fix backend dynamic import, fix shutdown app if stream is currently a…

…ctive.

node/app_api.py

@@ -68,16 +68,32 @@ async def validation_exception_handler(request, exc):
 
 
 def main():
-    # to allow api is runnable via project.scripts shortcut
+    # main function to allow api is runnable via project.scripts shortcut
     # ref: https://stackoverflow.com/a/70393344
-    uvicorn.run(
-        app,
-        host="0.0.0.0",
-        port=8000,
-        reload=False,
-        log_level="debug",
+    server = uvicorn.Server(
+        uvicorn.Config(
+            app,
+            host="0.0.0.0",
+            port=8000,
+            reload=False,
+            log_level="debug",
+        )
     )
 
+    # shutdown app workaround:
+    # workaround until https://github.com/encode/uvicorn/issues/1579 is fixed and
+    # shutdown can be handled properly.
+    # Otherwise the stream.mjpg if open will block shutdown of the server
+    # signal CTRL-C and systemctl stop would have no effect, app stalls
+    # signal.signal(signal.SIGINT, signal_handler) and similar
+    # don't work, because uvicorn is eating up signal handler
+    # currently: https://github.com/encode/uvicorn/issues/1579
+    # the workaround: currently we set force_exit to True to shutdown the server
+    server.force_exit = True  # leads to many exceptions on shutdown, but ... it is what it is...
+
+    # run
+    server.run()
+
 
 if __name__ == "__main__":
     main()

node/services/backends/cameras/abstractbackend.py

@@ -29,12 +29,30 @@ def __init__(self):
     def __repr__(self):
         return f"{self.__class__}"
 
-    def start(self):
+    @abstractmethod
+    def start(self, nominal_framerate: int = None):
         self._is_running: bool = True
 
+    @abstractmethod
     def stop(self):
         self._is_running: bool = False
 
     @abstractmethod
-    def test(self):
+    def start_stream(self):
+        pass
+
+    @abstractmethod
+    def stop_stream(self):
+        pass
+
+    @abstractmethod
+    def wait_for_lores_image(self):
+        pass
+
+    @abstractmethod
+    def do_capture(self, filename: str = None, number_frames: int = 1):
+        pass
+
+    @abstractmethod
+    def sync_tick(self, timestamp_ns: int):
         pass

node/services/backends/cameras/virtualcamera.py

@@ -1,17 +1,48 @@
+import io
 import logging
+import time
 
+import numpy
+from PIL import Image
+
+from ...config.models import ConfigBackendVirtualcamera
 from .abstractbackend import AbstractBackend
 
 logger = logging.getLogger(__name__)
 
 
-class VirtualcameraBackend(AbstractBackend):
-    def __init__(self):
+class VirtualCameraBackend(AbstractBackend):
+    def __init__(self, config: ConfigBackendVirtualcamera):
         super().__init__()
         # init with arguments
+        self._config = config
 
-    def start(self):
-        pass
+    def start(self, nominal_framerate: int = None):
+        super().start()
 
     def stop(self):
+        super().stop()
+
+    def start_stream(self):
+        pass
+
+    def stop_stream(self):
+        pass
+
+    def wait_for_lores_image(self):
+        time.sleep(0.05)
+
+        byte_io = io.BytesIO()
+        imarray = numpy.random.rand(200, 200, 3) * 255
+        random_image = Image.fromarray(imarray.astype("uint8"), "RGB")
+        random_image.save(byte_io, format="JPEG", quality=50)
+        # random_image = Image.new("RGB", (64, 64), color="green")
+        # random_image.save(byte_io, format="JPEG", quality=50)
+
+        return byte_io.getbuffer()
+
+    def do_capture(self, filename: str = None, number_frames: int = 1):
+        pass
+
+    def sync_tick(self, timestamp_ns: int):
         pass

node/services/sync_acquisition_service.py

@@ -54,7 +54,7 @@ def start(self):
         super().start()
 
         self._camera_backend: AbstractBackend = self._import_backend(self._config.backends.active_backend)(
-            getattr(self._config.backends, str((self._config.backends.active_backend).lower()))
+            getattr(self._config.backends, str(self._config.backends.active_backend).lower())
         )
 
         self._gpio_backend.start()

pyproject.toml

@@ -64,7 +64,7 @@ test = [
   "pytest-benchmark>=4.0.0",
   "pytest-cov>=4.1.0",
   "coverage[toml]>=7.4.0",
-
+  "numpy>=2.0.0",
 ]
 lint = [
   "ruff"