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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 seemingly 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
  • epoll, kqueue, select, i/o completion ports, sendfile behind the scenes
  • a couple of useful classes for putting the coroutine to sleep, wait for signals, queues, timeouts etc.

Quick introduction

A coroutine is just a generator wrapped in a helper class:

from cogen.core.coroutines import coroutine

@coroutine
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.coroutines import coroutine

@coroutine
def server():
    srv = sockets.Socket()
    print type(srv)
    srv.bind(('localhost',777))
    srv.listen(10)
    while 1:
        print "Listening..."
        conn, addr = yield srv.accept()
        print "Connection from %s:%s" % addr
        m.add(handler, args=(conn, addr))

@coroutine
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")
            sock.close()
            return
        yield sock.write(line)

m = schedulers.Scheduler()
m.add(server)
m.run()

Development

Takes place at: http://code.google.com/p/cogen/

Grab the latest and greatest from trunk with:

easy_install cogen==dev

Project details


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