SocketServer¶

class lsst.ts.ess.common.SocketServer(name: str, host: None | str, port: int, log: Logger, simulation_mode: int = 0, connect_callback: None | Callable[[BaseClientOrServer], Awaitable[None]] = None)¶

Bases: OneClientReadLoopServer

A socket server for exchanging JSON messages via TCP/IP.

See tcpip.OneClientReadLoopServer for the inner workings.

Parameters:

namestr: The name of the socket server.
hoststr or None: IP address for this server. If None then bind to all network interfaces.
portint: IP port for this server. If 0 then use a random port.
simulation_modeint, optional: Simulation mode. The default is 0: do not simulate.

Attributes Summary

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

Methods Summary

`basic_close_client`()	Close the connected client socket, if any.
`call_connect_callback`()	A client has connected or disconnected.
`close`()	Close socket server and client socket, and set done_task done.
`close_client`(**kwargs)	Stop sending telemetry and close the client.
`handle_received_heartbeat`()	Handle a received heartbeat.
`monitor_received_heartbeats`()	Monitor received heartbeats.
`read`(n)	Read up to n bytes.
`read_and_dispatch`()	Read, parse, and dispatch one item of data.
`read_into`(struct)	Read binary data from a stream reader into a `ctypes.Structure`.
`read_json`()	Read JSON data.
`read_loop`()	Read incoming data and handle them.
`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`.
`set_command_handler`(command_handler)	Set the command handler instance to use.
`start`(**kwargs)	Start 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_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.

valid_simulation_modes = (0, 1)¶

Methods Documentation

async basic_close_client() → None¶

Close the connected client socket, if any.

Also:

Reset self.connected_task to a new Future.
Call connect_callback, if a client was connected.

Unlike close_client, this does not touch self.should_be_connected.

Always safe to call.

async call_connect_callback() → None¶: A client has connected or disconnected.

async close() → None¶

Close socket server and client socket, and set done_task done.

Call connect_callback if a client was connected.

Always safe to call.

async close_client(**kwargs: Any) → None¶: Stop sending telemetry and close the client.

async handle_received_heartbeat() → None¶

Handle a received heartbeat.

Raises:

RuntimeError: In case a heartbeat is received but run_heartbeat_monitor_task is False.

async monitor_received_heartbeats() → None¶

Monitor received heartbeats.

Assume that the connection has dropped if no heartbeat was received for too long.

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_and_dispatch() → None¶

Read, parse, and dispatch one item of data.

Subclasses need to implement this method such that it reads and parses data and then dispatches handling the data to a method suitable for the subclass. Methods that might be helpful include:

read_json to read json-encoded data
read_str to read terminated strings
read_into to read binary structs

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_loop() → None¶

Read incoming data and handle them.

The actual reading is deferred to the read_and_dispatch method and needs to be implemented by subclasses.

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.

set_command_handler(command_handler: AbstractCommandHandler) → None¶

Set the command handler instance to use. All code using this SocketServer class must call this at least once before sending commands.

Parameters:

command_handlerAbstractCommandHandler: The command handler instance to use.

async start(**kwargs: Any) → None¶

Start 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.start_server, beyond host and port.

Raises:

RuntimeError: If start has already been called and has successfully constructed a server.

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_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.

Navigation

SocketServer¶