add context example

master
Jeffrey Paul 4 years ago
parent 28e607a8e8
commit b79a9b98f3
  1. 45
      go/context.go

@ -0,0 +1,45 @@
package main
// from
// https://www.ardanlabs.com/blog/2019/09/context-package-semantics-in-go.html
import (
"context"
"fmt"
"math/rand"
"time"
)
func main() {
// Set a duration.
duration := 150 * time.Millisecond
// Create a context that is both manually cancellable and will signal
// cancel at the specified duration.
ctx, cancel := context.WithTimeout(context.Background(), duration)
defer cancel()
// Create a channel to receive a signal that work is done.
ch := make(chan string, 1)
// Ask the goroutine to do some work for us.
go func() {
// Simulate work.
rand.Seed(time.Now().UnixNano())
ms := rand.Intn(300)
time.Sleep(time.Duration(ms) * time.Millisecond)
// Report the work is done.
ch <- "123"
}()
// Wait for the work to finish. If it takes too long, move on.
select {
case d := <-ch:
fmt.Println("work complete", d)
case <-ctx.Done():
fmt.Println("work cancelled")
}
}
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