Author: zturner
Date: Wed Oct 14 12:51:29 2015
New Revision: 250306
URL: http://llvm.org/viewvc/llvm-project?rev=250306&view=rev
Log:
Fix Python initialization for Python 3.
Python 3 reverses the order in which you must call Py_InitializeEx
and PyEval_InitThreads. Since that log is in itself already a
little nuanced, it is refactored into a function so that the reversal
is more clear. At the same time, there's a lot of logic during
Python initialization to save off a bunch of state and then restore
it after initialization is complete. To express this more cleanly,
it is refactored to an RAII-style pattern where state is saved off
on acquisition and restored on release.
Modified:
lldb/trunk/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
Modified:
lldb/trunk/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
URL:
http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp?rev=250306&r1=250305&r2=250306&view=diff
==============================================================================
---
lldb/trunk/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
(original)
+++
lldb/trunk/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
Wed Oct 14 12:51:29 2015
@@ -80,27 +80,101 @@ static ScriptInterpreterPython::SWIGPyth
static bool g_initialized = false;
-#if PY_MAJOR_VERSION >= 3 && defined(LLDB_PYTHON_HOME)
-typedef wchar_t PythonHomeChar;
+namespace
+{
+
+// Initializing Python is not a straightforward process. We cannot control
what
+// external code may have done before getting to this point in LLDB, including
+// potentially having already initialized Python, so we need to do a lot of
work
+// to ensure that the existing state of the system is maintained across our
+// initialization. We do this by using an RAII pattern where we save off
initial
+// state at the beginning, and restore it at the end
+struct InitializePythonRAII
+{
+public:
+ InitializePythonRAII() :
+ m_was_already_initialized(false),
+ m_gil_state(PyGILState_UNLOCKED)
+ {
+ // Python will muck with STDIN terminal state, so save off any current
TTY
+ // settings so we can restore them.
+ m_stdin_tty_state.Save(STDIN_FILENO, false);
+
+ InitializePythonHome();
+
+ // Python < 3.2 and Python >= 3.2 reversed the ordering requirements
for
+ // calling `Py_Initialize` and `PyEval_InitThreads`. < 3.2 requires
that you
+ // call `PyEval_InitThreads` first, and >= 3.2 requires that you call
it last.
+#if (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 2) || (PY_MAJOR_VERSION > 3)
+ Py_InitializeEx(0);
+ InitializeThreadsPrivate();
#else
-typedef char PythonHomeChar;
+ InitializeThreadsPrivate();
+ Py_InitializeEx(0);
#endif
+ }
-PythonHomeChar *
-GetDesiredPythonHome()
-{
+ ~InitializePythonRAII()
+ {
+ if (m_was_already_initialized)
+ {
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SCRIPT
| LIBLLDB_LOG_VERBOSE));
+
+ if (log)
+ {
+ log->Printf("Releasing PyGILState. Returning to state =
%slocked\n",
+ m_was_already_initialized == PyGILState_UNLOCKED ? "un" :
"");
+ }
+ PyGILState_Release(m_gil_state);
+ }
+ else
+ {
+ // We initialized the threads in this function, just unlock the
GIL.
+ PyEval_SaveThread();
+ }
+
+ m_stdin_tty_state.Restore();
+ }
+
+private:
+ void InitializePythonHome()
+ {
#if defined(LLDB_PYTHON_HOME)
#if PY_MAJOR_VERSION >= 3
- size_t size = 0;
- static PythonHomeChar *g_python_home = Py_DecodeLocale(LLDB_PYTHON_HOME,
&size);
- return g_python_home;
+ size_t size = 0;
+ static wchar_t *g_python_home = Py_DecodeLocale(LLDB_PYTHON_HOME,
&size);
#else
- static PythonHomeChar *g_python_home = LLDB_PYTHON_HOME;
- return g_python_home;
+ static char *g_python_home = LLDB_PYTHON_HOME;
#endif
-#else
- return nullptr;
+ Py_SetPythonHome(g_python_home);
#endif
+ }
+
+ void InitializeThreadsPrivate()
+ {
+ if (PyEval_ThreadsInitialized())
+ {
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SCRIPT
| LIBLLDB_LOG_VERBOSE));
+
+ m_was_already_initialized = true;
+ m_gil_state = PyGILState_Ensure();
+ if (log)
+ {
+ log->Printf("Ensured PyGILState. Previous state = %slocked\n",
+ m_gil_state == PyGILState_UNLOCKED ? "un" : "");
+ }
+ return;
+ }
+
+ // InitThreads acquires the GIL if it hasn't been called before.
+ PyEval_InitThreads();
+ }
+
+ TerminalState m_stdin_tty_state;
+ PyGILState_STATE m_gil_state;
+ bool m_was_already_initialized;
+};
+
}
static std::string ReadPythonBacktrace(PythonObject py_backtrace);
@@ -3104,28 +3178,10 @@ ScriptInterpreterPython::InitializePriva
Timer scoped_timer (__PRETTY_FUNCTION__, __PRETTY_FUNCTION__);
- // Python will muck with STDIN terminal state, so save off any current TTY
- // settings so we can restore them.
- TerminalState stdin_tty_state;
- stdin_tty_state.Save(STDIN_FILENO, false);
-
-#if defined(LLDB_PYTHON_HOME)
- Py_SetPythonHome(GetDesiredPythonHome());
-#endif
-
- PyGILState_STATE gstate;
- Log *log (lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SCRIPT |
LIBLLDB_LOG_VERBOSE));
- bool threads_already_initialized = false;
- if (PyEval_ThreadsInitialized ()) {
- gstate = PyGILState_Ensure ();
- if (log)
- log->Printf("Ensured PyGILState. Previous state = %slocked\n",
gstate == PyGILState_UNLOCKED ? "un" : "");
- threads_already_initialized = true;
- } else {
- // InitThreads acquires the GIL if it hasn't been called before.
- PyEval_InitThreads ();
- }
- Py_InitializeEx (0);
+ // RAII-based initialization which correctly handles
multiple-initialization, version-
+ // specific differences among Python 2 and Python 3, and saving and
restoring various
+ // other pieces of state that can get mucked with during initialization.
+ InitializePythonRAII initialize_guard;
if (g_swig_init_callback)
g_swig_init_callback ();
@@ -3146,17 +3202,6 @@ ScriptInterpreterPython::InitializePriva
AddToSysPath(AddLocation::Beginning, file_spec.GetPath(false));
PyRun_SimpleString ("sys.dont_write_bytecode = 1; import
lldb.embedded_interpreter; from lldb.embedded_interpreter import
run_python_interpreter; from lldb.embedded_interpreter import run_one_line");
-
- if (threads_already_initialized) {
- if (log)
- log->Printf("Releasing PyGILState. Returning to state =
%slocked\n", gstate == PyGILState_UNLOCKED ? "un" : "");
- PyGILState_Release (gstate);
- } else {
- // We initialized the threads in this function, just unlock the GIL.
- PyEval_SaveThread();
- }
-
- stdin_tty_state.Restore();
}
void
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