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Python

"""
gevent internals.
"""
from __future__ import absolute_import, print_function, division
try:
from errno import EBADF
except ImportError:
EBADF = 9
import io
import functools
import sys
import os
from gevent.hub import _get_hub_noargs as get_hub
from gevent._compat import PY2
from gevent._compat import integer_types
from gevent._compat import reraise
from gevent._compat import fspath
from gevent.lock import Semaphore, DummySemaphore
class cancel_wait_ex(IOError):
def __init__(self):
IOError.__init__(
self,
EBADF, 'File descriptor was closed in another greenlet')
class FileObjectClosed(IOError):
def __init__(self):
IOError.__init__(
self,
EBADF, 'Bad file descriptor (FileObject was closed)')
class UniversalNewlineBytesWrapper(io.TextIOWrapper):
"""
Uses TextWrapper to decode universal newlines, but returns the
results as bytes.
This is for Python 2 where the 'rU' mode did that.
"""
mode = None
def __init__(self, fobj, line_buffering):
# latin-1 has the ability to round-trip arbitrary bytes.
io.TextIOWrapper.__init__(self, fobj, encoding='latin-1',
newline=None,
line_buffering=line_buffering)
def read(self, *args, **kwargs):
result = io.TextIOWrapper.read(self, *args, **kwargs)
return result.encode('latin-1')
def readline(self, limit=-1):
result = io.TextIOWrapper.readline(self, limit)
return result.encode('latin-1')
def __iter__(self):
# readlines() is implemented in terms of __iter__
# and TextIOWrapper.__iter__ checks that readline returns
# a unicode object, which we don't, so we override
return self
def __next__(self):
line = self.readline()
if not line:
raise StopIteration
return line
next = __next__
class FlushingBufferedWriter(io.BufferedWriter):
def write(self, b):
ret = io.BufferedWriter.write(self, b)
self.flush()
return ret
class OpenDescriptor(object): # pylint:disable=too-many-instance-attributes
"""
Interprets the arguments to `open`. Internal use only.
Originally based on code in the stdlib's _pyio.py (Python implementation of
the :mod:`io` module), but modified for gevent:
- Native strings are returned on Python 2 when neither
'b' nor 't' are in the mode string and no encoding is specified.
- Universal newlines work in that mode.
- Allows unbuffered text IO.
"""
@staticmethod
def _collapse_arg(preferred_val, old_val, default):
if preferred_val is not None and old_val is not None:
raise TypeError
if preferred_val is None and old_val is None:
return default
return preferred_val if preferred_val is not None else old_val
def __init__(self, fobj, mode='r', bufsize=None, close=None,
encoding=None, errors=None, newline=None,
buffering=None, closefd=None):
# Based on code in the stdlib's _pyio.py from 3.8.
# pylint:disable=too-many-locals,too-many-branches,too-many-statements
closefd = self._collapse_arg(closefd, close, True)
del close
buffering = self._collapse_arg(buffering, bufsize, -1)
del bufsize
if not hasattr(fobj, 'fileno'):
if not isinstance(fobj, integer_types):
# Not a fd. Support PathLike on Python 2 and Python <= 3.5.
fobj = fspath(fobj)
if not isinstance(fobj, (str, bytes) + integer_types): # pragma: no cover
raise TypeError("invalid file: %r" % fobj)
if isinstance(fobj, (str, bytes)):
closefd = True
if not isinstance(mode, str):
raise TypeError("invalid mode: %r" % mode)
if not isinstance(buffering, integer_types):
raise TypeError("invalid buffering: %r" % buffering)
if encoding is not None and not isinstance(encoding, str):
raise TypeError("invalid encoding: %r" % encoding)
if errors is not None and not isinstance(errors, str):
raise TypeError("invalid errors: %r" % errors)
modes = set(mode)
if modes - set("axrwb+tU") or len(mode) > len(modes):
raise ValueError("invalid mode: %r" % mode)
creating = "x" in modes
reading = "r" in modes
writing = "w" in modes
appending = "a" in modes
updating = "+" in modes
text = "t" in modes
binary = "b" in modes
universal = 'U' in modes
can_write = creating or writing or appending or updating
if universal:
if can_write:
raise ValueError("mode U cannot be combined with 'x', 'w', 'a', or '+'")
# Just because the stdlib deprecates this, no need for us to do so as well.
# Especially not while we still support Python 2.
# import warnings
# warnings.warn("'U' mode is deprecated",
# DeprecationWarning, 4)
reading = True
if text and binary:
raise ValueError("can't have text and binary mode at once")
if creating + reading + writing + appending > 1:
raise ValueError("can't have read/write/append mode at once")
if not (creating or reading or writing or appending):
raise ValueError("must have exactly one of read/write/append mode")
if binary and encoding is not None:
raise ValueError("binary mode doesn't take an encoding argument")
if binary and errors is not None:
raise ValueError("binary mode doesn't take an errors argument")
if binary and newline is not None:
raise ValueError("binary mode doesn't take a newline argument")
if binary and buffering == 1:
import warnings
warnings.warn("line buffering (buffering=1) isn't supported in binary "
"mode, the default buffer size will be used",
RuntimeWarning, 4)
self.fobj = fobj
self.fileio_mode = (
(creating and "x" or "")
+ (reading and "r" or "")
+ (writing and "w" or "")
+ (appending and "a" or "")
+ (updating and "+" or "")
)
self.mode = self.fileio_mode + ('t' if text else '') + ('b' if binary else '')
self.creating = creating
self.reading = reading
self.writing = writing
self.appending = appending
self.updating = updating
self.text = text
self.binary = binary
self.can_write = can_write
self.can_read = reading or updating
self.native = (
not self.text and not self.binary # Neither t nor b given.
and not encoding and not errors # And no encoding or error handling either.
