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Coroutines and asynchronous I/O using enhanced generators from python 2.5, including a enhanced WSGI server.

Project description


This is a library for network oriented, coroutine based programming.

cogen’s goal is to enable writing code in a synchronous and easy manner in the form of generators that yield calls and receive the result from that yield. These calls translate to asynchronous and fast os calls in cogen’s internals.

Notable features

  • a WSGI server, HTTP1.1 compliant, with asynchronous extensions
  • use epoll, kqueue where supported, select based otherwise
  • a Queue with the same interface as the standard library Queue, but for coroutines

Quick introduction

Programming with cogen library should be straightforward, similar with programming threads but without all the problems. A coroutine is just a generator wrapped in a operation handling class:

def mycoro(bla):
    result = yield <operation>
    result = yield <operation>
  • the operation instructs the scheduler what to do with the coroutine: suspend it till something happens, add another coro in the scheduler, raise a event and so on.
  • if a operation has a result associated then the yield will return that result (eg. a string or a (connection, address) tuple) otherwise it will return the operation instance.

Echo server example

from cogen.core import sockets
from cogen.core import schedulers
from cogen.core.coroutine import coroutine

def server():
    srv = sockets.Socket()
    print type(srv)
    while 1:
        print "Listening..."
        conn, addr = yield srv.accept()
        print "Connection from %s:%s" % addr
        m.add(handler, args=(conn, addr))

def handler(sock, addr):
    yield sock.write("WELCOME TO ECHO SERVER !\r\n")

    while 1:
        line = yield sock.readline(8192)
        if line.strip() == 'exit':
            yield sock.write("GOOD BYE")
        yield sock.write(line)

m = schedulers.Scheduler()

Project details

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