asyncio-taskpool/src/asyncio_taskpool/server.py

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import logging
from abc import ABC, abstractmethod
from asyncio import AbstractServer
from asyncio.exceptions import CancelledError
from asyncio.streams import StreamReader, StreamWriter, start_unix_server
from asyncio.tasks import Task, create_task
from pathlib import Path
from typing import Tuple, Union, Optional
from . import constants
from .pool import SimpleTaskPool
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from .client import ControlClient, UnixControlClient
log = logging.getLogger(__name__)
def tasks_str(num: int) -> str:
return "tasks" if num != 1 else "task"
def get_cmd_arg(msg: str) -> Union[Tuple[str, Optional[int]], Tuple[None, None]]:
cmd = msg.strip().split(' ', 1)
if len(cmd) > 1:
try:
return cmd[0], int(cmd[1])
except ValueError:
return None, None
return cmd[0], None
class ControlServer(ABC): # TODO: Implement interface for normal TaskPool instances, not just SimpleTaskPool
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client_class = ControlClient
@abstractmethod
async def get_server_instance(self, client_connected_cb, **kwargs) -> AbstractServer:
raise NotImplementedError
@abstractmethod
def final_callback(self) -> None:
raise NotImplementedError
def __init__(self, pool: SimpleTaskPool, **server_kwargs) -> None:
self._pool: SimpleTaskPool = pool
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self._server_kwargs = server_kwargs
self._server: Optional[AbstractServer] = None
async def _start_tasks(self, writer: StreamWriter, num: int = None) -> None:
if num is None:
num = 1
log.debug("%s requests starting %s %s", self.client_class.__name__, num, tasks_str(num))
writer.write(str(await self._pool.start(num)).encode())
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def _stop_tasks(self, writer: StreamWriter, num: int = None) -> None:
if num is None:
num = 1
log.debug("%s requests stopping %s %s", self.client_class.__name__, num, tasks_str(num))
# the requested number may be greater than the total number of running tasks
writer.write(str(self._pool.stop(num)).encode())
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def _stop_all_tasks(self, writer: StreamWriter) -> None:
log.debug("%s requests stopping all tasks", self.client_class.__name__)
writer.write(str(self._pool.stop_all()).encode())
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def _pool_size(self, writer: StreamWriter) -> None:
log.debug("%s requests pool size", self.client_class.__name__)
writer.write(str(self._pool.size).encode())
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def _pool_func(self, writer: StreamWriter) -> None:
log.debug("%s requests pool function", self.client_class.__name__)
writer.write(self._pool.func_name.encode())
async def _listen(self, reader: StreamReader, writer: StreamWriter) -> None:
while self._server.is_serving():
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msg = (await reader.read(constants.MSG_BYTES)).decode().strip()
if not msg:
log.debug("%s disconnected", self.client_class.__name__)
break
cmd, arg = get_cmd_arg(msg)
if cmd == constants.CMD_START:
await self._start_tasks(writer, arg)
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elif cmd == constants.CMD_STOP:
self._stop_tasks(writer, arg)
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elif cmd == constants.CMD_STOP_ALL:
self._stop_all_tasks(writer)
elif cmd == constants.CMD_SIZE:
self._pool_size(writer)
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elif cmd == constants.CMD_FUNC:
self._pool_func(writer)
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else:
log.debug("%s sent invalid command: %s", self.client_class.__name__, msg)
writer.write(b"Invalid command!")
await writer.drain()
async def _client_connected_cb(self, reader: StreamReader, writer: StreamWriter) -> None:
log.debug("%s connected", self.client_class.__name__)
writer.write(str(self._pool).encode())
await writer.drain()
await self._listen(reader, writer)
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async def _serve_forever(self) -> None:
try:
async with self._server:
await self._server.serve_forever()
except CancelledError:
log.debug("%s stopped", self.__class__.__name__)
finally:
self.final_callback()
async def serve_forever(self) -> Task:
log.debug("Starting %s...", self.__class__.__name__)
self._server = await self.get_server_instance(self._client_connected_cb, **self._server_kwargs)
return create_task(self._serve_forever())
class UnixControlServer(ControlServer):
client_class = UnixControlClient
def __init__(self, pool: SimpleTaskPool, **server_kwargs) -> None:
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self._socket_path = Path(server_kwargs.pop('path'))
super().__init__(pool, **server_kwargs)
async def get_server_instance(self, client_connected_cb, **kwargs) -> AbstractServer:
srv = await start_unix_server(client_connected_cb, self._socket_path, **kwargs)
log.debug("Opened socket '%s'", str(self._socket_path))
return srv
def final_callback(self) -> None:
self._socket_path.unlink()
log.debug("Removed socket '%s'", str(self._socket_path))