)
self.universal = universal
self.buffering = buffering
self.encoding = encoding
self.errors = errors
self.newline = newline
self.closefd = closefd
default_buffer_size = io.DEFAULT_BUFFER_SIZE
def is_fd(self):
return isinstance(self.fobj, integer_types)
def open(self):
return self.open_raw_and_wrapped()[1]
def open_raw_and_wrapped(self):
raw = self.open_raw()
try:
return raw, self.wrapped(raw)
except:
raw.close()
raise
def open_raw(self):
if hasattr(self.fobj, 'fileno'):
return self.fobj
return io.FileIO(self.fobj, self.fileio_mode, self.closefd)
def wrapped(self, raw):
"""
Wraps the raw IO object (`RawIOBase` or `io.TextIOBase`) in
buffers, text decoding, and newline handling.
"""
# pylint:disable=too-many-branches
result = raw
buffering = self.buffering
line_buffering = False
if buffering == 1 or buffering < 0 and raw.isatty():
buffering = -1
line_buffering = True
if buffering < 0:
buffering = self.default_buffer_size
try:
bs = os.fstat(raw.fileno()).st_blksize
except (OSError, AttributeError):
pass
else:
if bs > 1:
buffering = bs
if buffering < 0: # pragma: no cover
raise ValueError("invalid buffering size")
if not isinstance(raw, io.BufferedIOBase) and \
(not hasattr(raw, 'buffer') or raw.buffer is None):
# Need to wrap our own buffering around it. If it
# is already buffered, don't do so.
if buffering != 0:
if self.updating:
Buffer = io.BufferedRandom
elif self.creating or self.writing or self.appending:
Buffer = io.BufferedWriter
elif self.reading:
Buffer = io.BufferedReader
else: # prgama: no cover
raise ValueError("unknown mode: %r" % self.mode)
try:
result = Buffer(raw, buffering)
except AttributeError:
# Python 2 file() objects don't have the readable/writable
# attributes. But they handle their own buffering.
result = raw
if self.binary:
if isinstance(raw, io.TextIOBase):
# Can't do it. The TextIO object will have its own buffer, and
# trying to read from the raw stream or the buffer without going through
# the TextIO object is likely to lead to problems with the codec.
raise ValueError("Unable to perform binary IO on top of text IO stream")
return result
# Either native or text at this point.
if PY2 and self.native:
# Neither text mode nor binary mode specified.
if self.universal:
# universal was requested, e.g., 'rU'
result = UniversalNewlineBytesWrapper(result, line_buffering)
else:
# Python 2 and text mode, or Python 3 and either text or native (both are the same)
if not isinstance(raw, io.TextIOBase):
# Avoid double-wrapping a TextIOBase in another TextIOWrapper.
# That tends not to work. See https://github.com/gevent/gevent/issues/1542
result = io.TextIOWrapper(result, self.encoding, self.errors, self.newline,
line_buffering)
if result is not raw:
# Set the mode, if possible, but only if we created a new
# object.
try:
result.mode = self.mode
except (AttributeError, TypeError):
# AttributeError: No such attribute
# TypeError: Readonly attribute (py2)
pass
return result
class FileObjectBase(object):
"""
Internal base class to ensure a level of consistency
between :class:`~.FileObjectPosix`, :class:`~.FileObjectThread`
and :class:`~.FileObjectBlock`.
"""
# 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',
)
_io = None
def __init__(self, fobj, closefd):
self._io = fobj
# We don't actually use this property ourself, but we save it (and
# pass it along) for compatibility.
self._close = closefd
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
@property
def closed(self):
"""True if the file is closed"""
return self._io is None
def close(self):
if self._io is None:
return
fobj = self._io
self._io = None
self._do_close(fobj, 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 at 0x%x %s_fobj=%r%s>' % (
self.__class__.__name__,
id(self),
'closed' if self.closed else '',
self.io,
self._extra_repr()
)
def _extra_repr(self):
return ''
def __enter__(self):
return self
def __exit__(self, *args):
self.close()
def __iter__(self):
return self
def __next__(self):
line = self.readline()
if not line:
raise StopIteration
return line
next = __next__
def __bool__(self):
return True
__nonzero__ = __bool__
class FileObjectBlock(FileObjectBase):
"""
FileObjectBlock()
A simple synchronous wrapper around a file object.
Adds no concurrency or gevent compatibility.
"""
def __init__(self, fobj, *args, **kwargs):
descriptor = OpenDescriptor(fobj, *args, **kwargs)
FileObjectBase.__init__(self, descriptor.open(), descriptor.closefd)
def _do_close(self, fobj, closefd):
fobj.close()
class FileObjectThread(FileObjectBase):
"""
FileObjectThread()
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, *args, **kwargs):
"""
: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 closefd: If True (the default) then when this object is closed,
the underlying object is closed as well. If *fobj* is a path, then
*closefd* must be True.
"""
lock = kwargs.pop('lock', True)
threadpool = kwargs.pop('threadpool', None)
descriptor = OpenDescriptor(*args, **kwargs)
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))
self.__io_holder = [descriptor.open()] # signal for _wrap_method
FileObjectBase.__init__(self, self.__io_holder[0], descriptor.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):
FileObjectBase._do_delegate_methods(self)
# 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