Class: EventHub::Processor

Inherits:
Object
  • Object
show all
Includes:
Helper
Defined in:
lib/eventhub/processor.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Helper

#class_to_array, #duration, #format_string, #get_host, #get_ip_adresses, #now_stamp

Constructor Details

#initialize(name = nil) ⇒ Processor

Returns a new instance of Processor.



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# File 'lib/eventhub/processor.rb', line 12

def initialize(name=nil)
	@name = name || class_to_array(self.class)[1..-1].join(".")
	@folder = Dir.pwd

	@started = Time.now

	@messages_successful 		= 0
	@messages_unsuccessful 	= 0


	@channel_receiver = nil
	@channel_sender		= nil
	@restart = true
end

Instance Attribute Details

#folder ⇒ Object

Returns the value of attribute folder.



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# File 'lib/eventhub/processor.rb', line 4

def folder
  @folder
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/eventhub/processor.rb', line 4

def name
  @name
end

Instance Method Details

#configuration ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 27

def configuration
	EventHub::Configuration.instance.data
end

#connection_settings ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 51

def connection_settings
	{ user: server_user, password: server_password, host: server_host, vhost: server_vhost }
end

#handle_message(metadata, payload) ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 168

def handle_message(metadata,payload)
	raise "Please implement method in derived class"
end

#heartbeat ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 196

def heartbeat
	message = Message.new
	message.origin_module_id 	= @name
	message.origin_type 			= "processor"
	message.origin_site_id 		= 'global'

	message.process_name    	= 'event_hub.heartbeat'

	now = Time.now
	message.body = {
		 version: 							self.version,
		 heartbeat: {             
		 started: 							now_stamp(@started),
		 stamp_last_beat:       now_stamp(now), 
		 uptime:                duration(now-@started),
		 heartbeat_cycle_in_s: 	self.heartbeat_cycle_in_s,
		 served_queues: 				[self.listener_queue],
		 host: 									get_host,
		 ip_adresses:           get_ip_adresses,
		 messages: {
		 	total: 								@messages_successful+@messages_unsuccessful,
		 	successful: 					@messages_successful,
		 	unsuccessful: 				@messages_unsuccessful
		 	}
		}
	}

	# send heartbeat message
	send_message(message)

	EventMachine.add_timer(self.heartbeat_cycle_in_s) { heartbeat }

end

#heartbeat_cycle_in_s ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 67

def heartbeat_cycle_in_s
	configuration.get('processor.heartbeat_cycle_in_s') || 300
end

#listener_queue ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 55

def listener_queue
	configuration.get('processor.listener_queue') || 'undefined_listener_queue'
end

#restart_in_s ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 63

def restart_in_s
	configuration.get('processor.restart_in_s') || 15
end

#send_message(message, exchange_name = EH_X_INBOUND) ⇒ Object

send message



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# File 'lib/eventhub/processor.rb', line 231

def send_message(message,exchange_name=EH_X_INBOUND)

	if @channel_sender.nil? || !@channel_sender.open?
		@channel_sender = AMQP::Channel.new(@connection, prefetch: 1)

		# use publisher confirm
		@channel_sender.confirm_select
		  
		# @channel.on_error { |ch, channel_close| EventHub.logger.error "Oops! a channel-level exception: #{channel_close.reply_text}" }
      # @channel.on_ack   { |basic_ack| EventHub.logger.info "Received basic_ack: multiple = #{basic_ack.multiple}, delivery_tag = #{basic_ack.delivery_tag}" }
	end

	exchange = @channel_sender.direct(exchange_name, :durable => true, :auto_delete => false) 
 		exchange.publish(message.to_json, :persistent => true)

rescue => e
		EventHub.logger.error("Unexpected exception while sending message to [#{exchange_name}]: #{e}")
end

#server_host ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 31

def server_host
	configuration.get('server.host') || 'localhost'
end

#server_management_port ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 43

def server_management_port
	configuration.get('server.management_port') || 15672
end

#server_password ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 39

def server_password
	configuration.get('server.password') || 'admin'
end

#server_user ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 35

def server_user
	configuration.get('server.user') || 'admin'
end

#server_vhost ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 47

def server_vhost
	configuration.get('server.vhost') || 'event_hub'
end

#sleep_break(seconds) ⇒ Object

breaks after n seconds or after interrupt



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# File 'lib/eventhub/processor.rb', line 250

def sleep_break( seconds ) # breaks after n seconds or after interrupt
		while (seconds > 0)
  		sleep(1)
  		seconds -= 1
  		break unless @restart
		end
end

