MQTT subscription

Gemfile.lock

@@ -616,4 +616,4 @@ RUBY VERSION
    ruby 3.0.6p216
 
 BUNDLED WITH
-   2.5.6
+   2.5.21

app/models/component.rb

@@ -5,8 +5,17 @@ class Component < ActiveRecord::Base
   belongs_to :sensor
 
   validates_presence_of :device, :sensor
-  validates :sensor_id, :uniqueness => { :scope => [:device_id] }
-  validates :key, :uniqueness => { :scope =>  [:device_id] }
+
+  # IMPORTANT: Validation of sensor/device uniqueness is done at the database level,
+  # as this allows us to use the create_or_find_by! method to atomically upsert components
+  # in the mqtt-task, avoiding component duplication due to race conditions.
+  # For some reason, create_or_find_by! ONLY works when the database constraint is
+  # the ONLY uniqueness constraint on those two values, so adding a rails validation here
+  # causes an error. Leaving the validations here commented out by way of documentation.
+  # See https://stackoverflow.com/questions/74566974/create-or-find-by-not-working-as-it-should-in-rails-6
+  # validates :sensor_id, :uniqueness => { :scope => [:device_id] }
+  # validates :key, :uniqueness => { :scope =>  [:device_id] }
+
 
   before_validation :set_key, on: :create
 

app/models/concerns/data_parser/storer.rb

@@ -54,7 +54,7 @@ def timestamp_parse(timestamp)
       end
 
       def sensor_reading(device, sensor)
-        component = device.find_or_create_component_for_sensor_reading(sensor)
+        component = device.create_or_find_component_for_sensor_reading(sensor)
         return nil if component.nil?
         value = component.normalized_value( (Float(sensor['value']) rescue sensor['value']) )
         {

app/models/device.rb

@@ -103,25 +103,25 @@ def sensor_map
     components.map { |c| [c.key, c.sensor.id]}.to_h
   end
 
-  def find_or_create_component_by_sensor_id(sensor_id)
+  def create_or_find_component_by_sensor_id(sensor_id)
     return nil if sensor_id.nil? || !Sensor.exists?(id: sensor_id)
-    components.find_or_create_by(sensor_id: sensor_id)
+    components.create_or_find_by!(sensor_id: sensor_id)
   end
 
-  def find_or_create_component_by_sensor_key(sensor_key)
+  def create_or_find_component_by_sensor_key(sensor_key)
     return nil if sensor_key.nil?
     sensor = Sensor.find_by(default_key: sensor_key)
     return nil if sensor.nil?
-    components.find_or_create_by(sensor_id: sensor.id)
+    components.create_or_find_by!(sensor_id: sensor.id)
   end
 
-  def find_or_create_component_for_sensor_reading(reading)
+  def create_or_find_component_for_sensor_reading(reading)
     key_or_id = reading["id"]
     if key_or_id.is_a?(Integer) || key_or_id =~ /\d+/
       # It's an integer and therefore a sensor id
-      find_or_create_component_by_sensor_id(key_or_id)
+      create_or_find_component_by_sensor_id(key_or_id)
     else
-      find_or_create_component_by_sensor_key(key_or_id)
+      create_or_find_component_by_sensor_key(key_or_id)
     end
   end
 
@@ -245,7 +245,10 @@ def remove_mac_address_for_newly_registered_device!
 
   def update_component_timestamps(timestamp, sensor_ids)
     components.select {|c| sensor_ids.include?(c.sensor_id) }.each do |component|
-      component.update_column(:last_reading_at, timestamp)
+      component.lock! if self.class.connection.transaction_open?
+      if !component.reload.last_reading_at || timestamp > component.last_reading_at
+        component.update_column(:last_reading_at, timestamp)
+      end
     end
   end
 

app/models/raw_storer.rb

@@ -30,7 +30,7 @@ def store data, mac, version, ip, raise_errors=false
 
         metric_id = device.find_sensor_id_by_key(metric)
 
-        component = device.find_or_create_component_by_sensor_id(metric_id)
+        component = device.create_or_find_component_by_sensor_id(metric_id)
         next if component.nil?
 
