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Code with bugs
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| package main | |
| import ( | |
| "fmt" | |
| "sync" | |
| "sync/atomic" | |
| "time" | |
| "unsafe" | |
| ) | |
| func main() { | |
| now := time.Now() | |
| l := new(lockFreeList) | |
| l.Add(&node{Value: 999999}) | |
| l.Add(&node{Value: 333333}) | |
| l.Add(&node{Value: 555555}) | |
| var wg sync.WaitGroup | |
| for i := 0; i < 10; i++ { | |
| wg.Add(1) | |
| go func(m int) { | |
| for j := m; j < 10000; j += 10 { | |
| l.Add(&node{Value: j}) | |
| //l.AddWithLock(&node{Value: j}) | |
| //l.LockFreeAdd(&node{Value: j}) | |
| } | |
| fmt.Println("Worker", m, "finished") | |
| wg.Done() | |
| }(i) | |
| } | |
| wg.Wait() | |
| fmt.Println(time.Now().Sub(now)) | |
| result := make(map[int]struct{}) | |
| hd := l.Head | |
| for hd != nil { | |
| n := ((*node)(hd)) | |
| if _, ok := result[n.Value]; ok { | |
| fmt.Println(n.Value, "repeated") | |
| time.Sleep(time.Millisecond * 300) | |
| } else { | |
| result[n.Value] = struct{}{} | |
| } | |
| hd = n.Next | |
| } | |
| fmt.Println("----", len(result)) | |
| for i := 0; i < 10; i++ { | |
| if _, ok := result[i]; !ok { | |
| fmt.Println(i, "missing") | |
| } | |
| } | |
| } | |
| type ( | |
| node struct { | |
| Value int | |
| Next unsafe.Pointer | |
| } | |
| lockFreeList struct { | |
| Head unsafe.Pointer | |
| Tail unsafe.Pointer | |
| sync.RWMutex | |
| } | |
| ) | |
| func (l *lockFreeList) addHead(n *node) bool { | |
| elem := unsafe.Pointer(n) | |
| ok := atomic.CompareAndSwapPointer(&l.Head, nil, elem) | |
| if !ok { | |
| return false | |
| } | |
| return atomic.CompareAndSwapPointer(&l.Tail, nil, elem) | |
| } | |
| func (l *lockFreeList) Add(n *node) { | |
| for { | |
| if l.Head == nil { | |
| ok := l.addHead(n) | |
| if ok { | |
| break | |
| } | |
| continue | |
| } | |
| //next := ((*node)(l.Tail)).Next | |
| elem := unsafe.Pointer(n) | |
| if !atomic.CompareAndSwapPointer(&((*node)(l.Tail)).Next, nil, elem) { | |
| continue | |
| } | |
| tail := l.Tail | |
| if !atomic.CompareAndSwapPointer(&l.Tail, tail, elem) { | |
| continue | |
| } | |
| break | |
| } | |
| } |
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