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