mirror of
https://github.com/SickGear/SickGear.git
synced 2024-11-27 23:23:38 +00:00
124 lines
4.3 KiB
Python
124 lines
4.3 KiB
Python
from __future__ import annotations
|
|
|
|
import select
|
|
import socket
|
|
from functools import partial
|
|
|
|
__all__ = ["wait_for_read", "wait_for_write"]
|
|
|
|
|
|
# How should we wait on sockets?
|
|
#
|
|
# There are two types of APIs you can use for waiting on sockets: the fancy
|
|
# modern stateful APIs like epoll/kqueue, and the older stateless APIs like
|
|
# select/poll. The stateful APIs are more efficient when you have a lots of
|
|
# sockets to keep track of, because you can set them up once and then use them
|
|
# lots of times. But we only ever want to wait on a single socket at a time
|
|
# and don't want to keep track of state, so the stateless APIs are actually
|
|
# more efficient. So we want to use select() or poll().
|
|
#
|
|
# Now, how do we choose between select() and poll()? On traditional Unixes,
|
|
# select() has a strange calling convention that makes it slow, or fail
|
|
# altogether, for high-numbered file descriptors. The point of poll() is to fix
|
|
# that, so on Unixes, we prefer poll().
|
|
#
|
|
# On Windows, there is no poll() (or at least Python doesn't provide a wrapper
|
|
# for it), but that's OK, because on Windows, select() doesn't have this
|
|
# strange calling convention; plain select() works fine.
|
|
#
|
|
# So: on Windows we use select(), and everywhere else we use poll(). We also
|
|
# fall back to select() in case poll() is somehow broken or missing.
|
|
|
|
|
|
def select_wait_for_socket(
|
|
sock: socket.socket,
|
|
read: bool = False,
|
|
write: bool = False,
|
|
timeout: float | None = None,
|
|
) -> bool:
|
|
if not read and not write:
|
|
raise RuntimeError("must specify at least one of read=True, write=True")
|
|
rcheck = []
|
|
wcheck = []
|
|
if read:
|
|
rcheck.append(sock)
|
|
if write:
|
|
wcheck.append(sock)
|
|
# When doing a non-blocking connect, most systems signal success by
|
|
# marking the socket writable. Windows, though, signals success by marked
|
|
# it as "exceptional". We paper over the difference by checking the write
|
|
# sockets for both conditions. (The stdlib selectors module does the same
|
|
# thing.)
|
|
fn = partial(select.select, rcheck, wcheck, wcheck)
|
|
rready, wready, xready = fn(timeout)
|
|
return bool(rready or wready or xready)
|
|
|
|
|
|
def poll_wait_for_socket(
|
|
sock: socket.socket,
|
|
read: bool = False,
|
|
write: bool = False,
|
|
timeout: float | None = None,
|
|
) -> bool:
|
|
if not read and not write:
|
|
raise RuntimeError("must specify at least one of read=True, write=True")
|
|
mask = 0
|
|
if read:
|
|
mask |= select.POLLIN
|
|
if write:
|
|
mask |= select.POLLOUT
|
|
poll_obj = select.poll()
|
|
poll_obj.register(sock, mask)
|
|
|
|
# For some reason, poll() takes timeout in milliseconds
|
|
def do_poll(t: float | None) -> list[tuple[int, int]]:
|
|
if t is not None:
|
|
t *= 1000
|
|
return poll_obj.poll(t)
|
|
|
|
return bool(do_poll(timeout))
|
|
|
|
|
|
def _have_working_poll() -> bool:
|
|
# Apparently some systems have a select.poll that fails as soon as you try
|
|
# to use it, either due to strange configuration or broken monkeypatching
|
|
# from libraries like eventlet/greenlet.
|
|
try:
|
|
poll_obj = select.poll()
|
|
poll_obj.poll(0)
|
|
except (AttributeError, OSError):
|
|
return False
|
|
else:
|
|
return True
|
|
|
|
|
|
def wait_for_socket(
|
|
sock: socket.socket,
|
|
read: bool = False,
|
|
write: bool = False,
|
|
timeout: float | None = None,
|
|
) -> bool:
|
|
# We delay choosing which implementation to use until the first time we're
|
|
# called. We could do it at import time, but then we might make the wrong
|
|
# decision if someone goes wild with monkeypatching select.poll after
|
|
# we're imported.
|
|
global wait_for_socket
|
|
if _have_working_poll():
|
|
wait_for_socket = poll_wait_for_socket
|
|
elif hasattr(select, "select"):
|
|
wait_for_socket = select_wait_for_socket
|
|
return wait_for_socket(sock, read, write, timeout)
|
|
|
|
|
|
def wait_for_read(sock: socket.socket, timeout: float | None = None) -> bool:
|
|
"""Waits for reading to be available on a given socket.
|
|
Returns True if the socket is readable, or False if the timeout expired.
|
|
"""
|
|
return wait_for_socket(sock, read=True, timeout=timeout)
|
|
|
|
|
|
def wait_for_write(sock: socket.socket, timeout: float | None = None) -> bool:
|
|
"""Waits for writing to be available on a given socket.
|
|
Returns True if the socket is readable, or False if the timeout expired.
|
|
"""
|
|
return wait_for_socket(sock, write=True, timeout=timeout)
|