         value = component.normalized_value( (Float(value) rescue value) )

app/models/storer.rb

@@ -23,18 +23,20 @@ def store device, reading, do_update = true
 
   def update_device(device, parsed_ts, sql_data)
     return if parsed_ts <= Time.at(0)
+    device.transaction do
+      device.lock!
+      if device.reload.last_reading_at.present?
+        # Comparison errors if device.last_reading_at is nil (new devices).
+        # Devices can post multiple readings, in a non-sorted order.
+        # Do not update data with an older timestamp.
+        return if parsed_ts < device.last_reading_at
+      end
 
-    if device.last_reading_at.present?
-      # Comparison errors if device.last_reading_at is nil (new devices).
-      # Devices can post multiple readings, in a non-sorted order.
-      # Do not update data with an older timestamp.
-      return if parsed_ts < device.last_reading_at
+      sql_data = device.data.present? ? device.data.merge(sql_data) : sql_data
+      device.update_columns(last_reading_at: parsed_ts, data: sql_data, state: 'has_published')
+      sensor_ids = sql_data.select { |k, v| k.is_a?(Integer) }.keys.compact.uniq
+      device.update_component_timestamps(parsed_ts, sensor_ids)
     end
-
-    sql_data = device.data.present? ? device.data.merge(sql_data) : sql_data
-    device.update_columns(last_reading_at: parsed_ts, data: sql_data, state: 'has_published')
-    sensor_ids = sql_data.select { |k, v| k.is_a?(Integer) }.keys.compact.uniq
-    device.update_component_timestamps(parsed_ts, sensor_ids)
   end
 
   def kairos_publish(reading_data)

compose.override.local.yml

@@ -7,7 +7,11 @@ services:
     restart: "no"
   sidekiq:
     restart: "no"
-  mqtt-task:
+  mqtt-task-main-1:
+    restart: "no"
+  mqtt-task-main-2:
+    restart: "no"
+  mqtt-task-secondary:
     restart: "no"
   telnet-task:
     restart: "no"

compose/app.yml

@@ -15,7 +15,9 @@ services:
       - auth
       - redis
       - sidekiq
-      - mqtt-task
+      - mqtt-task-main-1
+      - mqtt-task-main-2
+      - mqtt-task-secondary
       - telnet-task
       #- mqtt
     restart: always

compose/db.yml

@@ -1,6 +1,7 @@
 services:
    db:
     image: postgres:10
+    command: -c max_connections=200
     volumes:
       - sck-postgres:/var/lib/postgresql/data
     env_file: ../.env

compose/mqtt-task-common.yml

@@ -0,0 +1,14 @@
+services:
+  mqtt-task:
+    build: ../
+    env_file: ../.env
+    command: ./mqtt_subscriber.sh
+    restart: always
+    volumes:
+      - "../log:/app/log"
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "100m"
+    environment:
+      db_pool_size: 5

compose/mqtt-task.yml

@@ -1,14 +1,27 @@
 services:
-  mqtt-task:
-    build: ../
-    env_file: ../.env
-    command: bundle exec rake mqtt:sub
-    restart: always
-    volumes:
-      - "../log:/app/log"
-    logging:
-      driver: "json-file"
-      options:
-        max-size: "100m"
-    environment:
-      db_pool_size: 5
+  mqtt-task-main-1:
+    extends:
+      file: mqtt-task-common.yml
+      service: mqtt-task
+    environment: 
+      MQTT_CLIENT_ID: smartcitizen-api-staging-main-1
+      MQTT_CLEAN_SESSION: false
+  mqtt-task-main-2:
+    extends:
+      file: mqtt-task-common.yml
+      service: mqtt-task
+    environment: 
+      MQTT_CLIENT_ID: smartcitizen-api-staging-main-2
+      MQTT_CLEAN_SESSION: false
+  mqtt-task-secondary:
+    extends:
+      file: mqtt-task-common.yml
+      service: mqtt-task
+    environment: 
+      MQTT_CLIENT_ID: "smartcitizen-api-staging-secondary"
+      MQTT_CLEAN_SESSION: true
+    deploy:
+      mode: replicated
+      replicas: 2
+
+

compose/telnet-task.yml

@@ -5,4 +5,4 @@ services:
     command: bundle exec rake telnet:push
     restart: always
     environment:
-      db_pool_size: 5
+      db_pool_size: 2

