sleep(delay)
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}
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