from __future__ import absolute_import
from __future__ import print_function
import os
import sys
from io import BytesIO
from io import DEFAULT_BUFFER_SIZE
from io import FileIO
from io import RawIOBase
from io import UnsupportedOperation
from gevent._compat import reraise
from gevent._fileobjectcommon import cancel_wait_ex
from gevent._fileobjectcommon import FileObjectBase
from gevent._fileobjectcommon import OpenDescriptor
from gevent._fileobjectcommon import WriteIsWriteallMixin
from gevent._hub_primitives import wait_on_watcher
from gevent.hub import get_hub
from gevent.os import _read
from gevent.os import _write
from gevent.os import ignored_errors
from gevent.os import make_nonblocking
class GreenFileDescriptorIO(RawIOBase):
# Internal, undocumented, class. All that's documented is that this
# is a IOBase object. Constructor is private.
# Note that RawIOBase has a __del__ method that calls
# self.close(). (In C implementations like CPython, this is
# the type's tp_dealloc slot; prior to Python 3, the object doesn't
# appear to have a __del__ method, even though it functionally does)
_read_watcher = None
_write_watcher = None
_closed = False
_seekable = None
_keep_alive = None # An object that needs to live as long as we do.
def __init__(self, fileno, open_descriptor, closefd=True):
RawIOBase.__init__(self)
self._closefd = closefd
self._fileno = fileno
self.name = fileno
self.mode = open_descriptor.fileio_mode
make_nonblocking(fileno)
readable = open_descriptor.can_read
writable = open_descriptor.can_write
self.hub = get_hub()
io_watcher = self.hub.loop.io
try:
if readable:
self._read_watcher = io_watcher(fileno, 1)
if writable:
self._write_watcher = io_watcher(fileno, 2)
except:
# If anything goes wrong, it's important to go ahead and
# close these watchers *now*, especially under libuv, so
# that they don't get eventually reclaimed by the garbage
# collector at some random time, thanks to the C level
# slot (even though we don't seem to have any actual references
# at the Python level). Previously, if we didn't close now,
# that random close in the future would cause issues if we had duplicated
# the fileno (if a wrapping with statement had closed an open fileobject,
# for example)
# test__fileobject can show a failure if this doesn't happen
# TRAVIS=true GEVENT_LOOP=libuv python -m gevent.tests.test__fileobject \
# TestFileObjectPosix.test_seek TestFileObjectThread.test_bufsize_0
self.close()
raise
def isatty(self):
# TODO: Couldn't we just subclass FileIO?
f = FileIO(self._fileno, 'r', False)
try:
return f.isatty()
finally:
f.close()
def readable(self):
return self._read_watcher is not None
def writable(self):
return self._write_watcher is not None
def seekable(self):
if self._seekable is None:
try:
os.lseek(self._fileno, 0, os.SEEK_CUR)
except OSError:
self._seekable = False
else:
self._seekable = True
return self._seekable
def fileno(self):
return self._fileno
@property
def closed(self):
return self._closed
def __destroy_events(self):
read_event = self._read_watcher
write_event = self._write_watcher
hub = self.hub
self.hub = self._read_watcher = self._write_watcher = None
hub.cancel_waits_close_and_then(
(read_event, write_event),
cancel_wait_ex,
self.__finish_close,
self._closefd,
self._fileno,
self._keep_alive
)
def close(self):
if self._closed:
return
self.flush()
# TODO: Can we use 'read_event is not None and write_event is
# not None' to mean _closed?
self._closed = True
try:
self.__destroy_events()
finally:
self._fileno = self._keep_alive = None
@staticmethod
def __finish_close(closefd, fileno, keep_alive):
try:
if closefd:
os.close(fileno)
finally:
if hasattr(keep_alive, 'close'):
keep_alive.close()
# RawIOBase provides a 'read' method that will call readall() if
# the `size` was missing or -1 and otherwise call readinto(). We
# want to take advantage of this to avoid single byte reads when
# possible. This is highlighted by a bug in BufferedIOReader that
# calls read() in a loop when its readall() method is invoked;
# this was fixed in Python 3.3, but we still need our workaround for 2.7. See
# https://github.com/gevent/gevent/issues/675)
def __read(self, n):
if self._read_watcher is None:
raise UnsupportedOperation('read')
while 1:
try:
return _read(self._fileno, n)
except (IOError, OSError) as ex:
if ex.args[0] not in ignored_errors:
raise
wait_on_watcher(self._read_watcher, None, None, self.hub)
def readall(self):
ret = BytesIO()
while True:
try:
data = self.__read(DEFAULT_BUFFER_SIZE)
except cancel_wait_ex:
# We were closed while reading. A buffered reader
# just returns what it has handy at that point,
# so we do to.
data = None
if not data:
break
ret.write(data)
return ret.getvalue()
def readinto(self, b):
data = self.__read(len(b))
n = len(data)
try:
b[:n] = data
except TypeError as err:
import array
if not isinstance(b, array.array):
raise err
b[:n] = array.array(b'b', data)
return n
def write(self, b):
if self._write_watcher is None:
raise UnsupportedOperation('write')
while True:
try:
return _write(self._fileno, b)
except (IOError, OSError) as ex:
if ex.args[0] not in ignored_errors:
raise
wait_on_watcher(self._write_watcher, None, None, self.hub)
def seek(self, offset, whence=0):
try:
return os.lseek(self._fileno, offset, whence)
