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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package time
import (
"errors"
"runtime"
)
func init() {
// force US/Pacific for time zone tests
ForceUSPacificForTesting()
}
var Interrupt = interrupt
var DaysIn = daysIn
func empty(now int64, arg interface{}) {}
// Test that a runtimeTimer with a duration so large it overflows
// does not cause other timers to hang.
//
// This test has to be in internal_test.go since it fiddles with
// unexported data structures.
func CheckRuntimeTimerOverflow() error {
// We manually create a runtimeTimer to bypass the overflow
// detection logic in NewTimer: we're testing the underlying
// runtime.addtimer function.
r := &runtimeTimer{
when: runtimeNano() + (1<<63 - 1),
f: empty,
arg: nil,
}
startTimer(r)
timeout := 100 * Millisecond
switch runtime.GOOS {
// Allow more time for gobuilder to succeed.
case "windows":
timeout = Second
case "plan9":
// TODO(0intro): We don't know why it is needed.
timeout = 3 * Second
}
// Start a goroutine that should send on t.C before the timeout.
t := NewTimer(1)
defer func() {
// Subsequent tests won't work correctly if we don't stop the
// overflow timer and kick the timer proc back into service.
//
// The timer proc is now sleeping and can only be awoken by
// adding a timer to the *beginning* of the heap. We can't
// wake it up by calling NewTimer since other tests may have
// left timers running that should have expired before ours.
// Instead we zero the overflow timer duration and start it
// once more.
stopTimer(r)
t.Stop()
r.when = 0
startTimer(r)
}()
// Try to receive from t.C before the timeout. It will succeed
// iff the previous sleep was able to finish. We're forced to
// spin and yield after trying to receive since we can't start
// any more timers (they might hang due to the same bug we're
// now testing).
stop := Now().Add(timeout)
for {
select {
case <-t.C:
return nil // It worked!
default:
if Now().After(stop) {
return errors.New("runtime timer stuck: overflow in addtimer")
}
// Issue 6874. This test previously called runtime.Gosched to try to yield
// to the goroutine servicing t, however the scheduler has a bias towards the
// previously running goroutine in an idle system. Combined with high load due
// to all CPUs busy running tests t's goroutine could be delayed beyond the
// timeout window.
//
// Calling runtime.GC() reduces the worst case lantency for scheduling t by 20x
// under the current Go 1.3 scheduler.
runtime.GC()
}
}
}
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