1142 lines
39 KiB
Python
1142 lines
39 KiB
Python
"""Selector event loop for Unix with signal handling."""
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import errno
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import io
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import os
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import selectors
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import signal
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import socket
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import stat
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import subprocess
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import sys
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import threading
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import warnings
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from . import base_events
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from . import base_subprocess
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from . import constants
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from . import coroutines
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from . import events
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from . import futures
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from . import selector_events
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from . import tasks
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from . import transports
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from .log import logger
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__all__ = (
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'SelectorEventLoop',
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'AbstractChildWatcher', 'SafeChildWatcher',
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'FastChildWatcher', 'DefaultEventLoopPolicy',
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)
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if sys.platform == 'win32': # pragma: no cover
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raise ImportError('Signals are not really supported on Windows')
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def _sighandler_noop(signum, frame):
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"""Dummy signal handler."""
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pass
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class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
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"""Unix event loop.
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Adds signal handling and UNIX Domain Socket support to SelectorEventLoop.
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"""
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def __init__(self, selector=None):
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super().__init__(selector)
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self._signal_handlers = {}
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def close(self):
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super().close()
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if not sys.is_finalizing():
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for sig in list(self._signal_handlers):
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self.remove_signal_handler(sig)
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else:
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if self._signal_handlers:
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warnings.warn(f"Closing the loop {self!r} "
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f"on interpreter shutdown "
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f"stage, skipping signal handlers removal",
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ResourceWarning,
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source=self)
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self._signal_handlers.clear()
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def _process_self_data(self, data):
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for signum in data:
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if not signum:
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# ignore null bytes written by _write_to_self()
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continue
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self._handle_signal(signum)
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def add_signal_handler(self, sig, callback, *args):
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"""Add a handler for a signal. UNIX only.
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Raise ValueError if the signal number is invalid or uncatchable.
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Raise RuntimeError if there is a problem setting up the handler.
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"""
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if (coroutines.iscoroutine(callback) or
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coroutines.iscoroutinefunction(callback)):
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raise TypeError("coroutines cannot be used "
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"with add_signal_handler()")
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self._check_signal(sig)
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self._check_closed()
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try:
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# set_wakeup_fd() raises ValueError if this is not the
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# main thread. By calling it early we ensure that an
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# event loop running in another thread cannot add a signal
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# handler.
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signal.set_wakeup_fd(self._csock.fileno())
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except (ValueError, OSError) as exc:
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raise RuntimeError(str(exc))
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handle = events.Handle(callback, args, self, None)
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self._signal_handlers[sig] = handle
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try:
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# Register a dummy signal handler to ask Python to write the signal
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# number in the wakup file descriptor. _process_self_data() will
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# read signal numbers from this file descriptor to handle signals.
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signal.signal(sig, _sighandler_noop)
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# Set SA_RESTART to limit EINTR occurrences.
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signal.siginterrupt(sig, False)
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except OSError as exc:
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del self._signal_handlers[sig]
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if not self._signal_handlers:
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try:
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signal.set_wakeup_fd(-1)
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except (ValueError, OSError) as nexc:
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logger.info('set_wakeup_fd(-1) failed: %s', nexc)
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if exc.errno == errno.EINVAL:
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raise RuntimeError(f'sig {sig} cannot be caught')
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else:
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raise
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def _handle_signal(self, sig):
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"""Internal helper that is the actual signal handler."""
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handle = self._signal_handlers.get(sig)
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if handle is None:
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return # Assume it's some race condition.
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if handle._cancelled:
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self.remove_signal_handler(sig) # Remove it properly.
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else:
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self._add_callback_signalsafe(handle)
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def remove_signal_handler(self, sig):
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"""Remove a handler for a signal. UNIX only.
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Return True if a signal handler was removed, False if not.
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"""
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self._check_signal(sig)
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try:
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del self._signal_handlers[sig]
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except KeyError:
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return False
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if sig == signal.SIGINT:
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handler = signal.default_int_handler
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else:
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handler = signal.SIG_DFL
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try:
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signal.signal(sig, handler)
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except OSError as exc:
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if exc.errno == errno.EINVAL:
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raise RuntimeError(f'sig {sig} cannot be caught')
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else:
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raise
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if not self._signal_handlers:
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try:
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signal.set_wakeup_fd(-1)
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except (ValueError, OSError) as exc:
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logger.info('set_wakeup_fd(-1) failed: %s', exc)
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return True
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def _check_signal(self, sig):
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"""Internal helper to validate a signal.
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Raise ValueError if the signal number is invalid or uncatchable.
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Raise RuntimeError if there is a problem setting up the handler.
