Reduce the LockFileManager timeout, and provide unsafeRemoveLockFile

5 minutes is an eternity, so try to strike a better balance between
waiting long enough for any reasonable module build and not so long that
users kill the process because they think it's hanging.

Also give the client a way to delete the lock file after a timeout.

llvm-svn: 228603

llvm/include/llvm/Support/LockFileManager.h

@@ -77,6 +77,10 @@ public:
 
   /// \brief For a shared lock, wait until the owner releases the lock.
   WaitForUnlockResult waitForUnlock();
+
+  /// \brief Remove the lock file.  This may delete a different lock file than
+  /// the one previously read if there is a race.
+  std::error_code unsafeRemoveLockFile();
 };
 
 } // end namespace llvm

llvm/lib/Support/LockFileManager.cpp

@@ -186,8 +186,8 @@ LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock() {
   Interval.tv_sec = 0;
   Interval.tv_nsec = 1000000;
 #endif
-  // Don't wait more than five minutes for the file to appear.
-  unsigned MaxSeconds = 300;
+  // Don't wait more than one minute for the file to appear.
+  unsigned MaxSeconds = 60;
   bool LockFileGone = false;
   do {
     // Sleep for the designated interval, to allow the owning process time to
@@ -263,3 +263,7 @@ LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock() {
   // Give up.
   return Res_Timeout;
 }
+
+std::error_code LockFileManager::unsafeRemoveLockFile() {
+  return sys::fs::remove(LockFileName.str());
+}