Simple but workable event loop in Python (< 100 LOC)
Check out the series about the event loop on my blog Explain event loop in 100 lines of code and From Callback Hell to async/await Heaven.
Example using callback-style:
import socket as _socket
class EventLoop: pass
class Context: pass
class socket(Context): pass
def main(serv_addr):
sock = socket(_socket.AF_INET, _socket.SOCK_STREAM)
def _on_conn(err):
if err:
raise err
def _on_sent(err):
if err:
sock.close()
raise err
def _on_resp(err, resp=None):
sock.close()
if err:
raise err
print(resp)
sock.recv(1024, _on_resp)
sock.sendall(b'foobar', _on_sent)
sock.connect(serv_addr, _on_conn)
if __name__ == '__main__':
event_loop = EventLoop()
Context.set_event_loop(event_loop)
serv_addr = ('127.0.0.1', int(sys.argv[1]))
event_loop.run(main, serv_addr)Give it a try:
# server
> python server.py 53210
# client
> python event_loop.py 53210Example using async-await-like style:
import socket as _socket
class EventLoop: pass
class Context: pass
class socket(Context): pass
def http_get(sock):
try:
yield sock.sendall(b'GET / HTTP/1.1\r\nHost: t.co\r\n\r\n')
return sock.recv(1024)
finally:
sock.close()
def main(serv_addr):
sock = socket(AF_INET, SOCK_STREAM)
yield sock.connect(serv_addr)
resp = yield http_get(sock)
print(resp)
if __name__ == '__main__':
event_loop = EventLoop()
Context.set_event_loop(event_loop)
serv_addr = ('t.co', 80)
event_loop.run(main)Give it a try:
> python event_loop_gen.py 53210