kstat, a node.js addon for reading kstats
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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);