go-concurrency101/basics/mutex/main.go

40 lines
759 B
Go

package main
import (
"fmt"
"sync"
"time"
)
// SafeCounter is safe to use concurrently.
type SafeCounter struct {
mu sync.Mutex
v map[string]int
}
// Inc increments the counter for the given key.
func (c *SafeCounter) Inc(key string) {
c.mu.Lock()
// Lock so only one goroutine at a time can access the map c.v.
c.v[key]++
c.mu.Unlock()
}
// Value returns the current value of the counter for the given key.
func (c *SafeCounter) Value(key string) int {
c.mu.Lock()
// Lock so only one goroutine at a time can access the map c.v.
defer c.mu.Unlock()
return c.v[key]
}
func main() {
c := SafeCounter{v: make(map[string]int)}
for i := 0; i < 1000; i++ {
go c.Inc("somekey")
}
time.Sleep(time.Second)
fmt.Println(c.Value("somekey"))
}