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from __future__ import absolute_import, print_function, division
try:
from errno import EBADF
except ImportError:
EBADF = 9
import os
from io import TextIOWrapper
import functools
import sys
from gevent.hub import _get_hub_noargs as get_hub
from gevent._compat import integer_types
from gevent._compat import reraise
from gevent.lock import Semaphore, DummySemaphore
class cancel_wait_ex(IOError):
def __init__(self):
super(cancel_wait_ex, self).__init__(
EBADF, 'File descriptor was closed in another greenlet')
class FileObjectClosed(IOError):
def __init__(self):
super(FileObjectClosed, self).__init__(
EBADF, 'Bad file descriptor (FileObject was closed)')
class FileObjectBase(object):
"""
Internal base class to ensure a level of consistency
between FileObjectPosix and FileObjectThread
"""
# List of methods we delegate to the wrapping IO object, if they
# implement them and we do not.
_delegate_methods = (
# General methods
'flush',
'fileno',
'writable',
'readable',
'seek',
'seekable',
'tell',
# Read
'read',
'readline',
'readlines',
'read1',
# Write
'write',
'writelines',
'truncate',
)
# Whether we are translating universal newlines or not.
_translate = False
_translate_encoding = None
_translate_errors = None
def __init__(self, io, closefd):
"""
:param io: An io.IOBase-like object.
"""
self._io = io
# We don't actually use this property ourself, but we save it (and
# pass it along) for compatibility.
self._close = closefd
if self._translate:
# This automatically handles delegation by assigning to
# self.io
self.translate_newlines(None, self._translate_encoding, self._translate_errors)
else:
self._do_delegate_methods()
io = property(lambda s: s._io,
# Historically we either hand-wrote all the delegation methods
# to use self.io, or we simply used __getattr__ to look them up at
# runtime. This meant people could change the io attribute on the fly
# and it would mostly work (subprocess.py used to do that). We don't recommend
# that, but we still support it.
lambda s, nv: setattr(s, '_io', nv) or s._do_delegate_methods())
def _do_delegate_methods(self):
for meth_name in self._delegate_methods:
meth = getattr(self._io, meth_name, None)
implemented_by_class = hasattr(type(self), meth_name)
if meth and not implemented_by_class:
setattr(self, meth_name, self._wrap_method(meth))
elif hasattr(self, meth_name) and not implemented_by_class:
delattr(self, meth_name)
def _wrap_method(self, method):
"""
Wrap a method we're copying into our dictionary from the underlying
io object to do something special or different, if necessary.
"""
return method
def translate_newlines(self, mode, *text_args, **text_kwargs):
wrapper = TextIOWrapper(self._io, *text_args, **text_kwargs)
if mode:
wrapper.mode = mode
self.io = wrapper
self._translate = True
@property
def closed(self):
"""True if the file is closed"""
return self._io is None
def close(self):
if self._io is None:
return
io = self._io
self._io = None
self._do_close(io, self._close)
def _do_close(self, fobj, closefd):
raise NotImplementedError()
def __getattr__(self, name):
if self._io is None:
raise FileObjectClosed()
return getattr(self._io, name)
def __repr__(self):
return '<%s _fobj=%r%s>' % (self.__class__.__name__, self.io, self._extra_repr())
def _extra_repr(self):
return ''
def __enter__(self):
return self
def __exit__(self, *args):
self.close()
class FileObjectBlock(FileObjectBase):
def __init__(self, fobj, *args, **kwargs):
closefd = kwargs.pop('close', True)
if kwargs:
raise TypeError('Unexpected arguments: %r' % kwargs.keys())
if isinstance(fobj, integer_types):
if not closefd:
# we cannot do this, since fdopen object will close the descriptor
raise TypeError('FileObjectBlock does not support close=False on an fd.')
fobj = os.fdopen(fobj, *args)
super(FileObjectBlock, self).__init__(fobj, closefd)
def _do_close(self, fobj, closefd):
fobj.close()
class FileObjectThread(FileObjectBase):
"""
A file-like object wrapping another file-like object, performing all blocking
operations on that object in a background thread.
.. caution::
Attempting to change the threadpool or lock of an existing FileObjectThread
has undefined consequences.
.. versionchanged:: 1.1b1
The file object is closed using the threadpool. Note that whether or
not this action is synchronous or asynchronous is not documented.
"""
def __init__(self, fobj, mode=None, bufsize=-1, close=True, threadpool=None, lock=True):
"""
:param fobj: The underlying file-like object to wrap, or an integer fileno
that will be pass to :func:`os.fdopen` along with *mode* and *bufsize*.
:keyword bool lock: If True (the default) then all operations will
be performed one-by-one. Note that this does not guarantee that, if using
this file object from multiple threads/greenlets, operations will be performed
in any particular order, only that no two operations will be attempted at the
same time. You can also pass your own :class:`gevent.lock.Semaphore` to synchronize
file operations with an external resource.
:keyword bool close: If True (the default) then when this object is closed,
the underlying object is closed as well.
"""
closefd = close
self.threadpool = threadpool or get_hub().threadpool
self.lock = lock
if self.lock is True:
self.lock = Semaphore()
elif not self.lock:
self.lock = DummySemaphore()
if not hasattr(self.lock, '__enter__'):
raise TypeError('Expected a Semaphore or boolean, got %r' % type(self.lock))
if isinstance(fobj, integer_types):
if not closefd:
# we cannot do this, since fdopen object will close the descriptor
raise TypeError('FileObjectThread does not support close=False on an fd.')
if mode is None:
assert bufsize == -1, "If you use the default mode, you can't choose a bufsize"
fobj = os.fdopen(fobj)
else:
fobj = os.fdopen(fobj, mode, bufsize)
self.__io_holder = [fobj] # signal for _wrap_method
super(FileObjectThread, self).__init__(fobj, closefd)
def _do_close(self, fobj, closefd):
self.__io_holder[0] = None # for _wrap_method
try:
with self.lock:
self.threadpool.apply(fobj.flush)
finally:
if closefd:
# Note that we're not taking the lock; older code
# did fobj.close() without going through the threadpool at all,
# so acquiring the lock could potentially introduce deadlocks
# that weren't present before. Avoiding the lock doesn't make
# the existing race condition any worse.
# We wrap the close in an exception handler and re-raise directly
# to avoid the (common, expected) IOError from being logged by the pool
def close(_fobj=fobj):
try:
_fobj.close()
except: # pylint:disable=bare-except
return sys.exc_info()
finally:
_fobj = None
del fobj
exc_info = self.threadpool.apply(close)
del close
if exc_info:
reraise(*exc_info)
def _do_delegate_methods(self):
super(FileObjectThread, self)._do_delegate_methods()
if not hasattr(self, 'read1') and 'r' in getattr(self._io, 'mode', ''):
self.read1 = self.read
self.__io_holder[0] = self._io
def _extra_repr(self):
return ' threadpool=%r' % (self.threadpool,)
def __iter__(self):
return self
def next(self):
line = self.readline()
if line:
return line
raise StopIteration
__next__ = next
def _wrap_method(self, method):
# NOTE: We are careful to avoid introducing a refcycle
# within self. Our wrapper cannot refer to self.
io_holder = self.__io_holder
lock = self.lock
threadpool = self.threadpool
@functools.wraps(method)
def thread_method(*args, **kwargs):
if io_holder[0] is None:
# This is different than FileObjectPosix, etc,
# because we want to save the expensive trip through
# the threadpool.
raise FileObjectClosed()
with lock:
return threadpool.apply(method, args, kwargs)
return thread_method