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"""
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if not isinstance(sig, int):
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raise TypeError(f'sig must be an int, not {sig!r}')
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if sig not in signal.valid_signals():
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raise ValueError(f'invalid signal number {sig}')
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def _make_read_pipe_transport(self, pipe, protocol, waiter=None,
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extra=None):
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return _UnixReadPipeTransport(self, pipe, protocol, waiter, extra)
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def _make_write_pipe_transport(self, pipe, protocol, waiter=None,
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extra=None):
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return _UnixWritePipeTransport(self, pipe, protocol, waiter, extra)
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async def _make_subprocess_transport(self, protocol, args, shell,
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stdin, stdout, stderr, bufsize,
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extra=None, **kwargs):
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with events.get_child_watcher() as watcher:
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waiter = self.create_future()
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transp = _UnixSubprocessTransport(self, protocol, args, shell,
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stdin, stdout, stderr, bufsize,
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waiter=waiter, extra=extra,
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**kwargs)
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watcher.add_child_handler(transp.get_pid(),
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self._child_watcher_callback, transp)
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try:
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await waiter
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except Exception:
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transp.close()
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await transp._wait()
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raise
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return transp
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def _child_watcher_callback(self, pid, returncode, transp):
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self.call_soon_threadsafe(transp._process_exited, returncode)
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async def create_unix_connection(
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self, protocol_factory, path=None, *,
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ssl=None, sock=None,
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server_hostname=None,
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ssl_handshake_timeout=None):
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assert server_hostname is None or isinstance(server_hostname, str)
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if ssl:
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if server_hostname is None:
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raise ValueError(
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'you have to pass server_hostname when using ssl')
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else:
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if server_hostname is not None:
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raise ValueError('server_hostname is only meaningful with ssl')
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if ssl_handshake_timeout is not None:
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raise ValueError(
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'ssl_handshake_timeout is only meaningful with ssl')
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if path is not None:
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if sock is not None:
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raise ValueError(
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'path and sock can not be specified at the same time')
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path = os.fspath(path)
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sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0)
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try:
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sock.setblocking(False)
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await self.sock_connect(sock, path)
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except:
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sock.close()
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raise
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else:
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if sock is None:
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raise ValueError('no path and sock were specified')
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if (sock.family != socket.AF_UNIX or
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sock.type != socket.SOCK_STREAM):
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raise ValueError(
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f'A UNIX Domain Stream Socket was expected, got {sock!r}')
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sock.setblocking(False)
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transport, protocol = await self._create_connection_transport(
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sock, protocol_factory, ssl, server_hostname,
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ssl_handshake_timeout=ssl_handshake_timeout)
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return transport, protocol
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async def create_unix_server(
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self, protocol_factory, path=None, *,
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sock=None, backlog=100, ssl=None,
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ssl_handshake_timeout=None,
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start_serving=True):
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if isinstance(ssl, bool):
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raise TypeError('ssl argument must be an SSLContext or None')
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if ssl_handshake_timeout is not None and not ssl:
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raise ValueError(
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'ssl_handshake_timeout is only meaningful with ssl')
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if path is not None:
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if sock is not None:
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raise ValueError(
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'path and sock can not be specified at the same time')
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path = os.fspath(path)
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sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
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# Check for abstract socket. `str` and `bytes` paths are supported.
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if path[0] not in (0, '\x00'):
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try:
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if stat.S_ISSOCK(os.stat(path).st_mode):
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os.remove(path)
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except FileNotFoundError:
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pass
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except OSError as err:
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# Directory may have permissions only to create socket.
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logger.error('Unable to check or remove stale UNIX socket '
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'%r: %r', path, err)
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try:
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sock.bind(path)
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except OSError as exc:
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sock.close()
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if exc.errno == errno.EADDRINUSE:
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# Let's improve the error message by adding
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# with what exact address it occurs.
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msg = f'Address {path!r} is already in use'
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raise OSError(errno.EADDRINUSE, msg) from None
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else:
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raise
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except:
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sock.close()
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raise
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else:
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if sock is None:
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raise ValueError(
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'path was not specified, and no sock specified')
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if (sock.family != socket.AF_UNIX or
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sock.type != socket.SOCK_STREAM):
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raise ValueError(
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f'A UNIX Domain Stream Socket was expected, got {sock!r}')
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sock.setblocking(False)
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server = base_events.Server(self, [sock], protocol_factory,
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ssl, backlog, ssl_handshake_timeout)
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if start_serving:
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server._start_serving()
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# Skip one loop iteration so that all 'loop.add_reader'
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# go through.
