# -*- ruby -*-

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

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

# SNMP memory and swap utilization checks.

#

# Set 'usage' and 'available' keys as properties, in percentage/GBs,

# respectively.

#

# By default, doesn't warn on memory usage, only swap, since

# that's more indicitive of a problem.  You can still set the

# 'physical_warn_at' key to force warnings on ram usage, for embedded

# systems or other similar things without virtual memory.

#

class Arborist::Monitor::SNMP::Memory

	include Arborist::Monitor::SNMP

	extend Configurability, Loggability

	log_to :arborist_snmp

	# OIDS for discovering memory usage.

	#

	MEMORY = {

		total:  '1.3.6.1.4.1.2021.4.5.0',

		avail: '1.3.6.1.4.1.2021.4.6.0',

		windows: {

			label: '1.3.6.1.2.1.25.2.3.1.3',

			units: '1.3.6.1.2.1.25.2.3.1.4',

			total: '1.3.6.1.2.1.25.2.3.1.5',

			used:  '1.3.6.1.2.1.25.2.3.1.6'

		}

	}

	# OIDS for discovering swap usage.

	#

	SWAP = {

		total: '1.3.6.1.4.1.2021.4.3.0',

		avail: '1.3.6.1.4.1.2021.4.4.0'

	}

	# Global defaults for instances of this monitor

	#

	configurability( 'arborist.snmp.memory' ) do

		# What memory usage percentage qualifies as a warning

		setting :physical_warn_at, default: nil

		# What swap usage percentage qualifies as a warning

		setting :swap_warn_at, default: 60

	end

	### Return the properties used by this monitor.

	###

	def self::node_properties

		return USED_PROPERTIES

	end

	### Class #run creates a new instance and immediately runs it.

	###

	def self::run( nodes )

		return new.run( nodes )

	end

	### Perform the monitoring checks.

	###

	def run( nodes )

		super do |host, snmp|

			self.gather_memory( host, snmp )

		end

	end

	#########

	protected

	#########

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

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

	###

	def gather_memory( host, snmp )

		info = self.system =~ /windows\s+/i ? self.get_windows( snmp ) : self.get_mem( snmp )

		physical_warn_at = config[ 'physical_warn_at' ] || self.class.physical_warn_at

		swap_warn_at     = config[ 'swap_warn_at' ] || self.class.swap_warn_at

		self.log.debug "Memory data on %s: %p" % [ host, info ]

		memory, swap = info[:memory], info[:swap]

		self.results[ host ] = { memory: memory, swap: swap }

		memusage = memory[ :usage ].to_i

		if physical_warn_at && memusage >= physical_warn_at

			self.results[ host ][ :warning ] = "%0.1f memory utilization exceeds %0.1f percent" % [

				memusage,

				physical_warn_at

			]

		end

		swapusage = swap[ :usage ].to_i

		if swapusage >= swap_warn_at

			self.results[ host ][ :warning ] = "%0.1f swap utilization exceeds %0.1f percent" % [

				swapusage,

				swap_warn_at

			]

		end

	end

	### Return a hash of usage percentage in use, and free mem in

	### megs.

	###

	def get_mem( snmp )

		info  = {}

		info[ :memory ] = self.calc_memory( snmp, MEMORY )

		info[ :swap ]   = self.calc_memory( snmp, SWAP )

		return info

	end

	### Windows appends virtual and physical memory onto the last two items

	### of the storage iterator, because that made sense in someone's mind.

	### Walk the whole oid tree, and get the values we're after, return

	### a hash of usage percentage in use and free mem in megs.

	###

	def get_windows( snmp )

		info  = { memory: {}, swap: {} }

		mem_idx, swap_idx = nil

		snmp.walk( oid: MEMORY[:windows][:label] ).each_with_index do |(_, val), i|

			mem_idx  = i + 1 if val =~ /physical memory/i

			swap_idx = i + 1 if val =~ /virtual memory/i

		end

		return info unless mem_idx

		info[ :memory ] = self.calc_windows_memory( snmp, mem_idx )

		info[ :swap ]   = self.calc_windows_memory( snmp, swap_idx )

		return info

	end

	### Format usage and available amount, given an OID hash.

	###

	def calc_memory( snmp, oids )

		info = { usage: 0, available: 0 }

		avail = snmp.get( oid: oids[:avail] ).to_f

		total = snmp.get( oid: oids[:total] ).to_f

		used  = total - avail

		return info if avail.zero?

		info[ :usage ]     = (( used / total ) * 100 ).round( 2 )

		info[ :available ] = (( total - used ) / 1024 ).round( 2 )

		return info

	end

	### Format usage and available amount for windows.

	###

	def calc_windows_memory( snmp, idx)

		info = { usage: 0, available: 0 }

		return info unless idx

		units = snmp.get( oid: MEMORY[:windows][:units] + ".#{idx}" )

		total = snmp.get( oid: MEMORY[:windows][:total] + ".#{idx}" ).to_f * units

		used  = snmp.get( oid: MEMORY[:windows][:used] + ".#{idx}" ).to_f * units

		info[ :usage ]     = (( used / total ) * 100 ).round( 2 )

		info[ :available ] = (( total - used ) / 1024 / 1024 ).round( 2 )

		return info

	end

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