Common: Notifications

Setting notifier

By default, notifications are disabled and notifier isn't set. You must set the notifier during application initialization:

TableSync.notifier = TableSync::InstrumentAdapter::ActiveSupport

When you set the notifier, the notifications are automatically turned on:

TableSync.notifier = TableSync::InstrumentAdapter::ActiveSupport
p TableSync.notify # => "true"

Also, you can disable notifications: TableSync.notify = false.

ActiveSupport adapter

You can use an already existing ActiveSupport adapter:

  TableSync.notifier = TableSync::InstrumentAdapter::ActiveSupport

This instrumentation API is provided by Active Support. It allows to subscribe to notifications:

ActiveSupport::Notifications.subscribe(/tablesync/) do |name, start, finish, id, payload|
  # do something
end

Types of events available: "tablesync.receive.update", "tablesync.receive.destroy", "tablesync.publish.update" and "tablesync.publish.destroy".

You have access to the payload, which contains event, direction, table, schema and count.

{
  :event => :update,       # one of update / destroy
  :direction => :publish,  # one of publish / receive
  :table => "users",
  :schema => "public",
  :count => 1
}

See more at https://guides.rubyonrails.org/active_support_instrumentation.html

Custom adapters

You can also create a custom adapter. It is expected to respond to the following method:

  def notify(table:, event:, direction:, count:)
    # processes data about table_sync event
  end