db/migrate/20241009174732_unique_index_on_components.rb

@@ -0,0 +1,23 @@
+class UniqueIndexOnComponents < ActiveRecord::Migration[6.1]
+  def up
+    remove_index :components, [:device_id, :sensor_id]
+    add_index :components, [:device_id, :sensor_id], unique: true
+    execute %{
+      ALTER TABLE components ADD CONSTRAINT unique_sensor_for_device UNIQUE (device_id, sensor_id)
+    }
+    execute %{
+      ALTER TABLE components ADD CONSTRAINT unique_key_for_device UNIQUE (device_id, key)
+    }
+  end
+
+  def down
+    execute %{
+      ALTER TABLE components DROP CONSTRAINT IF EXISTS unique_key_for_device
+    }
+    execute %{
+      ALTER TABLE components DROP CONSTRAINT IF EXISTS unique_sensor_for_device
+    }
+    remove_index :components, [:device_id, :sensor_id], unique: true
+    add_index :components, [:device_id, :sensor_id]
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2024_08_12_081108) do
+ActiveRecord::Schema.define(version: 2024_10_09_174732) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "adminpack"
   enable_extension "hstore"
@@ -65,7 +65,9 @@
     t.string "key"
     t.integer "bus", default: 1, null: false
     t.datetime "last_reading_at"
-    t.index ["device_id", "sensor_id"], name: "index_components_on_device_id_and_sensor_id"
+    t.index ["device_id", "key"], name: "unique_key_for_device", unique: true
+    t.index ["device_id", "sensor_id"], name: "index_components_on_device_id_and_sensor_id", unique: true
+    t.index ["device_id", "sensor_id"], name: "unique_sensor_for_device", unique: true
   end
 
   create_table "devices", id: :serial, force: :cascade do |t|

env.example

@@ -18,6 +18,7 @@ REDIS_STORE=redis://redis:6379/3
 
 # MQTT Settings
 MQTT_HOST=mqtt
+#MQTT_SHARED_SUBSCRIPTION_GROUP="group1"
 #MQTT_CLEAN_SESSION=true
 #MQTT_CLIENT_ID=some_id
 #MQTT_PORT=port

lib/tasks/mqtt_subscriber.rake

@@ -3,15 +3,23 @@ namespace :mqtt do
   task sub: :environment do
     pid_file = Rails.root.join('tmp/pids/mqtt_subscriber.pid')
     File.open(pid_file, 'w') { |f| f.puts Process.pid }
-    mqtt_log = Logger.new('log/mqtt.log', 5, 100.megabytes)
 
     mqtt_clean_session = ENV.has_key?('MQTT_CLEAN_SESSION') ? ENV['MQTT_CLEAN_SESSION'] == "true" : true
     mqtt_client_id = ENV.has_key?('MQTT_CLIENT_ID') ? ENV['MQTT_CLIENT_ID'] : nil
     mqtt_host = ENV.has_key?('MQTT_HOST') ? ENV['MQTT_HOST'] : 'mqtt'
     mqtt_port = ENV.has_key?('MQTT_PORT') ? ENV['MQTT_PORT'] : 1883
     mqtt_ssl = ENV.has_key?('MQTT_SSL') ? ENV['MQTT_SSL'] : false
+    mqtt_shared_subscription_group = ENV.fetch("MQTT_SHARED_SUBSCRIPTION_GROUP", nil)
+    mqtt_queue_length_warning_threshold = ENV.fetch("MQTT_QUEUE_LENGTH_WARNING_THRESHOLD", "30").to_i
+
     mqtt_topics_string = ENV.fetch('MQTT_TOPICS', '')
     mqtt_topics = mqtt_topics_string.include?(",") ? mqtt_topics_string.split(",") : [ mqtt_topics_string ]
+
+    if mqtt_shared_subscription_group && mqtt_clean_session
+      mqtt_client_id += "-#{ENV.fetch("HOSTNAME")}"
+    end
+
+    mqtt_log = Logger.new("log/mqtt-#{mqtt_client_id}.log", 5, 100.megabytes)
     mqtt_log.info('MQTT TASK STARTING')
     mqtt_log.info("clean_session: #{mqtt_clean_session}")
     mqtt_log.info("client_id: #{mqtt_client_id}")
@@ -32,18 +40,18 @@ namespace :mqtt do
         mqtt_log.info "Using clean_session setting: #{client.clean_session}"
 
