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 ignore
     6  // +build ignore
     7  
     8  // Compute Fibonacci numbers with two goroutines
     9  // that pass integers back and forth.  No actual
    10  // concurrency, just threads and synchronization
    11  // and foreign code on multiple pthreads.
    12  
    13  package main
    14  
    15  import (
    16  	big "."
    17  	"runtime"
    18  )
    19  
    20  func fibber(c chan *big.Int, out chan string, n int64) {
    21  	// Keep the fibbers in dedicated operating system
    22  	// threads, so that this program tests coordination
    23  	// between pthreads and not just goroutines.
    24  	runtime.LockOSThread()
    25  
    26  	i := big.NewInt(n)
    27  	if n == 0 {
    28  		c <- i
    29  	}
    30  	for {
    31  		j := <-c
    32  		out <- j.String()
    33  		i.Add(i, j)
    34  		c <- i
    35  	}
    36  }
    37  
    38  func main() {
    39  	c := make(chan *big.Int)
    40  	out := make(chan string)
    41  	go fibber(c, out, 0)
    42  	go fibber(c, out, 1)
    43  	for i := 0; i < 200; i++ {
    44  		println(<-out)
    45  	}
    46  }
    47
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