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asyncio: New error handling API. Issue #20681.

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This commit is contained in:
Yury Selivanov 2014-02-18 18:02:19 -05:00
parent 6acc5e1330
commit 569efa2e4b
15 changed files with 491 additions and 99 deletions
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96
Lib/asyncio/base_events.py
View file

@ -122,6 +122,7 @@ class BaseEventLoop(events.AbstractEventLoop):
self._internal_fds = 0
self._running = False
self._clock_resolution = time.get_clock_info('monotonic').resolution
self._exception_handler = None
def _make_socket_transport(self, sock, protocol, waiter=None, *,
extra=None, server=None):
@ -254,7 +255,7 @@ class BaseEventLoop(events.AbstractEventLoop):
"""Like call_later(), but uses an absolute time."""
if tasks.iscoroutinefunction(callback):
raise TypeError("coroutines cannot be used with call_at()")
timer = events.TimerHandle(when, callback, args)
timer = events.TimerHandle(when, callback, args, self)
heapq.heappush(self._scheduled, timer)
return timer
@ -270,7 +271,7 @@ class BaseEventLoop(events.AbstractEventLoop):
"""
if tasks.iscoroutinefunction(callback):
raise TypeError("coroutines cannot be used with call_soon()")
handle = events.Handle(callback, args)
handle = events.Handle(callback, args, self)
self._ready.append(handle)
return handle
@ -625,6 +626,97 @@ class BaseEventLoop(events.AbstractEventLoop):
protocol, popen_args, False, stdin, stdout, stderr, bufsize, **kwargs)
return transport, protocol
def set_exception_handler(self, handler):
"""Set handler as the new event loop exception handler.
If handler is None, the default exception handler will
be set.
If handler is a callable object, it should have a
matching signature to '(loop, context)', where 'loop'
will be a reference to the active event loop, 'context'
will be a dict object (see `call_exception_handler()`
documentation for details about context).
"""
if handler is not None and not callable(handler):
raise TypeError('A callable object or None is expected, '
'got {!r}'.format(handler))
self._exception_handler = handler
def default_exception_handler(self, context):
"""Default exception handler.
This is called when an exception occurs and no exception
handler is set, and can be called by a custom exception
handler that wants to defer to the default behavior.
context parameter has the same meaning as in
`call_exception_handler()`.
"""
message = context.get('message')
if not message:
message = 'Unhandled exception in event loop'
exception = context.get('exception')
if exception is not None:
exc_info = (type(exception), exception, exception.__traceback__)
else:
exc_info = False
log_lines = [message]
for key in sorted(context):
if key in {'message', 'exception'}:
continue
log_lines.append('{}: {!r}'.format(key, context[key]))
logger.error('\n'.join(log_lines), exc_info=exc_info)
def call_exception_handler(self, context):
"""Call the current event loop exception handler.
context is a dict object containing the following keys
(new keys maybe introduced later):
- 'message': Error message;
- 'exception' (optional): Exception object;
- 'future' (optional): Future instance;
- 'handle' (optional): Handle instance;
- 'protocol' (optional): Protocol instance;
- 'transport' (optional): Transport instance;
- 'socket' (optional): Socket instance.
Note: this method should not be overloaded in subclassed
event loops. For any custom exception handling, use
`set_exception_handler()` method.
"""
if self._exception_handler is None:
try:
self.default_exception_handler(context)
except Exception:
# Second protection layer for unexpected errors
# in the default implementation, as well as for subclassed
# event loops with overloaded "default_exception_handler".
logger.error('Exception in default exception handler',
exc_info=True)
else:
try:
self._exception_handler(self, context)
except Exception as exc:
# Exception in the user set custom exception handler.
try:
# Let's try default handler.
self.default_exception_handler({
'message': 'Unhandled error in exception handler',
'exception': exc,
'context': context,
})
except Exception:
# Guard 'default_exception_handler' in case it's
# overloaded.
logger.error('Exception in default exception handler '
'while handling an unexpected error '
'in custom exception handler',
exc_info=True)
def _add_callback(self, handle):
"""Add a Handle to ready or scheduled."""
assert isinstance(handle, events.Handle), 'A Handle is required here'

