r228604 - Diagnose timeouts in the LockFileManager and delete the dead lock file

[Ben Langmuir]

Author: benlangmuir
Date: Mon Feb  9 14:35:13 2015
New Revision: 228604

URL: http://llvm.org/viewvc/llvm-project?rev=228604&view=rev
Log:
Diagnose timeouts in the LockFileManager and delete the dead lock file

If the lock file manager times out, we should give an error rather than
silently trying to load the existing module.  And delete the
(presumably) dead lock file, since it will otherwise prevent progress in
future invokations. This is unsound since we have no way to prove that
the lock file we are deleting is the same one we timed out on, but since
the lock is only to avoid excessive rebuilding anyway it should be okay.
Depends on llvm r228603.

Modified:
    cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td
    cfe/trunk/lib/Frontend/CompilerInstance.cpp

Modified: cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td?rev=228604&r1=228603&r2=228604&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticCommonKinds.td Mon Feb  9 14:35:13 2015
@@ -83,6 +83,8 @@ def err_module_not_found : Error<"module
 def err_module_not_built : Error<"could not build module '%0'">, DefaultFatal;
 def err_module_lock_failure : Error<
   "could not acquire lock file for module '%0'">, DefaultFatal;
+def err_module_lock_timeout : Error<
+  "timed out waiting to acquire lock file for module '%0'">, DefaultFatal;
 def err_module_cycle : Error<"cyclic dependency in module '%0': %1">, 
   DefaultFatal;
 def note_pragma_entered_here : Note<"#pragma entered here">;  

Modified: cfe/trunk/lib/Frontend/CompilerInstance.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInstance.cpp?rev=228604&r1=228603&r2=228604&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInstance.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInstance.cpp Mon Feb  9 14:35:13 2015
@@ -1022,9 +1022,19 @@ static bool compileAndLoadModule(Compile
     case llvm::LockFileManager::LFS_Shared:
       // Someone else is responsible for building the module. Wait for them to
       // finish.
-      if (Locked.waitForUnlock() == llvm::LockFileManager::Res_OwnerDied)
+      switch (Locked.waitForUnlock()) {
+      case llvm::LockFileManager::Res_Success:
+        ModuleLoadCapabilities |= ASTReader::ARR_OutOfDate;
+        break;
+      case llvm::LockFileManager::Res_OwnerDied:
         continue; // try again to get the lock.
-      ModuleLoadCapabilities |= ASTReader::ARR_OutOfDate;
+      case llvm::LockFileManager::Res_Timeout:
+        Diags.Report(ModuleNameLoc, diag::err_module_lock_timeout)
+            << Module->Name;
+        // Clear the lock file so that future invokations can make progress.
+        Locked.unsafeRemoveLockFile();
+        return false;
+      }
       break;
     }