bbf6d9b026
Bugfix for feeds
- removed categories related and up
- load new books now working
- category random now working
login page is free of non accessible elements
boolean custom column is vivible in UI
books with only with certain languages can be shown
book shelfs can be deleted from UI
Anonymous user view is more resticted
Added browse of series in sidebar
Dependencys in vendor folder are updated to newer versions (licencs files are now present)
Bugfix editing Authors names
Made upload on windows working
461 lines
16 KiB
Python
461 lines
16 KiB
Python
#!/usr/bin/env python
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#
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# Copyright 2012 Facebook
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Utilities for working with threads and ``Futures``.
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``Futures`` are a pattern for concurrent programming introduced in
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Python 3.2 in the `concurrent.futures` package (this package has also
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been backported to older versions of Python and can be installed with
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``pip install futures``). Tornado will use `concurrent.futures.Future` if
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it is available; otherwise it will use a compatible class defined in this
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module.
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"""
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from __future__ import absolute_import, division, print_function, with_statement
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import functools
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import platform
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import traceback
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import sys
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from tornado.log import app_log
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from tornado.stack_context import ExceptionStackContext, wrap
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from tornado.util import raise_exc_info, ArgReplacer
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try:
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from concurrent import futures
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except ImportError:
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futures = None
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# Can the garbage collector handle cycles that include __del__ methods?
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# This is true in cpython beginning with version 3.4 (PEP 442).
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_GC_CYCLE_FINALIZERS = (platform.python_implementation() == 'CPython' and
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sys.version_info >= (3, 4))
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class ReturnValueIgnoredError(Exception):
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pass
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# This class and associated code in the future object is derived
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# from the Trollius project, a backport of asyncio to Python 2.x - 3.x
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class _TracebackLogger(object):
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"""Helper to log a traceback upon destruction if not cleared.
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This solves a nasty problem with Futures and Tasks that have an
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exception set: if nobody asks for the exception, the exception is
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never logged. This violates the Zen of Python: 'Errors should
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never pass silently. Unless explicitly silenced.'
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However, we don't want to log the exception as soon as
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set_exception() is called: if the calling code is written
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properly, it will get the exception and handle it properly. But
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we *do* want to log it if result() or exception() was never called
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-- otherwise developers waste a lot of time wondering why their
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buggy code fails silently.
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An earlier attempt added a __del__() method to the Future class
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itself, but this backfired because the presence of __del__()
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prevents garbage collection from breaking cycles. A way out of
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this catch-22 is to avoid having a __del__() method on the Future
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class itself, but instead to have a reference to a helper object
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with a __del__() method that logs the traceback, where we ensure
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that the helper object doesn't participate in cycles, and only the
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Future has a reference to it.
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The helper object is added when set_exception() is called. When
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the Future is collected, and the helper is present, the helper
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object is also collected, and its __del__() method will log the
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traceback. When the Future's result() or exception() method is
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called (and a helper object is present), it removes the the helper
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object, after calling its clear() method to prevent it from
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logging.
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One downside is that we do a fair amount of work to extract the
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traceback from the exception, even when it is never logged. It
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would seem cheaper to just store the exception object, but that
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references the traceback, which references stack frames, which may
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reference the Future, which references the _TracebackLogger, and
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then the _TracebackLogger would be included in a cycle, which is
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what we're trying to avoid! As an optimization, we don't
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immediately format the exception; we only do the work when
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activate() is called, which call is delayed until after all the
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Future's callbacks have run. Since usually a Future has at least
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one callback (typically set by 'yield From') and usually that
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callback extracts the callback, thereby removing the need to
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format the exception.
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PS. I don't claim credit for this solution. I first heard of it
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in a discussion about closing files when they are collected.
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"""
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__slots__ = ('exc_info', 'formatted_tb')
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def __init__(self, exc_info):
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self.exc_info = exc_info
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self.formatted_tb = None
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def activate(self):
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exc_info = self.exc_info
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if exc_info is not None:
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self.exc_info = None
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self.formatted_tb = traceback.format_exception(*exc_info)
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def clear(self):
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self.exc_info = None
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self.formatted_tb = None
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def __del__(self):
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if self.formatted_tb:
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app_log.error('Future exception was never retrieved: %s',
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''.join(self.formatted_tb).rstrip())
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class Future(object):
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"""Placeholder for an asynchronous result.
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A ``Future`` encapsulates the result of an asynchronous
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operation. In synchronous applications ``Futures`` are used
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to wait for the result from a thread or process pool; in
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Tornado they are normally used with `.IOLoop.add_future` or by
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yielding them in a `.gen.coroutine`.
