micropython-lib/select/select.py

88 wiersze
2.6 KiB
Python

import ffi
import ustruct as struct
import os
import errno
import _libc
libc = _libc.get()
#int epoll_create(int size);
epoll_create = libc.func("i", "epoll_create", "i")
#int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);
epoll_ctl = libc.func("i", "epoll_ctl", "iiiP")
#int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout);
epoll_wait = libc.func("i", "epoll_wait", "ipii")
EPOLLIN = 0x001
EPOLLPRI = 0x002
EPOLLOUT = 0x004
EPOLLONESHOT = 1 << 30
EPOLLET = 1 << 31
EPOLL_CTL_ADD = 1
EPOLL_CTL_DEL = 2
EPOLL_CTL_MOD = 3
# TODO: struct epoll_event's 2nd member is union of uint64_t, etc.
# On x86, uint64_t is 4-byte aligned, on many other platforms - 8-byte.
# Until uctypes module can assign native struct offset, use dirty hack
# below.
# TODO: Get rid of all this dirtiness, move it on C side
if _libc.bitness > 32:
# On x86_64, epoll_event is packed struct
epoll_event = "<IO"
elif struct.calcsize("IQ") == 12:
epoll_event = "IO"
else:
epoll_event = "QO"
class Epoll:
def __init__(self, epfd):
self.epfd = epfd
self.evbuf = struct.pack(epoll_event, 0, None)
self.registry = {}
def register(self, fd, eventmask=EPOLLIN|EPOLLPRI|EPOLLOUT, retval=None):
"retval is extension to stdlib, value to use in results from .poll()."
if retval is None:
retval = fd
s = struct.pack(epoll_event, eventmask, retval)
r = epoll_ctl(self.epfd, EPOLL_CTL_ADD, fd, s)
if r == -1 and os.errno_.get() == errno.EEXIST:
r = epoll_ctl(self.epfd, EPOLL_CTL_MOD, fd, s)
os.check_error(r)
# We must keep reference to retval, or it may be GCed. And we must
# keep mapping from fd to retval to be able to get rid of this retval
# reference later.
self.registry[fd] = retval
def unregister(self, fd):
# Pass dummy event structure, to workaround kernel bug
r = epoll_ctl(self.epfd, EPOLL_CTL_DEL, fd, self.evbuf)
os.check_error(r)
del self.registry[fd]
def poll(self, timeout=-1):
s = bytearray(self.evbuf)
while True:
n = epoll_wait(self.epfd, s, 1, timeout)
if not os.check_error(n):
break
# TODO: what about timeout value?
res = []
if n > 0:
vals = struct.unpack(epoll_event, s)
res.append((vals[1], vals[0]))
return res
def close(self):
os.close(self.epfd)
def epoll(sizehint=4):
fd = epoll_create(sizehint)
os.check_error(fd)
return Epoll(fd)