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gevent + threads
"""This is an example of cooperating between a gevent hub and normal threads."""
import gevent
import socket as _socket
from gevent import hub, socket, _threading
conns = _threading.Queue()
def listen(watcher):
"""Listen for incoming connections.
This function runs in a separate Python thread. It doesn't use the gevent
primitives, and instead uses the normal Python ones. When it accepts a
connection, it sends a notification to the watcher (to wakeup the gevent
thread) and puts the connection into a thread safe queue.
:param watcher: gevent async watcher.
s = _socket.socket(_socket.AF_INET, _socket.SOCK_STREAM)
s.bind(('', 8080))
while True:
print 'listen: waiting for a connection'
conn, addr = s.accept()
print 'listen: accepted from', addr
print 'listen: appended to queue'
def on_connection():
"""Triggered whenever the listen function sends a notification.
Note that it's not permitted to block in this handler, so it just spawns
a new greenlet to handle the connection.
print 'on_connection: spawning handler'
def handle_connection():
"""Handles a single connection.
This is run in its own greenlet. It grabs a connection from the queue, and
handles it until the connection is closed. The connection from the queue
is not a gevent socket, but a normal Python socket, so this wraps the
socket in the gevent version.
print 'handle_connection: getting connection'
conn = conns.get()
conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM, _sock=conn)
print 'handle_connection: got connection'
f = conn.makefile()
for line in f:
print 'handle_connection:', repr(line)
print 'handle_connection: connection closed'
def ticker():
"""Prints a message once a second.
This is just a dummy ticker thread to show that the gevent loop is running.
while True:
print 'ticked'
watcher = hub.get_hub().loop.async()
_threading.start_new_thread(listen, (watcher,))
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