time: Sleep through interruptions

R=rsc
CC=golang-dev
https://golang.org/cl/202043

src/pkg/time/sleep.go

@@ -11,5 +11,16 @@ import (
 
 // Sleep pauses the current goroutine for at least ns nanoseconds. Higher resolution
 // sleeping may be provided by syscall.Nanosleep on some operating systems.
-// Sleep returns os.EINTR if interrupted.
-func Sleep(ns int64) os.Error { return os.NewSyscallError("sleep", syscall.Sleep(ns)) }
+func Sleep(ns int64) os.Error {
+	// TODO(cw): use monotonic-time once it's available
+	t := Nanoseconds()
+	end := t + ns
+	for t < end {
+		errno := syscall.Sleep(end - t)
+		if errno != 0 && errno != syscall.EINTR {
+			return os.NewSyscallError("sleep", errno)
+		}
+		t = Nanoseconds()
+	}
+	return nil
+}

src/pkg/time/sleep_test.go

+// Copyright 2009 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_test
+
+import (
+	"os"
+	"syscall"
+	"testing"
+	. "time"
+)
+
+func TestSleep(t *testing.T) {
+	const delay = int64(100e6)
+	go func() {
+		Sleep(delay / 2)
+		syscall.Kill(os.Getpid(), syscall.SIGCHLD)
+	}()
+	start := Nanoseconds()
+	Sleep(delay)
+	duration := Nanoseconds() - start
+	if duration < delay {
+		t.Fatalf("Sleep(%d) slept for only %d ns", delay, duration)
+	}
+}