Class: HQ::GrapherWeb::Handler

Inherits:
Object
  • Object
show all
Includes:
Tools::Escape
Defined in:
lib/hq/grapher-web/handler.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config_elem) ⇒ Handler

Returns a new instance of Handler.



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# File 'lib/hq/grapher-web/handler.rb', line 38

def initialize config_elem
	@config_elem = config_elem
end

Class Method Details

.get_provider(app_elem) ⇒ Object 



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# File 'lib/hq/grapher-web/handler.rb', line 9

def self.get_provider app_elem

	config_elem =
		app_elem.find_first "config"

	grapher_config_path =
		config_elem.attributes["path"]

	grapher_config_doc =
		XML::Document.file grapher_config_path

	grapher_config_elem =
		grapher_config_doc.root

	return proc do
		|env, params|

		handler =
			Handler.new \
				grapher_config_elem

		handler.handle \
			env,
			params

	end

end

Instance Method Details

#do_graph(graph_spec) ⇒ Object 



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# File 'lib/hq/grapher-web/handler.rb', line 115

def do_graph graph_spec

	require "RRD"

	Tempfile.open "mandar-rrd-" do
		|tmp|

		args = [
			tmp.path,
			"--start", graph_spec[:start],
			"--end", graph_spec[:end],
			"--width", graph_spec[:width],
			"--height", graph_spec[:height],
			"--slope-mode",
			"--rigid",
		]

		args += graph_spec[:data].map {
			|data|
			[
				"DEF",
				"#{data[:name]}=#{data[:source_file]}",
				data[:source_name],
				data[:source_function].upcase,
			].join(":")
		}

		args += graph_spec[:calc].map {
			|calc|
			"CDEF:#{calc[:name]}=#{calc[:rpn]}"
		}

		args += graph_spec[:outputs].map {
			|output|
			(
				[
					output[:type].upcase,
					"#{output[:data]}\##{output[:colour]}",
					output[:label],
				] + (output[:stack] ? [ "STACK" ] : [])
			).join(":")
		}

		args.map! { |arg| arg.to_s }

		RRD.graph *args

		return File.read tmp.path

	end

end

#handle(env, params) ⇒ Object 



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# File 'lib/hq/grapher-web/handler.rb', line 42

def handle env, params

	graph_name = params[:name]
	scale_name = params[:scale]

	rrd_database =
		@config_elem.attributes["database-path"]

	graph_elem =
		@config_elem.find_first("
			graph [@name = #{esc_xp graph_name}]
		")

	template_name =
		graph_elem.attributes["template"]

	template_elem =
		@config_elem.find_first("
			template [@name = #{esc_xp template_name}]
		")

	scale_elem =
		@config_elem.find_first("
			scale [@name = #{esc_xp scale_name}]
		")

	scale_steps = scale_elem.attributes["steps"].to_i
	scale_rows = scale_elem.attributes["rows"].to_i

	graph_spec = {
		:start => Time.now.to_i - scale_steps * scale_rows,
		:end => Time.now.to_i,
		:width => scale_rows,
		:height => 400,
		:data => template_elem.find("data").map { |data_elem|
			{
				:name => data_elem.attributes["name"],
				:source_file => "#{rrd_database}/#{graph_elem.attributes["source"]}.rrd",
				:source_name => data_elem.attributes["source"],
				:source_function => data_elem.attributes["function"],
			}
		},
		:calc => template_elem.find("calc").map { |calc_elem|
			{
				:name => calc_elem.attributes["name"],
				:rpn => calc_elem.attributes["rpn"],
			}
		},
		:outputs => template_elem.find("output").map { |output_elem|
			{
				:type => output_elem.attributes["type"].upcase,
				:data => output_elem.attributes["data"],
				:colour => output_elem.attributes["colour"],
				:label => output_elem.attributes["label"],
				:stack => output_elem.attributes["stack"] == "yes",
			}
		},
	}

	data = do_graph graph_spec

	headers = {
		"Content-Type" => "image/png"
	}

	body = [
		data
	]

	return [ 200, headers, body ]

end