31
Lib/asyncio/events.py
View file

@ -19,10 +19,11 @@ from .log import logger
class Handle:
"""Object returned by callback registration methods."""
__slots__ = ['_callback', '_args', '_cancelled']
__slots__ = ['_callback', '_args', '_cancelled', '_loop']
def __init__(self, callback, args):
def __init__(self, callback, args, loop):
assert not isinstance(callback, Handle), 'A Handle is not a callback'
self._loop = loop
self._callback = callback
self._args = args
self._cancelled = False
@ -39,9 +40,14 @@ class Handle:
def _run(self):
try:
self._callback(*self._args)
except Exception:
logger.exception('Exception in callback %s %r',
self._callback, self._args)
except Exception as exc:
msg = 'Exception in callback {}{!r}'.format(self._callback,
self._args)
self._loop.call_exception_handler({
'message': msg,
'exception': exc,
'handle': self,
})
self = None # Needed to break cycles when an exception occurs.
@ -50,9 +56,9 @@ class TimerHandle(Handle):
__slots__ = ['_when']
def __init__(self, when, callback, args):
def __init__(self, when, callback, args, loop):
assert when is not None
super().__init__(callback, args)
super().__init__(callback, args, loop)
self._when = when
@ -328,6 +334,17 @@ class AbstractEventLoop:
def remove_signal_handler(self, sig):
raise NotImplementedError
# Error handlers.
def set_exception_handler(self, handler):
raise NotImplementedError
def default_exception_handler(self, context):
raise NotImplementedError
def call_exception_handler(self, context):
raise NotImplementedError
class AbstractEventLoopPolicy:
"""Abstract policy for accessing the event loop."""

22
Lib/asyncio/futures.py
View file

@ -83,9 +83,10 @@ class _TracebackLogger:
in a discussion about closing files when they are collected.
"""
__slots__ = ['exc', 'tb']
__slots__ = ['exc', 'tb', 'loop']
def __init__(self, exc):
def __init__(self, exc, loop):
self.loop = loop
self.exc = exc
self.tb = None
@ -102,8 +103,11 @@ class _TracebackLogger:
def __del__(self):
if self.tb:
logger.error('Future/Task exception was never retrieved:\n%s',
''.join(self.tb))
msg = 'Future/Task exception was never retrieved:\n{tb}'
context = {
'message': msg.format(tb=''.join(self.tb)),
}
self.loop.call_exception_handler(context)
class Future:
@ -173,8 +177,12 @@ class Future:
# has consumed the exception
return
exc = self._exception
logger.error('Future/Task exception was never retrieved:',
exc_info=(exc.__class__, exc, exc.__traceback__))
context = {
'message': 'Future/Task exception was never retrieved',
'exception': exc,
'future': self,
}
self._loop.call_exception_handler(context)
def cancel(self):
"""Cancel the future and schedule callbacks.
@ -309,7 +317,7 @@ class Future:
if _PY34:
self._log_traceback = True
else:
self._tb_logger = _TracebackLogger(exception)
self._tb_logger = _TracebackLogger(exception, self._loop)
# Arrange for the logger to be activated after all callbacks
# have had a chance to call result() or exception().
self._loop.call_soon(self._tb_logger.activate)

33
Lib/asyncio/proactor_events.py
View file

@ -56,7 +56,12 @@ class _ProactorBasePipeTransport(transports.BaseTransport):
def _fatal_error(self, exc):
if not isinstance(exc, (BrokenPipeError, ConnectionResetError)):
logger.exception('Fatal error for %s', self)
self._loop.call_exception_handler({
'message': 'Fatal transport error',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
self._force_close(exc)
def _force_close(self, exc):
@ -103,8 +108,13 @@ class _ProactorBasePipeTransport(transports.BaseTransport):
self._protocol_paused = True
try:
self._protocol.pause_writing()
except Exception:
logger.exception('pause_writing() failed')
except Exception as exc:
self._loop.call_exception_handler({
'message': 'protocol.pause_writing() failed',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
def _maybe_resume_protocol(self):
if (self._protocol_paused and
@ -112,8 +122,13 @@ class _ProactorBasePipeTransport(transports.BaseTransport):
self._protocol_paused = False
try:
self._protocol.resume_writing()
except Exception:
logger.exception('resume_writing() failed')
except Exception as exc:
self._loop.call_exception_handler({
'message': 'protocol.resume_writing() failed',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
def set_write_buffer_limits(self, high=None, low=None):
if high is None:
@ -465,9 +480,13 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
conn, protocol,
extra={'peername': addr}, server=server)
f = self._proactor.accept(sock)
except OSError:
except OSError as exc:
if sock.fileno() != -1:
logger.exception('Accept failed')
self.call_exception_handler({
'message': 'Accept failed',
'exception': exc,
'socket': sock,
})
sock.close()
except futures.CancelledError:
sock.close()

