Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 1 | """Selector eventloop for Unix with signal handling.""" |
| 2 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 3 | import errno |
| 4 | import fcntl |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 5 | import os |
| 6 | import signal |
| 7 | import socket |
| 8 | import stat |
| 9 | import subprocess |
| 10 | import sys |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 11 | import threading |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 12 | |
| 13 | |
Guido van Rossum | 5969128 | 2013-10-30 14:52:03 -0700 | [diff] [blame] | 14 | from . import base_subprocess |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 15 | from . import constants |
| 16 | from . import events |
| 17 | from . import protocols |
| 18 | from . import selector_events |
| 19 | from . import tasks |
| 20 | from . import transports |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 21 | from .log import logger |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 22 | |
| 23 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 24 | __all__ = ['SelectorEventLoop', 'STDIN', 'STDOUT', 'STDERR', |
| 25 | 'AbstractChildWatcher', 'SafeChildWatcher', |
| 26 | 'FastChildWatcher', 'DefaultEventLoopPolicy', |
| 27 | ] |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 28 | |
| 29 | STDIN = 0 |
| 30 | STDOUT = 1 |
| 31 | STDERR = 2 |
| 32 | |
| 33 | |
| 34 | if sys.platform == 'win32': # pragma: no cover |
| 35 | raise ImportError('Signals are not really supported on Windows') |
| 36 | |
| 37 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 38 | class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop): |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 39 | """Unix event loop |
| 40 | |
| 41 | Adds signal handling to SelectorEventLoop |
| 42 | """ |
| 43 | |
| 44 | def __init__(self, selector=None): |
| 45 | super().__init__(selector) |
| 46 | self._signal_handlers = {} |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 47 | |
| 48 | def _socketpair(self): |
| 49 | return socket.socketpair() |
| 50 | |
Guido van Rossum | 0b69fbc | 2013-11-06 20:25:50 -0800 | [diff] [blame] | 51 | def close(self): |
| 52 | for sig in list(self._signal_handlers): |
| 53 | self.remove_signal_handler(sig) |
| 54 | super().close() |
| 55 | |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 56 | def add_signal_handler(self, sig, callback, *args): |
| 57 | """Add a handler for a signal. UNIX only. |
| 58 | |
| 59 | Raise ValueError if the signal number is invalid or uncatchable. |
| 60 | Raise RuntimeError if there is a problem setting up the handler. |
| 61 | """ |
| 62 | self._check_signal(sig) |
| 63 | try: |
| 64 | # set_wakeup_fd() raises ValueError if this is not the |
| 65 | # main thread. By calling it early we ensure that an |
| 66 | # event loop running in another thread cannot add a signal |
| 67 | # handler. |
| 68 | signal.set_wakeup_fd(self._csock.fileno()) |
| 69 | except ValueError as exc: |
| 70 | raise RuntimeError(str(exc)) |
| 71 | |
| 72 | handle = events.make_handle(callback, args) |
| 73 | self._signal_handlers[sig] = handle |
| 74 | |
| 75 | try: |
| 76 | signal.signal(sig, self._handle_signal) |
| 77 | except OSError as exc: |
| 78 | del self._signal_handlers[sig] |
| 79 | if not self._signal_handlers: |
| 80 | try: |
| 81 | signal.set_wakeup_fd(-1) |
| 82 | except ValueError as nexc: |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 83 | logger.info('set_wakeup_fd(-1) failed: %s', nexc) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 84 | |
| 85 | if exc.errno == errno.EINVAL: |
| 86 | raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| 87 | else: |
| 88 | raise |
| 89 | |
| 90 | def _handle_signal(self, sig, arg): |
