github.com/panjjo/go@v0.0.0-20161104043856-d62b31386338/src/runtime/internal/atomic/atomic_test.go (about)

     1  // Copyright 2015 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  package atomic_test
     6  
     7  import (
     8  	"runtime"
     9  	"runtime/internal/atomic"
    10  	"runtime/internal/sys"
    11  	"testing"
    12  	"unsafe"
    13  )
    14  
    15  func runParallel(N, iter int, f func()) {
    16  	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(int(N)))
    17  	done := make(chan bool)
    18  	for i := 0; i < N; i++ {
    19  		go func() {
    20  			for j := 0; j < iter; j++ {
    21  				f()
    22  			}
    23  			done <- true
    24  		}()
    25  	}
    26  	for i := 0; i < N; i++ {
    27  		<-done
    28  	}
    29  }
    30  
    31  func TestXadduintptr(t *testing.T) {
    32  	const N = 20
    33  	const iter = 100000
    34  	inc := uintptr(100)
    35  	total := uintptr(0)
    36  	runParallel(N, iter, func() {
    37  		atomic.Xadduintptr(&total, inc)
    38  	})
    39  	if want := uintptr(N * iter * inc); want != total {
    40  		t.Fatalf("xadduintpr error, want %d, got %d", want, total)
    41  	}
    42  	total = 0
    43  	runParallel(N, iter, func() {
    44  		atomic.Xadduintptr(&total, inc)
    45  		atomic.Xadduintptr(&total, uintptr(-int64(inc)))
    46  	})
    47  	if total != 0 {
    48  		t.Fatalf("xadduintpr total error, want %d, got %d", 0, total)
    49  	}
    50  }
    51  
    52  // Tests that xadduintptr correctly updates 64-bit values. The place where
    53  // we actually do so is mstats.go, functions mSysStat{Inc,Dec}.
    54  func TestXadduintptrOnUint64(t *testing.T) {
    55  	if sys.BigEndian != 0 {
    56  		// On big endian architectures, we never use xadduintptr to update
    57  		// 64-bit values and hence we skip the test.  (Note that functions
    58  		// mSysStat{Inc,Dec} in mstats.go have explicit checks for
    59  		// big-endianness.)
    60  		t.Skip("skip xadduintptr on big endian architecture")
    61  	}
    62  	const inc = 100
    63  	val := uint64(0)
    64  	atomic.Xadduintptr((*uintptr)(unsafe.Pointer(&val)), inc)
    65  	if inc != val {
    66  		t.Fatalf("xadduintptr should increase lower-order bits, want %d, got %d", inc, val)
    67  	}
    68  }