github.com/alexyer/taggedptr@v0.0.0-20160103160510-29e0338f9028/taggedptr_test.go (about)

     1  package taggedptr
     2  
     3  import (
     4  	"testing"
     5  	"unsafe"
     6  )
     7  
     8  type TestStruct struct {
     9  	Field int
    10  }
    11  
    12  func TestTag(t *testing.T) {
    13  	s := &TestStruct{42}
    14  
    15  	initialPtr := unsafe.Pointer(s)
    16  	newPtr, _ := Tag(unsafe.Pointer(s), 3)
    17  	s = (*TestStruct)(newPtr)
    18  
    19  	if unsafe.Pointer(s) != unsafe.Pointer(uintptr(initialPtr)|3) {
    20  		t.Fatal("wrong tag")
    21  	}
    22  
    23  	if _, err := Tag(unsafe.Pointer(s), 10); err == nil {
    24  		t.Fatal("expected error")
    25  	}
    26  }
    27  
    28  func TestGetPointer(t *testing.T) {
    29  	s := &TestStruct{42}
    30  	initialPtr := unsafe.Pointer(s)
    31  	newPtr, _ := Tag(unsafe.Pointer(s), 3)
    32  	s = (*TestStruct)(newPtr)
    33  
    34  	if ptr := GetPointer(unsafe.Pointer(s)); ptr != initialPtr {
    35  		t.Fatalf("got wrong pointer. expected: %p, got: %p", initialPtr, ptr)
    36  	}
    37  }
    38  
    39  func TestGetTag(t *testing.T) {
    40  	s := &TestStruct{42}
    41  	newPtr, _ := Tag(unsafe.Pointer(s), 3)
    42  	s = (*TestStruct)(newPtr)
    43  
    44  	if tag := GetTag(unsafe.Pointer(s)); tag != 3 {
    45  		t.Fatalf("got wrong pointer. expected: %d, got: %d", 3, tag)
    46  	}
    47  }
    48  
    49  func TestCompareAndSwap(t *testing.T) {
    50  	s := &TestStruct{42}
    51  	casPtr := unsafe.Pointer(s)
    52  	initialPtr := unsafe.Pointer(s)
    53  
    54  	if _ = CompareAndSwap(&casPtr, casPtr, casPtr, 0, 1); casPtr != unsafe.Pointer(uintptr(initialPtr)|1) {
    55  		t.Fatal("wrong cas")
    56  	}
    57  }
    58  
    59  func TestGet(t *testing.T) {
    60  	s := &TestStruct{42}
    61  	initialPtr := unsafe.Pointer(s)
    62  	newPtr, _ := Tag(unsafe.Pointer(s), 3)
    63  	s = (*TestStruct)(newPtr)
    64  
    65  	if ptr, tag := Get(unsafe.Pointer(s)); ptr != initialPtr || tag != 3 {
    66  		t.Fatalf("wrong get. expected: %p %d, got: %p %d", initialPtr, 3, ptr, tag)
    67  	}
    68  }
    69  
    70  func TestAttempTag(t *testing.T) {
    71  	s := &TestStruct{42}
    72  	casPtr := unsafe.Pointer(s)
    73  	initialPtr := unsafe.Pointer(s)
    74  
    75  	if _ = AttemptTag(&casPtr, casPtr, 1); casPtr != unsafe.Pointer(uintptr(initialPtr)|1) {
    76  		t.Fatal("wrong tag attempt")
    77  	}
    78  }