Asynchat and error handling

Orestis Markou orestis at orestis.gr
Wed Nov 5 19:20:23 CET 2008


Hello,

I'm trying to add some better error handling to an async_chat client.
What I want is to retry or terminate gracefully if the connection to
the server doesn't succeed. Here's what I have:

import asyncore, asynchat, socket

class http_client(asynchat.async_chat):

    def __init__(self, host):
        asynchat.async_chat.__init__(self)
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        terminator = '\x00\xDE\xED\xBE\xEF\x00'
        self.buffer = 'I can haz data?' + terminator
        self._connected = False
        self.set_terminator(terminator)
        self.connect( (host, 8080) )

    def handle_connect(self):
        print 'connected!'

    def handle_expt(self):
        if not self.connected:
            print 'not connected'
            self.close()


    def collect_incoming_data (self, data):
        print data

    def found_terminator (self):
        print 'terminator found, Closing'
        self.close()

    def writable(self):
        return (len(self.buffer) > 0)

    def handle_write(self):
        sent = self.send(self.buffer)
        self.buffer = self.buffer[sent:]

if __name__ == '__main__':
    c = http_client('localhost')
    asyncore.loop()

If the connection fails, handle_expt is called, and I can close the
client. However, I have no information from the error, so I can't
retry the connection. I would expect the call to "connect" to raise an
exception, but apparently it's swallowed somewhere. Is there any nice
way to do this?

Thanks!

-- 
orestis at orestis.gr
http://orestis.gr



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