http://scotdoyle.com/python-epoll-howto.html
Line 1: The select module contains the epoll functionality.
Line 13: Since sockets are blocking by default, this is necessary to use non-blocking (asynchronous) mode.
import socket, select EOL1 = b'\n\n'
EOL2 = b'\n\r\n'
response = b'HTTP/1.0 200 OK\r\nDate: Mon, 1 Jan 1996 01:01:01 GMT\r\n'
response += b'Content-Type: text/plain\r\nContent-Length: 13\r\n\r\n'
response += b'Hello, world!' serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serversocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
serversocket.bind(('0.0.0.0', 8080))
serversocket.listen(1)
serversocket.setblocking(0) epoll = select.epoll()
epoll.register(serversocket.fileno(), select.EPOLLIN) try:
connections = {}; requests = {}; responses = {}
while True:
events = epoll.poll(1)
for fileno, event in events:
if fileno == serversocket.fileno():
connection, address = serversocket.accept()
connection.setblocking(0)
epoll.register(connection.fileno(), select.EPOLLIN)
connections[connection.fileno()] = connection
requests[connection.fileno()] = b''
responses[connection.fileno()] = response
elif event & select.EPOLLIN:
requests[fileno] += connections[fileno].recv(1024)
if EOL1 in requests[fileno] or EOL2 in requests[fileno]:
epoll.modify(fileno, select.EPOLLOUT)
print('-'*40 + '\n' + requests[fileno].decode()[:-2])
elif event & select.EPOLLOUT:
byteswritten = connections[fileno].send(responses[fileno])
responses[fileno] = responses[fileno][byteswritten:]
if len(responses[fileno]) == 0:
epoll.modify(fileno, 0)
connections[fileno].shutdown(socket.SHUT_RDWR)
elif event & select.EPOLLHUP:
epoll.unregister(fileno)
connections[fileno].close()
del connections[fileno]
finally:
epoll.unregister(serversocket.fileno())
epoll.close()
serversocket.close()
epoll的register
| register(...)
| register(fd[, eventmask]) -> None
|
| Registers a new fd or modifies an already registered fd.
| fd is the target file descriptor of the operation.
| events is a bit set composed of the various EPOLL constants; the default
| is EPOLL_IN | EPOLL_OUT | EPOLL_PRI.
|
| The epoll interface supports all file descriptors that support poll.
Epoll的eventmask
http://man7.org/linux/man-pages/man2/poll.2.html
POLLIN There is data to read.
POLLPRI
There is urgent data to read (e.g., out-of-band data on
TCP socket; pseudoterminal master in packet mode has
seen state change in slave).
POLLOUT
Writing is now possible, though a write larger that the
available space in a socket or pipe will still block
(unless O_NONBLOCK is set).
POLLRDHUP (since Linux 2.6.17)
Stream socket peer closed connection, or shut down
writing half of connection. The _GNU_SOURCE feature
test macro must be defined (before including any header
files) in order to obtain this definition.
POLLERR
Error condition (output only).
POLLHUP
Hang up (output only).
POLLNVAL
Invalid request: fd not open (output only).
边缘触发(Edge Trigger)和条件触发(Level Trigger)
边缘触发 是指每当状态变化时发生一个io事件；
条件触发 是只要满足条件就发生一个io事件；