except IOError: # pylint:disable=try-except-raise
raise
except OSError as ex: # pylint:disable=duplicate-except
# Python 2.x
# make sure on Python 2.x we raise an IOError
# as documented for RawIOBase.
# See https://github.com/gevent/gevent/issues/1323
reraise(IOError, IOError(*ex.args), sys.exc_info()[2])
def __repr__(self):
return "<%s at 0x%x fileno=%s mode=%r>" % (
type(self).__name__, id(self), self._fileno, self.mode
)
class GreenFileDescriptorIOWriteall(WriteIsWriteallMixin,
GreenFileDescriptorIO):
pass
class GreenOpenDescriptor(OpenDescriptor):
def _do_open_raw(self):
if self.is_fd():
fileio = GreenFileDescriptorIO(self._fobj, self, closefd=self.closefd)
else:
# Either an existing file object or a path string (which
# we open to get a file object). In either case, the other object
# owns the descriptor and we must not close it.
closefd = False
raw = OpenDescriptor._do_open_raw(self)
fileno = raw.fileno()
fileio = GreenFileDescriptorIO(fileno, self, closefd=closefd)
fileio._keep_alive = raw
# We can usually do better for a name, though.
try:
fileio.name = raw.name
except AttributeError:
del fileio.name
return fileio
def _make_atomic_write(self, result, raw):
# Our return value from _do_open_raw is always a new
# object that we own, so we're always free to change
# the class.
assert result is not raw or self._raw_object_is_new(raw)
if result.__class__ is GreenFileDescriptorIO:
result.__class__ = GreenFileDescriptorIOWriteall
else:
result = OpenDescriptor._make_atomic_write(self, result, raw)
return result
[docs]class FileObjectPosix(FileObjectBase):
"""
FileObjectPosix()
A file-like object that operates on non-blocking files but
provides a synchronous, cooperative interface.
.. caution::
This object is only effective wrapping files that can be used meaningfully
with :func:`select.select` such as sockets and pipes.
In general, on most platforms, operations on regular files
(e.g., ``open('a_file.txt')``) are considered non-blocking
already, even though they can take some time to complete as
data is copied to the kernel and flushed to disk: this time
is relatively bounded compared to sockets or pipes, though.
A :func:`~os.read` or :func:`~os.write` call on such a file
will still effectively block for some small period of time.
Therefore, wrapping this class around a regular file is
unlikely to make IO gevent-friendly: reading or writing large
amounts of data could still block the event loop.
If you'll be working with regular files and doing IO in large
chunks, you may consider using
:class:`~gevent.fileobject.FileObjectThread` or
:func:`~gevent.os.tp_read` and :func:`~gevent.os.tp_write` to bypass this
concern.
.. tip::
Although this object provides a :meth:`fileno` method and so
can itself be passed to :func:`fcntl.fcntl`, setting the
:data:`os.O_NONBLOCK` flag will have no effect (reads will
still block the greenlet, although other greenlets can run).
However, removing that flag *will cause this object to no
longer be cooperative* (other greenlets will no longer run).
You can use the internal ``fileio`` attribute of this object
(a :class:`io.RawIOBase`) to perform non-blocking byte reads.
Note, however, that once you begin directly using this
attribute, the results from using methods of *this* object
are undefined, especially in text mode. (See :issue:`222`.)
.. versionchanged:: 1.1
Now uses the :mod:`io` package internally. Under Python 2, previously
used the undocumented class :class:`socket._fileobject`. This provides
better file-like semantics (and portability to Python 3).
.. versionchanged:: 1.2a1
Document the ``fileio`` attribute for non-blocking reads.
.. versionchanged:: 1.2a1
A bufsize of 0 in write mode is no longer forced to be 1.
Instead, the underlying buffer is flushed after every write
operation to simulate a bufsize of 0. In gevent 1.0, a
bufsize of 0 was flushed when a newline was written, while
in gevent 1.1 it was flushed when more than one byte was
written. Note that this may have performance impacts.
.. versionchanged:: 1.3a1
On Python 2, enabling universal newlines no longer forces unicode
IO.
.. versionchanged:: 1.5
The default value for *mode* was changed from ``rb`` to ``r``. This is consistent
with :func:`open`, :func:`io.open`, and :class:`~.FileObjectThread`, which is the
default ``FileObject`` on some platforms.
.. versionchanged:: 1.5
Stop forcing buffering. Previously, given a ``buffering=0`` argument,
*buffering* would be set to 1, and ``buffering=1`` would be forced to
the default buffer size. This was a workaround for a long-standing concurrency
issue. Now the *buffering* argument is interpreted as intended.
"""
default_bufsize = DEFAULT_BUFFER_SIZE
def __init__(self, *args, **kwargs):
descriptor = GreenOpenDescriptor(*args, **kwargs)
FileObjectBase.__init__(self, descriptor)
# This attribute is documented as available for non-blocking reads.
self.fileio = descriptor.opened_raw()
def _do_close(self, fobj, closefd):
try:
fobj.close()
# self.fileio already knows whether or not to close the
# file descriptor
self.fileio.close()
finally:
self.fileio = None