From 960797a0de24454ce0c8c15cbb26cb6fc7683e47 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 12 Dec 2012 02:20:18 +0100
Subject: [PATCH] Pre-Vista leveldb::port::InitOnce implementation

---
 src/leveldb/port/port_win.cc |  7 +------
 src/leveldb/port/port_win.h  | 22 ++++++++++++++++++++--
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/leveldb/port/port_win.cc b/src/leveldb/port/port_win.cc
index 7cf95379..15dfde1f 100644
--- a/src/leveldb/port/port_win.cc
+++ b/src/leveldb/port/port_win.cc
@@ -123,13 +123,8 @@ AtomicPointer::AtomicPointer(void* v) {
   Release_Store(v);
 }
 
-BOOL CALLBACK InitHandleFunction (PINIT_ONCE InitOnce, PVOID func, PVOID *lpContext) {
-  ((void (*)())func)();
-  return true;
-}
-
 void InitOnce(OnceType* once, void (*initializer)()) {
-  InitOnceExecuteOnce((PINIT_ONCE)once, InitHandleFunction, initializer, NULL);
+  once->InitOnce(initializer);
 }
 
 void* AtomicPointer::Acquire_Load() const {
diff --git a/src/leveldb/port/port_win.h b/src/leveldb/port/port_win.h
index c9e1cdad..849b0170 100644
--- a/src/leveldb/port/port_win.h
+++ b/src/leveldb/port/port_win.h
@@ -93,8 +93,26 @@ class CondVar {
   
 };
 
-typedef void* OnceType;
-#define LEVELDB_ONCE_INIT 0
+class OnceType {
+public:
+//    OnceType() : init_(false) {}
+    OnceType(const OnceType &once) : init_(once.init_) {}
+    OnceType(bool f) : init_(f) {}
+    void InitOnce(void (*initializer)()) {
+        mutex_.Lock();
+        if (!init_) {
+            init_ = true;
+            initializer();
+        }
+        mutex_.Unlock();
+    }
+
+private:
+    bool init_;
+    Mutex mutex_;
+};
+
+#define LEVELDB_ONCE_INIT false
 extern void InitOnce(port::OnceType*, void (*initializer)());
 
 // Storage for a lock-free pointer