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

include/llvm/System/Alarm.h

@@ -0,0 +1,42 @@
+//===- llvm/System/Alarm.h - Alarm Generation support  ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides an operating system independent interface to alarm(2) 
+// type functionality. The Alarm class allows a one-shot alarm to be set up 
+// at some number of seconds in the future. When the alarm triggers, a method
+// is called to process the event
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_ALARM_H
+#define LLVM_SYSTEM_ALARM_H
+
+namespace llvm {
+namespace sys {
+
+  /// This function registers an alarm to trigger some number of \p seconds in 
+  /// the future. When that time arrives, the \p callback is called. You can
+  /// only call this once. Each time 
+  /// @returns nothing
+  void SetupAlarm(
+    unsigned seconds ///< Number of seconds in future when alarm arrives
+  );
+
+  /// This function terminates the alarm previously set up 
+  /// @returns nothing
+  void TerminateAlarm();
+
+  /// This function acquires the status of the alarm. 
+  /// @returns -1=cancelled, 0=untriggered, 1=triggered
+  int AlarmStatus();
+
+} // End sys namespace
+} // End llvm namespace
+
+#endif

lib/System/Alarm.cpp

@@ -0,0 +1,34 @@
+//===- Alarm.cpp - Alarm Generation Support ---------------------*- C++ -*-===//
+//
+//                     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 Alarm functionality 
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/Alarm.h"
+#include "llvm/Config/config.h"
+
+namespace llvm {
+using namespace sys;
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only TRULY operating system
+//===          independent code.
+//===----------------------------------------------------------------------===//
+
+}
+
+// Include the platform-specific parts of this class.
+#ifdef LLVM_ON_UNIX
+#include "Unix/Alarm.inc"
+#endif
+#ifdef LLVM_ON_WIN32
+#include "Win32/Alarm.inc"
+#endif
+

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;
+}

lib/System/Win32/Alarm.inc

@@ -0,0 +1,36 @@
+//===-- Alarm.inc - Implement Win32 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 Win32 Alarm support.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cassert>
+using namespace llvm;
+
+/// NestedSOI - Sanity check.  Alarms cannot be nested or run in parallel.  
+/// This ensures that they never do.
+static bool NestedSOI = false;
+
+void sys::SetupAlarm(unsigned seconds) {
+  assert(!NestedSOI && "sys::SetupAlarm calls cannot be nested!");
+  NestedSOI = true;
+  // FIXME: Implement for Win32
+}
+
+void sys::TerminateAlarm() {
+  assert(NestedSOI && "sys::TerminateAlarm called without sys::SetupAlarm!");
+  // FIXME: Implement for Win32
+  NestedSOI = false;
+}
+
+int sys::AlarmStatus() {
+  // FIXME: Implement for Win32
+  return 0;
+}