# -*- ruby -*-

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

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

# SNMP memory availability checks.

# Returns total available memory in Kb to the 'available_memory' attribute.

#

class Arborist::Monitor::SNMP::Memory

	include Arborist::Monitor::SNMP

	extend Loggability

	log_to :arborist

	# OIDS for discovering memory usage.

	#

	MEMORY = {

		mem_avail: '1.3.6.1.4.1.2021.4.6.0'

	}

	# Global defaults for instances of this monitor

	#

	DEFAULT_OPTIONS = {

		error_at: 95, # in percent full

	}

	### 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 memory used is below this many kilobytes.

	attr_accessor :error_at

	### Perform the monitoring checks.

	###

	def run( nodes )

		super do |snmp, host|

			self.gather_free_memory( snmp, host )

		end

	end

	#########

	protected

	#########

	### Collect available memory information for +host+ from an existing

	### (and open) +snmp+ connection.

	###

	def gather_free_memory( snmp, host )

		self.log.debug "Getting available memory for: %s" % [ host ]

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

		self.log.debug "  Available memory on %s: %0.2f" % [ host, mem_avail ]

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

		error_at = config['error_at'] || self.error_at

		if mem_avail <= error_at

			@results[ host ] = {

				error: "Available memory is under %0.1fMB" % [ error_at.to_f / 1024 ],

				available_memory: mem_avail

			}

		else

			@results[ host ] = { available_memory: mem_avail }

		end

	end

end # class Arborist::Monitor::SNMP::Memory