question: public boolean doTransaction ( DB db , Object threadstate ) throws WorkloadException { boolean ret = true ; long st = System . nanoTime ( ) ; String op = operationchooser . nextString ( ) ; if ( op . compareTo ( "READ" ) == 0 ) { ret = doTransactionRead ( db ) ; } else if ( op . compareTo ( "UPDATE" ) == 0 ) { ret = doTransactionUpdate ( db ) ; } else if ( op . compareTo ( "INSERT" ) == 0 ) { ret = doTransactionInsert ( db ) ; } else if ( op . compareTo ( "SCAN" ) == 0 ) { ret = doTransactionScan ( db ) ; } else { ret = doTransactionReadModifyWrite ( db ) ; } long en = System . nanoTime ( ) ; _measurements . measure ( _operations . get ( op ) , ( int ) ( ( en - st ) / 1000 ) ) ; if ( ret ) _measurements . reportReturnCode ( _operations . get ( op ) , - 1 ) ; else { _measurements . reportReturnCode ( _operations . get ( op ) , 0 ) ; } return ret ; }
target:  Do one transaction operation. Because it will be called concurrently from multiple client threads, this  function must be thread safe. However, avoid synchronized, or the threads will block waiting for each  other, and it will be difficult to reach the target throughput. Ideally, this function would have no side effects other than DB operations.