kstat

kstat, a node.js addon for reading kstats

This is a simple node.js addon that allows one to read kernel statistics via the kstat framework on Solaris. The "kstat" module exports a single class, "Reader" that has the following methods:

Reader(): Takes an optional object specifying the kstats to read. This object may have the following members:

        class    =>  optional string denoting class of kstat(s) to read
        module   =>  optional string denoting module of kstat(s) to read
        name     =>  optional string denoting name of kstat(s) to read
        instance =>  optional integer denoting instance of kstat(s) to read

        Together, these members form a specification of kstats to read.

read(): Returns an array of kstats that match the specification with which the reader instance was constructed and an optional specification passed to this function. Each element of the array is an object that contains the following members:

        class    =>  string denoting class of kstat
        module   =>  string denoting module of kstat
        name     =>  string denoting name of kstat
        instance =>  integer denoting instance of kstat
        snaptime =>  nanoseconds since boot of this snapshot
        data     =>  an object containing the named kstat data itself

For example, here is a simple node.js program that dumps the kstats of class 'mib2':

var kstat = require('kstat'); var sys = require('sys'); var reader = new kstat.Reader({ 'class': 'mib2' } ); sys.puts(sys.inspect(reader.read()));

Here is a the same program that reads only the 'mib2' class kstats from the 'icmp' module:

var kstat = require('kstat'); var sys = require('sys'); var reader = new kstat.Reader({ 'class': 'mib2', module: 'icmp' } ); sys.puts(sys.inspect(reader.read()));

Finally, here is a simple program that prints the number of ICMP datagrams received per second:

var kstat = require('kstat'); var sys = require('sys'); var reader = new kstat.Reader({ 'class': 'mib2', module: 'icmp' } );

var data = []; var gen = 0;

setInterval(function() { data[gen] = reader.read()[0]; gen ^= 1;

    if (!(data[0] && data[1]))
            return;

      sys.puts(data[gen ^ 1].data.inDatagrams - data[gen].data.inDatagrams);

}, 1000);