Add threads_init back as a requirement for non-Python threaded repos

Re-add a "threads_init" function to gi for explicit intialization of Python
threading support. This was marked as deprecated in the previous cycle
because using Python threads already initializes everything.
However, we still need an explicit initalization when using repositories
with non-Python threads which may interact with Python callbacks
(GStreamer).

https://bugzilla.gnome.org/show_bug.cgi?id=710447

3 files changed, 19 insertions, 4 deletions

diff --git a/gi/__init__.py b/gi/__init__.py
index 0645d448..1060005d 100644
--- a/gi/__init__.py
+++ b/gi/__init__.py
@@ -27,6 +27,7 @@ __path__ = extend_path(__path__, __name__)
 from ._gi import _API
 from ._gi import Repository
 from ._gi import PyGIDeprecationWarning
+from ._gi import threads_init
 
 # Force loading the GObject typelib so we have available the wrappers for
 # base classes such as GInitiallyUnowned
@@ -35,6 +36,7 @@ gi  # pyflakes
 
 _API = _API  # pyflakes
 PyGIDeprecationWarning = PyGIDeprecationWarning
+threads_init
 
 import os
 
diff --git a/gi/gimodule.c b/gi/gimodule.c
index 9dfbd4ff..d84ecc02 100644
--- a/gi/gimodule.c
+++ b/gi/gimodule.c
@@ -600,6 +600,12 @@ pyg_channel_read(PyObject* self, PyObject *args, PyObject *kwargs)
     return NULL;
 }
 
+static PyObject *
+_pygi_threads_init (PyObject *self, PyObject *dummy)
+{
+    PyEval_InitThreads ();
+    Py_RETURN_NONE;
+}
 
 static PyMethodDef _gi_functions[] = {
     { "enum_add", (PyCFunction) _wrap_pyg_enum_add, METH_VARARGS | METH_KEYWORDS },
@@ -614,6 +620,10 @@ static PyMethodDef _gi_functions[] = {
     { "source_new", (PyCFunction) _wrap_pyg_source_new, METH_NOARGS },
     { "source_set_callback", (PyCFunction) pyg_source_set_callback, METH_VARARGS },
     { "io_channel_read", (PyCFunction) pyg_channel_read, METH_VARARGS },
+    { "threads_init", (PyCFunction) _pygi_threads_init, METH_NOARGS,
+                      "Initialize Python threading support. This only needs to be called "
+                      "when using GI repositories with non-Python threads which may interact "
+                      "with Python callbacks (GStreamer)."},
     { NULL, NULL, 0 }
 };
 
diff --git a/gi/overrides/GLib.py b/gi/overrides/GLib.py
index ddd65bd1..8f18682f 100644
--- a/gi/overrides/GLib.py
+++ b/gi/overrides/GLib.py
@@ -23,6 +23,7 @@ import signal
 import warnings
 import sys
 
+import gi
 from ..module import get_introspection_module
 from .._gi import (variant_new_tuple, variant_type_from_string, source_new,
                    source_set_callback, io_channel_read)
@@ -48,10 +49,12 @@ spawn_async = _glib.spawn_async
 
 
 def threads_init():
-    warnings.warn('threads_init no longer needs to be called. '
-                  'See: https://bugzilla.gnome.org/show_bug.cgi?id=686914',
-                  PyGIDeprecationWarning)
-
+    gi.threads_init()
+    warnings.warn('Since version 3.10, threads_init is no longer needed when mixing Python '
+                  'threads with GI. If you are using GI repositories with non-Python threads '
+                  'which may interact with Python callbacks (GStreamer), use: gi.threads_init() '
+                  'to get rid of this message. See: https://wiki.gnome.org/PyGObject/Threading',
+                  PyGIDeprecationWarning, stacklevel=2)
 
 __all__ += ['GError', 'OptionContext', 'OptionGroup', 'Pid',
             'spawn_async', 'threads_init']