TcpClient¶

class lsst.ts.m2com.TcpClient(host: str, port: int, callback_process_message: Callable[[...], Coroutine], *args: Any, log: Logger | None = None, sequence_generator: Generator | None = None, name: str = 'tcp-client', check_message_rate: bool = False)¶

Bases: Client

TCP/IP client.

Parameters¶

hoststr: Host address.
portint: Port to connect.
callback_process_messagecoroutine: Function to process the received message. It must has a keyward argument of “message” to receive the message as a dictionary.
*argsargs: Arguments needed in “callback_process_message” function call.
loglogging.Logger or None, optional: A logger. If None, a logger will be instantiated. (the default is None)
sequence_generatorgenerator or None, optional: Sequence generator. (the default is None)
namestr, optional: Name of the tcp-client. Used for logging/debugging purposes. The default is “tcp-client”)
check_message_ratebool, optional: Check the message rate or not. If True, the rate of message will be calculated and recorded in the debug logging message. (the default is False)

Attributes¶

loglogging.Logger: A logger.
timeoutfloat: Read timeout in second.
last_sequence_idint: Last sequence ID of command.

Attributes Summary

connected

Return True if self._reader and self._writer are connected.

Methods Summary

`basic_close`()	Close the connected client socket, if any, and set done_task done.
`call_connect_callback`()	Call self.__connect_callback.
`close`()	Cancel the task and close the connection.
`connect`([timeout])	Connect to the server.
`read`(n)	Read up to n bytes.
`read_into`(struct)	Read binary data from a stream reader into a `ctypes.Structure`.
`read_json`()	Read JSON data.
`read_str`()	Read and decode a terminated str; strip the terminator.
`readexactly`(n)	Read exactly n bytes.
`readline`()	Read a sequence of bytes ending with `\n`.
`readuntil`([separator])	Read one line, where “line” is a sequence of bytes ending with `separator`.
`start`(**kwargs)	Connect to the TCP/IP server.
`write`(data)	Write data and call `drain`.
`write_from`(*structs)	Write binary data from one or more `ctypes.Structure`s.
`write_json`(data)	Write data in JSON format.
`write_message`(msg_type, msg_name[, ...])	Writes message to the server.
`write_str`(line)	Encode, terminate, and write a str.
`writelines`(lines)	Write an iterable of bytes and call `drain`.

Attributes Documentation

connected¶

Return True if self._reader and self._writer are connected.

Note: if the other end drops the connection and if you are not trying to read data (e.g. in a background loop), then it takes the operating system awhile to realize the connection is lost. So this can return true for some unknown time after the connection has been dropped.

Methods Documentation

async basic_close() → None¶

Close the connected client socket, if any, and set done_task done.

Like close except does not clear self.should_be_connected, nor cancel self._monitor_connection_task.

async call_connect_callback() → None¶

Call self.__connect_callback.

This is always safe to call. It only calls the callback function if that function is not None and if the connection state has changed since the last time this method was called.

async close() → None¶

Cancel the task and close the connection.

Note: this function is safe to call even though there is no connection.

async connect(timeout: float = 10.0) → None¶

Connect to the server.

Parameters¶

timeoutfloat, optional: Timeout in second. (default is 10.0)

async read(n: int) → bytes¶

Read up to n bytes.

Parameters¶

nint: The number of bytes to read. If -1 then block until the other end closes its writer, then return all data seen.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.

async read_into(struct: Structure) → None¶

Read binary data from a stream reader into a ctypes.Structure.

Parameters¶

structctypes.Structure: Structure to set.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
asyncio.IncompleteReadError: If EOF is reached before n bytes can be read. Use the IncompleteReadError.partial attribute to get the partially read data.

async read_json() → Any¶

Read JSON data.

Read the data with read_str and return the json-decoded result.

