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// Copyright 2011, 2012, 2013 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package utils_test
import (
"time"
gc "gopkg.in/check.v1"
"github.com/juju/utils/v2"
)
func doSomething() (int, error) { return 0, nil }
func shouldRetry(error) bool { return false }
func doSomethingWith(int) {}
func ExampleAttempt_HasNext() {
// This example shows how Attempt.HasNext can be used to help
// structure an attempt loop. If the godoc example code allowed
// us to make the example return an error, we would uncomment
// the commented return statements.
attempts := utils.AttemptStrategy{
Total: 1 * time.Second,
Delay: 250 * time.Millisecond,
}
for attempt := attempts.Start(); attempt.Next(); {
x, err := doSomething()
if shouldRetry(err) && attempt.HasNext() {
continue
}
if err != nil {
// return err
return
}
doSomethingWith(x)
}
// return ErrTimedOut
return
}
func (*utilsSuite) TestAttemptTiming(c *gc.C) {
testAttempt := utils.AttemptStrategy{
Total: 0.25e9,
Delay: 0.1e9,
}
want := []time.Duration{0, 0.1e9, 0.2e9, 0.2e9}
got := make([]time.Duration, 0, len(want)) // avoid allocation when testing timing
t0 := time.Now()
for a := testAttempt.Start(); a.Next(); {
got = append(got, time.Now().Sub(t0))
}
got = append(got, time.Now().Sub(t0))
c.Assert(got, gc.HasLen, len(want))
const margin = 0.01e9
for i, got := range want {
lo := want[i] - margin
hi := want[i] + margin
if got < lo || got > hi {
c.Errorf("attempt %d want %g got %g", i, want[i].Seconds(), got.Seconds())
}
}
}
func (*utilsSuite) TestAttemptNextHasNext(c *gc.C) {
a := utils.AttemptStrategy{}.Start()
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.Next(), gc.Equals, false)
a = utils.AttemptStrategy{}.Start()
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.HasNext(), gc.Equals, false)
c.Assert(a.Next(), gc.Equals, false)
a = utils.AttemptStrategy{Total: 2e8}.Start()
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.HasNext(), gc.Equals, true)
time.Sleep(2e8)
c.Assert(a.HasNext(), gc.Equals, true)
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.Next(), gc.Equals, false)
a = utils.AttemptStrategy{Total: 1e8, Min: 2}.Start()
time.Sleep(1e8)
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.HasNext(), gc.Equals, true)
c.Assert(a.Next(), gc.Equals, true)
c.Assert(a.HasNext(), gc.Equals, false)
c.Assert(a.Next(), gc.Equals, false)
}
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