HITL - Add cross-process signal to toggle inflow of new connections.

habitat-hitl/habitat_hitl/_internal/networking/interprocess_record.py

@@ -4,7 +4,7 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
-from multiprocessing import Queue
+from multiprocessing import Queue, Value
 from typing import Any, List
 
 from habitat_hitl.core.types import (
@@ -27,6 +27,15 @@ def __init__(self, networking_config) -> None:
         self._connection_record_queue: Queue[ConnectionRecord] = Queue()
         self._disconnection_record_queue: Queue[DisconnectionRecord] = Queue()
         self._kick_signal_queue: Queue[int] = Queue()
+        self._allow_new_connections = Value("b", False)
+
+    def enable_new_connections(self, enabled: bool):
+        """Signal the networking process whether it should accept new connections."""
+        self._allow_new_connections.value = enabled  # type: ignore
+
+    def new_connections_allowed(self) -> bool:
+        """Get whether new connections are allowed."""
+        return self._allow_new_connections.value  # type: ignore
 
     def send_keyframe_to_networking_thread(
         self, keyframe: KeyframeAndMessages

habitat-hitl/habitat_hitl/_internal/networking/networking_process.py

@@ -328,12 +328,28 @@ async def send_keyframes(self) -> None:
             await asyncio.sleep(wait_time)
 
     def has_connection(self) -> bool:
+        """
+        Returns true if at least one user is connected.
+        """
         return len(self._connected_clients) > 0
 
+    def is_server_available(self) -> bool:
+        """
+        Returns true if the server should advertise itself as available.
+        """
+        return (
+            not self.has_connection()
+            and self._interprocess_record.new_connections_allowed()
+        )
+
     def can_accept_connection(self) -> bool:
+        """
+        Returns true if the server had the capacity for a new connection.
+        """
         return (
             len(self._connected_clients)
             < self._networking_config.max_client_count
+            and self._interprocess_record.new_connections_allowed()
         )
 
     def handle_disconnect(self, connection_id: int) -> None:
@@ -496,7 +512,7 @@ async def http_handler(request):
         # return an HTTP code to indicate available or not
         code = (
             networking_config.http_availability_server.code_available
-            if not network_mgr.has_connection()
+            if network_mgr.is_server_available()
             else networking_config.http_availability_server.code_unavailable
         )
         # print(f"Returned availability HTTP code {code}")