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await tasks.sleep(0, loop=self)
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return server
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async def _sock_sendfile_native(self, sock, file, offset, count):
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try:
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os.sendfile
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except AttributeError as exc:
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raise events.SendfileNotAvailableError(
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"os.sendfile() is not available")
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try:
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fileno = file.fileno()
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except (AttributeError, io.UnsupportedOperation) as err:
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raise events.SendfileNotAvailableError("not a regular file")
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try:
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fsize = os.fstat(fileno).st_size
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except OSError as err:
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raise events.SendfileNotAvailableError("not a regular file")
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blocksize = count if count else fsize
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if not blocksize:
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return 0 # empty file
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fut = self.create_future()
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self._sock_sendfile_native_impl(fut, None, sock, fileno,
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offset, count, blocksize, 0)
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return await fut
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def _sock_sendfile_native_impl(self, fut, registered_fd, sock, fileno,
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offset, count, blocksize, total_sent):
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fd = sock.fileno()
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if registered_fd is not None:
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# Remove the callback early. It should be rare that the
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# selector says the fd is ready but the call still returns
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# EAGAIN, and I am willing to take a hit in that case in
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# order to simplify the common case.
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self.remove_writer(registered_fd)
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if fut.cancelled():
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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return
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if count:
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blocksize = count - total_sent
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if blocksize <= 0:
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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fut.set_result(total_sent)
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return
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try:
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sent = os.sendfile(fd, fileno, offset, blocksize)
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except (BlockingIOError, InterruptedError):
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if registered_fd is None:
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self._sock_add_cancellation_callback(fut, sock)
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self.add_writer(fd, self._sock_sendfile_native_impl, fut,
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fd, sock, fileno,
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offset, count, blocksize, total_sent)
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except OSError as exc:
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if (registered_fd is not None and
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exc.errno == errno.ENOTCONN and
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type(exc) is not ConnectionError):
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# If we have an ENOTCONN and this isn't a first call to
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# sendfile(), i.e. the connection was closed in the middle
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# of the operation, normalize the error to ConnectionError
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# to make it consistent across all Posix systems.
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new_exc = ConnectionError(
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"socket is not connected", errno.ENOTCONN)
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new_exc.__cause__ = exc
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exc = new_exc
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if total_sent == 0:
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# We can get here for different reasons, the main
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# one being 'file' is not a regular mmap(2)-like
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# file, in which case we'll fall back on using
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# plain send().
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err = events.SendfileNotAvailableError(
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"os.sendfile call failed")
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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fut.set_exception(err)
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else:
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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fut.set_exception(exc)
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except Exception as exc:
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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fut.set_exception(exc)
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else:
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if sent == 0:
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# EOF
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self._sock_sendfile_update_filepos(fileno, offset, total_sent)
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fut.set_result(total_sent)
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else:
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offset += sent
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total_sent += sent
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if registered_fd is None:
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self._sock_add_cancellation_callback(fut, sock)
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self.add_writer(fd, self._sock_sendfile_native_impl, fut,
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fd, sock, fileno,
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offset, count, blocksize, total_sent)
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def _sock_sendfile_update_filepos(self, fileno, offset, total_sent):
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if total_sent > 0:
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os.lseek(fileno, offset, os.SEEK_SET)
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|
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def _sock_add_cancellation_callback(self, fut, sock):
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def cb(fut):
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if fut.cancelled():
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fd = sock.fileno()
|
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if fd != -1:
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self.remove_writer(fd)
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fut.add_done_callback(cb)
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|
|
|
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class _UnixReadPipeTransport(transports.ReadTransport):
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max_size = 256 * 1024 # max bytes we read in one event loop iteration
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def __init__(self, loop, pipe, protocol, waiter=None, extra=None):
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super().__init__(extra)
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self._extra['pipe'] = pipe
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self._loop = loop
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self._pipe = pipe
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self._fileno = pipe.fileno()
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self._protocol = protocol
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self._closing = False
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|
|
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mode = os.fstat(self._fileno).st_mode
|
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if not (stat.S_ISFIFO(mode) or
|
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stat.S_ISSOCK(mode) or
|
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stat.S_ISCHR(mode)):
|
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self._pipe = None
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self._fileno = None
|
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self._protocol = None
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raise ValueError("Pipe transport is for pipes/sockets only.")
