# -*- ruby -*-

# vim: set noet nosta sw=4 ts=4 :

require 'arborist/monitor/snmp' unless defined?( Arborist::Monitor::SNMP )

# SNMP swap usage checks.

# Returns swap used in a 'swap_in_use' attribute.

#

class Arborist::Monitor::SNMP::Swap

	include Arborist::Monitor::SNMP

	extend Loggability

	log_to :arborist

	# Global defaults for instances of this monitor

	#

	DEFAULT_OPTIONS = {

		error_at: 95, # in percent full

	}

	# OIDS for discovering memory usage.

	#

	MEMORY = {

		swap_total: '1.3.6.1.4.1.2021.4.3.0',

		swap_avail: '1.3.6.1.4.1.2021.4.4.0',

	}

	### This monitor is complex enough to require creating an instance from the caller.

	### Provide a friendlier error message the class was provided to exec() directly.

	###

	def self::run( nodes )

		return new.run( nodes )

	end

	### Create a new instance of this monitor.

	###

	def initialize( options=DEFAULT_OPTIONS )

		options = DEFAULT_OPTIONS.merge( options || {} )

		options.each do |name, value|

			self.public_send( "#{name.to_s}=", value )

		end

	end

	# Set an error if used swap exceeds this percentage.

	attr_accessor :error_at

	### Perform the monitoring checks.

	###

	def run( nodes )

		super do |snmp, host|

			self.gather_swap( snmp, host )

		end

	end

	#########

	protected

	#########

	### Collect used swap information for +host+ from an existing (and

	### open) +snmp+ connection.

	###

	def gather_swap( snmp, host )

		self.log.debug "Getting used swap for: %s" % [ host ]

		swap_total = snmp.get( SNMP::ObjectId.new(MEMORY[:swap_total]) ).varbind_list.first.value.to_f

		swap_avail = snmp.get( SNMP::ObjectId.new(MEMORY[:swap_avail]) ).varbind_list.first.value.to_f

		swap_in_use  = (( swap_avail.to_f / swap_total * 100 ) - 100 ).abs

		self.log.debug "  Swap in use on %s: %0.1f%%" % [ host, swap_in_use ]

		config = @identifiers[ host ].last || {}

		if swap_in_use >= ( config['error_at'] || self.error_at )

			@results[ host ] = {

				error: "%0.1f%% swap in use" % [ swap_in_use ],

				swap_in_use: swap_avail

			}

		else

			@results[ host ] = { swap_in_use: swap_in_use }

		end

	end

end # class Arborist::Monitor::SNMP::Swap