Add a new watchdog timer interface. The interface does not permit handling timeouts, so

it's only really useful if you're going to crash anyways. Use it in the pretty stack trace
printer to kill the compiler if we hang while printing the stack trace.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177962 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Watchdog.h

@@ -0,0 +1,38 @@
+//===--- Watchdog.h - Watchdog timer ----------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file declares the llvm::sys::Watchdog class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_WATCHDOG_H
+#define LLVM_SUPPORT_WATCHDOG_H
+
+#include "llvm/Support/Compiler.h"
+
+namespace llvm {
+  namespace sys {
+
+    /// This class provides an abstraction for a timeout around an operation
+    /// that must complete in a given amount of time. Failure to complete before
+    /// the timeout is an unrecoverable situation and no mechanisms to attempt
+    /// to handle it are provided.
+    class Watchdog {
+    public:
+      Watchdog(unsigned int seconds);
+      ~Watchdog();
+    private:
+      // Noncopyable.
+      Watchdog(const Watchdog &other) LLVM_DELETED_FUNCTION;
+      Watchdog &operator=(const Watchdog &other) LLVM_DELETED_FUNCTION;
+    };
+  }
+}
+
+#endif

lib/Support/CMakeLists.txt

@@ -95,6 +95,7 @@ add_llvm_library(LLVMSupport
   Unix/system_error.inc
   Unix/ThreadLocal.inc
   Unix/TimeValue.inc
+  Unix/Watchdog.inc
   Windows/DynamicLibrary.inc
   Windows/Host.inc
   Windows/Memory.inc
@@ -108,4 +109,5 @@ add_llvm_library(LLVMSupport
   Windows/system_error.inc
   Windows/ThreadLocal.inc
   Windows/TimeValue.inc
+  Windows/Watchdog.inc
   )

lib/Support/PrettyStackTrace.cpp

@@ -17,6 +17,7 @@
 #include "llvm/Config/config.h"     // Get autoconf configuration settings
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/ThreadLocal.h"
+#include "llvm/Support/Watchdog.h"
 #include "llvm/Support/raw_ostream.h"
 
 #ifdef HAVE_CRASHREPORTERCLIENT_H
@@ -37,7 +38,10 @@ static unsigned PrintStack(const PrettyStackTraceEntry *Entry, raw_ostream &OS){
   if (Entry->getNextEntry())
     NextID = PrintStack(Entry->getNextEntry(), OS);
   OS << NextID << ".\t";
-  Entry->print(OS);
+  {
+    sys::Watchdog W(5);
+    Entry->print(OS);
+  }
   
   return NextID+1;
 }

lib/Support/Unix/Watchdog.inc

@@ -0,0 +1,32 @@
+//===--- Unix/Watchdog.inc - Unix Watchdog Implementation -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the generic Unix implementation of the Watchdog class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+namespace llvm {
+  namespace sys {
+    Watchdog::Watchdog(unsigned int seconds) {
+#ifdef HAVE_UNISTD_H
+      alarm(seconds);
+#endif
+    }
+
+    Watchdog::~Watchdog() {
+#ifdef HAVE_UNISTD_H
+      alarm(0);
+#endif
+    }
+  }
+}

lib/Support/Watchdog.cpp

@@ -0,0 +1,23 @@
+//===---- Watchdog.cpp - Implement Watchdog ---------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements the Watchdog class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Watchdog.h"
+#include "llvm/Config/config.h"
+
+// Include the platform-specific parts of this class.
+#ifdef LLVM_ON_UNIX
+#include "Unix/Watchdog.inc"
+#endif
+#ifdef LLVM_ON_WIN32
+#include "Windows/Watchdog.inc"
+#endif

lib/Support/Windows/Watchdog.inc

@@ -0,0 +1,24 @@
+//===--- Windows/Watchdog.inc - Windows Watchdog Implementation -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the generic Windows implementation of the Watchdog class.
+//
+//===----------------------------------------------------------------------===//
+
+// TODO: implement.
+// Currently this is only used by PrettyStackTrace which is also unimplemented
+// on Windows. Roughly, a Windows implementation would use CreateWaitableTimer
+// and a second thread to run the TimerAPCProc.
+
+namespace llvm {
+  namespace sys {
+    Watchdog::Watchdog(unsigned int seconds) {}
+    Watchdog::~Watchdog() {}
+  }
+}