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46 lines
1.0 KiB
46 lines
1.0 KiB
// build
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test basic concurrency: the classic prime sieve.
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// Do not run - loops forever.
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package main
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// Send the sequence 2, 3, 4, ... to channel 'ch'.
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func Generate(ch chan<- int) {
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for i := 2; ; i++ {
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ch <- i // Send 'i' to channel 'ch'.
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}
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}
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// Copy the values from channel 'in' to channel 'out',
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// removing those divisible by 'prime'.
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func Filter(in <-chan int, out chan<- int, prime int) {
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for {
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i := <-in // Receive value of new variable 'i' from 'in'.
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if i%prime != 0 {
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out <- i // Send 'i' to channel 'out'.
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}
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}
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}
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// The prime sieve: Daisy-chain Filter processes together.
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func Sieve() {
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ch := make(chan int) // Create a new channel.
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go Generate(ch) // Start Generate() as a subprocess.
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for {
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prime := <-ch
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print(prime, "\n")
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ch1 := make(chan int)
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go Filter(ch, ch1, prime)
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ch = ch1
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}
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}
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func main() {
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Sieve()
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}
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