| 91 | """Internal helper that is the actual signal handler.""" |
| 92 | handle = self._signal_handlers.get(sig) |
| 93 | if handle is None: |
| 94 | return # Assume it's some race condition. |
| 95 | if handle._cancelled: |
| 96 | self.remove_signal_handler(sig) # Remove it properly. |
| 97 | else: |
| 98 | self._add_callback_signalsafe(handle) |
| 99 | |
| 100 | def remove_signal_handler(self, sig): |
| 101 | """Remove a handler for a signal. UNIX only. |
| 102 | |
| 103 | Return True if a signal handler was removed, False if not. |
| 104 | """ |
| 105 | self._check_signal(sig) |
| 106 | try: |
| 107 | del self._signal_handlers[sig] |
| 108 | except KeyError: |
| 109 | return False |
| 110 | |
| 111 | if sig == signal.SIGINT: |
| 112 | handler = signal.default_int_handler |
| 113 | else: |
| 114 | handler = signal.SIG_DFL |
| 115 | |
| 116 | try: |
| 117 | signal.signal(sig, handler) |
| 118 | except OSError as exc: |
| 119 | if exc.errno == errno.EINVAL: |
| 120 | raise RuntimeError('sig {} cannot be caught'.format(sig)) |
| 121 | else: |
| 122 | raise |
| 123 | |
| 124 | if not self._signal_handlers: |
| 125 | try: |
| 126 | signal.set_wakeup_fd(-1) |
| 127 | except ValueError as exc: |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 128 | logger.info('set_wakeup_fd(-1) failed: %s', exc) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 129 | |
| 130 | return True |
| 131 | |
| 132 | def _check_signal(self, sig): |
| 133 | """Internal helper to validate a signal. |
| 134 | |
| 135 | Raise ValueError if the signal number is invalid or uncatchable. |
| 136 | Raise RuntimeError if there is a problem setting up the handler. |
| 137 | """ |
| 138 | if not isinstance(sig, int): |
| 139 | raise TypeError('sig must be an int, not {!r}'.format(sig)) |
| 140 | |
| 141 | if not (1 <= sig < signal.NSIG): |
| 142 | raise ValueError( |
| 143 | 'sig {} out of range(1, {})'.format(sig, signal.NSIG)) |
| 144 | |
| 145 | def _make_read_pipe_transport(self, pipe, protocol, waiter=None, |
| 146 | extra=None): |
| 147 | return _UnixReadPipeTransport(self, pipe, protocol, waiter, extra) |
| 148 | |
| 149 | def _make_write_pipe_transport(self, pipe, protocol, waiter=None, |
| 150 | extra=None): |
| 151 | return _UnixWritePipeTransport(self, pipe, protocol, waiter, extra) |
| 152 | |
| 153 | @tasks.coroutine |
| 154 | def _make_subprocess_transport(self, protocol, args, shell, |
| 155 | stdin, stdout, stderr, bufsize, |
| 156 | extra=None, **kwargs): |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 157 | with events.get_child_watcher() as watcher: |
| 158 | transp = _UnixSubprocessTransport(self, protocol, args, shell, |
| 159 | stdin, stdout, stderr, bufsize, |
| 160 | extra=None, **kwargs) |
| 161 | watcher.add_child_handler(transp.get_pid(), |
| 162 | self._child_watcher_callback, transp) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 163 | yield from transp._post_init() |
| 164 | return transp |
| 165 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 166 | def _child_watcher_callback(self, pid, returncode, transp): |
| 167 | self.call_soon_threadsafe(transp._process_exited, returncode) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 168 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 169 | def _subprocess_closed(self, transp): |
| 170 | pass |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 171 | |
| 172 | |
| 173 | def _set_nonblocking(fd): |
| 174 | flags = fcntl.fcntl(fd, fcntl.F_GETFL) |
| 175 | flags = flags | os.O_NONBLOCK |
| 176 | fcntl.fcntl(fd, fcntl.F_SETFL, flags) |
| 177 | |
| 178 | |
| 179 | class _UnixReadPipeTransport(transports.ReadTransport): |
| 180 | |
| 181 | max_size = 256 * 1024 # max bytes we read in one eventloop iteration |
| 182 | |
