from threading import Thread from queue import Queue from os import mkfifo, remove, getpid, kill from os.path import exists, join from signal import SIGTERM from secrets import token_urlsafe from collections import namedtuple from abc import ABC, abstractmethod from traceback import print_exc class PipeWriterThread(Thread): def __init__(self, pipe_path): super().__init__() self._pipe_path = pipe_path self._write_queue = Queue() def write(self, message): self._write_queue.put(message, block=True) def run(self): while True: message = self._write_queue.get(block=True) if message is None: break with open(self._pipe_path, 'wb') as pipe: pipe.write(message) def stop(self): self._write_queue.put(None) self.join() class PipeReaderThread(Thread): _stop_sequence = b'stop_reading' def __init__(self, pipe_path, message_handler): super().__init__() self._message_handler = message_handler self._pipe_path = pipe_path def run(self): while True: with open(self._pipe_path, 'rb') as pipe: message = pipe.read() if message == self._stop_sequence: break try: self._message_handler(message) except: print_exc() kill(getpid(), SIGTERM) def stop(self): with open(self._pipe_path, 'wb') as pipe: pipe.write(self._stop_sequence) self.join() class PipeHandler: def __init__(self, *pipe_paths): self._pipe_paths = pipe_paths def recreate(self): self.remove() for pipe_path in self._pipe_paths: mkfifo(pipe_path) def remove(self): for pipe_path in self._pipe_paths: if exists(pipe_path): remove(pipe_path) class PipeIOServer(ABC): def __init__(self, in_pipe=None, out_pipe=None): self.in_pipe, self.out_pipe = in_pipe, out_pipe self._create_pipes() io_threads_dict = { 'reader': PipeReaderThread(self.in_pipe, self._handle_message), 'writer': PipeWriterThread(self.out_pipe) } IOThreadsTuple = namedtuple('IOThreadsTuple', sorted(io_threads_dict.keys())) self._io_threads = IOThreadsTuple(**io_threads_dict) def _create_pipes(self): if not self.in_pipe or not self.out_pipe: pipe_id = token_urlsafe(6) self.in_pipe = join('/tmp', f'in_pipe_{pipe_id}') self.out_pipe = join('/tmp', f'out_pipe_{pipe_id}') PipeHandler(self.in_pipe, self.out_pipe).recreate() @abstractmethod def _handle_message(self, message): raise NotImplementedError() def send(self, message): self._io_threads.writer.write(message) def run(self): for thread in self._io_threads: thread.start() def stop(self): for thread in self._io_threads: thread.stop() PipeHandler(self.in_pipe, self.out_pipe).remove()