On Tue, Jan 5, 2016 at 11:16 AM, David Hankins <dhank...@twitter.com> wrote:
> https://sourceforge.net/p/net-snmp/code/merge-requests/3/ > > I had quite a lot of fun on this project, and I'd like it to be merged > upstream. I know it's 71 commits, and may be easier to just read the final > 'snmp_api.c'. I'm also guessing all the source owners are volunteers, who > are busy. > > Anyway, it's been a few weeks, and I'm not complaining, but I'd > appreciate some comment on what you'd like to see improved to accept it > before I forget everything. > > I did this to expose the asynchronous API of NetSNMP of old which I'm > accustomed to, and (predictably) have been able to realize some significant > improvements in monitoring delay, experimentally. > > > Things I learned / issues to spur discussion; > > I used the new 'Capsule' API, which unfortunately makes it rely on Python > 2.7 or later. In retrospect, it might have been better to make the Session > and PDU objects "custom types," so that they can be accessed by Python > users similarly to the C structures they approximate, rather than what I > wound up doing for the callback function - making a dict that approximates > the C structure. > > I dug out placeholders for a grepped-out list of API functions. No doubt > some are internal and should be deleted, but it represents opportunities > for future work to expose more of the C API to Python users. I > prioritized what I needed, and did what I could in the week I had. > > I've used this library since the CMU-SNMP days, and I noticed the C API > was updated in a way that reduced some functionality from old CMU->UCD->NET > - I'm referring to the abstraction layer for SNMP transports. It used to > be (or so I remember) there was a sockaddr_in on the PDU structure, so you > could open a session with no peername, and then set the target address on a > PDU-by-PDU basis (this is important, for example, in monitoring systems at > scale to control the number of open sockets and allocated socket buffer). > The new abstraction structure puts an opaque object there, and the only way > to get the same functionality is to create a 'indexed sockaddr' object > manually, guessing that's what the default (UDP) transport is going to > require. A little hinky, but it works. But even if you have a reference > to the non-default transport you're using, there isn't a transport API > function to resolve a new opaque object (say from a hostname or IP address) > on demand. I'd be happy to submit a C API extension for merging if there > is consensus - I think there should be a way to resolve an opaque object > onto a PDU from a {multi,single}-session pointer and peername. It should > throw an error on transports that don't support multiple endpoints (e.g. > TCP). > > The netsnmp-python setup.py sets its version to 1.0a1. I think this > should simply be the netsnmp release version (and it should default to link > statically off --basedir=.. if possible, as most users build eggs which > should be as hermetic as possible). Any objection to changing one or both > of those? > > The versioning part of this is so trivial, I just did it. https://sourceforge.net/p/net-snmp/code/merge-requests/4/ > We'd really like to get MIB modules loaded out of egg or wheel files as > well, talking about hermetic eggs, rather than having the runtime try to > find them in magic local directories. This allows us to build python > binaries that are fully self contained, and all changes (including mib > updates) follow our software release for same. To do this I think the C > API will have to change, so that we can insert an abstraction layer where > the Python package loader is used instead of system file open routines to > read the MIB files. > > -- > Network Tools & Automation > Twitter, Inc. > -- Network Tools & Automation Twitter, Inc.
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