[Bro-Dev] WIP: Instrumentation plugin

[Gilbert Clark]

Hi all:

Just a brief note that 
https://github.com/cubic1271/bro-plugin-instrumentation exists as a work 
in progress, and should now be supported by the current bro master.

It knows four tricks at the moment:

* Per-packet statistics - memory, file I/O, and CPU information either 
every X seconds or every Y packets.  This differs from existing 
functionality only in the way data is gathered: it uses RDTSC to grab 
CPU cycles, hooks the malloc familiy of functions to gather memory data, 
and also hooks I/O methods to gather information about what is 
generating input / output in the application.
* Per-function statistics - memory information and aggregate cycle 
counts for the time spent in each bro function.
* Function call-graphs - output graphviz formatted call graphs that can 
be rendered via e.g. dot.
* Export of arbitrary data via HTTP - populate arbitrary JSON objects in 
bro script and serve them directly from a HTTP server embedded in the 
plugin.

Overhead is pretty high at the moment, and there are things that need to 
be researched on different platforms (e.g. mechanics of RDTSC, reduce 
error associated with cost of collecting data, etc). I haven't crashed 
it with the data I've thrown at it as of yet, but I'm sure it's only a 
matter of time...

It's a work in progress, so feedback / comments / concerns are welcome.

Hope something in there is interesting to someone :)

--Gilbert