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|
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os.set_blocking(self._fileno, False)
|
|
|
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self._loop.call_soon(self._protocol.connection_made, self)
|
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# only start reading when connection_made() has been called
|
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self._loop.call_soon(self._loop._add_reader,
|
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self._fileno, self._read_ready)
|
|
if waiter is not None:
|
|
# only wake up the waiter when connection_made() has been called
|
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self._loop.call_soon(futures._set_result_unless_cancelled,
|
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waiter, None)
|
|
|
|
def __repr__(self):
|
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info = [self.__class__.__name__]
|
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if self._pipe is None:
|
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info.append('closed')
|
|
elif self._closing:
|
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info.append('closing')
|
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info.append(f'fd={self._fileno}')
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selector = getattr(self._loop, '_selector', None)
|
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if self._pipe is not None and selector is not None:
|
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polling = selector_events._test_selector_event(
|
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selector, self._fileno, selectors.EVENT_READ)
|
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if polling:
|
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info.append('polling')
|
|
else:
|
|
info.append('idle')
|
|
elif self._pipe is not None:
|
|
info.append('open')
|
|
else:
|
|
info.append('closed')
|
|
return '<{}>'.format(' '.join(info))
|
|
|
|
def _read_ready(self):
|
|
try:
|
|
data = os.read(self._fileno, self.max_size)
|
|
except (BlockingIOError, InterruptedError):
|
|
pass
|
|
except OSError as exc:
|
|
self._fatal_error(exc, 'Fatal read error on pipe transport')
|
|
else:
|
|
if data:
|
|
self._protocol.data_received(data)
|
|
else:
|
|
if self._loop.get_debug():
|
|
logger.info("%r was closed by peer", self)
|
|
self._closing = True
|
|
self._loop._remove_reader(self._fileno)
|
|
self._loop.call_soon(self._protocol.eof_received)
|
|
self._loop.call_soon(self._call_connection_lost, None)
|
|
|
|
def pause_reading(self):
|
|
self._loop._remove_reader(self._fileno)
|
|
|
|
def resume_reading(self):
|
|
self._loop._add_reader(self._fileno, self._read_ready)
|
|
|
|
def set_protocol(self, protocol):
|
|
self._protocol = protocol
|
|
|
|
def get_protocol(self):
|
|
return self._protocol
|
|
|
|
def is_closing(self):
|
|
return self._closing
|
|
|
|
def close(self):
|
|
if not self._closing:
|
|
self._close(None)
|
|
|
|
def __del__(self):
|
|
if self._pipe is not None:
|
|
warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
|
|
source=self)
|
|
self._pipe.close()
|
|
|
|
def _fatal_error(self, exc, message='Fatal error on pipe transport'):
|
|
# should be called by exception handler only
|
|
if (isinstance(exc, OSError) and exc.errno == errno.EIO):
|
|
if self._loop.get_debug():
|
|
logger.debug("%r: %s", self, message, exc_info=True)
|
|
else:
|
|
self._loop.call_exception_handler({
|
|
'message': message,
|
|
'exception': exc,
|
|
'transport': self,
|
|
'protocol': self._protocol,
|
|
})
|
|
self._close(exc)
|
|
|
|
def _close(self, exc):
|
|
self._closing = True
|
|
self._loop._remove_reader(self._fileno)
|
|
self._loop.call_soon(self._call_connection_lost, exc)
|
|
|
|
def _call_connection_lost(self, exc):
|
|
try:
|
|
self._protocol.connection_lost(exc)
|
|
finally:
|
|
self._pipe.close()
|
|
self._pipe = None
|
|
self._protocol = None
|
|
self._loop = None
|
|
|
|
|
|
class _UnixWritePipeTransport(transports._FlowControlMixin,
|
|
transports.WriteTransport):
|
|
|
|
def __init__(self, loop, pipe, protocol, waiter=None, extra=None):
|
|
super().__init__(extra, loop)
|
|
self._extra['pipe'] = pipe
|
|
self._pipe = pipe
|
|
self._fileno = pipe.fileno()
|
|
self._protocol = protocol
|
|
self._buffer = bytearray()
|
|
self._conn_lost = 0
|
|
self._closing = False # Set when close() or write_eof() called.
|
|
|
|
mode = os.fstat(self._fileno).st_mode
|
|
is_char = stat.S_ISCHR(mode)
|
|
is_fifo = stat.S_ISFIFO(mode)
|
|
is_socket = stat.S_ISSOCK(mode)
|
|
if not (is_char or is_fifo or is_socket):
|
|
self._pipe = None
|
|
self._fileno = None
|
|
self._protocol = None
|
|
raise ValueError("Pipe transport is only for "
|
|
"pipes, sockets and character devices")
|
|
|
|
os.set_blocking(self._fileno, False)
|
|
self._loop.call_soon(self._protocol.connection_made, self)
