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