know if someone ping me

[Chris Gonnerman]

----- Original Message ----- 
From: "Alex Martelli" <aleax at aleax.it>


> You can do much better than this!  With newer syslogd's, at
> least on Linux, you can log to a named pipe, so your Python
> program can just 'loop' reading from that named pipe and be
> woken up for processing when there's something to process --
> a MUCH better idea than 'polling' (continuosly read from
> a file) in terms of system-load for infrequent events.

Polling implemented with a loop like this:

    while 1:
        line = fp.readline()
        if line == '':
            time.sleep(1)
        else:
            # process line here

is actually fairly efficient on Unixoid OS's.  You have up to a
one second delay before processing each line of the log, but 
such a delay is normally not a problem.

I actually wrote a chat program in the old days using this 
method (in C) and it ran fairly well AND left a log of the
communication automatically.

Blocking due to sleep() is just as good as blocking due to read()
on an empty pipe; polling with sleep() is just a *little bit* less
efficient than reading the pipe.