|
|
|
|
# On AIX, the reader trick (to be notified when the read end of the
|
|
# socket is closed) only works for sockets. On other platforms it
|
|
# works for pipes and sockets. (Exception: OS X 10.4? Issue #19294.)
|
|
if is_socket or (is_fifo and not sys.platform.startswith("aix")):
|
|
# only start reading when connection_made() has been called
|
|
self._loop.call_soon(self._loop._add_reader,
|
|
self._fileno, self._read_ready)
|
|
|
|
if waiter is not None:
|
|
# only wake up the waiter when connection_made() has been called
|
|
self._loop.call_soon(futures._set_result_unless_cancelled,
|
|
waiter, None)
|
|
|
|
def __repr__(self):
|
|
info = [self.__class__.__name__]
|
|
if self._pipe is None:
|
|
info.append('closed')
|
|
elif self._closing:
|
|
info.append('closing')
|
|
info.append(f'fd={self._fileno}')
|
|
selector = getattr(self._loop, '_selector', None)
|
|
if self._pipe is not None and selector is not None:
|
|
polling = selector_events._test_selector_event(
|
|
selector, self._fileno, selectors.EVENT_WRITE)
|
|
if polling:
|
|
info.append('polling')
|
|
else:
|
|
info.append('idle')
|
|
|
|
bufsize = self.get_write_buffer_size()
|
|
info.append(f'bufsize={bufsize}')
|
|
elif self._pipe is not None:
|
|
info.append('open')
|
|
else:
|
|
info.append('closed')
|
|
return '<{}>'.format(' '.join(info))
|
|
|
|
def get_write_buffer_size(self):
|
|
return len(self._buffer)
|
|
|
|
def _read_ready(self):
|
|
# Pipe was closed by peer.
|
|
if self._loop.get_debug():
|
|
logger.info("%r was closed by peer", self)
|
|
if self._buffer:
|
|
self._close(BrokenPipeError())
|
|
else:
|
|
self._close()
|
|
|
|
def write(self, data):
|
|
assert isinstance(data, (bytes, bytearray, memoryview)), repr(data)
|
|
if isinstance(data, bytearray):
|
|
data = memoryview(data)
|
|
if not data:
|
|
return
|
|
|
|
if self._conn_lost or self._closing:
|
|
if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
|
|
logger.warning('pipe closed by peer or '
|
|
'os.write(pipe, data) raised exception.')
|
|
self._conn_lost += 1
|
|
return
|
|
|
|
if not self._buffer:
|
|
# Attempt to send it right away first.
|
|
try:
|
|
n = os.write(self._fileno, data)
|
|
except (BlockingIOError, InterruptedError):
|
|
n = 0
|
|
except Exception as exc:
|
|
self._conn_lost += 1
|
|
self._fatal_error(exc, 'Fatal write error on pipe transport')
|
|
return
|
|
if n == len(data):
|
|
return
|
|
elif n > 0:
|
|
data = memoryview(data)[n:]
|
|
self._loop._add_writer(self._fileno, self._write_ready)
|
|
|
|
self._buffer += data
|
|
self._maybe_pause_protocol()
|
|
|
|
def _write_ready(self):
|
|
assert self._buffer, 'Data should not be empty'
|
|
|
|
try:
|
|
n = os.write(self._fileno, self._buffer)
|
|
except (BlockingIOError, InterruptedError):
|
|
pass
|
|
except Exception as exc:
|
|
self._buffer.clear()
|
|
self._conn_lost += 1
|
|
# Remove writer here, _fatal_error() doesn't it
|
|
# because _buffer is empty.
|
|
self._loop._remove_writer(self._fileno)
|
|
self._fatal_error(exc, 'Fatal write error on pipe transport')
|
|
else:
|
|
if n == len(self._buffer):
|
|
self._buffer.clear()
|
|
self._loop._remove_writer(self._fileno)
|
|
self._maybe_resume_protocol() # May append to buffer.
|
|
if self._closing:
|
|
self._loop._remove_reader(self._fileno)
|
|
self._call_connection_lost(None)
|
|
return
|
|
elif n > 0:
|
|
del self._buffer[:n]
|
|
|
|
def can_write_eof(self):
|
|
return True
|
|
|
|
def write_eof(self):
|
|
if self._closing:
|
|
return
|
|
assert self._pipe
|
|
self._closing = True
|
|
if not self._buffer:
|
|
self._loop._remove_reader(self._fileno)
|
|
self._loop.call_soon(self._call_connection_lost, None)
|
|
|
|
def set_protocol(self, protocol):
|
|
self._protocol = protocol
|
|
|
|
def get_protocol(self):
|
|
return self._protocol
|
|
|
|
def is_closing(self):
|
|
return self._closing
|
|
|
|
def close(self):
|
|
if self._pipe is not None and not self._closing:
|
|
# write_eof is all what we needed to close the write pipe
|
|
self.write_eof()
|
|
|
|
def __del__(self):
|
|
if self._pipe is not None:
|
|
warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
|
|
source=self)
|
|
self._pipe.close()
|
|
|
|
def abort(self):
|
|
self._close(None)
|
|
|
|
def _fatal_error(self, exc, message='Fatal error on pipe transport'):
|
|
# should be called by exception handler only
|
|
if isinstance(exc, base_events._FATAL_ERROR_IGNORE):
|
|
if self._loop.get_debug():
|
|
logger.debug("%r: %s", self, message, exc_info=True)
|
|
else:
|
|
self._loop.call_exception_handler({
|
|
'message': message,
|
|
'exception': exc,
|
|
'transport': self,
|
|
'protocol': self._protocol,
|
|
})
|
|
self._close(exc)
|
|
|
|
def _close(self, exc=None):
|
|
self._closing = True
|
|
if self._buffer:
|
|
self._loop._remove_writer(self._fileno)
|
|
self._buffer.clear()
|
|
self._loop._remove_reader(self._fileno)
|
|
self._loop.call_soon(self._call_connection_lost, exc)
|
|
|
|
def _call_connection_lost(self, exc):
|
|
try:
|
|
self._protocol.connection_lost(exc)
|
|
finally:
|
|
self._pipe.close()
|
|
self._pipe = None
|
|
self._protocol = None
|
|
self._loop = None
|
|
|
|
|
|
class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport):
|
|
|
|
def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs):
|
|
stdin_w = None
|
|
if stdin == subprocess.PIPE:
