Class: Wal::RecordWatcher::TemporaryTableRecordWatcher

Inherits:
Object
  • Object
show all
Includes:
Watcher, Watcher::SeparatedEvents
Defined in:
lib/wal/record_watcher.rb

Instance Method Summary collapse

Methods included from Watcher::SeparatedEvents

#on_event

Methods included from Watcher

#on_event, #should_watch_table?, #valid_context_prefix?

Constructor Details

#initialize(watcher, batch_size: 5_000) ⇒ TemporaryTableRecordWatcher

Returns a new instance of TemporaryTableRecordWatcher.



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# File 'lib/wal/record_watcher.rb', line 233

def initialize(watcher, batch_size: 5_000)
  @watcher = watcher
  @batch_size = 5_000
end

Instance Method Details

#on_begin(event) ⇒ Object 



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# File 'lib/wal/record_watcher.rb', line 238

def on_begin(event)
  @table = begin
    table_name = "temp_record_watcher_#{SecureRandom.alphanumeric(10).downcase}"

    base_class.connection.create_table(table_name, temporary: true) do |t|
      t.bigint :transaction_id, null: false
      t.bigint :lsn, null: false
      t.column :action, :string, null: false
      t.string :table_name, null: false
      t.bigint :primary_key
      t.jsonb :old, null: false, default: {}
      t.jsonb :new, null: false, default: {}
      t.jsonb :context, null: false, default: {}
    end

    unique_index = %i[table_name primary_key]

    base_class.connection.add_index table_name, unique_index, unique: true

    Class.new(base_class) do
      self.table_name = table_name

      # All this sh$#1t was necessary because AR schema cache doesn't work with temporary tables...
      insert_all_class = Class.new(::ActiveRecord::InsertAll) do
        unique_index_definition = ::ActiveRecord::ConnectionAdapters::IndexDefinition.new(
          table_name, "unique_index", true, unique_index
        )
        define_method(:find_unique_index_for) { |_| unique_index_definition }
      end

      define_singleton_method(:upsert) do |attributes, update_only: nil|
        insert_all_class
          .new(
            none,
            connection,
            [attributes],
            on_duplicate: :update,
            unique_by: unique_index,
            update_only:,
            returning: nil,
            record_timestamps: nil,
          )
          .execute
      end
    end
  end
end

#on_commit(_event) ⇒ Object 



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# File 'lib/wal/record_watcher.rb', line 286

def on_commit(_event)
  @table
    .in_batches(of: @batch_size)
    .each_record
    .lazy
    .filter_map { |persisted_event| deserialize(persisted_event) }
    .each { |event| @watcher.on_record_changed(event) }

  base_class.connection.drop_table @table.table_name
end

#on_delete(event) ⇒ Object 



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# File 'lib/wal/record_watcher.rb', line 305

def on_delete(event)
  case @table.where(table_name: event.full_table_name, primary_key: event.primary_key).pluck(:action, :old).first
  in ["insert", _]
    @table.where(table_name: event.full_table_name, primary_key: event.primary_key).delete_all
  in ["update", old]
    @table.upsert(serialize(event).merge(old:))
  in ["delete", _]
    # We don't need to store another delete
  else
    @table.upsert(serialize(event))
  end
end

#on_insert(event) ⇒ Object 



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# File 'lib/wal/record_watcher.rb', line 297

def on_insert(event)
  @table.upsert(serialize(event))
end

#on_update(event) ⇒ Object 



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# File 'lib/wal/record_watcher.rb', line 301

def on_update(event)
  @table.upsert(serialize(event), update_only: %w[new])
end