def select(rlist, wlist, xlist, timeout=None): # pylint:disable=unused-argument
"""An implementation of :meth:`select.select` that blocks only the current greenlet.
.. caution:: *xlist* is ignored.
.. versionchanged:: 1.2a1
Raise a :exc:`ValueError` if timeout is negative. This matches Python 3's
behaviour (Python 2 would raise a ``select.error``). Previously gevent had
undefined behaviour.
.. versionchanged:: 1.2a1
Raise an exception if any of the file descriptors are invalid.
"""
if timeout is not None and timeout < 0:
# Raise an error like the real implementation; which error
# depends on the version. Python 3, where select.error is OSError,
# raises a ValueError (which makes sense). Older pythons raise
# the error from the select syscall...but we don't actually get there.
# We choose to just raise the ValueError as it makes more sense and is
# forward compatible
raise ValueError("timeout must be non-negative")
# First, do a poll with the original select system call. This is
# the most efficient way to check to see if any of the file
# descriptors have previously been closed and raise the correct
# corresponding exception. (Because libev tends to just return
# them as ready, or, if built with EV_VERIFY >= 2 and libev >=
# 4.27, crash the process. And libuv also tends to crash the
# process.)
#
# We accept the *xlist* here even though we can't
# below because this is all about error handling.
sel_results = ((), (), ())
try:
sel_results = _original_select(rlist, wlist, xlist, 0)
except error as e:
enumber = getattr(e, 'errno', None) or e.args[0]
if enumber != EINTR:
# Ignore interrupted syscalls
raise
if sel_results[0] or sel_results[1] or sel_results[2] or (
timeout is not None and timeout == 0):
# If we actually had stuff ready, go ahead and return it. No need
# to go through the trouble of doing our own stuff.
# Likewise, if the timeout is 0, we already did a 0 timeout
# select and we don't need to do it again. Note that in libuv,
# zero duration timers may be called immediately, without
# cycling the event loop at all. 2.7/test_telnetlib.py "hangs"
# calling zero-duration timers if we go to the loop here.
# However, because this is typically a place where scheduling switches
# can occur, we need to make sure that's still the case; otherwise a single
# consumer could monopolize the thread. (shows up in test_ftplib.)
_g_sleep()
return sel_results
result = SelectResult()
return result.select(rlist, wlist, timeout)
def select(rlist, wlist, xlist, timeout=None): # pylint:disable=unused-argument
"""An implementation of :meth:`select.select` that blocks only the current greenlet.
.. caution:: *xlist* is ignored.
.. versionchanged:: 1.2a1
Raise a :exc:`ValueError` if timeout is negative. This matches Python 3's
behaviour (Python 2 would raise a ``select.error``). Previously gevent had
undefined behaviour.
.. versionchanged:: 1.2a1
Raise an exception if any of the file descriptors are invalid.
"""
if timeout is not None and timeout < 0:
# Raise an error like the real implementation; which error
# depends on the version. Python 3, where select.error is OSError,
# raises a ValueError (which makes sense). Older pythons raise
# the error from the select syscall...but we don't actually get there.
# We choose to just raise the ValueError as it makes more sense and is
# forward compatible
raise ValueError("timeout must be non-negative")
# First, do a poll with the original select system call. This
# is the most efficient way to check to see if any of the file descriptors
# have previously been closed and raise the correct corresponding exception.
# (Because libev tends to just return them as ready...)
# We accept the *xlist* here even though we can't below because this is all about
# error handling.
sel_results = ((), (), ())
try:
sel_results = _original_select(rlist, wlist, xlist, 0)
except error as e:
enumber = getattr(e, 'errno', None) or e.args[0]
if enumber != EINTR:
# Ignore interrupted syscalls
raise
if sel_results[0] or sel_results[1] or sel_results[2] or (timeout is not None and timeout == 0):
# If we actually had stuff ready, go ahead and return it. No need
# to go through the trouble of doing our own stuff.
# Likewise, if the timeout is 0, we already did a 0 timeout
# select and we don't need to do it again. Note that in libuv,
# zero duration timers may be called immediately, without
# cycling the event loop at all. 2.7/test_telnetlib.py "hangs"
# calling zero-duration timers if we go to the loop here.
# However, because this is typically a place where scheduling switches
# can occur, we need to make sure that's still the case; otherwise a single
# consumer could monopolize the thread. (shows up in test_ftplib.)
_g_sleep()
return sel_results
result = SelectResult()
return result.select(rlist, wlist, timeout)
