Re: [pysnmp-users] CLI interaction?

[Craig S. <cs...@en...>]

On Wed, Nov 11, 2015 at 06:56:36PM -0600, Michael R Anderson wrote:
> I am using cly to drive my CLI.  It works great.  I recently added
> pysmp.  Now when it gets to runDispatcher() (in it's own thread), it
> looks like my CLI input line gets hijacked so that no more command
> line input can be done.
I actually have written some test code showing a simple stdin reader 
working with pysnmp. It happily loops around servicing the snmp sockets
and the stdin socket. Even uses the nice new hlapi (nice work Ilya).
I thought, ok good, you get the data from stdin and feed it into cly
and the world is good.

but...  cly uses raw_input[1] and that blocks :(

So you have options:
1) re-write a cly InputDriver that doesn't use raw_input() but something
a little less block-happy
2) Use threads, one for the input, one for SNMP and somehow get them
to talk to each other (but you might have a raw_input blocks on my
IPC socket problem anyhow)
3) Use a simple stdin input and somehow wedge the input characters into
cly's parser.
4) Depending on the design of the app, either have cly running or SNMP 
running but not both.

The last option would mean using your own Interact class and running
every until some flag changed, the interact would need to make
that check function below return true when it wants snmp to run.

while True:
  while doInput:
    myInteract.once()  
    if checkWeShouldDoSomeSnmpNow():
      doInput = False
  else:
    # Now we sit here doing SNMP
    transportDispatcher.runDispatcher()
    doInput = True

or something like that.

 - Craig


[1] https://github.com/alecthomas/cly/blob/master/cly/interactive.py#L131

-- 
Craig Small (@smallsees)   http://enc.com.au/       csmall at : enc.com.au
Debian GNU/Linux           http://www.debian.org/   csmall at : debian.org
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