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// build
// Copyright 2009 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.
// Test basic concurrency: the classic prime sieve.
// Do not run - loops forever.
package main
// Send the sequence 2, 3, 4, ... to channel 'ch'.
func Generate(ch chan<- int) {
for i := 2; ; i++ {
ch <- i // Send 'i' to channel 'ch'.
}
}
// Copy the values from channel 'in' to channel 'out',
// removing those divisible by 'prime'.
func Filter(in <-chan int, out chan<- int, prime int) {
for {
i := <-in // Receive value of new variable 'i' from 'in'.
if i%prime != 0 {
out <- i // Send 'i' to channel 'out'.
}
}
}
// The prime sieve: Daisy-chain Filter processes together.
func Sieve() {
ch := make(chan int) // Create a new channel.
go Generate(ch) // Start Generate() as a subprocess.
for {
prime := <-ch
print(prime, "\n")
ch1 := make(chan int)
go Filter(ch, ch1, prime)
ch = ch1
}
}
func main() {
Sieve()
}
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