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`tornado.concurrent.Future` is similar to
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`concurrent.futures.Future`, but not thread-safe (and therefore
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faster for use with single-threaded event loops).
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In addition to ``exception`` and ``set_exception``, methods ``exc_info``
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and ``set_exc_info`` are supported to capture tracebacks in Python 2.
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The traceback is automatically available in Python 3, but in the
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Python 2 futures backport this information is discarded.
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This functionality was previously available in a separate class
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``TracebackFuture``, which is now a deprecated alias for this class.
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.. versionchanged:: 4.0
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`tornado.concurrent.Future` is always a thread-unsafe ``Future``
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with support for the ``exc_info`` methods. Previously it would
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be an alias for the thread-safe `concurrent.futures.Future`
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if that package was available and fall back to the thread-unsafe
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implementation if it was not.
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.. versionchanged:: 4.1
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If a `.Future` contains an error but that error is never observed
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(by calling ``result()``, ``exception()``, or ``exc_info()``),
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a stack trace will be logged when the `.Future` is garbage collected.
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This normally indicates an error in the application, but in cases
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where it results in undesired logging it may be necessary to
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suppress the logging by ensuring that the exception is observed:
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``f.add_done_callback(lambda f: f.exception())``.
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"""
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def __init__(self):
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self._done = False
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self._result = None
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self._exc_info = None
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self._log_traceback = False # Used for Python >= 3.4
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self._tb_logger = None # Used for Python <= 3.3
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self._callbacks = []
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def cancel(self):
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"""Cancel the operation, if possible.
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Tornado ``Futures`` do not support cancellation, so this method always
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returns False.
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"""
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return False
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def cancelled(self):
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"""Returns True if the operation has been cancelled.
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Tornado ``Futures`` do not support cancellation, so this method
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always returns False.
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"""
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return False
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def running(self):
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"""Returns True if this operation is currently running."""
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return not self._done
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def done(self):
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"""Returns True if the future has finished running."""
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return self._done
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def _clear_tb_log(self):
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self._log_traceback = False
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if self._tb_logger is not None:
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self._tb_logger.clear()
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self._tb_logger = None
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def result(self, timeout=None):
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"""If the operation succeeded, return its result. If it failed,
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re-raise its exception.
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"""
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self._clear_tb_log()
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if self._result is not None:
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return self._result
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if self._exc_info is not None:
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raise_exc_info(self._exc_info)
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self._check_done()
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return self._result
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def exception(self, timeout=None):
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"""If the operation raised an exception, return the `Exception`
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object. Otherwise returns None.
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"""
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self._clear_tb_log()
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if self._exc_info is not None:
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return self._exc_info[1]
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else:
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self._check_done()
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return None
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def add_done_callback(self, fn):
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"""Attaches the given callback to the `Future`.
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It will be invoked with the `Future` as its argument when the Future
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has finished running and its result is available. In Tornado
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consider using `.IOLoop.add_future` instead of calling
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`add_done_callback` directly.
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"""
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if self._done:
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fn(self)
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else:
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self._callbacks.append(fn)
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def set_result(self, result):
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"""Sets the result of a ``Future``.
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It is undefined to call any of the ``set`` methods more than once
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on the same object.
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"""
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self._result = result
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self._set_done()
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def set_exception(self, exception):
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"""Sets the exception of a ``Future.``"""
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self.set_exc_info(
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(exception.__class__,
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exception,
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getattr(exception, '__traceback__', None)))
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def exc_info(self):
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"""Returns a tuple in the same format as `sys.exc_info` or None.
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.. versionadded:: 4.0
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"""
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self._clear_tb_log()
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return self._exc_info
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def set_exc_info(self, exc_info):
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"""Sets the exception information of a ``Future.``
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Preserves tracebacks on Python 2.
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.. versionadded:: 4.0
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"""
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self._exc_info = exc_info
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self._log_traceback = True
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if not _GC_CYCLE_FINALIZERS:
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self._tb_logger = _TracebackLogger(exc_info)
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try:
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self._set_done()
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finally:
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# Activate the logger after all callbacks have had a
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# chance to call result() or exception().
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if self._log_traceback and self._tb_logger is not None:
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self._tb_logger.activate()
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self._exc_info = exc_info
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def _check_done(self):
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if not self._done:
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raise Exception("DummyFuture does not support blocking for results")
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def _set_done(self):
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self._done = True
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for cb in self._callbacks:
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try:
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cb(self)
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except Exception:
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app_log.exception('exception calling callback %r for %r',
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cb, self)
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self._callbacks = None
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# On Python 3.3 or older, objects with a destructor part of a reference
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# cycle are never destroyed. It's no longer the case on Python 3.4 thanks to
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# the PEP 442.
