Golang差劲的查找prime算法

pips/pip_prime.go

package pips
type PrimePip struct {
}
func NewPrimePip() *PrimePip {
 primePip := &PrimePip{}
 return primePip
}
func (primePip *PrimePip) RepeatFn(
 done <-chan interface{},
 fn func() interface{},
) <-chan interface{} {
 valueStream := make(chan interface{})
 go func() {
 defer close(valueStream)
 for {
 select {
 case <-done:
 return
 case valueStream <- fn():
 }
 }
 }()
 return valueStream
}
func (primePip *PrimePip) Take(
 done <-chan interface{},
 valueStream <-chan interface{},
 num int,
) <-chan interface{} {
 takeStream := make(chan interface{})
 go func() {
 defer close(takeStream)
 for i := 0; i < num; i++ {
 select {
 case <-done:
 return
 case takeStream <- <-valueStream:
 }
 }
 }()
 return takeStream
}
func (primePip *PrimePip) ToInt(
 done <-chan interface{},
 valueStream <-chan interface{},
) <-chan int {
 intStream := make(chan int)
 go func() {
 defer close(intStream)
 for v := range valueStream {
 select {
 case <-done:
 return
 case intStream <- v.(int):
 }
 }
 }()
 return intStream
}
func (primePip *PrimePip) PrimeFinder(
 done <-chan interface{},
 intStream <-chan int,
) <-chan interface{} {
 primeStream := make(chan interface{})
 go func() {
 defer close(primeStream)
 for integer := range intStream {
 integer -= 1
 prime := true
 for divisor := integer - 1; divisor > 1; divisor-- {
 if integer%divisor == 0 {
 prime = false
 break
 }
 }
 if prime {
 select {
 case <-done:
 return
 case primeStream <- integer:
 }
 }
 }
 }()
 return primeStream
}

fanin1.go

package main
import (
 "fanin1/pips"
 "fmt"
 "math/rand"
 "time"
)
func main() {
 rand := func() interface{} {
 return rand.Intn(50000000)
 }
 done := make(chan interface{})
 defer close(done)
 primeP := pips.NewPrimePip()
 intStream := primeP.ToInt(done, primeP.RepeatFn(done, rand))
 start := time.Now()
 for prime := range primeP.Take(done, primeP.PrimeFinder(done, intStream), 10) {
 fmt.Printf("\t%v\n", prime)
 }
 fmt.Printf("Time consomed: %v \n", time.Since(start))
}

程序输出如下,可见使用pipline的效率极低,查找10个 5000万内的素数,花了18s。

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