|
|
# Use a socket pair for stdin, since not all platforms
|
|
# support selecting read events on the write end of a
|
|
# socket (which we use in order to detect closing of the
|
|
# other end). Notably this is needed on AIX, and works
|
|
# just fine on other platforms.
|
|
stdin, stdin_w = socket.socketpair()
|
|
self._proc = subprocess.Popen(
|
|
args, shell=shell, stdin=stdin, stdout=stdout, stderr=stderr,
|
|
universal_newlines=False, bufsize=bufsize, **kwargs)
|
|
if stdin_w is not None:
|
|
stdin.close()
|
|
self._proc.stdin = open(stdin_w.detach(), 'wb', buffering=bufsize)
|
|
|
|
|
|
class AbstractChildWatcher:
|
|
"""Abstract base class for monitoring child processes.
|
|
|
|
Objects derived from this class monitor a collection of subprocesses and
|
|
report their termination or interruption by a signal.
|
|
|
|
New callbacks are registered with .add_child_handler(). Starting a new
|
|
process must be done within a 'with' block to allow the watcher to suspend
|
|
its activity until the new process if fully registered (this is needed to
|
|
prevent a race condition in some implementations).
|
|
|
|
Example:
|
|
with watcher:
|
|
proc = subprocess.Popen("sleep 1")
|
|
watcher.add_child_handler(proc.pid, callback)
|
|
|
|
Notes:
|
|
Implementations of this class must be thread-safe.
|
|
|
|
Since child watcher objects may catch the SIGCHLD signal and call
|
|
waitpid(-1), there should be only one active object per process.
|
|
"""
|
|
|
|
def add_child_handler(self, pid, callback, *args):
|
|
"""Register a new child handler.
|
|
|
|
Arrange for callback(pid, returncode, *args) to be called when
|
|
process 'pid' terminates. Specifying another callback for the same
|
|
process replaces the previous handler.
|
|
|
|
Note: callback() must be thread-safe.
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
def remove_child_handler(self, pid):
|
|
"""Removes the handler for process 'pid'.
|
|
|
|
The function returns True if the handler was successfully removed,
|
|
False if there was nothing to remove."""
|
|
|
|
raise NotImplementedError()
|
|
|
|
def attach_loop(self, loop):
|
|
"""Attach the watcher to an event loop.
|
|
|
|
If the watcher was previously attached to an event loop, then it is
|
|
first detached before attaching to the new loop.
|
|
|
|
Note: loop may be None.
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
def close(self):
|
|
"""Close the watcher.
|
|
|
|
This must be called to make sure that any underlying resource is freed.
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
def __enter__(self):
|
|
"""Enter the watcher's context and allow starting new processes
|
|
|
|
This function must return self"""
|
|
raise NotImplementedError()
|
|
|
|
def __exit__(self, a, b, c):
|
|
"""Exit the watcher's context"""
|
|
raise NotImplementedError()
|
|
|
|
|
|
class BaseChildWatcher(AbstractChildWatcher):
|
|
|
|
def __init__(self):
|
|
self._loop = None
|
|
self._callbacks = {}
|
|
|
|
def close(self):
|
|
self.attach_loop(None)
|
|
|
|
def _do_waitpid(self, expected_pid):
|
|
raise NotImplementedError()
|
|
|
|
def _do_waitpid_all(self):
|
|
raise NotImplementedError()
|
|
|
|
def attach_loop(self, loop):
|
|
assert loop is None or isinstance(loop, events.AbstractEventLoop)
|
|
|
|
if self._loop is not None and loop is None and self._callbacks:
|
|
warnings.warn(
|
|
'A loop is being detached '
|
|
'from a child watcher with pending handlers',
|
|
RuntimeWarning)
|
|
|
|
if self._loop is not None:
|
|
self._loop.remove_signal_handler(signal.SIGCHLD)
|
|
|
|
self._loop = loop
|
|
if loop is not None:
|
|
loop.add_signal_handler(signal.SIGCHLD, self._sig_chld)
