py: Merge read_event() and get_ready_requests()

We always call CameraManager.read_event() and
CameraManager.get_ready_requests(), so to simplify the use merge the
read_event() into the get_ready_requests().

This has the side effect that get_ready_requests() will now block if
there is no event ready. If we ever need to call get_ready_requests() in
a polling manner we will need a new function which behaves differently.

However, afaics the only sensible way to manage the event loop is to use
select/poll on the eventfd and then call get_ready_requests() once,
which is the use case what the current merged function supports.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/cam/cam.py

@@ -243,8 +243,6 @@ class CaptureState:
     # Called from renderer when there is a libcamera event
     def event_handler(self):
         try:
-            self.cm.read_event()
-
             reqs = self.cm.get_ready_requests()
 
             for req in reqs:

src/py/libcamera/py_main.cpp

@@ -213,15 +213,12 @@ PYBIND11_MODULE(_libcamera, m)
 			return gEventfd;
 		})
 
-		.def("read_event", [](CameraManager &) {
+		.def("get_ready_requests", [](CameraManager &) {
 			uint8_t buf[8];
 
-			int ret = read(gEventfd, buf, 8);
-			if (ret != 8)
+			if (read(gEventfd, buf, 8) != 8)
 				throw std::system_error(errno, std::generic_category());
-		})
 
-		.def("get_ready_requests", [](CameraManager &) {
 			std::vector<Request *> v;
 
 			{

test/py/unittests.py

@@ -210,8 +210,6 @@ class SimpleCaptureMethods(CameraTesterBase):
         reqs = []
 
         while True:
-            cm.read_event()
-
             ready_reqs = cm.get_ready_requests()
 
             reqs += ready_reqs
@@ -283,8 +281,6 @@ class SimpleCaptureMethods(CameraTesterBase):
         while running:
             events = sel.select()
             for key, _ in events:
-                cm.read_event()
-
                 ready_reqs = cm.get_ready_requests()
 
                 reqs += ready_reqs