| 183 | def __init__(self, loop, pipe, protocol, waiter=None, extra=None): |
| 184 | super().__init__(extra) |
| 185 | self._extra['pipe'] = pipe |
| 186 | self._loop = loop |
| 187 | self._pipe = pipe |
| 188 | self._fileno = pipe.fileno() |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 189 | mode = os.fstat(self._fileno).st_mode |
| 190 | if not (stat.S_ISFIFO(mode) or stat.S_ISSOCK(mode)): |
| 191 | raise ValueError("Pipe transport is for pipes/sockets only.") |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 192 | _set_nonblocking(self._fileno) |
| 193 | self._protocol = protocol |
| 194 | self._closing = False |
| 195 | self._loop.add_reader(self._fileno, self._read_ready) |
| 196 | self._loop.call_soon(self._protocol.connection_made, self) |
| 197 | if waiter is not None: |
| 198 | self._loop.call_soon(waiter.set_result, None) |
| 199 | |
| 200 | def _read_ready(self): |
| 201 | try: |
| 202 | data = os.read(self._fileno, self.max_size) |
| 203 | except (BlockingIOError, InterruptedError): |
| 204 | pass |
| 205 | except OSError as exc: |
| 206 | self._fatal_error(exc) |
| 207 | else: |
| 208 | if data: |
| 209 | self._protocol.data_received(data) |
| 210 | else: |
| 211 | self._closing = True |
| 212 | self._loop.remove_reader(self._fileno) |
| 213 | self._loop.call_soon(self._protocol.eof_received) |
| 214 | self._loop.call_soon(self._call_connection_lost, None) |
| 215 | |
Guido van Rossum | 57497ad | 2013-10-18 07:58:20 -0700 | [diff] [blame] | 216 | def pause_reading(self): |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 217 | self._loop.remove_reader(self._fileno) |
| 218 | |
Guido van Rossum | 57497ad | 2013-10-18 07:58:20 -0700 | [diff] [blame] | 219 | def resume_reading(self): |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 220 | self._loop.add_reader(self._fileno, self._read_ready) |
| 221 | |
| 222 | def close(self): |
| 223 | if not self._closing: |
| 224 | self._close(None) |
| 225 | |
| 226 | def _fatal_error(self, exc): |
| 227 | # should be called by exception handler only |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 228 | logger.exception('Fatal error for %s', self) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 229 | self._close(exc) |
| 230 | |
| 231 | def _close(self, exc): |
| 232 | self._closing = True |
| 233 | self._loop.remove_reader(self._fileno) |
| 234 | self._loop.call_soon(self._call_connection_lost, exc) |
| 235 | |
| 236 | def _call_connection_lost(self, exc): |
| 237 | try: |
| 238 | self._protocol.connection_lost(exc) |
| 239 | finally: |
| 240 | self._pipe.close() |
| 241 | self._pipe = None |
| 242 | self._protocol = None |
| 243 | self._loop = None |
| 244 | |
| 245 | |
| 246 | class _UnixWritePipeTransport(transports.WriteTransport): |
| 247 | |
| 248 | def __init__(self, loop, pipe, protocol, waiter=None, extra=None): |
| 249 | super().__init__(extra) |
| 250 | self._extra['pipe'] = pipe |
| 251 | self._loop = loop |
| 252 | self._pipe = pipe |
| 253 | self._fileno = pipe.fileno() |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 254 | mode = os.fstat(self._fileno).st_mode |
| 255 | is_socket = stat.S_ISSOCK(mode) |
| 256 | is_pipe = stat.S_ISFIFO(mode) |
| 257 | if not (is_socket or is_pipe): |
| 258 | raise ValueError("Pipe transport is for pipes/sockets only.") |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 259 | _set_nonblocking(self._fileno) |
| 260 | self._protocol = protocol |
| 261 | self._buffer = [] |
| 262 | self._conn_lost = 0 |
| 263 | self._closing = False # Set when close() or write_eof() called. |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 264 | |
| 265 | # On AIX, the reader trick only works for sockets. |
| 266 | # On other platforms it works for pipes and sockets. |
| 267 | # (Exception: OS X 10.4? Issue #19294.) |
