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# Copyright 1999-2018 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
import array
import errno
import logging
import os
from portage.util import writemsg_level
from portage.util.futures import asyncio
from _emerge.AsynchronousTask import AsynchronousTask
class AbstractPollTask(AsynchronousTask):
__slots__ = ("_registered",)
_bufsize = 4096
def isAlive(self):
return bool(self._registered)
def _read_array(self, f):
"""
NOTE: array.fromfile() is used here only for testing purposes,
because it has bugs in all known versions of Python (including
Python 2.7 and Python 3.2). See PipeReaderArrayTestCase.
A benchmark that copies bytes from /dev/zero to /dev/null shows
that arrays give a 15% performance improvement for Python 2.7.14.
However, arrays significantly *decrease* performance for Python 3.
"""
buf = array.array('B')
try:
buf.fromfile(f, self._bufsize)
except EOFError:
pass
except TypeError:
# Python 3.2:
# TypeError: read() didn't return bytes
pass
except IOError as e:
# EIO happens with pty on Linux after the
# slave end of the pty has been closed.
if e.errno == errno.EIO:
# EOF: return empty string of bytes
pass
elif e.errno == errno.EAGAIN:
# EAGAIN: return None
buf = None
else:
raise
if buf is not None:
try:
# Python >=3.2
buf = buf.tobytes()
except AttributeError:
buf = buf.tostring()
return buf
def _read_buf(self, fd):
"""
Read self._bufsize into a string of bytes, handling EAGAIN and
EIO. This will only call os.read() once, so the caller should
call this method in a loop until either None or an empty string
of bytes is returned. An empty string of bytes indicates EOF.
None indicates EAGAIN.
NOTE: os.read() will be called regardless of the event flags,
since otherwise data may be lost (see bug #531724).
@param fd: file descriptor (non-blocking mode required)
@type fd: int
@rtype: bytes or None
@return: A string of bytes, or None
"""
# NOTE: array.fromfile() is no longer used here because it has
# bugs in all known versions of Python (including Python 2.7
# and Python 3.2).
buf = None
try:
buf = os.read(fd, self._bufsize)
except OSError as e:
# EIO happens with pty on Linux after the
# slave end of the pty has been closed.
if e.errno == errno.EIO:
# EOF: return empty string of bytes
buf = b''
elif e.errno == errno.EAGAIN:
# EAGAIN: return None
buf = None
else:
raise
return buf
def _async_wait(self):
self._unregister()
super(AbstractPollTask, self)._async_wait()
def _unregister(self):
self._registered = False
def _wait_loop(self, timeout=None):
loop = self.scheduler
tasks = [self.async_wait()]
if timeout is not None:
tasks.append(asyncio.ensure_future(
asyncio.sleep(timeout, loop=loop), loop=loop))
try:
loop.run_until_complete(asyncio.ensure_future(
asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED,
loop=loop), loop=loop))
finally:
for task in tasks:
task.cancel()
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