| """Selector event loop for Unix with signal handling.""" |
| |
| import errno |
| import os |
| import signal |
| import socket |
| import stat |
| import subprocess |
| import sys |
| import threading |
| import warnings |
| |
| |
| from . import base_events |
| from . import base_subprocess |
| from . import compat |
| from . import constants |
| from . import coroutines |
| from . import events |
| from . import futures |
| from . import selector_events |
| from . import selectors |
| from . import transports |
| from .coroutines import coroutine |
| from .log import logger |
| |
| |
| __all__ = ['SelectorEventLoop', |
| 'AbstractChildWatcher', 'SafeChildWatcher', |
| 'FastChildWatcher', 'DefaultEventLoopPolicy', |
| ] |
| |
| if sys.platform == 'win32': # pragma: no cover |
| raise ImportError('Signals are not really supported on Windows') |
| |
| |
| def _sighandler_noop(signum, frame): |
| """Dummy signal handler.""" |
| pass |
| |
| |
| try: |
| _fspath = os.fspath |
| except AttributeError: |
| # Python 3.5 or earlier |
| _fspath = lambda path: path |
| |
| |
| class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop): |
| """Unix event loop. |
| |
| Adds signal handling and UNIX Domain Socket support to SelectorEventLoop. |
| """ |
| |
| def __init__(self, selector=None): |
| super().__init__(selector) |
| self._signal_handlers = {} |
| |
| def _socketpair(self): |
| return socket.socketpair() |
| |
| def close(self): |
| super().close() |
| if not sys.is_finalizing(): |
| for sig in list(self._signal_handlers): |
| self.remove_signal_handler(sig) |
| else: |
| if self._signal_handlers: |
| warnings.warn(f"Closing the loop {self!r} " |
| f"on interpreter shutdown " |
| f"stage, skipping signal handlers removal", |
| ResourceWarning, |
| source=self) |
| self._signal_handlers.clear() |
| |
| def _process_self_data(self, data): |
| for signum in data: |
| if not signum: |
| # ignore null bytes written by _write_to_self() |
| continue |
| self._handle_signal(signum) |
| |
| def add_signal_handler(self, sig, callback, *args): |
| """Add a handler for a signal. UNIX only. |
| |
| Raise ValueError if the signal number is invalid or uncatchable. |
| Raise RuntimeError if there is a problem setting up the handler. |
| """ |
| if (coroutines.iscoroutine(callback) |
| or coroutines.iscoroutinefunction(callback)): |
| raise TypeError("coroutines cannot be used " |
| "with add_signal_handler()") |
| self._check_signal(sig) |
| self._check_closed() |
| try: |
| # set_wakeup_fd() raises ValueError if this is not the |
| # main thread. By calling it early we ensure that an |
| # event loop running in another thread cannot add a signal |
| # handler. |
| signal.set_wakeup_fd(self._csock.fileno()) |
| except (ValueError, OSError) as exc: |
| raise RuntimeError(str(exc)) |
| |
| handle = events.Handle(callback, args, self) |
| self._signal_handlers[sig] = handle |
| |
| try: |
| # Register a dummy signal handler to ask Python to write the signal |
| # number in the wakup file descriptor. _process_self_data() will |
| # read signal numbers from this file descriptor to handle signals. |
| signal.signal(sig, _sighandler_noop) |
| |
| # Set SA_RESTART to limit EINTR occurrences. |
| signal.siginterrupt(sig, False) |
| except OSError as exc: |
| del self._signal_handlers[sig] |
| if not self._signal_handlers: |
| try: |
| signal.set_wakeup_fd(-1) |
| except (ValueError, OSError) as nexc: |
| logger.info('set_wakeup_fd(-1) failed: %s', nexc) |
| |
| if exc.errno == errno.EINVAL: |
| raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| else: |
| raise |
| |
| def _handle_signal(self, sig): |
| """Internal helper that is the actual signal handler.""" |
| handle = self._signal_handlers.get(sig) |
| if handle is None: |
| return # Assume it's some race condition. |
| if handle._cancelled: |
| self.remove_signal_handler(sig) # Remove it properly. |
| else: |
| self._add_callback_signalsafe(handle) |
| |
| def remove_signal_handler(self, sig): |
| """Remove a handler for a signal. UNIX only. |
| |
| Return True if a signal handler was removed, False if not. |
| """ |
| self._check_signal(sig) |
| try: |
| del self._signal_handlers[sig] |
| except KeyError: |
| return False |
| |
