question: public void withTransaction ( Closure closure ) throws SQLException { boolean savedCacheConnection = cacheConnection ; cacheConnection = true ; Connection connection = null ; boolean savedAutoCommit = true ; try { connection = createConnection ( ) ; savedAutoCommit = connection . getAutoCommit ( ) ; connection . setAutoCommit ( false ) ; callClosurePossiblyWithConnection ( closure , connection ) ; connection . commit ( ) ; } catch ( SQLException e ) { handleError ( connection , e ) ; throw e ; } catch ( RuntimeException e ) { handleError ( connection , e ) ; throw e ; } catch ( Error e ) { handleError ( connection , e ) ; throw e ; } catch ( Exception e ) { handleError ( connection , e ) ; throw new SQLException ( "Unexpected exception during transaction" , e ) ; } finally { if ( connection != null ) { try { connection . setAutoCommit ( savedAutoCommit ) ; } catch ( SQLException e ) { LOG . finest ( "Caught exception resetting auto commit: " + e . getMessage ( ) + " - continuing" ) ; } } cacheConnection = false ; closeResources ( connection , null ) ; cacheConnection = savedCacheConnection ; if ( dataSource != null && ! cacheConnection ) { useConnection = null ; } } }
target:  Performs the closure within a transaction using a cached connection. If the closure takes a single argument, it will be called with the connection, otherwise it will be called with no arguments.