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Merge pull request #469 from canton7/feature/custom-serial
Work around bug in pyserial's PosixPollSerial
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custom_components/foxess_modbus/client/custom_modbus_tcp_client.py
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,113 @@ | ||
| import logging | ||
| import select | ||
| import socket | ||
| import time | ||
| from typing import Any | ||
| from typing import cast | ||
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| from pymodbus.client import ModbusTcpClient | ||
| from pymodbus.exceptions import ConnectionException | ||
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| _LOGGER = logging.getLogger(__name__) | ||
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| class CustomModbusTcpClient(ModbusTcpClient): | ||
| """Custom ModbusTcpClient subclass with some hacks""" | ||
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| def __init__(self, delay_on_connect: int | None, **kwargs: Any) -> None: | ||
| super().__init__(**kwargs) | ||
| self._delay_on_connect = delay_on_connect | ||
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| def connect(self) -> bool: | ||
| was_connected = self.socket is not None | ||
| if not was_connected: | ||
| _LOGGER.debug("Connecting to %s", self.params) | ||
| is_connected = cast(bool, super().connect()) | ||
| # pymodbus doesn't disable Nagle's algorithm. This slows down reads quite substantially as the | ||
| # TCP stack waits to see if we're going to send anything else. Disable it ourselves. | ||
| if not was_connected and is_connected: | ||
| assert self.socket is not None | ||
| self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True) | ||
| if self._delay_on_connect is not None: | ||
| time.sleep(self._delay_on_connect) | ||
| return is_connected | ||
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| # Replacement of ModbusTcpClient to use poll rather than select, see | ||
| # https://github.com/nathanmarlor/foxess_modbus/issues/275 | ||
| def recv(self, size: int) -> bytes: | ||
| """Read data from the underlying descriptor.""" | ||
| super(ModbusTcpClient, self).recv(size) | ||
| if not self.socket: | ||
| raise ConnectionException(str(self)) | ||
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| # socket.recv(size) waits until it gets some data from the host but | ||
| # not necessarily the entire response that can be fragmented in | ||
| # many packets. | ||
| # To avoid split responses to be recognized as invalid | ||
| # messages and to be discarded, loops socket.recv until full data | ||
| # is received or timeout is expired. | ||
| # If timeout expires returns the read data, also if its length is | ||
| # less than the expected size. | ||
| self.socket.setblocking(0) | ||
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| # In the base method this is 'timeout = self.comm_params.timeout', but that changed from 'self.params.timeout' | ||
| # in 3.4.1. So we don't have a consistent way to access the timeout. | ||
| # However, this just mirrors what we set, which is the default of 3s. So use that. | ||
| # Annoyingly 3.4.1 | ||
| timeout = 3 | ||
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| # If size isn't specified read up to 4096 bytes at a time. | ||
| if size is None: | ||
| recv_size = 4096 | ||
| else: | ||
| recv_size = size | ||
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| data: list[bytes] = [] | ||
| data_length = 0 | ||
| time_ = time.time() | ||
| end = time_ + timeout | ||
| poll = select.poll() | ||
| # We don't need to call poll.unregister, since we're deallocing the poll. register just adds the socket to a | ||
| # dict owned by the poll object (the underlying syscall has no concept of register/unregister, and just takes an | ||
| # array of fds to poll). If we hit a disconnection the socket.fileno() becomes -1 anyway, so unregistering will | ||
| # fail | ||
| poll.register(self.socket, select.POLLIN) | ||
| while recv_size > 0: | ||
| poll_res = poll.poll(end - time_) | ||
| # We expect a single-element list if this succeeds, or an empty list if it timed out | ||
| if len(poll_res) > 0: | ||
| if (recv_data := self.socket.recv(recv_size)) == b"": | ||
| return self._handle_abrupt_socket_close( # type: ignore[no-any-return] | ||
| size, data, time.time() - time_ | ||
| ) | ||
| data.append(recv_data) | ||
| data_length += len(recv_data) | ||
| time_ = time.time() | ||
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| # If size isn't specified continue to read until timeout expires. | ||
