TelemetryClient

class lsst.ts.mtmount.TelemetryClient(host, port=50035, connection_timeout=10)

Bases: Client

Read telemetry data from the TMA and publish as SAL messages.

Notes

Methods with the name “_preprocess_{sal_topic_name}” are used to tweak telemetry data. They receive one argument: the raw telemetry data as a dict, and must modify it “in place”.

Attributes Summary

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

Methods Summary

amain()
basic_close()	Close the connected client socket, if any, and set done_task done.
call_connect_callback()	Call self.__connect_callback.
close()	Close the connected client socket, if any, and set done_task done.
connect_callback(client)
get_preprocessor(sal_topic_name)	Get the preprocessor for this topic, if it exists, else None.
heartbeat_loop()	Output telemetryClientHeartbeat telemetry at regular intervals.
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_loop()	Read and process status from the low-level controller.
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.
signal_handler()	Handle signals such as SIGTERM.
start()	Connect to the telemetry port and start the read loop.
write(data)	Write data and call drain.
write_from(*structs)	Write binary data from one or more ctypes.Structures.
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.

on_drive_states = frozenset({'Discrete Motion', 'Standstill', 'Stopping'})

Methods Documentation

async classmethod amain()

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

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

Call connect_callback if a client was connected.

async connect_callback(client)

get_preprocessor(sal_topic_name)

Get the preprocessor for this topic, if it exists, else None.

Parameters:

sal_topic_namestr

Name of SAL telemetry topic, e.g. “tel_azimuthDrives”.

async heartbeat_loop()

Output telemetryClientHeartbeat telemetry at regular intervals.

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_loop()

Read and process status from the low-level controller.

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.

signal_handler()

Handle signals such as SIGTERM.

async start()

Connect to the telemetry port and start the read loop.

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.