fib.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build test_run
     6  
     7  // Compute Fibonacci numbers with two goroutines
     8  // that pass integers back and forth.  No actual
     9  // concurrency, just threads and synchronization
    10  // and foreign code on multiple pthreads.
    11  
    12  package main
    13  
    14  import (
    15  	"runtime"
    16  	"strconv"
    17  
    18  	"cgostdio/stdio"
    19  )
    20  
    21  func fibber(c, out chan int64, i int64) {
    22  	// Keep the fibbers in dedicated operating system
    23  	// threads, so that this program tests coordination
    24  	// between pthreads and not just goroutines.
    25  	runtime.LockOSThread()
    26  
    27  	if i == 0 {
    28  		c <- i
    29  	}
    30  	for {
    31  		j := <-c
    32  		stdio.Stdout.WriteString(strconv.FormatInt(j, 10) + "\n")
    33  		out <- j
    34  		<-out
    35  		i += j
    36  		c <- i
    37  	}
    38  }
    39  
    40  func main() {
    41  	c := make(chan int64)
    42  	out := make(chan int64)
    43  	go fibber(c, out, 0)
    44  	go fibber(c, out, 1)
    45  	<-out
    46  	for i := 0; i < 90; i++ {
    47  		out <- 1
    48  		<-out
    49  	}
    50  }
    51
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