seq_test.go

Documentation: github.com/google/uuid

     1  // Copyright 2016 Google Inc.  All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package uuid
     6  
     7  import (
     8  	"flag"
     9  	"runtime"
    10  	"testing"
    11  	"time"
    12  )
    13  
    14  // This test is only run when --regressions is passed on the go test line.
    15  var regressions = flag.Bool("regressions", false, "run uuid regression tests")
    16  
    17  // TestClockSeqRace tests for a particular race condition of returning two
    18  // identical Version1 UUIDs.  The duration of 1 minute was chosen as the race
    19  // condition, before being fixed, nearly always occurred in under 30 seconds.
    20  func TestClockSeqRace(t *testing.T) {
    21  	if !*regressions {
    22  		t.Skip("skipping regression tests")
    23  	}
    24  	duration := time.Minute
    25  
    26  	done := make(chan struct{})
    27  	defer close(done)
    28  
    29  	ch := make(chan UUID, 10000)
    30  	ncpu := runtime.NumCPU()
    31  	switch ncpu {
    32  	case 0, 1:
    33  		// We can't run the test effectively.
    34  		t.Skip("skipping race test, only one CPU detected")
    35  		return
    36  	default:
    37  		runtime.GOMAXPROCS(ncpu)
    38  	}
    39  	for i := 0; i < ncpu; i++ {
    40  		go func() {
    41  			for {
    42  				select {
    43  				case <-done:
    44  					return
    45  				case ch <- Must(NewUUID()):
    46  				}
    47  			}
    48  		}()
    49  	}
    50  
    51  	uuids := make(map[string]bool)
    52  	cnt := 0
    53  	start := time.Now()
    54  	for u := range ch {
    55  		s := u.String()
    56  		if uuids[s] {
    57  			t.Errorf("duplicate uuid after %d in %v: %s", cnt, time.Since(start), s)
    58  			return
    59  		}
    60  		uuids[s] = true
    61  		if time.Since(start) > duration {
    62  			return
    63  		}
    64  		cnt++
    65  	}
    66  }
    67
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