| 268 | if is_socket or not sys.platform.startswith("aix"): |
| 269 | self._loop.add_reader(self._fileno, self._read_ready) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 270 | |
| 271 | self._loop.call_soon(self._protocol.connection_made, self) |
| 272 | if waiter is not None: |
| 273 | self._loop.call_soon(waiter.set_result, None) |
| 274 | |
| 275 | def _read_ready(self): |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 276 | # Pipe was closed by peer. |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 277 | self._close() |
| 278 | |
| 279 | def write(self, data): |
| 280 | assert isinstance(data, bytes), repr(data) |
| 281 | if not data: |
| 282 | return |
| 283 | |
| 284 | if self._conn_lost or self._closing: |
| 285 | if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES: |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 286 | logger.warning('pipe closed by peer or ' |
| 287 | 'os.write(pipe, data) raised exception.') |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 288 | self._conn_lost += 1 |
| 289 | return |
| 290 | |
| 291 | if not self._buffer: |
| 292 | # Attempt to send it right away first. |
| 293 | try: |
| 294 | n = os.write(self._fileno, data) |
| 295 | except (BlockingIOError, InterruptedError): |
| 296 | n = 0 |
| 297 | except Exception as exc: |
| 298 | self._conn_lost += 1 |
| 299 | self._fatal_error(exc) |
| 300 | return |
| 301 | if n == len(data): |
| 302 | return |
| 303 | elif n > 0: |
| 304 | data = data[n:] |
| 305 | self._loop.add_writer(self._fileno, self._write_ready) |
| 306 | |
| 307 | self._buffer.append(data) |
| 308 | |
| 309 | def _write_ready(self): |
| 310 | data = b''.join(self._buffer) |
| 311 | assert data, 'Data should not be empty' |
| 312 | |
| 313 | self._buffer.clear() |
| 314 | try: |
| 315 | n = os.write(self._fileno, data) |
| 316 | except (BlockingIOError, InterruptedError): |
| 317 | self._buffer.append(data) |
| 318 | except Exception as exc: |
| 319 | self._conn_lost += 1 |
| 320 | # Remove writer here, _fatal_error() doesn't it |
| 321 | # because _buffer is empty. |
| 322 | self._loop.remove_writer(self._fileno) |
| 323 | self._fatal_error(exc) |
| 324 | else: |
| 325 | if n == len(data): |
| 326 | self._loop.remove_writer(self._fileno) |
| 327 | if self._closing: |
| 328 | self._loop.remove_reader(self._fileno) |
| 329 | self._call_connection_lost(None) |
| 330 | return |
| 331 | elif n > 0: |
| 332 | data = data[n:] |
| 333 | |
| 334 | self._buffer.append(data) # Try again later. |
| 335 | |
| 336 | def can_write_eof(self): |
| 337 | return True |
| 338 | |
| 339 | # TODO: Make the relationships between write_eof(), close(), |
| 340 | # abort(), _fatal_error() and _close() more straightforward. |
| 341 | |
| 342 | def write_eof(self): |
| 343 | if self._closing: |
| 344 | return |
| 345 | assert self._pipe |
| 346 | self._closing = True |
| 347 | if not self._buffer: |
| 348 | self._loop.remove_reader(self._fileno) |
| 349 | self._loop.call_soon(self._call_connection_lost, None) |
| 350 | |
| 351 | def close(self): |
| 352 | if not self._closing: |
| 353 | # write_eof is all what we needed to close the write pipe |
| 354 | self.write_eof() |
| 355 | |
| 356 | def abort(self): |
| 357 | self._close(None) |
| 358 | |
| 359 | def _fatal_error(self, exc): |
| 360 | # should be called by exception handler only |
Guido van Rossum | fc29e0f | 2013-10-17 15:39:45 -0700 | [diff] [blame] | 361 | logger.exception('Fatal error for %s', self) |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 362 | self._close(exc) |
| 363 | |
| 364 | def _close(self, exc=None): |
| 365 | self._closing = True |
| 366 | if self._buffer: |
| 367 | self._loop.remove_writer(self._fileno) |
| 368 | self._buffer.clear() |
