Class: OnlineMigrations::BackgroundDataMigrations::MigrationJob

Inherits:
Object
  • Object
show all
Includes:
Sidekiq::IterableJob
Defined in:
lib/online_migrations/background_data_migrations/migration_job.rb

Overview

Sidekiq job responsible for running background data migrations.

Constant Summary collapse

TICKER_INTERVAL =

seconds

5

Instance Method Summary collapse

Constructor Details

#initialize ⇒ MigrationJob

Returns a new instance of MigrationJob.



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 24

def initialize
  super

  @migration = nil
  @data_migration = nil

  @ticker = Ticker.new(TICKER_INTERVAL) do |ticks, duration|
    # TODO: use 'cursor' accessor from sidekiq in the future.
    # https://github.com/sidekiq/sidekiq/pull/6606
    @migration.persist_progress(@_cursor, ticks, duration)

    # When using a scheduler, these are running only from a single shard, but when inline -
    # these are run from each shard (not needed, but simplifies the implementation).
    #
    # Do not reload the migration when running inline, because it can be from a different shard
    # than the "default" shard (which is used to lookup background migrations).
    if !Utils.run_background_migrations_inline?
      # Reload to check if the migration's status changed etc.
      @migration.reload
    end
  end

  @throttle_checked_at = current_time
end

Instance Method Details

#build_enumerator(migration_id, cursor:) ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 78

def build_enumerator(migration_id, cursor:)
  @migration = BackgroundDataMigrations::Migration.find(migration_id)
  cursor ||= @migration.cursor

  @migration.on_shard_if_present do
    @data_migration = @migration.data_migration
    collection_enum = @data_migration.build_enumerator(cursor: cursor)

    if collection_enum
      if !collection_enum.is_a?(Enumerator)
        raise ArgumentError, <<~MSG.squish
          #{@data_migration.class.name}#build_enumerator must return an Enumerator,
          got #{collection_enum.class.name}.
        MSG
      end

      collection_enum
    else
      collection = @data_migration.collection

      case collection
      when ActiveRecord::Relation
        options = {
          cursor: cursor,
          batch_size: @data_migration.class.active_record_enumerator_batch_size || 100,
        }
        active_record_records_enumerator(collection, **options)
      when ActiveRecord::Batches::BatchEnumerator
        if collection.start || collection.finish
          raise ArgumentError, <<~MSG.squish
            #{@data_migration.class.name}#collection does not support
            a batch enumerator with the "start" or "finish" options.
          MSG
        end

        active_record_relations_enumerator(
          collection.relation,
          batch_size: collection.batch_size,
          cursor: cursor,
          use_ranges: collection.use_ranges
        )
      when Array
        array_enumerator(collection, cursor: cursor)
      else
        raise ArgumentError, <<~MSG.squish
          #{@data_migration.class.name}#collection must be either an ActiveRecord::Relation,
          ActiveRecord::Batches::BatchEnumerator, or Array.
        MSG
      end
    end
  end
end

#each_iteration(item, _migration_id) ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 131

def each_iteration(item, _migration_id)
  if @migration.cancelling? || @migration.cancelled? || @migration.pausing? || @migration.paused?
    # Finish this exact sidekiq job. When the migration is paused
    # and will be resumed, a new job will be enqueued.
    finished = true
    throw :abort, finished
  elsif should_throttle?
    ActiveSupport::Notifications.instrument("throttled.background_data_migrations", migration: @migration)
    finished = false
    throw :abort, finished
  else
    @data_migration.around_process do
      @migration.data_migration.process(item)

      # Migration is refreshed regularly by ticker.
      pause = @migration.iteration_pause.to_f
      sleep(pause) if pause > 0
    end
    @ticker.tick
  end
end

#on_complete ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 71

def on_complete
  # Job was manually cancelled.
  @migration.cancel if cancelled?

  @migration.complete
end

#on_resume ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 53

def on_resume
  if @migration.errored? # the job was retried
    @migration.update!(
      status: :running,
      error_class: nil,
      error_message: nil,
      backtrace: nil
    )
  end

  @data_migration.after_resume
end

#on_start ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 49

def on_start
  @migration.start
end

#on_stop ⇒ Object 



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# File 'lib/online_migrations/background_data_migrations/migration_job.rb', line 66

def on_stop
  @ticker.persist
  @migration.stop
end