Fix very high cpu usage when a console fenrir under root and an x fenrir under your user are running at the same time.

src/fenrirscreenreader/core/remoteInstanceRegistry.py

@@ -12,6 +12,7 @@ import time
 
 
 INSTANCE_TIMEOUT_SEC = 30.0
+REGISTRY_DIR_MODE = 0o1777
 
 
 def get_registry_dir():
@@ -26,8 +27,8 @@ def get_instance_file(pid=None):
 
 def write_instance(instance_data):
     registry_dir = get_registry_dir()
-    os.makedirs(registry_dir, mode=0o755, exist_ok=True)
-    os.chmod(registry_dir, 0o755)
+    os.makedirs(registry_dir, mode=REGISTRY_DIR_MODE, exist_ok=True)
+    os.chmod(registry_dir, REGISTRY_DIR_MODE)
     prune_stale_instances()
     instance_data["updated_at"] = time.time()
     instance_path = get_instance_file(instance_data.get("pid"))

src/fenrirscreenreader/remoteDriver/unixDriver.py

@@ -114,6 +114,17 @@ class driver(remoteDriver):
         }
         remoteInstanceRegistry.write_instance(instance_data)
 
+    def _try_register_instance(self):
+        try:
+            self._register_instance()
+            return True
+        except Exception as e:
+            self.env["runtime"]["DebugManager"].write_debug_out(
+                "unixDriver could not register instance: " + str(e),
+                debug.DebugLevel.ERROR,
+            )
+            return False
+
     def _socket_file_matches_socket(self, fenrir_sock, socket_file):
         try:
             if os.stat(socket_file).st_uid != os.getuid():
@@ -328,11 +339,11 @@ class driver(remoteDriver):
         if not self.fenrirSocks:
             return
 
-        self._register_instance()
+        self._try_register_instance()
         last_register = time.time()
         while active.value:
             if time.time() - last_register > 10.0:
-                self._register_instance()
+                self._try_register_instance()
                 last_register = time.time()
 
             # Check if the client is still connected and if data is available:

tests/unit/test_remote_instance_registry.py

@@ -1,9 +1,24 @@
 import json
+import stat
 import time
 
 from fenrirscreenreader.core import remoteInstanceRegistry
 
 
+def test_write_instance_creates_shared_sticky_registry_directory(
+    tmp_path, monkeypatch
+):
+    registry_dir = tmp_path / "instances"
+    monkeypatch.setattr(
+        remoteInstanceRegistry, "get_registry_dir", lambda: str(registry_dir)
+    )
+
+    remoteInstanceRegistry.write_instance({"pid": 456})
+
+    mode = stat.S_IMODE(registry_dir.stat().st_mode)
+    assert mode == 0o1777
+
+
 def test_write_instance_prunes_stale_registry_files(tmp_path, monkeypatch):
     monkeypatch.setattr(
         remoteInstanceRegistry, "get_registry_dir", lambda: str(tmp_path)

tests/unit/test_unix_remote_driver.py

@@ -3,6 +3,30 @@ from unittest.mock import Mock, mock_open, patch
 from fenrirscreenreader.remoteDriver import unixDriver
 
 
+def test_watchdog_keeps_serving_when_instance_registration_fails(
+    mock_environment,
+):
+    driver = unixDriver.driver()
+    driver.env = mock_environment
+    driver.fenrirSocks = [Mock()]
+    active = Mock(value=True)
+    event_queue = Mock()
+
+    def stop_after_select(*_args):
+        active.value = False
+        return ([], [], [])
+
+    with patch.object(driver, "_get_socket_candidates", return_value=[]), patch.object(
+        driver, "_register_instance", side_effect=PermissionError("denied")
+    ), patch(
+        "fenrirscreenreader.remoteDriver.unixDriver.select.select",
+        side_effect=stop_after_select,
+    ) as select_call:
+        driver.watch_dog(active, event_queue)
+
+    select_call.assert_called_once()
+
+
 class FakeClientSocket:
     def __init__(self, data):
         self.data = data