github.com/AESNooper/go/src@v0.0.0-20220218095104-b56a4ab1bbbb/runtime/futex_test.go (about)

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