| 369 | self._loop.remove_reader(self._fileno) |
| 370 | self._loop.call_soon(self._call_connection_lost, exc) |
| 371 | |
| 372 | def _call_connection_lost(self, exc): |
| 373 | try: |
| 374 | self._protocol.connection_lost(exc) |
| 375 | finally: |
| 376 | self._pipe.close() |
| 377 | self._pipe = None |
| 378 | self._protocol = None |
| 379 | self._loop = None |
| 380 | |
| 381 | |
Guido van Rossum | 5969128 | 2013-10-30 14:52:03 -0700 | [diff] [blame] | 382 | class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport): |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 383 | |
Guido van Rossum | 5969128 | 2013-10-30 14:52:03 -0700 | [diff] [blame] | 384 | def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs): |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 385 | stdin_w = None |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 386 | if stdin == subprocess.PIPE: |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 387 | # Use a socket pair for stdin, since not all platforms |
| 388 | # support selecting read events on the write end of a |
| 389 | # socket (which we use in order to detect closing of the |
| 390 | # other end). Notably this is needed on AIX, and works |
| 391 | # just fine on other platforms. |
| 392 | stdin, stdin_w = self._loop._socketpair() |
Guido van Rossum | 27b7c7e | 2013-10-17 13:40:50 -0700 | [diff] [blame] | 393 | self._proc = subprocess.Popen( |
| 394 | args, shell=shell, stdin=stdin, stdout=stdout, stderr=stderr, |
| 395 | universal_newlines=False, bufsize=bufsize, **kwargs) |
Guido van Rossum | 934f6ea | 2013-10-21 20:37:14 -0700 | [diff] [blame] | 396 | if stdin_w is not None: |
| 397 | stdin.close() |
| 398 | self._proc.stdin = open(stdin_w.detach(), 'rb', buffering=bufsize) |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 399 | |
| 400 | |
| 401 | class AbstractChildWatcher: |
| 402 | """Abstract base class for monitoring child processes. |
| 403 | |
| 404 | Objects derived from this class monitor a collection of subprocesses and |
| 405 | report their termination or interruption by a signal. |
| 406 | |
| 407 | New callbacks are registered with .add_child_handler(). Starting a new |
| 408 | process must be done within a 'with' block to allow the watcher to suspend |
| 409 | its activity until the new process if fully registered (this is needed to |
| 410 | prevent a race condition in some implementations). |
| 411 | |
| 412 | Example: |
| 413 | with watcher: |
| 414 | proc = subprocess.Popen("sleep 1") |
| 415 | watcher.add_child_handler(proc.pid, callback) |
| 416 | |
| 417 | Notes: |
| 418 | Implementations of this class must be thread-safe. |
| 419 | |
| 420 | Since child watcher objects may catch the SIGCHLD signal and call |
| 421 | waitpid(-1), there should be only one active object per process. |
| 422 | """ |
| 423 | |
| 424 | def add_child_handler(self, pid, callback, *args): |
| 425 | """Register a new child handler. |
| 426 | |
| 427 | Arrange for callback(pid, returncode, *args) to be called when |
| 428 | process 'pid' terminates. Specifying another callback for the same |
| 429 | process replaces the previous handler. |
| 430 | |
| 431 | Note: callback() must be thread-safe |
| 432 | """ |
| 433 | raise NotImplementedError() |
| 434 | |
| 435 | def remove_child_handler(self, pid): |
| 436 | """Removes the handler for process 'pid'. |
| 437 | |
| 438 | The function returns True if the handler was successfully removed, |
| 439 | False if there was nothing to remove.""" |
| 440 | |
| 441 | raise NotImplementedError() |
| 442 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 443 | def attach_loop(self, loop): |
| 444 | """Attach the watcher to an event loop. |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 445 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 446 | If the watcher was previously attached to an event loop, then it is |
