github.com/aloncn/graphics-go@v0.0.1/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  	"testing"
    11  	"unsafe"
    12  )
    13  
    14  func runParallel(N, iter int, f func()) {
    15  	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(int(N)))
    16  	done := make(chan bool)
    17  	for i := 0; i < N; i++ {
    18  		go func() {
    19  			for j := 0; j < iter; j++ {
    20  				f()
    21  			}
    22  			done <- true
    23  		}()
    24  	}
    25  	for i := 0; i < N; i++ {
    26  		<-done
    27  	}
    28  }
    29  
    30  func TestXadduintptr(t *testing.T) {
    31  	const N = 20
    32  	const iter = 100000
    33  	inc := uintptr(100)
    34  	total := uintptr(0)
    35  	runParallel(N, iter, func() {
    36  		atomic.Xadduintptr(&total, inc)
    37  	})
    38  	if want := uintptr(N * iter * inc); want != total {
    39  		t.Fatalf("xadduintpr error, want %d, got %d", want, total)
    40  	}
    41  	total = 0
    42  	runParallel(N, iter, func() {
    43  		atomic.Xadduintptr(&total, inc)
    44  		atomic.Xadduintptr(&total, uintptr(-int64(inc)))
    45  	})
    46  	if total != 0 {
    47  		t.Fatalf("xadduintpr total error, want %d, got %d", 0, total)
    48  	}
    49  }
    50  
    51  // Tests that xadduintptr correctly updates 64-bit values.  The place where
    52  // we actually do so is mstats.go, functions mSysStat{Inc,Dec}.
    53  func TestXadduintptrOnUint64(t *testing.T) {
    54  	/*	if runtime.BigEndian != 0 {
    55  		// On big endian architectures, we never use xadduintptr to update
    56  		// 64-bit values and hence we skip the test.  (Note that functions
    57  		// mSysStat{Inc,Dec} in mstats.go have explicit checks for
    58  		// big-endianness.)
    59  		return
    60  	}*/
    61  	const inc = 100
    62  	val := uint64(0)
    63  	atomic.Xadduintptr((*uintptr)(unsafe.Pointer(&val)), inc)
    64  	if inc != val {
    65  		t.Fatalf("xadduintptr should increase lower-order bits, want %d, got %d", inc, val)
    66  	}
    67  }