Debounced updatable

app/models/concerns/cable_ready/updatable.rb

@@ -6,6 +6,26 @@ module CableReady
   module Updatable
     extend ::ActiveSupport::Concern
 
+    class MemoryDebounceAdapter
+      include Singleton
+      include MonitorMixin
+
+      delegate_missing_to :@dict
+
+      def initialize
+        super
+        @dict = {}
+      end
+
+      def []=(key, value)
+        synchronize do
+          @dict[key] = value
+        end
+      end
+    end
+
+    mattr_accessor :debounce_adapter, default: MemoryDebounceAdapter.instance
+
     included do |base|
       if defined?(ActiveRecord) && base < ActiveRecord::Base
         include ExtendHasMany
@@ -30,11 +50,14 @@ def self.enable_cable_ready_updates(*options)
           options = options.extract_options!
           options = {
             on: [:create, :update, :destroy],
-            if: -> { true }
+            if: -> { true },
+            debounce: 0.seconds
           }.merge(options)
 
           enabled_operations = Array(options[:on])
 
+          @debounce_time = options[:debounce]
+
           after_commit(ModelUpdatableCallbacks.new(:create, enabled_operations), {on: :create, if: options[:if]})
           after_commit(ModelUpdatableCallbacks.new(:update, enabled_operations), {on: :update, if: options[:if]})
           after_commit(ModelUpdatableCallbacks.new(:destroy, enabled_operations), {on: :destroy, if: options[:if]})
@@ -52,6 +75,8 @@ def self.skip_cable_ready_updates
     private
 
     module ClassMethods
+      include Compoundable
+
       def has_many(name, scope = nil, **options, &extension)
         option = if options.has_key?(:enable_updates)
           warn "DEPRECATED: please use `enable_cable_ready_updates` instead. The `enable_updates` option will be removed from a future version of CableReady 5"
@@ -180,7 +205,24 @@ def build_options(option)
       def broadcast_updates(model_class, options)
         return if skip_updates_classes.any? { |klass| klass >= self }
         raise("ActionCable must be enabled to use Updatable") unless defined?(ActionCable)
-        ActionCable.server.broadcast(model_class, options)
+
+        if debounce_time > 0.seconds
+          key = compound([model_class, *options])
+          old_wait_until = CableReady::Updatable.debounce_adapter[key]
+          now = Time.now.to_f
+
+          if old_wait_until.nil? || old_wait_until < now
+            new_wait_until = now + debounce_time.to_f
+            CableReady::Updatable.debounce_adapter[key] = new_wait_until
+            ActionCable.server.broadcast(model_class, options)
+          end
+        else
+          ActionCable.server.broadcast(model_class, options)
+        end
+      end
+
+      def debounce_time
+        @debounce_time ||= 0.seconds
       end
 
       def skip_updates_classes

test/dummy/app/models/site.rb

@@ -0,0 +1,5 @@
+class Site < ApplicationRecord
+  include CableReady::Updatable
+
+  enable_cable_ready_updates debounce: 3.seconds
+end

test/dummy/db/migrate/20230301080311_create_sites.rb

@@ -0,0 +1,9 @@
+class CreateSites < ActiveRecord::Migration[6.1]
+  def change
+    create_table :sites do |t|
+      t.string :name
+
+      t.timestamps
+    end
+  end
+end

test/dummy/db/schema.rb

@@ -1,5 +1,3 @@
-# frozen_string_literal: true
-
 # This file is auto-generated from the current state of the database. Instead
 # of editing this file, please use the migrations feature of Active Record to
 # incrementally modify your database, and then regenerate this schema definition.
@@ -12,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_05_18_072701) do
+ActiveRecord::Schema.define(version: 2023_03_01_080311) do
 
   create_table "accounts", force: :cascade do |t|
     t.string "account_number"
@@ -78,6 +76,12 @@
     t.datetime "updated_at", precision: 6, null: false
   end
 
+  create_table "sites", force: :cascade do |t|
+    t.string "name"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+  end
+
   create_table "suppliers", force: :cascade do |t|
     t.string "name"
     t.datetime "created_at", precision: 6, null: false

test/dummy/test/fixtures/sites.yml

@@ -0,0 +1,7 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  name: MyString
+
+two:
+  name: MyString

test/dummy/test/models/site_test.rb

@@ -0,0 +1,7 @@
+require "test_helper"
+
+class SiteTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end

test/lib/cable_ready/updatable_test.rb

@@ -229,4 +229,21 @@ class TestEnableUpdatesOption < ActiveRecord::Base
     end
   end
   # standard:enable Lint/ConstantDefinitionInBlock
+
+  test "only sends out a ping once per debounce period" do
+    site = Site.create(name: "Front Page")
+
+    mock_server = mock("server")
+    mock_server.expects(:broadcast).with(Site, {changed: ["name", "updated_at"]}).twice
+    mock_server.expects(:broadcast).with(site.to_global_id, {changed: ["name", "updated_at"]}).twice
+
+    ActionCable.stubs(:server).returns(mock_server)
+
+    # debounce time is 3 seconds, so the last update should trigger its own broadcast
+    site.update(name: "Landing Page 1")
+    travel(1.second)
+    site.update(name: "Landing Page 2")
+    travel(3.seconds)
+    site.update(name: "Landing Page 3")
+  end
 end