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if _GC_CYCLE_FINALIZERS:
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def __del__(self):
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if not self._log_traceback:
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# set_exception() was not called, or result() or exception()
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# has consumed the exception
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return
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tb = traceback.format_exception(*self._exc_info)
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app_log.error('Future %r exception was never retrieved: %s',
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self, ''.join(tb).rstrip())
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TracebackFuture = Future
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if futures is None:
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FUTURES = Future
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else:
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FUTURES = (futures.Future, Future)
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def is_future(x):
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return isinstance(x, FUTURES)
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class DummyExecutor(object):
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def submit(self, fn, *args, **kwargs):
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future = TracebackFuture()
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try:
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future.set_result(fn(*args, **kwargs))
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except Exception:
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future.set_exc_info(sys.exc_info())
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return future
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def shutdown(self, wait=True):
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pass
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dummy_executor = DummyExecutor()
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def run_on_executor(fn):
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"""Decorator to run a synchronous method asynchronously on an executor.
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The decorated method may be called with a ``callback`` keyword
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argument and returns a future.
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This decorator should be used only on methods of objects with attributes
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``executor`` and ``io_loop``.
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"""
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@functools.wraps(fn)
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def wrapper(self, *args, **kwargs):
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callback = kwargs.pop("callback", None)
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future = self.executor.submit(fn, self, *args, **kwargs)
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if callback:
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self.io_loop.add_future(future,
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lambda future: callback(future.result()))
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return future
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return wrapper
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_NO_RESULT = object()
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def return_future(f):
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"""Decorator to make a function that returns via callback return a
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`Future`.
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The wrapped function should take a ``callback`` keyword argument
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and invoke it with one argument when it has finished. To signal failure,
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the function can simply raise an exception (which will be
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captured by the `.StackContext` and passed along to the ``Future``).
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From the caller's perspective, the callback argument is optional.
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If one is given, it will be invoked when the function is complete
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with `Future.result()` as an argument. If the function fails, the
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callback will not be run and an exception will be raised into the
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surrounding `.StackContext`.
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If no callback is given, the caller should use the ``Future`` to
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wait for the function to complete (perhaps by yielding it in a
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`.gen.engine` function, or passing it to `.IOLoop.add_future`).
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Usage::
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@return_future
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def future_func(arg1, arg2, callback):
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# Do stuff (possibly asynchronous)
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callback(result)
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@gen.engine
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def caller(callback):
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yield future_func(arg1, arg2)
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callback()
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Note that ``@return_future`` and ``@gen.engine`` can be applied to the
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same function, provided ``@return_future`` appears first. However,
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consider using ``@gen.coroutine`` instead of this combination.
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"""
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replacer = ArgReplacer(f, 'callback')
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@functools.wraps(f)
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def wrapper(*args, **kwargs):
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future = TracebackFuture()
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callback, args, kwargs = replacer.replace(
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lambda value=_NO_RESULT: future.set_result(value),
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args, kwargs)
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def handle_error(typ, value, tb):
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future.set_exc_info((typ, value, tb))
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return True
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exc_info = None
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with ExceptionStackContext(handle_error):
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try:
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result = f(*args, **kwargs)
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if result is not None:
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raise ReturnValueIgnoredError(
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"@return_future should not be used with functions "
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"that return values")
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except:
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exc_info = sys.exc_info()
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raise
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if exc_info is not None:
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# If the initial synchronous part of f() raised an exception,
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# go ahead and raise it to the caller directly without waiting
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# for them to inspect the Future.
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future.result()
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# If the caller passed in a callback, schedule it to be called
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# when the future resolves. It is important that this happens
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# just before we return the future, or else we risk confusing
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# stack contexts with multiple exceptions (one here with the
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# immediate exception, and again when the future resolves and
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# the callback triggers its exception by calling future.result()).
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if callback is not None:
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def run_callback(future):
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result = future.result()
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if result is _NO_RESULT:
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callback()
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else:
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callback(future.result())
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future.add_done_callback(wrap(run_callback))
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return future
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return wrapper
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def chain_future(a, b):
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"""Chain two futures together so that when one completes, so does the other.
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The result (success or failure) of ``a`` will be copied to ``b``, unless
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``b`` has already been completed or cancelled by the time ``a`` finishes.
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"""
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def copy(future):
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assert future is a
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if b.done():
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return
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if (isinstance(a, TracebackFuture) and isinstance(b, TracebackFuture)
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and a.exc_info() is not None):
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b.set_exc_info(a.exc_info())
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elif a.exception() is not None:
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b.set_exception(a.exception())
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else:
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b.set_result(a.result())
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a.add_done_callback(copy)
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