Class: Gitlab::Database::LockWritesManager

Inherits:
Object
  • Object
show all
Defined in:
lib/gitlab/database/lock_writes_manager.rb

Constant Summary collapse

TRIGGER_FUNCTION_NAME = 
'gitlab_schema_prevent_write'
EXPECTED_TRIGGER_RECORD_COUNT =

Triggers to block INSERT / UPDATE / DELETE Triggers on TRUNCATE are not added to the information_schema.triggers See www.postgresql.org/message-id/16934.1568989957%40sss.pgh.pa.us

3

Instance Method Summary collapse

Constructor Details

#initialize(table_name:, connection:, database_name:, with_retries: true, logger: nil, dry_run: false, force: true) ⇒ LockWritesManager

table_name can include schema name as a prefix. For example: ‘gitlab_partitions_static.events_03’, otherwise, it will default to current used schema, for example ‘public’.



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# File 'lib/gitlab/database/lock_writes_manager.rb', line 15

def initialize(
  table_name:, connection:, database_name:,
  with_retries: true, logger: nil, dry_run: false, force: true
)
  @table_name = table_name.to_s
  @connection = connection
  @database_name = database_name
  @logger = logger
  @dry_run = dry_run
  @force = force
  @with_retries = with_retries

  @table_name_without_schema = ActiveRecord::ConnectionAdapters::PostgreSQL::Utils
    .extract_schema_qualified_name(table_name.to_s)
    .identifier
end

Instance Method Details

#lock_writes ⇒ Object 



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# File 'lib/gitlab/database/lock_writes_manager.rb', line 42

def lock_writes
  unless force
    unless table_exist?
      logger&.info "Skipping lock_writes, because #{table_name} does not exist"
      return result_hash(action: 'skipped')
    end

    if table_locked_for_writes?
      logger&.info "Skipping lock_writes, because #{table_name} is already locked for writes"
      return result_hash(action: 'skipped')
    end
  end

  logger&.info Rainbow("Database: '#{database_name}', Table: '#{table_name}': Lock Writes").yellow
  sql_statement = <<~SQL
    CREATE OR REPLACE TRIGGER #{write_trigger_name}
      BEFORE INSERT OR UPDATE OR DELETE OR TRUNCATE
      ON #{table_name}
      FOR EACH STATEMENT EXECUTE FUNCTION #{TRIGGER_FUNCTION_NAME}();
  SQL

  result = process_query(sql_statement, 'lock')

  result_hash(action: result)
rescue ActiveRecord::StatementInvalid => e
  # Errors like Gitlab::Database::GitlabSchema::UnknownSchemaError, PG::UndefinedTable
  # are raised under this error
  logger&.warn "Failed lock_writes, because #{table_name} raised an error. Error: #{e}"
  result_hash(action: 'skipped')
end

#table_locked_for_writes? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/lock_writes_manager.rb', line 32

def table_locked_for_writes?
  query = <<~SQL
      SELECT COUNT(*) from information_schema.triggers
      WHERE event_object_table = '#{table_name_without_schema}'
      AND trigger_name = '#{write_trigger_name}'
  SQL

  connection.select_value(query) == EXPECTED_TRIGGER_RECORD_COUNT
end

#unlock_writes ⇒ Object 



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# File 'lib/gitlab/database/lock_writes_manager.rb', line 73

def unlock_writes
  if force || table_locked_for_writes?
    logger&.info Rainbow("Database: '#{database_name}', Table: '#{table_name}': Allow Writes").green
    sql_statement = <<~SQL
      DROP TRIGGER IF EXISTS #{write_trigger_name} ON #{table_name};
    SQL

    result = process_query(sql_statement, 'unlock')

    result_hash(action: result)
  else
    logger&.info "Skipping unlock_writes, because #{table_name} is already unlocked for writes"
    result_hash(action: 'skipped')
  end
end