github.com/aloncn/graphics-go@v0.0.1/src/time/internal_test.go (about)

     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  func init() {
     8  	// force US/Pacific for time zone tests
     9  	ForceUSPacificForTesting()
    10  }
    11  
    12  var Interrupt = interrupt
    13  var DaysIn = daysIn
    14  
    15  func empty(arg interface{}, seq uintptr) {}
    16  
    17  // Test that a runtimeTimer with a duration so large it overflows
    18  // does not cause other timers to hang.
    19  //
    20  // This test has to be in internal_test.go since it fiddles with
    21  // unexported data structures.
    22  func CheckRuntimeTimerOverflow() {
    23  	// We manually create a runtimeTimer to bypass the overflow
    24  	// detection logic in NewTimer: we're testing the underlying
    25  	// runtime.addtimer function.
    26  	r := &runtimeTimer{
    27  		when: runtimeNano() + (1<<63 - 1),
    28  		f:    empty,
    29  		arg:  nil,
    30  	}
    31  	startTimer(r)
    32  
    33  	// Start a goroutine that should send on t.C right away.
    34  	t := NewTimer(1)
    35  
    36  	defer func() {
    37  		// Subsequent tests won't work correctly if we don't stop the
    38  		// overflow timer and kick the timer proc back into service.
    39  		//
    40  		// The timer proc is now sleeping and can only be awoken by
    41  		// adding a timer to the *beginning* of the heap. We can't
    42  		// wake it up by calling NewTimer since other tests may have
    43  		// left timers running that should have expired before ours.
    44  		// Instead we zero the overflow timer duration and start it
    45  		// once more.
    46  		stopTimer(r)
    47  		t.Stop()
    48  		r.when = 0
    49  		startTimer(r)
    50  	}()
    51  
    52  	// If the test fails, we will hang here until the timeout in the testing package
    53  	// fires, which is 10 minutes. It would be nice to catch the problem sooner,
    54  	// but there is no reliable way to guarantee that timerproc schedules without
    55  	// doing something involving timerproc itself. Previous failed attempts have
    56  	// tried calling runtime.Gosched and runtime.GC, but neither is reliable.
    57  	// So we fall back to hope: We hope we don't hang here.
    58  	<-t.C
    59  }