name : resource_sharer.py # # We use a background thread for sharing fds on Unix, and for sharing sockets on # Windows. # # A client which wants to pickle a resource registers it with the resource # sharer and gets an identifier in return. The unpickling process will connect # to the resource sharer, sends the identifier and its pid, and then receives # the resource. # import os import signal import socket import sys import threading from . import process from .context import reduction from . import util __all__ = ['stop'] if sys.platform == 'win32': __all__ += ['DupSocket'] class DupSocket(object): '''Picklable wrapper for a socket.''' def __init__(self, sock): new_sock = sock.dup() def send(conn, pid): share = new_sock.share(pid) conn.send_bytes(share) self._id = _resource_sharer.register(send, new_sock.close) def detach(self): '''Get the socket. This should only be called once.''' with _resource_sharer.get_connection(self._id) as conn: share = conn.recv_bytes() return socket.fromshare(share) else: __all__ += ['DupFd'] class DupFd(object): '''Wrapper for fd which can be used at any time.''' def __init__(self, fd): new_fd = os.dup(fd) def send(conn, pid): reduction.send_handle(conn, new_fd, pid) def close(): os.close(new_fd) self._id = _resource_sharer.register(send, close) def detach(self): '''Get the fd. This should only be called once.''' with _resource_sharer.get_connection(self._id) as conn: return reduction.recv_handle(conn) class _ResourceSharer(object): '''Manager for resouces using background thread.''' def __init__(self): self._key = 0 self._cache = {} self._old_locks = [] self._lock = threading.Lock() self._listener = None self._address = None self._thread = None util.register_after_fork(self, _ResourceSharer._afterfork) def register(self, send, close): '''Register resource, returning an identifier.''' with self._lock: if self._address is None: self._start() self._key += 1 self._cache[self._key] = (send, close) return (self._address, self._key) @staticmethod def get_connection(ident): '''Return connection from which to receive identified resource.''' from .connection import Client address, key = ident c = Client(address, authkey=process.current_process().authkey) c.send((key, os.getpid())) return c def stop(self, timeout=None): '''Stop the background thread and clear registered resources.''' from .connection import Client with self._lock: if self._address is not None: c = Client(self._address, authkey=process.current_process().authkey) c.send(None) c.close() self._thread.join(timeout) if self._thread.is_alive(): util.sub_warning('_ResourceSharer thread did ' 'not stop when asked') self._listener.close() self._thread = None self._address = None self._listener = None for key, (send, close) in self._cache.items(): close() self._cache.clear() def _afterfork(self): for key, (send, close) in self._cache.items(): close() self._cache.clear() # If self._lock was locked at the time of the fork, it may be broken # -- see issue 6721. Replace it without letting it be gc'ed. self._old_locks.append(self._lock) self._lock = threading.Lock() if self._listener is not None: self._listener.close() self._listener = None self._address = None self._thread = None def _start(self): from .connection import Listener assert self._listener is None util.debug('starting listener and thread for sending handles') self._listener = Listener(authkey=process.current_process().authkey) self._address = self._listener.address t = threading.Thread(target=self._serve) t.daemon = True t.start() self._thread = t def _serve(self): if hasattr(signal, 'pthread_sigmask'): signal.pthread_sigmask(signal.SIG_BLOCK, range(1, signal.NSIG)) while 1: try: with self._listener.accept() as conn: msg = conn.recv() if msg is None: break key, destination_pid = msg send, close = self._cache.pop(key) try: send(conn, destination_pid) finally: close() except: if not util.is_exiting(): sys.excepthook(*sys.exc_info()) _resource_sharer = _ResourceSharer() stop = _resource_sharer.stop