mirror of
https://github.com/moparisthebest/SickRage
synced 2024-11-18 07:15:13 -05:00
269 lines
8.3 KiB
Python
269 lines
8.3 KiB
Python
#!/usr/bin/env python
|
|
#
|
|
# Copyright 2012 Facebook
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
# not use this file except in compliance with the License. You may obtain
|
|
# a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
# License for the specific language governing permissions and limitations
|
|
# under the License.
|
|
"""Utilities for working with threads and ``Futures``.
|
|
|
|
``Futures`` are a pattern for concurrent programming introduced in
|
|
Python 3.2 in the `concurrent.futures` package (this package has also
|
|
been backported to older versions of Python and can be installed with
|
|
``pip install futures``). Tornado will use `concurrent.futures.Future` if
|
|
it is available; otherwise it will use a compatible class defined in this
|
|
module.
|
|
"""
|
|
from __future__ import absolute_import, division, print_function, with_statement
|
|
|
|
import functools
|
|
import sys
|
|
|
|
from tornado.stack_context import ExceptionStackContext, wrap
|
|
from tornado.util import raise_exc_info, ArgReplacer
|
|
|
|
try:
|
|
from concurrent import futures
|
|
except ImportError:
|
|
futures = None
|
|
|
|
|
|
class ReturnValueIgnoredError(Exception):
|
|
pass
|
|
|
|
|
|
class _DummyFuture(object):
|
|
def __init__(self):
|
|
self._done = False
|
|
self._result = None
|
|
self._exception = None
|
|
self._callbacks = []
|
|
|
|
def cancel(self):
|
|
return False
|
|
|
|
def cancelled(self):
|
|
return False
|
|
|
|
def running(self):
|
|
return not self._done
|
|
|
|
def done(self):
|
|
return self._done
|
|
|
|
def result(self, timeout=None):
|
|
self._check_done()
|
|
if self._exception:
|
|
raise self._exception
|
|
return self._result
|
|
|
|
def exception(self, timeout=None):
|
|
self._check_done()
|
|
if self._exception:
|
|
return self._exception
|
|
else:
|
|
return None
|
|
|
|
def add_done_callback(self, fn):
|
|
if self._done:
|
|
fn(self)
|
|
else:
|
|
self._callbacks.append(fn)
|
|
|
|
def set_result(self, result):
|
|
self._result = result
|
|
self._set_done()
|
|
|
|
def set_exception(self, exception):
|
|
self._exception = exception
|
|
self._set_done()
|
|
|
|
def _check_done(self):
|
|
if not self._done:
|
|
raise Exception("DummyFuture does not support blocking for results")
|
|
|
|
def _set_done(self):
|
|
self._done = True
|
|
for cb in self._callbacks:
|
|
# TODO: error handling
|
|
cb(self)
|
|
self._callbacks = None
|
|
|
|
if futures is None:
|
|
Future = _DummyFuture
|
|
else:
|
|
Future = futures.Future
|
|
|
|
|
|
class TracebackFuture(Future):
|
|
"""Subclass of `Future` which can store a traceback with
|
|
exceptions.
|
|
|
|
The traceback is automatically available in Python 3, but in the
|
|
Python 2 futures backport this information is discarded.
|
|
"""
|
|
def __init__(self):
|
|
super(TracebackFuture, self).__init__()
|
|
self.__exc_info = None
|
|
|
|
def exc_info(self):
|
|
return self.__exc_info
|
|
|
|
def set_exc_info(self, exc_info):
|
|
"""Traceback-aware replacement for
|
|
`~concurrent.futures.Future.set_exception`.
|
|
"""
|
|
self.__exc_info = exc_info
|
|
self.set_exception(exc_info[1])
|
|
|
|
def result(self, timeout=None):
|
|
if self.__exc_info is not None:
|
|
raise_exc_info(self.__exc_info)
|
|
else:
|
|
return super(TracebackFuture, self).result(timeout=timeout)
|
|
|
|
|
|
class DummyExecutor(object):
|
|
def submit(self, fn, *args, **kwargs):
|
|
future = TracebackFuture()
|
|
try:
|
|
future.set_result(fn(*args, **kwargs))
|
|
except Exception:
|
|
future.set_exc_info(sys.exc_info())
|
|
return future
|
|
|
|
def shutdown(self, wait=True):
|
|
pass
|
|
|
|
dummy_executor = DummyExecutor()
|
|
|
|
|
|
def run_on_executor(fn):
|
|
"""Decorator to run a synchronous method asynchronously on an executor.
