libgo/go/time/internal_test.go

   1 // Copyright 2011 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 package time
   6
   7 import (
   8         "errors"
   9         "runtime"
  10 )
  11
  12 func init() {
  13         // force US/Pacific for time zone tests
  14         ForceUSPacificForTesting()
  15 }
  16
  17 var Interrupt = interrupt
  18 var DaysIn = daysIn
  19
  20 func empty(now int64, arg interface{}) {}
  21
  22 // Test that a runtimeTimer with a duration so large it overflows
  23 // does not cause other timers to hang.
  24 //
  25 // This test has to be in internal_test.go since it fiddles with
  26 // unexported data structures.
  27 func CheckRuntimeTimerOverflow() error {
  28         // We manually create a runtimeTimer to bypass the overflow
  29         // detection logic in NewTimer: we're testing the underlying
  30         // runtime.addtimer function.
  31         r := &runtimeTimer{
  32                 when: nano() + (1<<63 - 1),
  33                 f:    empty,
  34                 arg:  nil,
  35         }
  36         startTimer(r)
  37
  38         timeout := 100 * Millisecond
  39         if runtime.GOOS == "windows" {
  40                 // Allow more time for gobuilder to succeed.
  41                 timeout = Second
  42         }
  43
  44         // Start a goroutine that should send on t.C before the timeout.
  45         t := NewTimer(1)
  46
  47         defer func() {
  48                 // Subsequent tests won't work correctly if we don't stop the
  49                 // overflow timer and kick the timer proc back into service.
  50                 //
  51                 // The timer proc is now sleeping and can only be awoken by
  52                 // adding a timer to the *beginning* of the heap. We can't
  53                 // wake it up by calling NewTimer since other tests may have
  54                 // left timers running that should have expired before ours.
  55                 // Instead we zero the overflow timer duration and start it
  56                 // once more.
  57                 stopTimer(r)
  58                 t.Stop()
  59                 r.when = 0
  60                 startTimer(r)
  61         }()
  62
  63         // Try to receive from t.C before the timeout. It will succeed
  64         // iff the previous sleep was able to finish. We're forced to
  65         // spin and yield after trying to receive since we can't start
  66         // any more timers (they might hang due to the same bug we're
  67         // now testing).
  68         stop := Now().Add(timeout)
  69         for {
  70                 select {
  71                 case <-t.C:
  72                         return nil // It worked!
  73                 default:
  74                         if Now().After(stop) {
  75                                 return errors.New("runtime timer stuck: overflow in addtimer")
  76                         }
  77                         runtime.Gosched()
  78                 }
  79         }
  80 }