         message_handler = MqttMessagesHandler.new
-
+        prefix = mqtt_shared_subscription_group ? "$share/#{mqtt_shared_subscription_group}" : "$queue"
         client.subscribe(*mqtt_topics.flat_map { |topic|
           topic = topic == "" ? topic : topic + "/"
           [
-            "$queue/#{topic}device/sck/+/readings" => 2,
-            "$queue/#{topic}device/sck/+/readings/raw" => 2,
-            "$queue/#{topic}device/sck/+/hello" => 2,
-            "$queue/#{topic}device/sck/+/info" => 2,
-            "$queue/#{topic}device/inventory" => 2
+            "#{prefix}/#{topic}device/sck/+/readings" => 2,
+            "#{prefix}/#{topic}device/sck/+/readings/raw" => 2,
+            "#{prefix}/#{topic}device/sck/+/hello" => 2,
+            "#{prefix}/#{topic}device/sck/+/info" => 2,
+            "#{prefix}/#{topic}device/inventory" => 2
           ]
         })
-
+        threshold_passed = false
         client.get do |topic, message|
           Sentry.with_scope do
             begin
@@ -52,6 +60,14 @@ namespace :mqtt do
               end
               mqtt_log.info "Processed MQTT message in #{time}"
               mqtt_log.info "MQTT queue length: #{client.queue_length}"
+              if client.queue_length >= mqtt_queue_length_warning_threshold
+                if !threshold_passed
+                  Sentry.capture_message("Warning: Internal MQTT queue length is #{client.queue_length} (>= #{mqtt_queue_length_warning_threshold} on client #{mqtt_client_id}).")
+                  threshold_passed = true
+                end
+              else
+                threshold_passed = false
+              end
             rescue Exception => e
               mqtt_log.info e
               Sentry.capture_exception(e)

mqtt_subscriber.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+bundle exec rake mqtt:sub

spec/models/component_spec.rb

@@ -8,7 +8,7 @@
 
   it "validates uniqueness of board to sensor" do
     component = create(:component, device: create(:device), sensor: create(:sensor))
-    expect{ create(:component, device: component.device, sensor: component.sensor) }.to raise_error(ActiveRecord::RecordInvalid)
+    expect{ create(:component, device: component.device, sensor: component.sensor) }.to raise_error(ActiveRecord::RecordNotUnique)
   end
 
   describe "creating a unique sensor key" do

spec/models/device_spec.rb

@@ -635,19 +635,19 @@
     end
   end
 
-  describe "#find_or_create_component_by_sensor_id" do
+  describe "#create_or_find_component_by_sensor_id" do
     context "when the sensor exists and a component already exists for this device" do
       it "returns the existing component" do
         sensor = create(:sensor)
         component = create(:component, sensor: sensor, device: device)
-        expect(device.find_or_create_component_by_sensor_id(sensor.id)).to eq(component)
+        expect(device.create_or_find_component_by_sensor_id(sensor.id)).to eq(component)
       end
     end
 
     context "when the sensor exists and a component does not already exist for this device" do
       it "returns a new valid component with the correct sensor and device" do
         sensor = create(:sensor)
-        component = device.find_or_create_component_by_sensor_id(sensor.id)
+        component = device.create_or_find_component_by_sensor_id(sensor.id)
         expect(component).not_to be_blank
         expect(component).to be_a Component
         expect(component.valid?).to be(true)
@@ -660,13 +660,13 @@
     context "when no sensor exists with this id" do
       it "returns nil" do
         create(:sensor, id: 12345)
-        expect(device.find_or_create_component_by_sensor_id(54321)).to be_blank
+        expect(device.create_or_find_component_by_sensor_id(54321)).to be_blank
       end
     end
 
     context "when the id is nil" do
       it "returns nil" do
-        expect(device.find_or_create_component_by_sensor_id(nil)).to be_blank
+        expect(device.create_or_find_component_by_sensor_id(nil)).to be_blank
       end
     end
 

spec/spec_helper.rb

@@ -14,7 +14,6 @@
 # users commonly want.
 #
 # See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
-
 RSpec.configure do |config|
   # rspec-expectations config goes here. You can use an alternate
   # assertion/expectation library such as wrong or the stdlib/minitest