receive_event: Make it optionally semi-nonblocking

kernelci/api/helper.py

@@ -64,9 +64,16 @@ def unsubscribe_filters(self, sub_id):
             self._filters.pop(sub_id)
         self.api.unsubscribe(sub_id)
 
-    def receive_event_data(self, sub_id):
-        """Receive CloudEvent from Pub/Sub and return its data payload"""
-        return self.api.receive_event(sub_id).data
+    def receive_event_data(self, sub_id, block=True):
+        """Receive CloudEvent from Pub/Sub and return its data payload
+        If block is False, on receiving an "keep-alive" event,
+        such as "BEEP" ping, it will return None instead of the data.
+        Without this, it will block until an event is received.
+        """
+        event = self.api.receive_event(sub_id, block=block)
+        if event is None:
+            return None
+        return event.data
 
     def pop_event_data(self, list_name):
         """Receive CloudEvent from Redis list and return its data payload"""

kernelci/api/latest.py

@@ -163,7 +163,7 @@ def unsubscribe(self, sub_id: int):
     def send_event(self, channel: str, data):
         self._post('/'.join(['publish', channel]), data)
 
-    def receive_event(self, sub_id: int):
+    def receive_event(self, sub_id: int, block: bool = True):
         path = '/'.join(['listen', str(sub_id)])
         while True:
             resp = self._get(path)
@@ -172,6 +172,10 @@ def receive_event(self, sub_id: int):
                 continue
             event = from_json(data)
             if event.data == 'BEEP':
+                if not block:
+                    # If block is False, return None
+                    # for semi-nonblocking operation
+                    return None
                 continue
             return event