public Object getNextValue()

in empire-db/src/main/java/org/apache/empire/dbms/DBMSHandlerBase.java [139:209]
61 lines of code
8 McCabe index (conditional complexity)

        public Object getNextValue(String SeqName, long minValue, Connection conn)
        {
            DBMSHandler dbms = db.getDbms();
            // Create a Command
            PreparedStatement stmt = null;
            try
            {   // The select Statement
                DBCommand cmd = dbms.createCommand(db.isPreparedStatementsEnabled());
                DBCmdParam nameParam = cmd.addParam(SeqName);
                cmd.select(C_SEQVALUE);
                cmd.select(C_TIMESTAMP);
                cmd.where (C_SEQNAME.is(nameParam));
                String selectCmd = cmd.getSelect();
                // Get the next Value
                long seqValue = 0;
                while (seqValue == 0)
                {
                    // stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
                    stmt = conn.prepareStatement(selectCmd, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
                    stmt.setString(1, SeqName);
                    // Query existing value
                    ResultSet rs = stmt.executeQuery();
                    if (rs.next())
                    { // Read the Sequence Value
                        seqValue = Math.max(rs.getLong(1) + 1, minValue);
                        java.sql.Timestamp current = rs.getTimestamp(2);
                        dbms.closeResultSet(rs);
                        // Update existing Record
                        cmd.clear();
                        DBCmdParam name = cmd.addParam(SeqName);
                        DBCmdParam time = cmd.addParam(current);
                        cmd.set(C_SEQVALUE.to(seqValue));
                        cmd.set(C_TIMESTAMP.to(DBDatabase.SYSDATE));
                        cmd.where(C_SEQNAME.is(name));
                        cmd.where(C_TIMESTAMP.is(time));
                        if (dbms.executeSQL(cmd.getUpdate(), cmd.getParamValues(), conn, null) < 1)
                            seqValue = 0; // Try again
                    } 
                    else
                    { // Close Reader
                        dbms.closeResultSet(rs);
                        // sequence does not exist
                        seqValue = minValue;
                        log.warn("Sequence {} does not exist! Creating sequence with start-value of {}", SeqName, seqValue);
                        // create a new sequence entry
                        cmd.clear();
                        cmd.set(C_SEQNAME.to(SeqName));
                        cmd.set(C_SEQVALUE.to(seqValue));
                        cmd.set(C_TIMESTAMP.to(DBDatabase.SYSDATE));
                        if (dbms.executeSQL(cmd.getInsert(), cmd.getParamValues(), conn, null) < 1)
                            seqValue = 0; // Try again
                    }
                    // check for concurrency problem
                    if (seqValue == 0)
                        log.warn("Failed to increment sequence {}. Trying again!", SeqName);
                    // close
                    closeStatement(stmt);
                    cmd.clear();
                    rs = null;
                }
                if (log.isInfoEnabled())
                    log.info("Sequence {} incremented to {}.", SeqName, seqValue);
                return new Long(seqValue);
            } catch (SQLException e) {
                // throw exception
                throw new EmpireSQLException(this, e);
            } finally
            { // Cleanup
                closeStatement(stmt);
            }
        }