Implement a generic polled Alarm function. This merely removes the system

dependent portion of the lib/Support/SlowOperationTimer code into the
lib/System implementation where it can be ported to different platforms.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24937 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 68 insertions, 0 deletions

diff --git a/lib/System/Unix/Alarm.inc b/lib/System/Unix/Alarm.inc
new file mode 100644
index 0000000..1480802
--- /dev/null
+++ b/lib/System/Unix/Alarm.inc
@@ -0,0 +1,68 @@
+//===-- Alarm.inc - Implement Unix Alarm Support --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the UNIX Alarm support.
+//
+//===----------------------------------------------------------------------===//
+
+#include <signal.h>
+#include <unistd.h>
+#include <cassert>
+using namespace llvm;
+
+/// AlarmCancelled - This flag is set by the SIGINT signal handler if the
+/// user presses CTRL-C.
+static volatile bool AlarmCancelled = false;
+
+/// AlarmTriggered - This flag is set by the SIGALRM signal handler if the 
+/// alarm was triggered.
+static volatile bool AlarmTriggered = false;
+
+/// NestedSOI - Sanity check.  Alarms cannot be nested or run in parallel.  
+/// This ensures that they never do.
+static bool NestedSOI = false;
+
+static RETSIGTYPE SigIntHandler(int Sig) {
+  AlarmCancelled = true;
+  signal(SIGINT, SigIntHandler);
+}
+
+static RETSIGTYPE SigAlarmHandler(int Sig) {
+  AlarmTriggered = true;
+}
+
+static void (*OldSigIntHandler) (int);
+
+void sys::SetupAlarm(unsigned seconds) {
+  assert(!NestedSOI && "sys::SetupAlarm calls cannot be nested!");
+  NestedSOI = true;
+  AlarmCancelled = false;
+  AlarmTriggered = false;
+  ::signal(SIGALRM, SigAlarmHandler);
+  OldSigIntHandler = ::signal(SIGINT, SigIntHandler);
+  ::alarm(seconds);
+}
+
+void sys::TerminateAlarm() {
+  assert(NestedSOI && "sys::TerminateAlarm called without sys::SetupAlarm!");
+  ::alarm(0);
+  ::signal(SIGALRM, SIG_DFL);
+  ::signal(SIGINT, OldSigIntHandler);
+  AlarmCancelled = false;
+  AlarmTriggered = false;
+  NestedSOI = false;
+}
+
+int sys::AlarmStatus() {
+  if (AlarmCancelled)
+    return -1;
+  if (AlarmTriggered)
+    return 1;
+  return 0;
+}