From: Zachary Turner <zturner@google.com>
Date: Tue, 17 Jun 2014 19:57:15 +0000 (+0000)
Subject: Change libclang initialization to use std::call_once instead of
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e15a4d01d20b94111073eac67155979620ff98f8;p=clang

Change libclang initialization to use std::call_once instead of
hand rolled once-initialization, and rename the mutex to be more
descriptive of its actual purpose.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211121 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 962e3a3406..cbe7cf5346 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -51,6 +51,7 @@
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
+#include <mutex>
 
 #ifdef __APPLE__
 #include <pthread.h>
@@ -2559,8 +2560,8 @@ buildPieces(unsigned NameFlags, bool IsMemberRefExpr,
 // Misc. API hooks.
 //===----------------------------------------------------------------------===//               
 
-static llvm::sys::Mutex EnableMultithreadingMutex;
-static bool EnabledMultithreading;
+static llvm::sys::Mutex LoggingMutex;
+static std::once_flag LibclangGlobalInitFlag;
 
 static void fatal_error_handler(void *user_data, const std::string& reason,
                                 bool gen_crash_diag) {
@@ -2570,6 +2571,12 @@ static void fatal_error_handler(void *user_data, const std::string& reason,
   ::abort();
 }
 
+static void initializeLibClang() {
+  // Install our error handler, and make sure multi-threading is enabled.
+  llvm::llvm_start_multithreaded();
+  llvm::install_fatal_error_handler(fatal_error_handler, nullptr);
+}
+
 extern "C" {
 CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
                           int displayDiagnostics) {
@@ -2578,15 +2585,7 @@ CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
   if (!getenv("LIBCLANG_DISABLE_CRASH_RECOVERY"))
     llvm::CrashRecoveryContext::Enable();
 
-  // Enable support for multithreading in LLVM.
-  {
-    llvm::sys::ScopedLock L(EnableMultithreadingMutex);
-    if (!EnabledMultithreading) {
-      llvm::install_fatal_error_handler(fatal_error_handler, nullptr);
-      llvm::llvm_start_multithreaded();
-      EnabledMultithreading = true;
-    }
-  }
+  std::call_once(LibclangGlobalInitFlag, initializeLibClang);
 
   CIndexer *CIdxr = new CIndexer();
   if (excludeDeclarationsFromPCH)
@@ -6962,7 +6961,7 @@ Logger &cxindex::Logger::operator<<(const llvm::format_object_base &Fmt) {
 cxindex::Logger::~Logger() {
   LogOS.flush();
 
-  llvm::sys::ScopedLock L(EnableMultithreadingMutex);
+  llvm::sys::ScopedLock L(LoggingMutex);
 
   static llvm::TimeRecord sBeginTR = llvm::TimeRecord::getCurrentTime();