#start(detached = false) ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 71

def start(detached=false)
	daemonize if detached

	EventHub.logger.info("Processor [#{@name}] base folder [#{@folder}]")

	while @restart

		begin 
			AMQP.start(self.connection_settings) do |connection, open_ok|

				@connection = connection
				
				# deal with tcp connection issues
				@connection.on_tcp_connection_loss do |conn, settings|
		  		EventHub.logger.warn("Processor lost tcp connection. Trying to restart in #{self.restart_in_s} seconds...")
		  		stop_processor(true)
		  	end

				# create channel
				@channel_receiver = AMQP::Channel.new(@connection, prefetch: 1)

		  	# connect to queue
		  	@queue = @channel_receiver.queue(self.listener_queue, durable: true, auto_delete: false)

		  	# subscribe to queue
			  @queue.subscribe(:ack => true) do |metadata, payload|	  	

			  	
			  	begin
			  		messages_to_send = []

			  		# try to convert to Evenhub message
			  		message = Message.from_json(payload)
			  		EventHub.logger.info("-> #{message.to_s}")

			  		if message.status_code == STATUS_INVALID
			  			messages_to_send << message
			  			EventHub.logger.info("-> #{message.to_s} => Put to queue [#{EH_X_INBOUND}].")
			  		else
				  		# pass received message to handler or dervied handler
				  		messages_to_send = Array(handle_message(message))
				  	end

			  		# forward invalid or returned messages to dispatcher
				  	messages_to_send.each do |message|
				  		send_message(message)
				  	end
				  	@channel_receiver.acknowledge(metadata.delivery_tag)
				  	@messages_successful += 1
				  	
			  	rescue => e
			  		@channel_receiver.reject(metadata.delivery_tag,false)
			  		@messages_unsuccessful += 1
			  		EventHub.logger.error("Unexpected exception in handle_message method: #{e}. Message dead lettered.")
						EventHub.logger.save_detailed_error(e)
			  	end
			  end

			  EventHub.logger.info("Processor [#{@name}] is listening to vhost [#{self.server_vhost}], queue [#{self.listener_queue}]")

			  # Singnal Listening
			  Signal.trap("TERM") {stop_processor}
			  Signal.trap("INT")  {stop_processor}

			  # post_start is a custom post start routing to be overwritten
				post_start

			  # Various timers
			  EventMachine.add_timer(@watchdog_cycle_in_s) { watchdog }

			  heartbeat
			end
		rescue => e
			Signal.trap("TERM") { stop_processor }
			Signal.trap("INT")  { stop_processor }

			id = EventHub.logger.save_detailed_error(e)
			EventHub.logger.error("Unexpected exception: #{e}, see => #{id}. Trying to restart in #{self.restart_in_s} seconds...")
			
			sleep_break self.restart_in_s
		end

	end # while

	# post_start is a custom post start routing to be overwritten
	post_stop

	EventHub.logger.info("Processor [#{@name}] has been stopped")
ensure
	# remove pid file
	begin
		File.delete("#{@folder}/#{@name}.pid")	
	rescue
		# ignore exceptions here
	end
end

#version ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 8

def version
	"1.0.0"
end

#watchdog ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 172

def watchdog
	begin
		response = RestClient.get "http://#{self.server_user}:#{self.server_password}@#{self.server_host}:#{self.server_management_port}/api/queues/#{self.server_vhost}/#{self.listener_queue}/bindings", { :content_type => :json}
			data = JSON.parse(response.body)
	
			if response.code != 200
				EventHub.logger.warn("Watchdog: Server did not answered properly. Trying to restart in #{self.restart_in_s} seconds...")
				EventMachine.add_timer(self.restart_in_s) { stop_processor(true) }
			elsif data.size == 0
				EventHub.logger.warn("Watchdog: Something is wrong with the vhost, queue, and/or bindings. Trying to restart in #{self.restart_in_s} seconds...")
				EventMachine.add_timer(self.restart_in_s) { stop_processor(true) }
				# does it make sence ? Needs maybe more checks in future
			else
				# Watchdog is happy :-)
			# add timer for next check
			EventMachine.add_timer(self.watchdog_cycle_in_s) { watchdog }
		end	
			
	rescue => e
		EventHub.logger.error("Watchdog: Unexpected exception: #{e}. Trying to restart in #{self.restart_in_s} seconds...")
		stop_processor
	end
end

#watchdog_cycle_in_s ⇒ Object 



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# File 'lib/eventhub/processor.rb', line 59

def watchdog_cycle_in_s
	configuration.get('processor.watchdog_cycle_is_s') || 15
end