Context / Writing cancellable functions / Essential Go
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package main
import (
"context"
"fmt"
"time"
)
func longMathOp(ctx context.Context, n int) (int, error) {
res := n
for i := 0; i < 100; i++ {
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
res += i
// simulate long operation by sleeping
time.Sleep(time.Millisecond)
}
}
return res, nil
}
func main() {
ctx, _ := context.WithTimeout(context.Background(), time.Millisecond*200)
res, err := longMathOp(ctx, 5)
fmt.Printf("Called longMathOp() with 200ms timeout. res; %d, err: %v\n", res, err)
ctx, _ = context.WithTimeout(context.Background(), time.Millisecond*10)
res, err = longMathOp(ctx, 5)
fmt.Printf("Called longMathOp() with 10ms timeout. res: %d, err: %v\n", res, err)
}
Go
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