Class: OnlineMigrations::BackgroundSchemaMigrations::Migration

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

Overview

Note:

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

Class representing background schema migration.

Constant Summary collapse

STATUSES = 
[
  :enqueued,    # The migration has been enqueued by the user.
  :running,     # The migration is being performed by a migration executor.
  :errored,     # The migration raised an error during last run.
  :failed,      # The migration raises an error when running and retry attempts exceeded.
  :succeeded,   # The migration finished without error.
  :cancelled,   # The migration was cancelled by the user.
]
MAX_IDENTIFIER_LENGTH = 
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Instance Method Summary collapse

Instance Method Details

#can_be_cancelled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 98

def can_be_cancelled?
  !succeeded? && !cancelled?
end

#can_be_paused? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 94

def can_be_paused?
  false
end

#cancelled! ⇒ Object Also known as: cancel

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



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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 80

def cancelled!
  return super if !composite?

  transaction do
    super
    children.each { |child| child.cancelled! if !child.succeeded? }
  end
end

#completed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 75

def completed?
  succeeded? || failed?
end

#index_addition? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 167

def index_addition?
  definition.match?(/create (unique )?index/i)
end

#pausable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 90

def pausable?
  false
end

#progress ⇒ Float

Returns the progress of the background schema migration.

Returns:

  • (Float) —

    value in range from 0.0 to 100.0



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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 106

def progress
  if succeeded?
    100.0
  elsif composite?
    progresses = children.map(&:progress)
    # There should not be composite migrations without children,
    # but children may be deleted for some reason, so we need to
    # make a check to avoid 0 division error.
    if progresses.any?
      (progresses.sum.to_f / progresses.size).round(2)
    else
      0.0
    end
  else
    0.0
  end
end

#retry ⇒ Object

Mark this migration as ready to be processed again.

This is used to manually retrying failed migrations.



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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 138

def retry
  if composite? && failed?
    transaction do
      update!(status: :enqueued, finished_at: nil)
      children.failed.each(&:retry)
    end

    true
  elsif failed?
    transaction do
      parent.update!(status: :enqueued, finished_at: nil) if parent

      update!(
        status: :enqueued,
        attempts: 0,
        started_at: nil,
        finished_at: nil,
        error_class: nil,
        error_message: nil,
        backtrace: nil
      )
    end

    true
  else
    false
  end
end

#stuck? ⇒ Boolean

Whether the migration is considered stuck (is running for some configured time).

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 126

def stuck?
  # Composite migrations are not considered stuck.
  return false if composite?

  stuck_timeout = (statement_timeout || 1.day) + 10.minutes
  running? && updated_at <= stuck_timeout.seconds.ago
end