|
|
|
|
# Prevent a race condition in case a child terminated
|
|
# during the switch.
|
|
self._do_waitpid_all()
|
|
|
|
def _sig_chld(self):
|
|
try:
|
|
self._do_waitpid_all()
|
|
except Exception as exc:
|
|
# self._loop should always be available here
|
|
# as '_sig_chld' is added as a signal handler
|
|
# in 'attach_loop'
|
|
self._loop.call_exception_handler({
|
|
'message': 'Unknown exception in SIGCHLD handler',
|
|
'exception': exc,
|
|
})
|
|
|
|
def _compute_returncode(self, status):
|
|
if os.WIFSIGNALED(status):
|
|
# The child process died because of a signal.
|
|
return -os.WTERMSIG(status)
|
|
elif os.WIFEXITED(status):
|
|
# The child process exited (e.g sys.exit()).
|
|
return os.WEXITSTATUS(status)
|
|
else:
|
|
# The child exited, but we don't understand its status.
|
|
# This shouldn't happen, but if it does, let's just
|
|
# return that status; perhaps that helps debug it.
|
|
return status
|
|
|
|
|
|
class SafeChildWatcher(BaseChildWatcher):
|
|
"""'Safe' child watcher implementation.
|
|
|
|
This implementation avoids disrupting other code spawning processes by
|
|
polling explicitly each process in the SIGCHLD handler instead of calling
|
|
os.waitpid(-1).
|
|
|
|
This is a safe solution but it has a significant overhead when handling a
|
|
big number of children (O(n) each time SIGCHLD is raised)
|
|
"""
|
|
|
|
def close(self):
|
|
self._callbacks.clear()
|
|
super().close()
|
|
|
|
def __enter__(self):
|
|
return self
|
|
|
|
def __exit__(self, a, b, c):
|
|
pass
|
|
|
|
def add_child_handler(self, pid, callback, *args):
|
|
if self._loop is None:
|
|
raise RuntimeError(
|
|
"Cannot add child handler, "
|
|
"the child watcher does not have a loop attached")
|
|
|
|
self._callbacks[pid] = (callback, args)
|
|
|
|
# Prevent a race condition in case the child is already terminated.
|
|
self._do_waitpid(pid)
|
|
|
|
def remove_child_handler(self, pid):
|
|
try:
|
|
del self._callbacks[pid]
|
|
return True
|
|
except KeyError:
|
|
return False
|
|
|
|
def _do_waitpid_all(self):
|
|
|
|
for pid in list(self._callbacks):
|
|
self._do_waitpid(pid)
|
|
|
|
def _do_waitpid(self, expected_pid):
|
|
assert expected_pid > 0
|
|
|
|
try:
|
|
pid, status = os.waitpid(expected_pid, os.WNOHANG)
|
|
except ChildProcessError:
|
|
# The child process is already reaped
|
|
# (may happen if waitpid() is called elsewhere).
|
|
pid = expected_pid
|
|
returncode = 255
|
|
logger.warning(
|
|
"Unknown child process pid %d, will report returncode 255",
|
|
pid)
|
|
else:
|
|
if pid == 0:
|
|
# The child process is still alive.
|
|
return
|
|
|
|
returncode = self._compute_returncode(status)
|
|
if self._loop.get_debug():
|
|
logger.debug('process %s exited with returncode %s',
|
|
expected_pid, returncode)
|
|
|
|
try:
|
|
callback, args = self._callbacks.pop(pid)
|
|
except KeyError: # pragma: no cover
|
|
# May happen if .remove_child_handler() is called
|
|
# after os.waitpid() returns.
|
|
if self._loop.get_debug():
|
|
logger.warning("Child watcher got an unexpected pid: %r",
|
|
pid, exc_info=True)
|
|
else:
|
|
callback(pid, returncode, *args)
|
|
|
|
|
|
class FastChildWatcher(BaseChildWatcher):
|
|
"""'Fast' child watcher implementation.
|
|
|
|
This implementation reaps every terminated processes by calling
|
|
os.waitpid(-1) directly, possibly breaking other code spawning processes
|
|
and waiting for their termination.
|
|
|
|
There is no noticeable overhead when handling a big number of children
|
|
(O(1) each time a child terminates).
