Merge pull request #2003 from alexanderkjeldaas/documented-locking-part-2

Documented locking part 1+2

src/sync.h

@@ -9,15 +9,36 @@
 #include <boost/thread/recursive_mutex.hpp>
 #include <boost/thread/locks.hpp>
 #include <boost/thread/condition_variable.hpp>
+#include "threadsafety.h"
 
+// Template mixin that adds -Wthread-safety locking annotations to a
+// subset of the mutex API.
+template <typename PARENT>
+class LOCKABLE AnnotatedMixin : public PARENT
+{
+public:
+    void lock() EXCLUSIVE_LOCK_FUNCTION()
+    {
+      PARENT::lock();
+    }
 
+    void unlock() UNLOCK_FUNCTION()
+    {
+      PARENT::unlock();
+    }
 
+    bool try_lock() EXCLUSIVE_TRYLOCK_FUNCTION(true)
+    {
+      return PARENT::try_lock();
+    }
+};
 
 /** Wrapped boost mutex: supports recursive locking, but no waiting  */
-typedef boost::recursive_mutex CCriticalSection;
+// TODO: We should move away from using the recursive lock by default.
+typedef AnnotatedMixin<boost::recursive_mutex> CCriticalSection;
 
 /** Wrapped boost mutex: supports waiting but not recursive locking */
-typedef boost::mutex CWaitableCriticalSection;
+typedef AnnotatedMixin<boost::mutex> CWaitableCriticalSection;
 
 #ifdef DEBUG_LOCKORDER
 void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);