浅谈Golang原子atomic

package main
import (
  "fmt"
  "sync"
  "sync/atomic"
)
func atomicAdd() {
  var data, data2 int64
  var wg sync.WaitGroup
  for i := 0; i < 1000; i++ {
    wg.Add(1)
    go func() {
      atomic.AddInt64(&data, 1)
      data2++
      wg.Done()
    }()
  }
  wg.Wait()
  fmt.Println("data", data, "data2", data2)
}
// From medium: https://medium.com/a-journey-with-go/go-how-to-reduce-lock-contention-with-the-atomic-package-ba3b2664b549
type Config struct {
  a []int
}
// 用 go run -race main.go atomic.go 观察data races
func dataRaces() {
  cfg := &Config{}
  go func() {
    i := 0
    for {
      i++
      cfg.a = []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}
    }
  }()
  var wg sync.WaitGroup
  for n := 0; n < 4; n++ {
    wg.Add(1)
    go func() {
      for n := 0; n < 100; n++ {
        fmt.Printf("%v\n", cfg)
      }
      wg.Done()
    }()
  }
  wg.Wait()
}
func dataRacesWithLock() {
  var mu sync.RWMutex
  cfg := &Config{}
  go func() {
    i := 0
    for {
      i++
      mu.Lock()
      cfg.a = []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}
      mu.Unlock()
    }
  }()
  var wg sync.WaitGroup
  for n := 0; n < 4; n++ {
    wg.Add(1)
    go func() {
      for n := 0; n < 100; n++ {
        mu.RLock()
        fmt.Printf("%v\n", cfg)
        mu.RUnlock()
      }
      wg.Done()
    }()
  }
  wg.Wait()
}
func dataRacesWithAtomic() {
  var v atomic.Value
  go func() {
    i := 0
    for {
      i++
      cfg := &Config{a: []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}}
      v.Store(cfg)
    }
  }()
  var wg sync.WaitGroup
  for n := 0; n < 4; n++ {
    wg.Add(1)
    go func() {
      for n := 0; n < 100; n++ {
        cfg := v.Load()
        fmt.Printf("%v\n", cfg)
      }
      wg.Done()
    }()
  }
  wg.Wait()
}
// cas相关的代码，建议直接参考源码中的相关实现