| 447 | first detached before attaching to the new loop. |
| 448 | |
| 449 | Note: loop may be None. |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 450 | """ |
| 451 | raise NotImplementedError() |
| 452 | |
| 453 | def close(self): |
| 454 | """Close the watcher. |
| 455 | |
| 456 | This must be called to make sure that any underlying resource is freed. |
| 457 | """ |
| 458 | raise NotImplementedError() |
| 459 | |
| 460 | def __enter__(self): |
| 461 | """Enter the watcher's context and allow starting new processes |
| 462 | |
| 463 | This function must return self""" |
| 464 | raise NotImplementedError() |
| 465 | |
| 466 | def __exit__(self, a, b, c): |
| 467 | """Exit the watcher's context""" |
| 468 | raise NotImplementedError() |
| 469 | |
| 470 | |
| 471 | class BaseChildWatcher(AbstractChildWatcher): |
| 472 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 473 | def __init__(self): |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 474 | self._loop = None |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 475 | |
| 476 | def close(self): |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 477 | self.attach_loop(None) |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 478 | |
| 479 | def _do_waitpid(self, expected_pid): |
| 480 | raise NotImplementedError() |
| 481 | |
| 482 | def _do_waitpid_all(self): |
| 483 | raise NotImplementedError() |
| 484 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 485 | def attach_loop(self, loop): |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 486 | assert loop is None or isinstance(loop, events.AbstractEventLoop) |
| 487 | |
| 488 | if self._loop is not None: |
| 489 | self._loop.remove_signal_handler(signal.SIGCHLD) |
| 490 | |
| 491 | self._loop = loop |
| 492 | if loop is not None: |
| 493 | loop.add_signal_handler(signal.SIGCHLD, self._sig_chld) |
| 494 | |
| 495 | # Prevent a race condition in case a child terminated |
| 496 | # during the switch. |
| 497 | self._do_waitpid_all() |
| 498 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 499 | def _sig_chld(self): |
| 500 | try: |
| 501 | self._do_waitpid_all() |
| 502 | except Exception: |
| 503 | logger.exception('Unknown exception in SIGCHLD handler') |
| 504 | |
| 505 | def _compute_returncode(self, status): |
| 506 | if os.WIFSIGNALED(status): |
| 507 | # The child process died because of a signal. |
| 508 | return -os.WTERMSIG(status) |
| 509 | elif os.WIFEXITED(status): |
| 510 | # The child process exited (e.g sys.exit()). |
| 511 | return os.WEXITSTATUS(status) |
| 512 | else: |
| 513 | # The child exited, but we don't understand its status. |
| 514 | # This shouldn't happen, but if it does, let's just |
| 515 | # return that status; perhaps that helps debug it. |
| 516 | return status |
| 517 | |
| 518 | |
| 519 | class SafeChildWatcher(BaseChildWatcher): |
| 520 | """'Safe' child watcher implementation. |
| 521 | |
| 522 | This implementation avoids disrupting other code spawning processes by |
| 523 | polling explicitly each process in the SIGCHLD handler instead of calling |
| 524 | os.waitpid(-1). |
| 525 | |
| 526 | This is a safe solution but it has a significant overhead when handling a |
| 527 | big number of children (O(n) each time SIGCHLD is raised) |
| 528 | """ |
| 529 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 530 | def __init__(self): |
| 531 | super().__init__() |
| 532 | self._callbacks = {} |
| 533 | |
| 534 | def close(self): |
| 535 | self._callbacks.clear() |
| 536 | super().close() |
| 537 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 538 | def __enter__(self): |
| 539 | return self |
| 540 | |
