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Source file src/runtime/futex_test.go

Documentation: runtime

     1  // Copyright 2013 The Go Authors. 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  // Futex is only available on DragonFly BSD, FreeBSD and Linux.
     6  // The race detector emits calls to split stack functions so it breaks
     7  // the test.
     8  
     9  // +build dragonfly freebsd linux
    10  // +build !race
    11  
    12  package runtime_test
    13  
    14  import (
    15  	"runtime"
    16  	"sync"
    17  	"sync/atomic"
    18  	"testing"
    19  	"time"
    20  )
    21  
    22  type futexsleepTest struct {
    23  	mtx uint32
    24  	ns  int64
    25  	msg string
    26  	ch  chan *futexsleepTest
    27  }
    28  
    29  var futexsleepTests = []futexsleepTest{
    30  	beforeY2038: {mtx: 0, ns: 86400 * 1e9, msg: "before the year 2038"},
    31  	afterY2038:  {mtx: 0, ns: (1<<31 + 100) * 1e9, msg: "after the year 2038"},
    32  }
    33  
    34  const (
    35  	beforeY2038 = iota
    36  	afterY2038
    37  )
    38  
    39  func TestFutexsleep(t *testing.T) {
    40  	if runtime.GOMAXPROCS(0) > 1 {
    41  		// futexsleep doesn't handle EINTR or other signals,
    42  		// so spurious wakeups may happen.
    43  		t.Skip("skipping; GOMAXPROCS>1")
    44  	}
    45  
    46  	start := time.Now()
    47  	var wg sync.WaitGroup
    48  	for i := range futexsleepTests {
    49  		tt := &futexsleepTests[i]
    50  		tt.mtx = 0
    51  		tt.ch = make(chan *futexsleepTest, 1)
    52  		wg.Add(1)
    53  		go func(tt *futexsleepTest) {
    54  			runtime.Entersyscall()
    55  			runtime.Futexsleep(&tt.mtx, 0, tt.ns)
    56  			runtime.Exitsyscall()
    57  			tt.ch <- tt
    58  			wg.Done()
    59  		}(tt)
    60  	}
    61  loop:
    62  	for {
    63  		select {
    64  		case tt := <-futexsleepTests[beforeY2038].ch:
    65  			t.Errorf("futexsleep test %q finished early after %s", tt.msg, time.Since(start))
    66  			break loop
    67  		case tt := <-futexsleepTests[afterY2038].ch:
    68  			// Looks like FreeBSD 10 kernel has changed
    69  			// the semantics of timedwait on userspace
    70  			// mutex to make broken stuff look broken.
    71  			switch {
    72  			case runtime.GOOS == "freebsd" && runtime.GOARCH == "386":
    73  				t.Log("freebsd/386 may not work correctly after the year 2038, see golang.org/issue/7194")
    74  			default:
    75  				t.Errorf("futexsleep test %q finished early after %s", tt.msg, time.Since(start))
    76  				break loop
    77  			}
    78  		case <-time.After(time.Second):
    79  			break loop
    80  		}
    81  	}
    82  	for i := range futexsleepTests {
    83  		tt := &futexsleepTests[i]
    84  		atomic.StoreUint32(&tt.mtx, 1)
    85  		runtime.Futexwakeup(&tt.mtx, 1)
    86  	}
    87  	wg.Wait()
    88  }
    89  

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