fix: Retry on timeout (#4)

Author: victor-tutor

examples/example.py

@@ -3,10 +3,7 @@
 from aiosocks import Socks5Addr
 
 from tcp_modbus_aio.client import TCPModbusClient
-from tcp_modbus_aio.exceptions import (
-    ModbusCommunicationFailureError,
-    ModbusCommunicationTimeoutError,
-)
+from tcp_modbus_aio.exceptions import ModbusCommunicationFailureError
 from tcp_modbus_aio.typed_functions import ReadCoils
 
 DIGITAL_IN_COILS = list(range(8))
@@ -32,8 +29,6 @@ async def example() -> None:
                     )
                     assert response is not None, "we expect a response from ReadCoils"
                     print(response.data)  # noqa: T201
-                except ModbusCommunicationTimeoutError as e:
-                    print(f"{type(e).__name__}({e})")
                 except ModbusCommunicationFailureError as e:
                     print(f"{type(e).__name__}({e})")
 

tcp_modbus_aio/client.py

@@ -13,7 +13,7 @@
 
 from tcp_modbus_aio.exceptions import (
     ModbusCommunicationFailureError,
-    ModbusCommunicationTimeoutError,
+    ModbusConcurrencyError,
     ModbusNotConnectedError,
 )
 from tcp_modbus_aio.ping import ping_ip
@@ -57,7 +57,6 @@ class TCPModbusClient:
     KEEPALIVE_MAX_FAILS: ClassVar = 5
 
     PING_LOOP_PERIOD: ClassVar = 1
-    CONSECUTIVE_TIMEOUTS_TO_RECONNECT: ClassVar = 5
     COOLDOWN_BEFORE_RECONNECTING_SEC: ClassVar = 0.01
 
     def __init__(
@@ -90,9 +89,6 @@ def __init__(
         self._reader: asyncio.StreamReader | None = None
         self._writer: asyncio.StreamWriter | None = None
 
-        # Number of current consecutive modbus calls that resulted in a timeout
-        self._consecutive_timeouts = 0
-
         # Last ping time in seconds from ping loop, or None if the last ping failed
         self._last_ping: float | None = None
 
@@ -192,7 +188,7 @@ async def _get_tcp_connection(
             )
             if self.logger is not None:
                 self.logger.warning(f"[{self}][_get_tcp_connection] {msg}")
-            raise ModbusCommunicationTimeoutError(msg)
+            raise ModbusCommunicationFailureError(msg)
         except OSError:
             msg = f"Cannot connect to TCP modbus device at {self.host}:{self.port}"
             if self.logger is not None:
@@ -447,7 +443,7 @@ async def send_modbus_message(
                     self._comms_lock.acquire(), time_budget_remaining
                 )
             except asyncio.TimeoutError:
-                raise ModbusCommunicationTimeoutError(
+                raise ModbusConcurrencyError(
                     f"Failed to acquire lock to send request {msg_str} to modbus device {self.host}"
                 )
         time_budget_remaining -= lock_t()
@@ -515,20 +511,7 @@ async def send_modbus_message(
                     return None
 
                 raise
-        except asyncio.TimeoutError as e:
-            self._consecutive_timeouts += 1
-            if self._consecutive_timeouts >= self.CONSECUTIVE_TIMEOUTS_TO_RECONNECT:
-                if self.logger is not None:
-                    self.logger.warning(
-                        f"[{self}][send_modbus_message] {self._consecutive_timeouts} consecutive timeouts, "
-                        "clearing connection"
-                    )
-                self.clear_tcp_connection()
-
-            raise ModbusCommunicationTimeoutError(
-                f"Request {msg_str} timed out to {self.host}:{self.port}"
-            ) from e
-        except (OSError, EOFError) as e:
+        except (OSError, EOFError, asyncio.TimeoutError) as e:
             if self.logger is not None:
                 self.logger.warning(
                     f"[{self}][send_modbus_message] {type(e).__name__}({e}) while sending request {msg_str}, "

tcp_modbus_aio/exceptions.py

@@ -4,16 +4,10 @@
 class ModbusCommunicationFailureError(ModbusError):
     """Generic modbus communication error."""
 
-    pass
 
-
-class ModbusCommunicationTimeoutError(ModbusCommunicationFailureError):
-    """Timeout in communicating with modbus device."""
-
-    pass
+class ModbusConcurrencyError(ModbusError):
+    """Too many concurrent requests"""
 
 
 class ModbusNotConnectedError(ModbusCommunicationFailureError):
     """Modbus not connected error."""
-
-    pass