working server and client

src/asyncio_taskpool/server.py

@@ -0,0 +1,115 @@
+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 TaskPool
+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):
+    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: TaskPool, **server_kwargs) -> None:
+        self._pool: TaskPool = pool
+        self._server_kwargs = server_kwargs
+        self._server: Optional[AbstractServer] = None
+
+    def _start_tasks(self, num: int, writer: StreamWriter) -> None:
+        log.debug("Client requests starting %s tasks", num)
+        self._pool.start(num)
+        size = self._pool.size
+        writer.write(f"{num} new {tasks_str(num)} started! {size} {tasks_str(size)} active now.".encode())
+
+    def _stop_tasks(self, num: int, writer: StreamWriter) -> None:
+        log.debug("Client requests stopping %s tasks", num)
+        num = self._pool.stop(num)  # the requested number may be greater than the total number of running tasks
+        size = self._pool.size
+        writer.write(f"{num} {tasks_str(num)} stopped! {size} {tasks_str(size)} left.".encode())
+
+    def _stop_all_tasks(self, writer: StreamWriter) -> None:
+        log.debug("Client requests stopping all tasks")
+        num = self._pool.stop_all()
+        writer.write(f"Remaining {num} {tasks_str(num)} stopped!".encode())
+
+    async def _client_connected_cb(self, reader: StreamReader, writer: StreamWriter) -> None:
+        log.debug("%s connected", self.client_class.__name__)
+        writer.write(f"{self.__class__.__name__} for {self._pool}".encode())
+        await writer.drain()
+        while True:
+            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:
+                self._start_tasks(arg, writer)
+            elif cmd == constants.CMD_STOP:
+                self._stop_tasks(arg, writer)
+            elif cmd == constants.CMD_STOP_ALL:
+                self._stop_all_tasks(writer)
+            else:
+                log.debug("%s sent invalid command: %s", self.client_class.__name__, msg)
+                writer.write(b"Invalid command!")
+            await writer.drain()
+
+    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: TaskPool, **server_kwargs) -> None:
+        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))