From 69a2d6f55afb2bc42bc19e754bcebee39ecdb8bc Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Thu, 10 Jan 2013 02:01:35 +0000
Subject: Fix a race condition in the lock-file manager: once the lock file is
 gone, check for the actual file we care about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172033 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/LockFileManager.cpp | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

(limited to 'lib/Support/LockFileManager.cpp')

diff --git a/lib/Support/LockFileManager.cpp b/lib/Support/LockFileManager.cpp
index 075d8a5a66..31eec751b7 100644
--- a/lib/Support/LockFileManager.cpp
+++ b/lib/Support/LockFileManager.cpp
@@ -64,6 +64,7 @@ bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) {
 
 LockFileManager::LockFileManager(StringRef FileName)
 {
+  this->FileName = FileName;
   LockFileName = FileName;
   LockFileName += ".lock";
 
@@ -175,6 +176,7 @@ void LockFileManager::waitForUnlock() {
 #endif
   // Don't wait more than an hour for the file to appear.
   const unsigned MaxSeconds = 3600;
+  bool LockFileGone = false;
   do {
     // Sleep for the designated interval, to allow the owning process time to
     // finish up and remove the lock file.
@@ -185,10 +187,18 @@ void LockFileManager::waitForUnlock() {
 #else
     nanosleep(&Interval, NULL);
 #endif
-    // If the file no longer exists, we're done.
+    // If the lock file no longer exists, wait for the actual file.
     bool Exists = false;
-    if (!sys::fs::exists(LockFileName.str(), Exists) && !Exists)
-      return;
+    if (!LockFileGone) {
+      if (!sys::fs::exists(LockFileName.str(), Exists) && !Exists) {
+        LockFileGone = true;
+        Exists = false;
+      }
+    }
+    if (LockFileGone) {
+      if (!sys::fs::exists(FileName.str(), Exists) && Exists)
+        return;
+    }
 
     if (!processStillExecuting((*Owner).first, (*Owner).second))
       return;
-- 
cgit v1.2.3-70-g09d2


From 5c43245bf459c77077b607e1b55e6928cfbe464e Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Thu, 21 Feb 2013 00:27:28 +0000
Subject: Provide a "None" value for convenience when using Optional<T>()

This implementation of NoneType/None does have some holes but I haven't
found one that doesn't - open to improvement.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175696 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/None.h         | 27 +++++++++++++++++++++++++++
 include/llvm/ADT/Optional.h     |  2 ++
 lib/Support/LockFileManager.cpp |  4 ++--
 3 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 include/llvm/ADT/None.h

(limited to 'lib/Support/LockFileManager.cpp')

diff --git a/include/llvm/ADT/None.h b/include/llvm/ADT/None.h
new file mode 100644
index 0000000000..83c952178a
--- /dev/null
+++ b/include/llvm/ADT/None.h
@@ -0,0 +1,27 @@
+//===-- None.h - Simple null value for implicit construction ------*- 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 None, an enumerant for use in implicit constructors
+//  of various (usually templated) types to make such construction more
+//  terse.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_NONE_H
+#define LLVM_ADT_NONE_H
+
+namespace llvm {
+/// \brief A simple null object to allow implicit construction of Optional<T>
+/// and similar types without having to spell out the specialization's name.
+enum NoneType {
+  None
+};
+}
+
+#endif
diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h
index 6c91a13a5b..b0d09f6960 100644
--- a/include/llvm/ADT/Optional.h
+++ b/include/llvm/ADT/Optional.h
@@ -16,6 +16,7 @@
 #ifndef LLVM_ADT_OPTIONAL_H
 #define LLVM_ADT_OPTIONAL_H
 
+#include "llvm/ADT/None.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/AlignOf.h"
 #include <cassert>
@@ -31,6 +32,7 @@ class Optional {
   AlignedCharArrayUnion<T> storage;
   bool hasVal;
 public:
+  Optional(NoneType) : hasVal(false) {}
   explicit Optional() : hasVal(false) {}
   Optional(const T &y) : hasVal(true) {
     new (storage.buffer) T(y);
diff --git a/lib/Support/LockFileManager.cpp b/lib/Support/LockFileManager.cpp
index 31eec751b7..92d8b83cf9 100644
--- a/lib/Support/LockFileManager.cpp
+++ b/lib/Support/LockFileManager.cpp
@@ -31,7 +31,7 @@ LockFileManager::readLockFile(StringRef LockFileName) {
   // to read, so we just return.
   bool Exists = false;
   if (sys::fs::exists(LockFileName, Exists) || !Exists)
-    return Optional<std::pair<std::string, int> >();
+    return None;
 
   // Read the owning host and PID out of the lock file. If it appears that the
   // owning process is dead, the lock file is invalid.
@@ -45,7 +45,7 @@ LockFileManager::readLockFile(StringRef LockFileName) {
   // Delete the lock file. It's invalid anyway.
   bool Existed;
   sys::fs::remove(LockFileName, Existed);
-  return Optional<std::pair<std::string, int> >();
+  return None;
 }
 
 bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) {
-- 
cgit v1.2.3-70-g09d2