Class: OnlineMigrations::BackgroundMigrations::Migration

Inherits:
ApplicationRecord
  • Object
show all
Defined in:
lib/online_migrations/background_migrations/migration.rb

Overview

Note:

The records of this class should not be created manually, but via enqueue_background_migration helper inside migrations.

Class representing background data migration.

Constant Summary collapse

STATUSES = 
[
  :enqueued,    # The migration has been enqueued by the user.
  :running,     # The migration is being performed by a migration executor.
  :paused,      # The migration was paused in the middle of the run by the user.
  :finishing,   # The migration is being manually finishing inline by the user.
  :failed,      # The migration raises an exception when running.
  :succeeded,   # The migration finished without error.
]

Instance Method Summary collapse

Instance Method Details

#completed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_migrations/migration.rb', line 76

def completed?
  succeeded? || failed?
end

#interval_elapsed? ⇒ Boolean

Returns whether the interval between previous step run has passed.

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_migrations/migration.rb', line 155

def interval_elapsed?
  last_active_job = migration_jobs.active.order(:updated_at).last

  if last_active_job && !last_active_job.stuck?
    false
  elsif batch_pause > 0 && (job = last_completed_job)
    job.finished_at + batch_pause <= Time.current
  else
    true
  end
end

#last_completed_job ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 104

def last_completed_job
  migration_jobs.completed.order(:finished_at).last
end

#last_job ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 100

def last_job
  migration_jobs.order(:max_value).last
end

#migration_class ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 136

def migration_class
  BackgroundMigration.named(migration_name)
end

#migration_model ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 148

def migration_model
  migration_relation.model
end

#migration_name=(class_name) ⇒ Object Also known as: name= 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 70

def migration_name=(class_name)
  class_name = class_name.name if class_name.is_a?(Class)
  write_attribute(:migration_name, self.class.normalize_migration_name(class_name))
end

#migration_object ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 140

def migration_object
  @migration_object ||= migration_class.new(*arguments)
end

#migration_relation ⇒ Object 



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# File 'lib/online_migrations/background_migrations/migration.rb', line 144

def migration_relation
  migration_object.relation
end

#paused! ⇒ Object

Overwrite enum's generated method to correctly work for composite migrations.



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# File 'lib/online_migrations/background_migrations/migration.rb', line 81

def paused!
  return super if !composite?

  transaction do
    super
    children.each { |child| child.paused! if child.enqueued? || child.running? }
  end
end

#progress ⇒ Float?

Returns the progress of the background migration.

Returns:

  • (Float, nil) —
    • when background migration is configured to not track progress, returns nil
    • otherwise returns value in range from 0.0 to 100.0


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# File 'lib/online_migrations/background_migrations/migration.rb', line 114

def progress
  if succeeded?
    100.0
  elsif composite?
    rows_counts = children.to_a.pluck(:rows_count)
    if rows_counts.none?(nil)
      total_rows_count = rows_counts.sum

      progresses = children.map do |child|
        child.progress * child.rows_count / total_rows_count # weighted progress
      end

      progresses.sum.round(2)
    end
  elsif rows_count
    jobs_rows_count = migration_jobs.succeeded.sum(:batch_size)
    # The last migration job may need to process the amount of rows
    # less than the batch size, so we can get a value > 1.0.
    ([jobs_rows_count.to_f / rows_count, 1.0].min * 100).round(2)
  end
end

#retry_failed_jobs ⇒ Object

Manually retry failed jobs.

This method marks failed jobs as ready to be processed again, and they will be picked up on the next Scheduler run.



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# File 'lib/online_migrations/background_migrations/migration.rb', line 172

def retry_failed_jobs
  iterator = BatchIterator.new(migration_jobs.failed)
  iterator.each_batch(of: 100) do |batch|
    transaction do
      batch.each(&:retry)
      enqueued!
    end
  end
end

#running! ⇒ Object

Overwrite enum's generated method to correctly work for composite migrations.



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# File 'lib/online_migrations/background_migrations/migration.rb', line 91

def running!
  return super if !composite?

  transaction do
    super
    children.each { |child| child.running! if child.paused? }
  end
end