| if sig == signal.SIGINT: |
| handler = signal.default_int_handler |
| else: |
| handler = signal.SIG_DFL |
| |
| try: |
| signal.signal(sig, handler) |
| except OSError as exc: |
| if exc.errno == errno.EINVAL: |
| raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| else: |
| raise |
| |
| if not self._signal_handlers: |
| try: |
| signal.set_wakeup_fd(-1) |
| except (ValueError, OSError) as exc: |
| logger.info('set_wakeup_fd(-1) failed: %s', exc) |
| |
| return True |
| |
| def _check_signal(self, sig): |
| """Internal helper to validate a signal. |
| |
| Raise ValueError if the signal number is invalid or uncatchable. |
| Raise RuntimeError if there is a problem setting up the handler. |
| """ |
| if not isinstance(sig, int): |
| raise TypeError('sig must be an int, not {!r}'.format(sig)) |
| |
| if not (1 <= sig < signal.NSIG): |
| raise ValueError( |
| 'sig {} out of range(1, {})'.format(sig, signal.NSIG)) |
| |
| def _make_read_pipe_transport(self, pipe, protocol, waiter=None, |
| extra=None): |
| return _UnixReadPipeTransport(self, pipe, protocol, waiter, extra) |
| |
| def _make_write_pipe_transport(self, pipe, protocol, waiter=None, |
| extra=None): |
| return _UnixWritePipeTransport(self, pipe, protocol, waiter, extra) |
| |
| @coroutine |
| def _make_subprocess_transport(self, protocol, args, shell, |
| stdin, stdout, stderr, bufsize, |
| extra=None, **kwargs): |
| with events.get_child_watcher() as watcher: |
| waiter = self.create_future() |
| transp = _UnixSubprocessTransport(self, protocol, args, shell, |
| stdin, stdout, stderr, bufsize, |
| waiter=waiter, extra=extra, |
| **kwargs) |
| |
| watcher.add_child_handler(transp.get_pid(), |
| self._child_watcher_callback, transp) |
| try: |
| yield from waiter |
| except Exception as exc: |
| # Workaround CPython bug #23353: using yield/yield-from in an |
| # except block of a generator doesn't clear properly |
| # sys.exc_info() |
| err = exc |
| else: |
| err = None |
| |
| if err is not None: |
| transp.close() |
| yield from transp._wait() |
| raise err |
| |
| return transp |
| |
| def _child_watcher_callback(self, pid, returncode, transp): |
| self.call_soon_threadsafe(transp._process_exited, returncode) |
| |
| @coroutine |
| def create_unix_connection(self, protocol_factory, path, *, |
| ssl=None, sock=None, |
| server_hostname=None): |
| assert server_hostname is None or isinstance(server_hostname, str) |
| if ssl: |
| if server_hostname is None: |
| raise ValueError( |
| 'you have to pass server_hostname when using ssl') |
| else: |
| if server_hostname is not None: |
| raise ValueError('server_hostname is only meaningful with ssl') |
| |
| if path is not None: |
| if sock is not None: |
| raise ValueError( |
| 'path and sock can not be specified at the same time') |
| |
| sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0) |
| try: |
| sock.setblocking(False) |
| yield from self.sock_connect(sock, path) |
| except: |
| sock.close() |
| raise |
| |
| else: |
| if sock is None: |
| raise ValueError('no path and sock were specified') |
| if (sock.family != socket.AF_UNIX or |
| not base_events._is_stream_socket(sock.type)): |
| raise ValueError( |
| 'A UNIX Domain Stream Socket was expected, got {!r}' |
| .format(sock)) |
| sock.setblocking(False) |
| |
| transport, protocol = yield from self._create_connection_transport( |
| sock, protocol_factory, ssl, server_hostname) |
| return transport, protocol |
| |
| @coroutine |
| def create_unix_server(self, protocol_factory, path=None, *, |
| sock=None, backlog=100, ssl=None): |
| if isinstance(ssl, bool): |
| raise TypeError('ssl argument must be an SSLContext or None') |
| |
| if path is not None: |
| if sock is not None: |
| raise ValueError( |
| 'path and sock can not be specified at the same time') |
| |
| path = _fspath(path) |
| sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) |
| |
| # Check for abstract socket. `str` and `bytes` paths are supported. |
| if path[0] not in (0, '\x00'): |
| try: |
| if stat.S_ISSOCK(os.stat(path).st_mode): |
| os.remove(path) |
| except FileNotFoundError: |
| pass |
| except OSError as err: |
| # Directory may have permissions only to create socket. |
| logger.error('Unable to check or remove stale UNIX socket %r: %r', path, err) |
