misc/cgo/test: deflake TestParallelSleep once more

Fixes #5480.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/9475043

diff --git a/misc/cgo/test/callback_c.c b/misc/cgo/test/callback_c.c
index 47f07301bfebaa872e783c9fd18c88d261741c02..032011ae5ddf81e753a19be8a43af528f261857f 100644 (file)
--- a/misc/cgo/test/callback_c.c
+++ b/misc/cgo/test/callback_c.c
@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include <sys/types.h>
+#include <unistd.h>
 #include "_cgo_export.h"
 
 void
@@ -29,9 +30,30 @@ IntoC(void)
        BackIntoGo();
 }
 
-void
+#ifdef WIN32
+#include <windows.h>
+long long
+mysleep(int seconds) {
+       long long st = GetTickCount();
+       sleep(seconds);
+       return st;
+}
+#else
+#include <sys/time.h>
+long long
+mysleep(int seconds) {
+       long long st;
+       struct timeval tv;
+       gettimeofday(&tv, NULL);
+       st = tv.tv_sec * 1000 + tv.tv_usec / 1000;
+       sleep(seconds);
+       return st;
+}
+#endif
+
+long long
 twoSleep(int n)
 {
        BackgroundSleep(n);
-       sleep(n);
+       return mysleep(n);
 }

diff --git a/misc/cgo/test/issue1560.go b/misc/cgo/test/issue1560.go
index 147ce94b58cb88718335903cf46c56d1c8266e05..c46954b0747e0ebd2ef44ad2687fe3d9de4210cc 100644 (file)
--- a/misc/cgo/test/issue1560.go
+++ b/misc/cgo/test/issue1560.go
@@ -5,71 +5,46 @@
 package cgotest
 
 /*
-#include <unistd.h>
+// mysleep returns the absolute start time in ms.
+long long mysleep(int seconds);
 
-unsigned int sleep(unsigned int seconds);
-
-extern void BackgroundSleep(int);
-void twoSleep(int);
+// twoSleep returns the absolute start time of the first sleep
+// in ms.
+long long twoSleep(int);
 */
 import "C"
 
 import (
-       "runtime"
        "testing"
        "time"
 )
 
-var sleepDone = make(chan bool)
+var sleepDone = make(chan int64)
 
-func parallelSleep(n int) {
-       C.twoSleep(C.int(n))
-       <-sleepDone
+// parallelSleep returns the absolute difference between the start time
+// of the two sleeps.
+func parallelSleep(n int) int64 {
+       t := int64(C.twoSleep(C.int(n))) - <-sleepDone
+       if t < 0 {
+               return -t
+       }
+       return t
 }
 
 //export BackgroundSleep
 func BackgroundSleep(n int32) {
        go func() {
-               C.sleep(C.uint(n))
-               sleepDone <- true
-       }()
-}
-
-// wasteCPU starts a background goroutine to waste CPU
-// to cause the power management to raise the CPU frequency.
-// On ARM this has the side effect of making sleep more accurate.
-func wasteCPU() chan struct{} {
-       done := make(chan struct{})
-       go func() {
-               for {
-                       select {
-                       case <-done:
-                               return
-                       default:
-                       }
-               }
+               sleepDone <- int64(C.mysleep(C.int(n)))
        }()
-       // pause for a short amount of time to allow the
-       // power management to recognise load has risen.
-       <-time.After(300 * time.Millisecond)
-       return done
 }
 
 func testParallelSleep(t *testing.T) {
-       if runtime.GOARCH == "arm" {
-               // on ARM, the 1.3s deadline is frequently missed,
-               // and burning cpu seems to help
-               defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
-               defer close(wasteCPU())
-       }
-
        sleepSec := 1
-       start := time.Now()
-       parallelSleep(sleepSec)
-       dt := time.Since(start)
-       t.Logf("sleep(%d) slept for %v", sleepSec, dt)
+       dt := time.Duration(parallelSleep(sleepSec)) * time.Millisecond
+       t.Logf("difference in start time for two sleep(%d) is %v", sleepSec, dt)
        // bug used to run sleeps in serial, producing a 2*sleepSec-second delay.
-       if dt >= time.Duration(sleepSec)*1300*time.Millisecond {
+       // we detect if the start times of those sleeps are > 0.5*sleepSec-second.
+       if dt >= time.Duration(sleepSec)*time.Second/2 {
                t.Fatalf("parallel %d-second sleeps slept for %f seconds", sleepSec, dt.Seconds())
        }
 }