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) ⇒ 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)
  @table_name = table_name
  @connection = connection
  @database_name = database_name
  @logger = logger
  @dry_run = dry_run
  @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 38

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

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

  execute_sql_statement(sql_statement)

  result_hash(action: dry_run ? 'needs_lock' : 'locked')
end

#table_locked_for_writes? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/lock_writes_manager.rb', line 28

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 57

def unlock_writes
  unless table_locked_for_writes?
    logger&.info "Skipping unlock_writes, because #{table_name} is already unlocked for writes"
    return result_hash(action: 'skipped')
  end

  logger&.info "Database: '#{database_name}', Table: '#{table_name}': Allow Writes".color(:green)
  sql_statement = <<~SQL
    DROP TRIGGER IF EXISTS #{write_trigger_name} ON #{table_name};
  SQL

  execute_sql_statement(sql_statement)

  result_hash(action: dry_run ? 'needs_unlock' : 'unlocked')
end