| 541 | def __exit__(self, a, b, c): |
| 542 | pass |
| 543 | |
| 544 | def add_child_handler(self, pid, callback, *args): |
| 545 | self._callbacks[pid] = callback, args |
| 546 | |
| 547 | # Prevent a race condition in case the child is already terminated. |
| 548 | self._do_waitpid(pid) |
| 549 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 550 | def remove_child_handler(self, pid): |
| 551 | try: |
| 552 | del self._callbacks[pid] |
| 553 | return True |
| 554 | except KeyError: |
| 555 | return False |
| 556 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 557 | def _do_waitpid_all(self): |
| 558 | |
| 559 | for pid in list(self._callbacks): |
| 560 | self._do_waitpid(pid) |
| 561 | |
| 562 | def _do_waitpid(self, expected_pid): |
| 563 | assert expected_pid > 0 |
| 564 | |
| 565 | try: |
| 566 | pid, status = os.waitpid(expected_pid, os.WNOHANG) |
| 567 | except ChildProcessError: |
| 568 | # The child process is already reaped |
| 569 | # (may happen if waitpid() is called elsewhere). |
| 570 | pid = expected_pid |
| 571 | returncode = 255 |
| 572 | logger.warning( |
| 573 | "Unknown child process pid %d, will report returncode 255", |
| 574 | pid) |
| 575 | else: |
| 576 | if pid == 0: |
| 577 | # The child process is still alive. |
| 578 | return |
| 579 | |
| 580 | returncode = self._compute_returncode(status) |
| 581 | |
| 582 | try: |
| 583 | callback, args = self._callbacks.pop(pid) |
| 584 | except KeyError: # pragma: no cover |
| 585 | # May happen if .remove_child_handler() is called |
| 586 | # after os.waitpid() returns. |
| 587 | pass |
| 588 | else: |
| 589 | callback(pid, returncode, *args) |
| 590 | |
| 591 | |
| 592 | class FastChildWatcher(BaseChildWatcher): |
| 593 | """'Fast' child watcher implementation. |
| 594 | |
| 595 | This implementation reaps every terminated processes by calling |
| 596 | os.waitpid(-1) directly, possibly breaking other code spawning processes |
| 597 | and waiting for their termination. |
| 598 | |
| 599 | There is no noticeable overhead when handling a big number of children |
| 600 | (O(1) each time a child terminates). |
| 601 | """ |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 602 | def __init__(self): |
| 603 | super().__init__() |
| 604 | self._callbacks = {} |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 605 | self._lock = threading.Lock() |
| 606 | self._zombies = {} |
| 607 | self._forks = 0 |
| 608 | |
| 609 | def close(self): |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 610 | self._callbacks.clear() |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 611 | self._zombies.clear() |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 612 | super().close() |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 613 | |
| 614 | def __enter__(self): |
| 615 | with self._lock: |
| 616 | self._forks += 1 |
| 617 | |
| 618 | return self |
| 619 | |
| 620 | def __exit__(self, a, b, c): |
| 621 | with self._lock: |
| 622 | self._forks -= 1 |
| 623 | |
| 624 | if self._forks or not self._zombies: |
| 625 | return |
| 626 | |
| 627 | collateral_victims = str(self._zombies) |
| 628 | self._zombies.clear() |
| 629 | |
| 630 | logger.warning( |
| 631 | "Caught subprocesses termination from unknown pids: %s", |
| 632 | collateral_victims) |
| 633 | |
| 634 | def add_child_handler(self, pid, callback, *args): |
| 635 | assert self._forks, "Must use the context manager" |
| 636 | |
| 637 | self._callbacks[pid] = callback, args |
| 638 | |
| 639 | try: |
| 640 | # Ensure that the child is not already terminated. |
| 641 | # (raise KeyError if still alive) |
| 642 | returncode = self._zombies.pop(pid) |
| 643 | |
| 644 | # Child is dead, therefore we can fire the callback immediately. |
| 645 | # First we remove it from the dict. |