35
Lib/asyncio/selector_events.py
View file

@ -112,7 +112,11 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
# Some platforms (e.g. Linux keep reporting the FD as
# ready, so we remove the read handler temporarily.
# We'll try again in a while.
logger.exception('Accept out of system resource (%s)', exc)
self.call_exception_handler({
'message': 'socket.accept() out of system resource',
'exception': exc,
'socket': sock,
})
self.remove_reader(sock.fileno())
self.call_later(constants.ACCEPT_RETRY_DELAY,
self._start_serving,
@ -132,7 +136,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
def add_reader(self, fd, callback, *args):
"""Add a reader callback."""
handle = events.Handle(callback, args)
handle = events.Handle(callback, args, self)
try:
key = self._selector.get_key(fd)
except KeyError:
@ -167,7 +171,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
def add_writer(self, fd, callback, *args):
"""Add a writer callback.."""
handle = events.Handle(callback, args)
handle = events.Handle(callback, args, self)
try:
key = self._selector.get_key(fd)
except KeyError:
@ -364,8 +368,13 @@ class _FlowControlMixin(transports.Transport):
self._protocol_paused = True
try:
self._protocol.pause_writing()
except Exception:
logger.exception('pause_writing() failed')
except Exception as exc:
self._loop.call_exception_handler({
'message': 'protocol.pause_writing() failed',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
def _maybe_resume_protocol(self):
if (self._protocol_paused and
@ -373,8 +382,13 @@ class _FlowControlMixin(transports.Transport):
self._protocol_paused = False
try:
self._protocol.resume_writing()
except Exception:
logger.exception('resume_writing() failed')
except Exception as exc:
self._loop.call_exception_handler({
'message': 'protocol.resume_writing() failed',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
def set_write_buffer_limits(self, high=None, low=None):
if high is None:
@ -435,7 +449,12 @@ class _SelectorTransport(_FlowControlMixin, transports.Transport):
def _fatal_error(self, exc):
# Should be called from exception handler only.
if not isinstance(exc, (BrokenPipeError, ConnectionResetError)):
logger.exception('Fatal error for %s', self)
self._loop.call_exception_handler({
'message': 'Fatal transport error',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
self._force_close(exc)
def _force_close(self, exc):

18
Lib/asyncio/test_utils.py
View file

@ -4,6 +4,7 @@ import collections
import contextlib
import io
import os
import re
import socket
import socketserver
import sys
@ -301,7 +302,7 @@ class TestLoop(base_events.BaseEventLoop):
raise AssertionError("Time generator is not finished")
def add_reader(self, fd, callback, *args):
self.readers[fd] = events.Handle(callback, args)
self.readers[fd] = events.Handle(callback, args, self)
def remove_reader(self, fd):
self.remove_reader_count[fd] += 1
@ -320,7 +321,7 @@ class TestLoop(base_events.BaseEventLoop):
handle._args, args)
def add_writer(self, fd, callback, *args):
self.writers[fd] = events.Handle(callback, args)
self.writers[fd] = events.Handle(callback, args, self)
def remove_writer(self, fd):
self.remove_writer_count[fd] += 1
@ -362,3 +363,16 @@ class TestLoop(base_events.BaseEventLoop):
def MockCallback(**kwargs):
return unittest.mock.Mock(spec=['__call__'], **kwargs)
class MockPattern(str):
"""A regex based str with a fuzzy __eq__.
Use this helper with 'mock.assert_called_with', or anywhere
where a regexp comparison between strings is needed.
For instance:
mock_call.assert_called_with(MockPattern('spam.*ham'))
"""
def __eq__(self, other):
return bool(re.search(str(self), other, re.S))

26
Lib/asyncio/unix_events.py
View file

@ -65,7 +65,7 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
except ValueError as exc:
raise RuntimeError(str(exc))
handle = events.Handle(callback, args)
handle = events.Handle(callback, args, self)
self._signal_handlers[sig] = handle
try:
@ -294,7 +294,12 @@ class _UnixReadPipeTransport(transports.ReadTransport):
def _fatal_error(self, exc):
# should be called by exception handler only
if not (isinstance(exc, OSError) and exc.errno == errno.EIO):
logger.exception('Fatal error for %s', self)
self._loop.call_exception_handler({
'message': 'Fatal transport error',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
self._close(exc)
def _close(self, exc):
@ -441,7 +446,12 @@ class _UnixWritePipeTransport(selector_events._FlowControlMixin,
def _fatal_error(self, exc):
# should be called by exception handler only
if not isinstance(exc, (BrokenPipeError, ConnectionResetError)):
logger.exception('Fatal error for %s', self)
self._loop.call_exception_handler({
'message': 'Fatal transport error',
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
self._close(exc)
def _close(self, exc=None):
@ -582,8 +592,14 @@ class BaseChildWatcher(AbstractChildWatcher):
def _sig_chld(self):
try:
self._do_waitpid_all()
except Exception:
logger.exception('Unknown exception in SIGCHLD handler')
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):

8
Lib/asyncio/windows_events.py
View file

@ -156,9 +156,13 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
if pipe is None:
return
f = self._proactor.accept_pipe(pipe)
except OSError:
except OSError as exc:
if pipe and pipe.fileno() != -1:
logger.exception('Pipe accept failed')
self.call_exception_handler({
'message': 'Pipe accept failed',
'exception': exc,
'pipe': pipe,
})
pipe.close()
except futures.CancelledError:
if pipe: