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// Copyright 2016 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package uuid
import (
"flag"
"runtime"
"testing"
"time"
)
// This test is only run when --regressions is passed on the go test line.
var regressions = flag.Bool("regressions", false, "run uuid regression tests")
// TestClockSeqRace tests for a particular race condition of returning two
// identical Version1 UUIDs. The duration of 1 minute was chosen as the race
// condition, before being fixed, nearly always occurred in under 30 seconds.
func TestClockSeqRace(t *testing.T) {
if !*regressions {
t.Skip("skipping regression tests")
}
duration := time.Minute
done := make(chan struct{})
defer close(done)
ch := make(chan UUID, 10000)
ncpu := runtime.NumCPU()
switch ncpu {
case 0, 1:
// We can't run the test effectively.
t.Skip("skipping race test, only one CPU detected")
return
default:
runtime.GOMAXPROCS(ncpu)
}
for i := 0; i < ncpu; i++ {
go func() {
for {
select {
case <-done:
return
case ch <- Must(NewUUID()):
}
}
}()
}
uuids := make(map[string]bool)
cnt := 0
start := time.Now()
for u := range ch {
s := u.String()
if uuids[s] {
t.Errorf("duplicate uuid after %d in %v: %s", cnt, time.Since(start), s)
return
}
uuids[s] = true
if time.Since(start) > duration {
return
}
cnt++
}
}
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