| |
| try: |
| sock.bind(path) |
| except OSError as exc: |
| sock.close() |
| if exc.errno == errno.EADDRINUSE: |
| # Let's improve the error message by adding |
| # with what exact address it occurs. |
| msg = 'Address {!r} is already in use'.format(path) |
| raise OSError(errno.EADDRINUSE, msg) from None |
| else: |
| raise |
| except: |
| sock.close() |
| raise |
| else: |
| if sock is None: |
| raise ValueError( |
| 'path was not specified, and no sock specified') |
| |
| if (sock.family != socket.AF_UNIX or |
| not base_events._is_stream_socket(sock.type)): |
| raise ValueError( |
| 'A UNIX Domain Stream Socket was expected, got {!r}' |
| .format(sock)) |
| |
| server = base_events.Server(self, [sock]) |
| sock.listen(backlog) |
| sock.setblocking(False) |
| self._start_serving(protocol_factory, sock, ssl, server) |
| return server |
| |
| |
| if hasattr(os, 'set_blocking'): |
| def _set_nonblocking(fd): |
| os.set_blocking(fd, False) |
| else: |
| import fcntl |
| |
| def _set_nonblocking(fd): |
| flags = fcntl.fcntl(fd, fcntl.F_GETFL) |
| flags = flags | os.O_NONBLOCK |
| fcntl.fcntl(fd, fcntl.F_SETFL, flags) |
| |
| |
| class _UnixReadPipeTransport(transports.ReadTransport): |
| |
| max_size = 256 * 1024 # max bytes we read in one event loop iteration |
| |
| def __init__(self, loop, pipe, protocol, waiter=None, extra=None): |
| super().__init__(extra) |
| self._extra['pipe'] = pipe |
| self._loop = loop |
| self._pipe = pipe |
| self._fileno = pipe.fileno() |
| self._protocol = protocol |
| self._closing = False |
| |
| mode = os.fstat(self._fileno).st_mode |
| if not (stat.S_ISFIFO(mode) or |
| stat.S_ISSOCK(mode) or |
| stat.S_ISCHR(mode)): |
| self._pipe = None |
| self._fileno = None |
| self._protocol = None |
| raise ValueError("Pipe transport is for pipes/sockets only.") |
| |
| _set_nonblocking(self._fileno) |
| |
| self._loop.call_soon(self._protocol.connection_made, self) |
| # 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('fd=%s' % 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_READ) |
| if polling: |
| info.append('polling') |
| else: |
| info.append('idle') |
| elif self._pipe is not None: |
| info.append('open') |
| else: |
| info.append('closed') |
| return '<%s>' % ' '.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) |
| |
| # On Python 3.3 and older, objects with a destructor part of a reference |
| # cycle are never destroyed. It's not more the case on Python 3.4 thanks |
| # to the PEP 442. |
| if compat.PY34: |
| def __del__(self): |
| if self._pipe is not None: |
| warnings.warn("unclosed transport %r" % self, 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") |
| |
| _set_nonblocking(self._fileno) |
| 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('fd=%s' % 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('bufsize=%s' % bufsize) |
| elif self._pipe is not None: |
| info.append('open') |
| else: |
| info.append('closed') |
| return '<%s>' % ' '.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() |
| |
| # On Python 3.3 and older, objects with a destructor part of a reference |
| # cycle are never destroyed. It's not more the case on Python 3.4 thanks |
| # to the PEP 442. |
| if compat.PY34: |
| def __del__(self): |
| if self._pipe is not None: |
| warnings.warn("unclosed transport %r" % self, 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 |
| |
| |
| if hasattr(os, 'set_inheritable'): |
| # Python 3.4 and newer |
| _set_inheritable = os.set_inheritable |
| else: |
| import fcntl |
| |
| def _set_inheritable(fd, inheritable): |
| cloexec_flag = getattr(fcntl, 'FD_CLOEXEC', 1) |
| |
| old = fcntl.fcntl(fd, fcntl.F_GETFD) |
| if not inheritable: |
| fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag) |
| else: |
| fcntl.fcntl(fd, fcntl.F_SETFD, old & ~cloexec_flag) |
| |
| |
| 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 = self._loop._socketpair() |
| |
| # Mark the write end of the stdin pipe as non-inheritable, |
| # needed by close_fds=False on Python 3.3 and older |
| # (Python 3.4 implements the PEP 446, socketpair returns |
| # non-inheritable sockets) |
| _set_inheritable(stdin_w.fileno(), False) |
| 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 |
