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.
  :failed,      # The migration raises an exception when running.
  :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

#attempts_exceeded? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 171

def attempts_exceeded?
  attempts >= max_attempts
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 87

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 82

def completed?
  succeeded? || failed?
end

#connection_class ⇒ Object 



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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 162

def connection_class
  if connection_class_name && (klass = connection_class_name.safe_constantize)
    Utils.find_connection_class(klass)
  else
    ActiveRecord::Base
  end
end

#index_addition? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 157

def index_addition?
  definition.match?(/create (unique )?index/i)
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 101

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 133

def retry
  if composite? && failed?
    children.failed.each(&:retry)
    update!(
      status: self.class.statuses[:enqueued],
      finished_at: nil
    )
    true
  elsif failed?
    update!(
      status: self.class.statuses[:enqueued],
      attempts: 0,
      started_at: nil,
      finished_at: nil,
      error_class: nil,
      error_message: nil,
      backtrace: nil
    )
    true
  else
    false
  end
end

#run ⇒ Object 



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# File 'lib/online_migrations/background_schema_migrations/migration.rb', line 176

def run
  on_shard do
    connection = connection_class.connection

    connection.with_lock_retries do
      statement_timeout = self.statement_timeout || OnlineMigrations.config.statement_timeout

      with_statement_timeout(connection, statement_timeout) do
        if index_addition?
          index = connection.indexes(table_name).find { |i| i.name == name }
          if index
            # Use index validity from https://github.com/rails/rails/pull/45160
            # when switching to ActiveRecord >= 7.1.
            schema = connection.send(:__schema_for_table, table_name)
            if connection.send(:__index_valid?, name, schema: schema)
              return
            else
              connection.remove_index(table_name, name: name, algorithm: :concurrently)
            end
          end
        end

        connection.execute(definition)
      end
    end
  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 121

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