| if size: | ||
| recv_size = size - data_length | ||
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| # Timeout is reduced also if some data has been received in order | ||
| # to avoid infinite loops when there isn't an expected response | ||
| # size and the slave sends noisy data continuously. | ||
| if time_ > end: | ||
| break | ||
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| return b"".join(data) | ||
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| # Replacement of ModbusTcpClient to use poll rather than select, see | ||
| # https://github.com/nathanmarlor/foxess_modbus/issues/275 | ||
| def _check_read_buffer(self) -> bytes | None: | ||
| """Check read buffer.""" | ||
| time_ = time.time() | ||
| end = time_ + self.params.timeout | ||
| data = None | ||
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| assert self.socket is not None | ||
| poll = select.poll() | ||
| poll.register(self.socket, select.POLLIN) | ||
| poll_res = poll.poll(end - time_) | ||
| if len(poll_res) > 0: | ||
| data = self.socket.recv(1024) | ||
| return data |
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76
custom_components/foxess_modbus/client/protocol_pollserial.py
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| """ | ||
| Custom protocol handler for pyserial, which uses poll but doesn't have | ||
| https://github.com/pyserial/pyserial/issues/617 | ||
| """ | ||
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| import os | ||
| import select | ||
| from enum import Enum | ||
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| import serial | ||
| from serial import serialposix | ||
| from serial.serialutil import PortNotOpenError | ||
| from serial.serialutil import SerialException | ||
| from serial.serialutil import Timeout | ||
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| class _PollResult(Enum): | ||
| TIMEOUT = 0 | ||
| ABORT = 1 | ||
| DATA = 2 | ||
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| class Serial(serialposix.Serial): | ||
| """ | ||
| From https://github.com/pyserial/pyserial/blob/7aeea35429d15f3eefed10bbb659674638903e3a/serial/serialposix.py, | ||
| but with https://github.com/pyserial/pyserial/pull/618 applied | ||
| """ | ||
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| @serial.Serial.port.setter # type: ignore | ||
| def port(self, value: str) -> None: | ||
| if value is not None: | ||
| serial.Serial.port.__set__(self, value.removeprefix("pollserial://")) | ||
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| def read(self, size: int = 1) -> bytes: | ||
| """\ | ||
| Read size bytes from the serial port. If a timeout is set it may | ||
| return less characters as requested. With no timeout it will block | ||
| until the requested number of bytes is read. | ||
| """ | ||
| if not self.is_open: | ||
| raise PortNotOpenError() | ||
| read = bytearray() | ||
| timeout = Timeout(self._timeout) | ||
| poll = select.poll() | ||
| poll.register(self.fd, select.POLLIN | select.POLLERR | select.POLLHUP | select.POLLNVAL) | ||
| poll.register(self.pipe_abort_read_r, select.POLLIN | select.POLLERR | select.POLLHUP | select.POLLNVAL) | ||
| if size > 0: | ||
| while len(read) < size: | ||
| # wait until device becomes ready to read (or something fails) | ||
| result = _PollResult.TIMEOUT # In case poll returns an empty list | ||
| for fd, event in poll.poll(None if timeout.is_infinite else (timeout.time_left() * 1000)): | ||
| if fd == self.pipe_abort_read_r: | ||
| os.read(self.pipe_abort_read_r, 1000) | ||
| result = _PollResult.ABORT | ||
| break | ||
| if event & (select.POLLERR | select.POLLHUP | select.POLLNVAL): | ||
| raise SerialException("device reports error (poll)") | ||
| result = _PollResult.DATA | ||
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| if result == _PollResult.DATA: | ||
| buf = os.read(self.fd, size - len(read)) | ||
| read.extend(buf) | ||
| if ( | ||
| result == _PollResult.TIMEOUT | ||
| or result == _PollResult.ABORT | ||
| or timeout.expired() | ||
| or (self._inter_byte_timeout is not None and self._inter_byte_timeout > 0) | ||
| and not buf | ||
| ): | ||
| break # early abort on timeout | ||
| return bytes(read) | ||
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| # This needs to have a very particular name, as it's registered by string in modbus_client | ||
| assert Serial.__module__ == "custom_components.foxess_modbus.client.protocol_pollserial" | ||
| assert Serial.__name__ == "Serial" |
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