select.go

     1  // run
     2  
     3  // Copyright 2009 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // Test simple select.
     8  
     9  package main
    10  
    11  var counter uint
    12  var shift uint
    13  
    14  func GetValue() uint {
    15  	counter++
    16  	return 1 << shift
    17  }
    18  
    19  func Send(a, b chan uint) int {
    20  	var i int
    21  
    22  LOOP:
    23  	for {
    24  		select {
    25  		case a <- GetValue():
    26  			i++
    27  			a = nil
    28  		case b <- GetValue():
    29  			i++
    30  			b = nil
    31  		default:
    32  			break LOOP
    33  		}
    34  		shift++
    35  	}
    36  	return i
    37  }
    38  
    39  func main() {
    40  	a := make(chan uint, 1)
    41  	b := make(chan uint, 1)
    42  	if v := Send(a, b); v != 2 {
    43  		println("Send returned", v, "!= 2")
    44  		panic("fail")
    45  	}
    46  	if av, bv := <-a, <-b; av|bv != 3 {
    47  		println("bad values", av, bv)
    48  		panic("fail")
    49  	}
    50  	if v := Send(a, nil); v != 1 {
    51  		println("Send returned", v, "!= 1")
    52  		panic("fail")
    53  	}
    54  	if counter != 10 {
    55  		println("counter is", counter, "!= 10")
    56  		panic("fail")
    57  	}
    58  }
    59
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