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June 8, 2020 08:52
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How to make lock-free go struct thread-safe
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| package main | |
| import ( | |
| "github.com/AlekSi/pointer" | |
| log "github.com/sirupsen/logrus" | |
| "sync" | |
| "sync/atomic" | |
| "unsafe" | |
| ) | |
| type A struct { | |
| B int64 | |
| C string | |
| D *string | |
| } | |
| var globalA unsafe.Pointer | |
| func main() { | |
| globalA = unsafe.Pointer(&A{ | |
| B: 0, | |
| C: "12", | |
| D: pointer.ToString("12.E"), | |
| }) | |
| var wg sync.WaitGroup | |
| wg.Add(100) | |
| for i := 0; i < 100; i++ { | |
| go worker(i, &wg) | |
| } | |
| wg.Wait() | |
| } | |
| func worker(workerID int, wg *sync.WaitGroup) { | |
| defer wg.Done() | |
| for i := 0; i < 100; i++ { | |
| for j := 0; ; j++ { | |
| original := globalA | |
| copied := copyA((*A)(original)) | |
| log.WithField("workerID", workerID).WithField("iter", i).WithField("retry", j).WithField("A.B", copied.B).Infof("Copying A") | |
| copied.B += 1 | |
| if atomic.CompareAndSwapPointer(&globalA, original, unsafe.Pointer(&copied)) { | |
| log.WithField("workerID", workerID).WithField("iter", i).WithField("retry", j).WithField("A.B", copied.B).Infof("OK") | |
| break | |
| } else { | |
| log.WithField("workerID", workerID).WithField("iter", i).WithField("retry", j).WithField("A.B", copied.B).Infof("Fail, Will retry") | |
| } | |
| } | |
| } | |
| } | |
| func copyA(a *A) A { | |
| return A{ | |
| B: a.B, | |
| C: a.C, | |
| D: pointer.ToString(pointer.GetString(a.D)), | |
| } | |
| } |
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