|
|
"""
|
|
def __init__(self):
|
|
super().__init__()
|
|
self._lock = threading.Lock()
|
|
self._zombies = {}
|
|
self._forks = 0
|
|
|
|
def close(self):
|
|
self._callbacks.clear()
|
|
self._zombies.clear()
|
|
super().close()
|
|
|
|
def __enter__(self):
|
|
with self._lock:
|
|
self._forks += 1
|
|
|
|
return self
|
|
|
|
def __exit__(self, a, b, c):
|
|
with self._lock:
|
|
self._forks -= 1
|
|
|
|
if self._forks or not self._zombies:
|
|
return
|
|
|
|
collateral_victims = str(self._zombies)
|
|
self._zombies.clear()
|
|
|
|
logger.warning(
|
|
"Caught subprocesses termination from unknown pids: %s",
|
|
collateral_victims)
|
|
|
|
def add_child_handler(self, pid, callback, *args):
|
|
assert self._forks, "Must use the context manager"
|
|
|
|
if self._loop is None:
|
|
raise RuntimeError(
|
|
"Cannot add child handler, "
|
|
"the child watcher does not have a loop attached")
|
|
|
|
with self._lock:
|
|
try:
|
|
returncode = self._zombies.pop(pid)
|
|
except KeyError:
|
|
# The child is running.
|
|
self._callbacks[pid] = callback, args
|
|
return
|
|
|
|
# The child is dead already. We can fire the callback.
|
|
callback(pid, returncode, *args)
|
|
|
|
def remove_child_handler(self, pid):
|
|
try:
|
|
del self._callbacks[pid]
|
|
return True
|
|
except KeyError:
|
|
return False
|
|
|
|
def _do_waitpid_all(self):
|
|
# Because of signal coalescing, we must keep calling waitpid() as
|
|
# long as we're able to reap a child.
|
|
while True:
|
|
try:
|
|
pid, status = os.waitpid(-1, os.WNOHANG)
|
|
except ChildProcessError:
|
|
# No more child processes exist.
|
|
return
|
|
else:
|
|
if pid == 0:
|
|
# A child process is still alive.
|
|
return
|
|
|
|
returncode = self._compute_returncode(status)
|
|
|
|
with self._lock:
|
|
try:
|
|
callback, args = self._callbacks.pop(pid)
|
|
except KeyError:
|
|
# unknown child
|
|
if self._forks:
|
|
# It may not be registered yet.
|
|
self._zombies[pid] = returncode
|
|
if self._loop.get_debug():
|
|
logger.debug('unknown process %s exited '
|
|
'with returncode %s',
|
|
pid, returncode)
|
|
continue
|
|
callback = None
|
|
else:
|
|
if self._loop.get_debug():
|
|
logger.debug('process %s exited with returncode %s',
|
|
pid, returncode)
|
|
|
|
if callback is None:
|
|
logger.warning(
|
|
"Caught subprocess termination from unknown pid: "
|
|
"%d -> %d", pid, returncode)
|
|
else:
|
|
callback(pid, returncode, *args)
|
|
|
|
|
|
class _UnixDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
|
|
"""UNIX event loop policy with a watcher for child processes."""
|
|
_loop_factory = _UnixSelectorEventLoop
|
|
|
|
def __init__(self):
|
|
super().__init__()
|
|
self._watcher = None
|
|
|
|
def _init_watcher(self):
|
|
with events._lock:
|
|
if self._watcher is None: # pragma: no branch
|
|
self._watcher = SafeChildWatcher()
|
|
if isinstance(threading.current_thread(),
|
|
threading._MainThread):
|
|
self._watcher.attach_loop(self._local._loop)
|
|
|
|
def set_event_loop(self, loop):
|
|
"""Set the event loop.
|
|
|
|
As a side effect, if a child watcher was set before, then calling
|
|
.set_event_loop() from the main thread will call .attach_loop(loop) on
|
|
the child watcher.
|
|
"""
|
|
|
|
super().set_event_loop(loop)
|
|
|
|
if (self._watcher is not None and
|
|
isinstance(threading.current_thread(), threading._MainThread)):
|
|
self._watcher.attach_loop(loop)
|
|
|
|
def get_child_watcher(self):
|
|
"""Get the watcher for child processes.
|
|
|
|
If not yet set, a SafeChildWatcher object is automatically created.
|
|
"""
|
|
if self._watcher is None:
|
|
self._init_watcher()
|
|
|
|
return self._watcher
|
|
|
|
def set_child_watcher(self, watcher):
|
|
"""Set the watcher for child processes."""
|
|
|
|
assert watcher is None or isinstance(watcher, AbstractChildWatcher)
|
|
|
|
if self._watcher is not None:
|
|
self._watcher.close()
|
|
|
|
self._watcher = watcher
|
|
|
|
|
|
SelectorEventLoop = _UnixSelectorEventLoop
|
|
DefaultEventLoopPolicy = _UnixDefaultEventLoopPolicy
|