Added timestamping to incoming values and timeout to signal descriptor

Added timestamping to ValueDescriptor to be able to record on a
timebase, timebase uses monotonic_ns() which is a system wide timebase
that can be called by connectors written in a host of languages

Added timeout to signal descriptors, live values now return None when
they are timed out

src/dynalab_core/__init__.py

@@ -32,6 +32,7 @@ class Core:
         self._state: Literal["uninitd", "initd", "started", "stopping", "stopped"] = (
             "unintid"
         )
+        self._recording = threading.Event()
         self._core_version: VersionDescriptor = CORE_VERSION
         self._stop_event: threading.Event = threading.Event()
         self._core_config: CoreConfig = config
@@ -103,6 +104,12 @@ class Core:
             extra={"event": "core.stopped", "core_state": self._state},
         )
 
+    def start_recording(self) -> None:
+        self._recording.set()
+
+    def stop_recording(self) -> None:
+        self._recording.clear()
+
     def get_signal_descriptor(self, signal_id: UUID) -> SignalDescriptor | None:
         return self._connector_registry.get_signal_descriptor(signal_id)
 
@@ -136,7 +143,15 @@ class Core:
                     live_value = self._live_values.get(message.signal_id)
 
                     if live_value is None:
-                        live_value = Value()
+                        signal_descriptor = (
+                            self._connector_registry.get_signal_descriptor(
+                                message.signal_id
+                            )
+                        )
+
+                        live_value = Value(
+                            signal_descriptor.timeout_ms if signal_descriptor else 2000
+                        )
                         self._live_values[message.signal_id] = live_value
 
-                live_value.update(message.value)
+                live_value.update(message.value, message.timestamp)

src/dynalab_core/protocols/packets/data.py

@@ -11,6 +11,7 @@ class ValueDescriptor(BaseModel):
     type: Literal["value_descriptor"] = "value_descriptor"
     signal_id: UUID
     value: float
+    timestamp: int
 
 
 class ValueBatch(BaseModel):

src/dynalab_core/protocols/packets/handshake.py

@@ -17,6 +17,7 @@ class SignalDescriptor(BaseModel):
     min_value: float | None = None
     max_value: float | None = None
     unit: str | None = None
+    timeout_ms: int = 2000
 
 
 class DynaLabHello(BaseModel):

src/dynalab_core/values.py

@@ -4,17 +4,27 @@
 
 
 from threading import Lock
+from time import monotonic, monotonic_ns
 
 
 class Value:
-    _value: float = 0
-    _last_updated: int = 0
-    _lock: Lock = Lock()
+    def __init__(self, timeout_ms: int) -> None:
+        self._value: float = 0
+        self._last_updated: int = 0
+        self._timeout_ms: int = timeout_ms
+        self._lock: Lock = Lock()
 
-    def update(self, value: float) -> None:
+    def update(self, value: float, timestamp: int) -> None:
         with self._lock:
             self._value = value
+            self._last_updated = timestamp
 
-    def get(self) -> float:
+    def get(self) -> float | None:
+        now = monotonic_ns()
+        if (
+            now > self._last_updated + self._timeout_ms * 1_000_000
+            or self._last_updated == 0
+        ):
+            return None
         with self._lock:
             return self._value

test/manual/peer.py

@@ -4,7 +4,7 @@ import threading
 from concurrent.futures import CancelledError as FutureCancelledError
 from concurrent.futures import TimeoutError as FutureTimeoutError
 from statistics import mean
-from time import monotonic, perf_counter
+from time import monotonic, monotonic_ns, perf_counter
 from uuid import UUID, uuid4
 
 from rich.logging import RichHandler
@@ -117,8 +117,7 @@ def value_sender_thread(
                 next_send_time += period
 
             value = ValueDescriptor(
-                signal_id=signal_id,
-                value=2.0,
+                signal_id=signal_id, value=2.0, timestamp=monotonic_ns()
             )
 
             message = ValueBatch(
@@ -216,9 +215,7 @@ async def perform_handshake(
         connector_version=CONNECTOR_VERSION.get_version(),
         signals=[
             SignalDescriptor(
-                id=signal_id,
-                name="Dummy signal",
-                type="number",
+                id=signal_id, name="Dummy signal", type="number", timeout_ms=5000
             )
         ],
     )