| 646 | # (raise KeyError if .remove_child_handler() was called in-between) |
| 647 | del self._callbacks[pid] |
| 648 | except KeyError: |
| 649 | pass |
| 650 | else: |
| 651 | callback(pid, returncode, *args) |
| 652 | |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 653 | def remove_child_handler(self, pid): |
| 654 | try: |
| 655 | del self._callbacks[pid] |
| 656 | return True |
| 657 | except KeyError: |
| 658 | return False |
| 659 | |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 660 | def _do_waitpid_all(self): |
| 661 | # Because of signal coalescing, we must keep calling waitpid() as |
| 662 | # long as we're able to reap a child. |
| 663 | while True: |
| 664 | try: |
| 665 | pid, status = os.waitpid(-1, os.WNOHANG) |
| 666 | except ChildProcessError: |
| 667 | # No more child processes exist. |
| 668 | return |
| 669 | else: |
| 670 | if pid == 0: |
| 671 | # A child process is still alive. |
| 672 | return |
| 673 | |
| 674 | returncode = self._compute_returncode(status) |
| 675 | |
| 676 | try: |
| 677 | callback, args = self._callbacks.pop(pid) |
| 678 | except KeyError: |
| 679 | # unknown child |
| 680 | with self._lock: |
| 681 | if self._forks: |
| 682 | # It may not be registered yet. |
| 683 | self._zombies[pid] = returncode |
| 684 | continue |
| 685 | |
| 686 | logger.warning( |
| 687 | "Caught subprocess termination from unknown pid: " |
| 688 | "%d -> %d", pid, returncode) |
| 689 | else: |
| 690 | callback(pid, returncode, *args) |
| 691 | |
| 692 | |
| 693 | class _UnixDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy): |
| 694 | """XXX""" |
| 695 | _loop_factory = _UnixSelectorEventLoop |
| 696 | |
| 697 | def __init__(self): |
| 698 | super().__init__() |
| 699 | self._watcher = None |
| 700 | |
| 701 | def _init_watcher(self): |
| 702 | with events._lock: |
| 703 | if self._watcher is None: # pragma: no branch |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 704 | self._watcher = SafeChildWatcher() |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 705 | if isinstance(threading.current_thread(), |
| 706 | threading._MainThread): |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 707 | self._watcher.attach_loop(self._local._loop) |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 708 | |
| 709 | def set_event_loop(self, loop): |
| 710 | """Set the event loop. |
| 711 | |
| 712 | As a side effect, if a child watcher was set before, then calling |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 713 | .set_event_loop() from the main thread will call .attach_loop(loop) on |
| 714 | the child watcher. |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 715 | """ |
| 716 | |
| 717 | super().set_event_loop(loop) |
| 718 | |
| 719 | if self._watcher is not None and \ |
| 720 | isinstance(threading.current_thread(), threading._MainThread): |
Guido van Rossum | 2bcae70 | 2013-11-13 15:50:08 -0800 | [diff] [blame^] | 721 | self._watcher.attach_loop(loop) |
Guido van Rossum | 0eaa5ac | 2013-11-04 15:50:46 -0800 | [diff] [blame] | 722 | |
| 723 | def get_child_watcher(self): |
| 724 | """Get the child watcher |
| 725 | |
| 726 | If not yet set, a SafeChildWatcher object is automatically created. |
| 727 | """ |
| 728 | if self._watcher is None: |
| 729 | self._init_watcher() |
| 730 | |
| 731 | return self._watcher |
| 732 | |
| 733 | def set_child_watcher(self, watcher): |
| 734 | """Set the child watcher""" |
| 735 | |
| 736 | assert watcher is None or isinstance(watcher, AbstractChildWatcher) |
| 737 | |
| 738 | if self._watcher is not None: |
| 739 | self._watcher.close() |
| 740 | |
| 741 | self._watcher = watcher |
| 742 | |
| 743 | SelectorEventLoop = _UnixSelectorEventLoop |
| 744 | DefaultEventLoopPolicy = _UnixDefaultEventLoopPolicy |