feat: implement non-polling, interruptible waiting of gui instruction response with timeout

bec_widgets/cli/client_utils.py

@@ -14,7 +14,7 @@ from typing import TYPE_CHECKING
 
 from bec_lib.endpoints import MessageEndpoints
 from bec_lib.utils.import_utils import isinstance_based_on_class_name, lazy_import, lazy_import_from
-from qtpy.QtCore import QCoreApplication
+from qtpy.QtCore import QEventLoop, QSocketNotifier, QTimer
 
 import bec_widgets.cli.client as client
 from bec_widgets.cli.auto_updates import AutoUpdates
@@ -24,6 +24,8 @@ if TYPE_CHECKING:
 
     from bec_widgets.cli.client import BECDockArea, BECFigure
 
+from bec_lib.serialization import MsgpackSerialization
+
 messages = lazy_import("bec_lib.messages")
 # from bec_lib.connector import MessageObject
 MessageObject = lazy_import_from("bec_lib.connector", ("MessageObject",))
@@ -205,6 +207,48 @@ class RPCResponseTimeoutError(Exception):
         )
 
 
+class QtRedisMessageWaiter:
+    def __init__(self, redis_connector, message_to_wait):
+        self.ev_loop = QEventLoop()
+        self.response = None
+        self.connector = redis_connector
+        self.message_to_wait = message_to_wait
+        self.pubsub = redis_connector._redis_conn.pubsub()
+        self.pubsub.subscribe(self.message_to_wait.endpoint)
+        fd = self.pubsub.connection._sock.fileno()
+        self.notifier = QSocketNotifier(fd, QSocketNotifier.Read)
+        self.notifier.activated.connect(self._pubsub_readable)
+
+    def _msg_received(self, msg_obj):
+        self.response = msg_obj.value
+        self.ev_loop.quit()
+
+    def wait(self, timeout=1):
+        timer = QTimer()
+        timer.singleShot(timeout * 1000, self.ev_loop.quit)
+        self.ev_loop.exec_()
+        timer.stop()
+        self.notifier.setEnabled(False)
+        self.pubsub.close()
+        return self.response
+
+    def _pubsub_readable(self, fd):
+        while True:
+            msg = self.pubsub.get_message()
+            if msg:
+                if msg["type"] == "subscribe":
+                    # get_message buffers, so we may already have the answer
+                    # let's check...
+                    continue
+                else:
+                    break
+            else:
+                return
+        channel = msg["channel"].decode()
+        msg = MessageObject(topic=channel, value=MsgpackSerialization.loads(msg["data"]))
+        self.connector._execute_callback(self._msg_received, msg, {})
+
+
 class RPCBase:
     def __init__(self, gui_id: str = None, config: dict = None, parent=None) -> None:
         self._client = BECDispatcher().client
@@ -231,7 +275,7 @@ class RPCBase:
             parent = parent._parent
         return parent
 
-    def _run_rpc(self, method, *args, wait_for_rpc_response=True, **kwargs):
+    def _run_rpc(self, method, *args, wait_for_rpc_response=True, timeout=3, **kwargs):
         """
         Run the RPC call.
 
@@ -253,16 +297,24 @@ class RPCBase:
 
         # pylint: disable=protected-access
         receiver = self._root._gui_id
+        if wait_for_rpc_response:
+            redis_msg = QtRedisMessageWaiter(
+                self._client.connector, MessageEndpoints.gui_instruction_response(request_id)
+            )
+
         self._client.connector.set_and_publish(MessageEndpoints.gui_instructions(receiver), rpc_msg)
 
-        if not wait_for_rpc_response:
-            return None
-        response = self._wait_for_response(request_id)
-        # get class name
-        if not response.content["accepted"]:
-            raise ValueError(response.content["message"]["error"])
-        msg_result = response.content["message"].get("result")
-        return self._create_widget_from_msg_result(msg_result)
+        if wait_for_rpc_response:
+            response = redis_msg.wait(timeout)
+
+            if response is None:
+                raise RPCResponseTimeoutError(request_id, timeout)
+
+            # get class name
+            if not response.accepted:
+                raise ValueError(response.message["error"])
+            msg_result = response.message.get("result")
+            return self._create_widget_from_msg_result(msg_result)
 
     def _create_widget_from_msg_result(self, msg_result):
         if msg_result is None:
@@ -285,30 +337,6 @@ class RPCBase:
             return cls(parent=self, **msg_result)
         return msg_result
 
-    def _wait_for_response(self, request_id: str, timeout: int = 5):
-        """
-        Wait for the response from the server.
-
-        Args:
-            request_id(str): The request ID.
-            timeout(int): The timeout in seconds.
-
-        Returns:
-            The response from the server.
-        """
-        start_time = time.time()
-        response = None
-
-        while response is None and self.gui_is_alive() and (time.time() - start_time) < timeout:
-            response = self._client.connector.get(
-                MessageEndpoints.gui_instruction_response(request_id)
-            )
-            QCoreApplication.processEvents()  # keep UI responsive (and execute signals/slots)
-        if response is None and (time.time() - start_time) >= timeout:
-            raise RPCResponseTimeoutError(request_id, timeout)
-
-        return response
-
     def gui_is_alive(self):
         """
         Check if the GUI is alive.

bec_widgets/examples/jupyter_console/jupyter_console_window.py

@@ -136,17 +136,18 @@ if __name__ == "__main__":  # pragma: no cover
 
     module_path = os.path.dirname(bec_widgets.__file__)
 
+    app = QApplication(sys.argv)
+    app.setApplicationName("Jupyter Console")
+    app.setApplicationDisplayName("Jupyter Console")
+    qdarktheme.setup_theme("auto")
+    icon = QIcon()
+    icon.addFile(os.path.join(module_path, "assets", "terminal_icon.png"), size=QSize(48, 48))
+    app.setWindowIcon(icon)
+
     bec_dispatcher = BECDispatcher()
     client = bec_dispatcher.client
     client.start()
 
-    app = QApplication(sys.argv)
-    app.setApplicationName("Jupyter Console")
-    app.setApplicationDisplayName("Jupyter Console")
-    # qdarktheme.setup_theme("auto")
-    icon = QIcon()
-    icon.addFile(os.path.join(module_path, "assets", "terminal_icon.png"), size=QSize(48, 48))
-    app.setWindowIcon(icon)
     win = JupyterConsoleWindow()
     win.show()
 

bec_widgets/utils/bec_dispatcher.py

@@ -9,7 +9,7 @@ import redis
 from bec_lib.client import BECClient
 from bec_lib.redis_connector import MessageObject, RedisConnector
 from bec_lib.service_config import ServiceConfig
-from qtpy.QtCore import QObject
+from qtpy.QtCore import QCoreApplication, QObject
 from qtpy.QtCore import Signal as pyqtSignal
 
 if TYPE_CHECKING:
@@ -71,6 +71,7 @@ class BECDispatcher:
 
     _instance = None
     _initialized = False
+    qapp = None
 
     def __new__(cls, client=None, config: str = None, *args, **kwargs):
         if cls._instance is None:
@@ -82,6 +83,9 @@ class BECDispatcher:
         if self._initialized:
             return
 
+        if not QCoreApplication.instance():
+            BECDispatcher.qapp = QCoreApplication([])
+
         self._slots = collections.defaultdict(set)
         self.client = client