libgo/misc/cgo/gmp/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 }