Expose background job info to Python

Add `bpy.app.is_job_running(job_type)` as high-level indicator. Job
types currently exposed are `WM_JOB_TYPE_RENDER`,
`WM_JOB_TYPE_RENDER_PREVIEW`, and `WM_JOB_TYPE_OBJECT_BAKE`, as strings
with the `WM_JOB_TYPE_` prefix removed. The functions can be polled by
Python code to determine whether such background work is still ongoing
or not.

Furthermore, new app handles are added for
`object_bake_{pre,complete,canceled}`, which are called respectively
before an object baking job starts, completes sucessfully, and stops due
to a cancellation.

Motivation: There are various cases where Python can trigger the
execution of a background job, without getting notification that that
background job is done. As a result, it's hard to do things like
cleanups, or auto-quitting Blender after the work is done.

The approach in this commit can easily be extended with other job types,
when the need arises. The rendering of asset previews is one that's
likely to be added sooner than later, as there have already been
requests about this.

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D14587

1 files changed, 54 insertions, 0 deletions

diff --git a/source/blender/python/intern/bpy_app.c b/source/blender/python/intern/bpy_app.c
index 621cc79a8db..f54bf3e2774 100644
--- a/source/blender/python/intern/bpy_app.c
+++ b/source/blender/python/intern/bpy_app.c
@@ -36,15 +36,19 @@
 #include "BKE_appdir.h"
 #include "BKE_blender_version.h"
 #include "BKE_global.h"
+#include "BKE_main.h"
 
 #include "DNA_ID.h"
 
 #include "UI_interface_icons.h"
 
+#include "RNA_enum_types.h" /* For `rna_enum_wm_job_type_items`. */
+
 /* for notifiers */
 #include "WM_api.h"
 #include "WM_types.h"
 
+#include "../generic/py_capi_rna.h"
 #include "../generic/py_capi_utils.h"
 #include "../generic/python_utildefines.h"
 
@@ -450,6 +454,44 @@ static PyGetSetDef bpy_app_getsets[] = {
     {NULL, NULL, NULL, NULL, NULL},
 };
 
+PyDoc_STRVAR(bpy_app_is_job_running_doc,
+             ".. staticmethod:: is_job_running(job_type)\n"
+             "\n"
+             "   Check whether a job of the given type is running.\n"
+             "\n"
+             "   :arg job_type: job type in ['RENDER', 'RENDER_PREVIEW', OBJECT_BAKE]."
+             "   :type job_type: str\n"
+             "   :return: Whether a job of the given type is currently running.\n"
+             "   :rtype: bool.\n");
+static PyObject *bpy_app_is_job_running(PyObject *UNUSED(self), PyObject *args, PyObject *kwds)
+{
+  struct BPy_EnumProperty_Parse job_type_enum = {
+      .items = rna_enum_wm_job_type_items,
+      .value = 0,
+  };
+  static const char *_keywords[] = {"job_type", NULL};
+  static _PyArg_Parser _parser = {
+      "O&" /* `job_type` */
+      ":is_job_running",
+      _keywords,
+      0,
+  };
+  if (!_PyArg_ParseTupleAndKeywordsFast(
+          args, kwds, &_parser, pyrna_enum_value_parse_string, &job_type_enum)) {
+    return NULL;
+  }
+  wmWindowManager *wm = G_MAIN->wm.first;
+  return PyBool_FromLong(WM_jobs_has_running_type(wm, job_type_enum.value));
+}
+
+static struct PyMethodDef bpy_app_methods[] = {
+    {"is_job_running",
+     (PyCFunction)bpy_app_is_job_running,
+     METH_VARARGS | METH_KEYWORDS | METH_STATIC,
+     bpy_app_is_job_running_doc},
+    {NULL, NULL, 0, NULL},
+};
+
 static void py_struct_seq_getset_init(void)
 {
   /* tricky dynamic members, not to py-spec! */
@@ -459,6 +501,17 @@ static void py_struct_seq_getset_init(void)
     Py_DECREF(item);
   }
 }
+
+static void py_struct_seq_method_init(void)
+{
+  for (PyMethodDef *method = bpy_app_methods; method->ml_name; method++) {
+    BLI_assert_msg(method->ml_flags & METH_STATIC, "Only static methods make sense for 'bpy.app'");
+    PyObject *item = PyCFunction_New(method, NULL);
+    PyDict_SetItemString(BlenderAppType.tp_dict, method->ml_name, item);
+    Py_DECREF(item);
+  }
+}
+
 /* end dynamic bpy.app */
 
 PyObject *BPY_app_struct(void)
@@ -477,6 +530,7 @@ PyObject *BPY_app_struct(void)
 
   /* kindof a hack ontop of PyStructSequence */
   py_struct_seq_getset_init();
+  py_struct_seq_method_init();
 
   return ret;
 }