|
|
|
|
The decorated method may be called with a ``callback`` keyword
|
|
argument and returns a future.
|
|
|
|
This decorator should be used only on methods of objects with attributes
|
|
``executor`` and ``io_loop``.
|
|
"""
|
|
@functools.wraps(fn)
|
|
def wrapper(self, *args, **kwargs):
|
|
callback = kwargs.pop("callback", None)
|
|
future = self.executor.submit(fn, self, *args, **kwargs)
|
|
if callback:
|
|
self.io_loop.add_future(future,
|
|
lambda future: callback(future.result()))
|
|
return future
|
|
return wrapper
|
|
|
|
|
|
_NO_RESULT = object()
|
|
|
|
|
|
def return_future(f):
|
|
"""Decorator to make a function that returns via callback return a
|
|
`Future`.
|
|
|
|
The wrapped function should take a ``callback`` keyword argument
|
|
and invoke it with one argument when it has finished. To signal failure,
|
|
the function can simply raise an exception (which will be
|
|
captured by the `.StackContext` and passed along to the ``Future``).
|
|
|
|
From the caller's perspective, the callback argument is optional.
|
|
If one is given, it will be invoked when the function is complete
|
|
with `Future.result()` as an argument. If the function fails, the
|
|
callback will not be run and an exception will be raised into the
|
|
surrounding `.StackContext`.
|
|
|
|
If no callback is given, the caller should use the ``Future`` to
|
|
wait for the function to complete (perhaps by yielding it in a
|
|
`.gen.engine` function, or passing it to `.IOLoop.add_future`).
|
|
|
|
Usage::
|
|
|
|
@return_future
|
|
def future_func(arg1, arg2, callback):
|
|
# Do stuff (possibly asynchronous)
|
|
callback(result)
|
|
|
|
@gen.engine
|
|
def caller(callback):
|
|
yield future_func(arg1, arg2)
|
|
callback()
|
|
|
|
Note that ``@return_future`` and ``@gen.engine`` can be applied to the
|
|
same function, provided ``@return_future`` appears first. However,
|
|
consider using ``@gen.coroutine`` instead of this combination.
|
|
"""
|
|
replacer = ArgReplacer(f, 'callback')
|
|
|
|
@functools.wraps(f)
|
|
def wrapper(*args, **kwargs):
|
|
future = TracebackFuture()
|
|
callback, args, kwargs = replacer.replace(
|
|
lambda value=_NO_RESULT: future.set_result(value),
|
|
args, kwargs)
|
|
|
|
def handle_error(typ, value, tb):
|
|
future.set_exc_info((typ, value, tb))
|
|
return True
|
|
exc_info = None
|
|
with ExceptionStackContext(handle_error):
|
|
try:
|
|
result = f(*args, **kwargs)
|
|
if result is not None:
|
|
raise ReturnValueIgnoredError(
|
|
"@return_future should not be used with functions "
|
|
"that return values")
|
|
except:
|
|
exc_info = sys.exc_info()
|
|
raise
|
|
if exc_info is not None:
|
|
# If the initial synchronous part of f() raised an exception,
|
|
# go ahead and raise it to the caller directly without waiting
|
|
# for them to inspect the Future.
|
|
raise_exc_info(exc_info)
|
|
|
|
# If the caller passed in a callback, schedule it to be called
|
|
# when the future resolves. It is important that this happens
|
|
# just before we return the future, or else we risk confusing
|
|
# stack contexts with multiple exceptions (one here with the
|
|
# immediate exception, and again when the future resolves and
|
|
# the callback triggers its exception by calling future.result()).
|
|
if callback is not None:
|
|
def run_callback(future):
|
|
result = future.result()
|
|
if result is _NO_RESULT:
|
|
callback()
|
|
else:
|
|
callback(future.result())
|
|
future.add_done_callback(wrap(run_callback))
|
|
return future
|
|
return wrapper
|
|
|
|
|
|
def chain_future(a, b):
|
|
"""Chain two futures together so that when one completes, so does the other.
|
|
|
|
The result (success or failure) of ``a`` will be copied to ``b``.
|
|
"""
|
|
def copy(future):
|
|
assert future is a
|
|
if (isinstance(a, TracebackFuture) and isinstance(b, TracebackFuture)
|
|
and a.exc_info() is not None):
|
|
b.set_exc_info(a.exc_info())
|
|
elif a.exception() is not None:
|
|
b.set_exception(a.exception())
|
|
else:
|
|
b.set_result(a.result())
|
|
a.add_done_callback(copy)
|