Returns¶

datatyping.Any: Data decoded from JSON.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
asyncio.IncompleteReadError: If EOF is reached before the complete separator is found and the internal buffer is reset.
LimitOverrunError: If the amount of data read exceeds the configured stream lmit. The data is left in the internal buffer and can be read again.
TypeError: If the data are of a type that cannot be decoded from JSON.
json.JSONDecodeError: If the data cannot be decoded from JSON.

async read_str() → str¶

Read and decode a terminated str; strip the terminator.

Read until self.terminator, strip the terminator, and decode the data as self.encoding with strict error handling.

Returns¶

linestr: Line of data, as a str with the terminator stripped.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
asyncio.IncompleteReadError: If EOF is reached before the complete separator is found and the internal buffer is reset.
LimitOverrunError: If the amount of data read exceeds the configured stream lmit. The data is left in the internal buffer and can be read again.
UnicodeError: If decoding fails.

async readexactly(n: int) → bytes¶

Read exactly n bytes.

Parameters¶

nint: The number of bytes to read.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
asyncio.IncompleteReadError: If EOF is reached before n bytes can be read. Use the IncompleteReadError.partial attribute to get the partially read data.

async readline() → bytes¶

Read a sequence of bytes ending with \n.

If EOF is received and \n was not found, the method returns partially read data.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.

async readuntil(separator: bytes = b'\n') → bytes¶

Read one line, where “line” is a sequence of bytes ending with separator.

Read data from the stream until separator is found.

On success, the data and separator will be removed from the internal buffer (consumed). Returned data will include the separator at the end.

See also read_str, which is more convenient for most use cases.

Parameters¶

separatorbytes: The desired separator. The default matches the standard library, rather than using terminator.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
asyncio.IncompleteReadError: If EOF is reached before the complete separator is found and the internal buffer is reset.
LimitOverrunError: If the amount of data read exceeds the configured stream lmit. The data is left in the internal buffer and can be read again.

async start(**kwargs: Any) → None¶

Connect to the TCP/IP server.

This is called automatically by the constructor, and is not intended to be called by the user. It is a public method so that subclasses can override it.

Parameters¶

**kwargsdict [str, typing.Any]: Additional keyword arguments for asyncio.open_connection, beyond host and port.

Raises¶

RuntimeError: If start already called.

async write(data: bytes) → None¶

Write data and call drain.

Parameters¶

databytes: The data to write.

Raises¶

ConnectionError: If self.connected false before writing begins.

async write_from(*structs: Structure) → None¶

Write binary data from one or more ctypes.Structures.

Parameters¶

structslist [ctypes.Structure]: Structures to write.

Raises¶

ConnectionError: If self.connected false before writing begins.

async write_json(data: Any) → None¶

Write data in JSON format.

Encode the data as json and write the result with write_str.

Parameters¶

dataany: The data to be written, typically a dict, but any json-encodable data is acceptable.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
UnicodeError: If encoding fails.
json.JSONEncodeError: If the data cannot be json-encoded.

async write_message(msg_type: MsgType, msg_name: str, msg_details: dict | None = None, comp_name: str | None = None) → None¶

Writes message to the server.

Parameters¶

msg_typeenum MsgType: Message type.
msg_namestr: Message name.
msg_detailsdict or None, optional: Message details. (the default is None)
comp_namestr or None, optional: Specific component name used in the event or telemetry. (the default is None)

Raises¶

RuntimeError: When there is no TCP/IP connection.
ValueError: If ‘id’ is in the message details already.
ValueError: When the message type is not supported.

async write_str(line: str) → None¶

Encode, terminate, and write a str.

Encode the str as self.encoding with strict error handling, and append self.terminator.

Parameters¶

linestr: The line of data to be written.

Raises¶

ConnectionError: If the connection is lost before, or while, reading.
UnicodeError: If encoding fails.

async writelines(lines: Iterable) → None¶

Write an iterable of bytes and call drain.

Parameters¶

linescollections.abc.Iterable [bytes]: The data to write, as an iterable collection of bytes.

Raises¶

ConnectionError: If self.connected false before writing begins.

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