Added commands module.

This commit is contained in:
Fabio Manganiello 2023-08-13 23:21:36 +02:00
parent 97adc3f775
commit efef9d7bc0
Signed by untrusted user: blacklight
GPG key ID: D90FBA7F76362774
4 changed files with 172 additions and 0 deletions

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from abc import ABC, abstractmethod
import json
from logging import getLogger, Logger
class Command(ABC):
"""
Base class for application commands.
"""
END_OF_COMMAND = b'\x00'
"""End-of-command marker."""
def __init__(self, **args) -> None:
self.args = args
@property
def logger(self) -> Logger:
"""
The command class logger.
"""
return getLogger(self.__class__.__name__)
@abstractmethod
def __call__(self, app, *_, **__):
"""
Execute the command.
"""
raise NotImplementedError()
def __str__(self) -> str:
"""
:return: A JSON representation of the command.
"""
return json.dumps(
{
'type': 'command',
'command': self.__class__.__name__,
'args': self.args,
}
)
def to_bytes(self):
"""
:return: A JSON representation of the command.
"""
return str(self).encode('utf-8') + self.END_OF_COMMAND
@classmethod
def parse(cls, data: bytes) -> "Command":
"""
:param data: A JSON representation of the command.
:raise ValueError: If the data is invalid.
:return: The command instance or None if the data is invalid.
"""
import platypush.commands
try:
json_data = json.loads(data.decode('utf-8'))
except json.JSONDecodeError as e:
raise ValueError from e
kind = json_data.pop('type', None)
if kind != 'command':
raise ValueError(f'Invalid command type: {kind}')
command_name = json_data.get('command')
if not command_name:
raise ValueError(f'Invalid command name: {command_name}')
cmd_class = getattr(platypush.commands, command_name, None)
if not (cmd_class and issubclass(cmd_class, Command)):
raise ValueError(f'Invalid command class: {command_name}')
try:
return cmd_class(**json_data.get('args', {}))
except Exception as e:
raise ValueError(e) from e

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from logging import getLogger
from socket import socket
from typing import Optional
from platypush.commands import Command
# pylint: disable=too-few-public-methods
class CommandReader:
"""
Reads command objects from file-like I/O objects.
"""
_max_bufsize = 8192
"""Maximum size of a command that can be queued in the stream."""
_bufsize = 1024
"""Size of the buffer used to read commands from the socket."""
def __init__(self):
self.logger = getLogger(__name__)
self._buf = bytes()
def _parse_command(self, data: bytes) -> Optional[Command]:
"""
Parses a command from the received data.
:param data: Data received from the socket
:return: The parsed command
"""
try:
return Command.parse(data)
except ValueError as e:
self.logger.warning('Error while parsing command: %s', e)
return None
def read(self, sock: socket) -> Optional[Command]:
"""
Parses the next command from the file-like I/O object.
:param fp: The file-like I/O object to read from.
:return: The parsed command.
"""
try:
data = sock.recv(self._bufsize)
except OSError as e:
self.logger.warning(
'Error while reading from socket %s: %s', sock.getsockname(), e
)
return None
for ch in data:
if bytes([ch]) == Command.END_OF_COMMAND:
cmd = self._parse_command(self._buf)
self._buf = bytes()
if cmd:
return cmd
elif len(self._buf) >= self._max_bufsize:
self.logger.warning(
'The received command is too long: length=%d', len(self._buf)
)
self._buf = bytes()
break
else:
self._buf += bytes([ch])
return None

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from logging import getLogger
from socket import socket
from platypush.commands import Command
# pylint: disable=too-few-public-methods
class CommandWriter:
"""
Writes command objects to file-like I/O objects.
"""
def __init__(self):
self.logger = getLogger(__name__)
def write(self, cmd: Command, sock: socket):
"""
Writes a command to a file-like I/O object.
:param cmd: The command to write.
:param fp: The file-like I/O object to write to.
"""
buf = cmd.to_bytes()
sock.sendall(buf)