Bug? asyncore.dispatcher_with_send trouble

Freddie lion-freddie at zebra-madcowdisease.giraffe-org
Wed Jul 7 05:27:28 CEST 2004


Hi,

I've been mangling python-irclib into an asyncore class, so it fits in 
nicely with the rest of my app. I ran into a problem with 
asyncore.dispatcher_with_send (Python 2.3.4), though. Not sure if this 
is the right place to file a bug, but here goes:


class dispatcher_with_send(dispatcher):

     def __init__(self, sock=None):
         dispatcher.__init__(self, sock)
         self.out_buffer = ''

     def initiate_send(self):
         num_sent = 0
         num_sent = dispatcher.send(self, self.out_buffer[:512])
         self.out_buffer = self.out_buffer[num_sent:]

     def handle_write(self):
         self.initiate_send()

     def writable(self):
         return (not self.connected) or len(self.out_buffer)

     def send(self, data):
         if self.debug:
             self.log_info('sending %s' % repr(data))
         self.out_buffer = self.out_buffer + data
         self.initiate_send()


I assumed that disp.send('chunkofdata') would merely put it in the out 
buffer until the socket is writable, but this isn't what happens. It 
tries to send() the data straight away, which can raise an exception... 
and since we're not inside the asyncore.write() function, handle_error 
is never called.

Here's the fixed version that I've cobbled together:


class buffered_dispatcher(asyncore.dispatcher):
     def __init__(self, sock=None):
         asyncore.dispatcher.__init__(self, sock)
         self.out_buffer = ''

     # We only want to be writable if we're connecting, or something is 
in our
     # buffer.
     def writable(self):
         return (not self.connected) or len(self.out_buffer)

     # Send some data from our buffer when we can write
     def handle_write(self):
         sent = asyncore.dispatcher.send(self, self.out_buffer)
         self.out_buffer = self.out_buffer[sent:]

     # We want buffered output, duh
     def send(self, data):
         self.out_buffer += data


Hopefully this saves someone else half an hour of annoyance at some point :)

    Freddie



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