Implementing the notion of externally-acquirable ScriptInterpreter lock

With this notion, if parties outside the ScriptInterpreter itself need to acquire a lock on script APIs, they can do so by a pattern like this:

{
auto lock = interpeter->AcquireInterpreterLock();
// do whatever you need to do...
} // lock will automatically be released here

This might be useful for classes that use the Python convenience objects (e.g. PythonDictionary) to ensure they keep the underlying interpreter in a safe and controlled condition while they call through the C API functions
Of course, the ScriptInterpreter still manages its internal locking correctly when necessary :-)

llvm-svn: 178189

lldb/source/Interpreter/ScriptInterpreterPython.cpp

@@ -135,6 +135,7 @@ ScriptInterpreterPython::Locker::Locker (ScriptInterpreterPython *py_interpreter
                                          uint16_t on_entry,
                                          uint16_t on_leave,
                                          FILE* wait_msg_handle) :
+    ScriptInterpreterLocker (),
     m_teardown_session( (on_leave & TearDownSession) == TearDownSession ),
     m_python_interpreter(py_interpreter),
     m_tmp_fh(wait_msg_handle)
@@ -2806,6 +2807,15 @@ ScriptInterpreterPython::GetDocumentationForItem(const char* item, std::string&
     }
 }
 
+std::auto_ptr<ScriptInterpreterLocker>
+ScriptInterpreterPython::AcquireInterpreterLock ()
+{
+    std::auto_ptr<ScriptInterpreterLocker> py_lock(new Locker(this,
+                                                              Locker::AcquireLock | Locker::InitSession,
+                                                              Locker::FreeLock | Locker::TearDownSession));
+    return py_lock;
+}
+
 void
 ScriptInterpreterPython::InitializeInterpreter (SWIGInitCallback python_swig_init_callback)
 {