private JdbcResponse executeQuery()

in modules/core/src/main/java/org/apache/ignite/internal/processors/odbc/jdbc/JdbcRequestHandler.java [584:798]
150 lines of code
32 McCabe index (conditional complexity)

    private JdbcResponse executeQuery(JdbcQueryExecuteRequest req) {
        GridQueryCancel cancel = null;

        boolean unregisterReq = false;

        if (isCancellationSupported()) {
            synchronized (reqMux) {
                JdbcQueryDescriptor desc = reqRegister.get(req.requestId());

                // Query was already cancelled and unregistered.
                if (desc == null)
                    return null;

                cancel = desc.cancelHook();

                desc.incrementUsageCount();
            }
        }

        try {
            int cursorCnt = jdbcCursors.size();

            if (maxCursors > 0 && cursorCnt >= maxCursors)
                return new JdbcResponse(IgniteQueryErrorCode.UNKNOWN, "Too many open cursors (either close other " +
                    "open cursors or increase the limit through " +
                    "ClientConnectorConfiguration.maxOpenCursorsPerConnection) [maximum=" + maxCursors +
                    ", current=" + cursorCnt + ']');

            assert !cliCtx.isStream();

            String sql = req.sqlQuery();

            SqlFieldsQueryEx qry;

            switch (req.expectedStatementType()) {
                case ANY_STATEMENT_TYPE:
                    qry = new SqlFieldsQueryEx(sql, null);

                    break;

                case SELECT_STATEMENT_TYPE:
                    qry = new SqlFieldsQueryEx(sql, true);

                    break;

                default:
                    assert req.expectedStatementType() == JdbcStatementType.UPDATE_STMT_TYPE;

                    qry = new SqlFieldsQueryEx(sql, false);

                    if (cliCtx.isSkipReducerOnUpdate())
                        ((SqlFieldsQueryEx)qry).setSkipReducerOnUpdate(true);
            }

            setupQuery(qry, prepareSchemaName(req.schemaName()));

            qry.setArgs(req.arguments());
            qry.setAutoCommit(req.autoCommit());

            if (req.explicitTimeout()) {
                // Timeout is handled on a client side, do not handle it on a server side.
                qry.setTimeout(0, TimeUnit.MILLISECONDS);
            }

            if (req.pageSize() <= 0)
                return new JdbcResponse(IgniteQueryErrorCode.UNKNOWN, "Invalid fetch size: " + req.pageSize());

            qry.setPageSize(req.pageSize());

            String schemaName = req.schemaName();

            if (F.isEmpty(schemaName))
                schemaName = QueryUtils.DFLT_SCHEMA;

            qry.setSchema(schemaName);

            int txId = txId(req.txId());

            List<FieldsQueryCursor<List<?>>> results = txEnabledForConnection()
                ? invokeInTransaction(txId, req.autoCommit(), qry, cancel)
                : querySqlFields(qry, cancel);

            FieldsQueryCursor<List<?>> fieldsCur = results.get(0);

            if (fieldsCur instanceof BulkLoadContextCursor) {
                BulkLoadContextCursor blCur = (BulkLoadContextCursor)fieldsCur;

                BulkLoadProcessor blProc = blCur.bulkLoadProcessor();
                BulkLoadAckClientParameters clientParams = blCur.clientParams();

                JdbcBulkLoadProcessor proc = new JdbcBulkLoadProcessor(blProc, req.requestId());

                jdbcCursors.put(proc.cursorId(), proc);

                // responses for the same query on the client side
                return resultToResonse(new JdbcBulkLoadAckResult(proc.cursorId(), clientParams));
            }

            if (results.size() == 1) {
                JdbcQueryCursor cur = new JdbcQueryCursor(req.pageSize(), req.maxRows(),
                    (QueryCursorEx<List<?>>)fieldsCur, req.requestId());

                jdbcCursors.put(cur.cursorId(), cur);

                cur.openIterator();

                JdbcQueryExecuteResult res;

                PartitionResult partRes = null;

                if (fieldsCur instanceof QueryCursorImpl)
                    partRes = ((QueryCursorImpl<List<?>>)fieldsCur).partitionResult();

                if (cur.isQuery()) {
                    res = new JdbcQueryExecuteResult(
                        cur.cursorId(),
                        cur.fetchRows(),
                        !cur.hasNext(),
                        isClientPartitionAwarenessApplicable(req.partitionResponseRequest(), partRes) ? partRes : null,
                        txId
                    );
                }
                else {
                    List<List<Object>> items = cur.fetchRows();

                    assert items != null && items.size() == 1 && items.get(0).size() == 1
                        && items.get(0).get(0) instanceof Long :
                        "Invalid result set for not-SELECT query. [qry=" + sql +
                            ", res=" + S.toString(List.class, items) + ']';

                    res = new JdbcQueryExecuteResult(
                        cur.cursorId(),
                        (Long)items.get(0).get(0),
                        isClientPartitionAwarenessApplicable(req.partitionResponseRequest(), partRes) ? partRes : null,
                        txId
                    );
                }

                if (res.last() && (!res.isQuery() || autoCloseCursors)) {
                    jdbcCursors.remove(cur.cursorId());

                    unregisterReq = true;

                    cur.close();
                }

                return resultToResonse(res);
            }
            else {
                List<JdbcResultInfo> jdbcResults = new ArrayList<>(results.size());
                List<List<Object>> items = null;
                boolean last = true;

                for (FieldsQueryCursor<List<?>> c : results) {
                    QueryCursorEx<List<?>> qryCur = (QueryCursorEx<List<?>>)c;

                    JdbcResultInfo jdbcRes;

                    if (qryCur.isQuery()) {
                        JdbcQueryCursor cur = new JdbcQueryCursor(req.pageSize(), req.maxRows(), qryCur, req.requestId());

                        jdbcCursors.put(cur.cursorId(), cur);

                        jdbcRes = new JdbcResultInfo(true, -1, cur.cursorId());

                        cur.openIterator();

                        if (items == null) {
                            items = cur.fetchRows();
                            last = cur.hasNext();
                        }
                    }
                    else
                        jdbcRes = new JdbcResultInfo(false, (Long)((List<?>)qryCur.getAll().get(0)).get(0), -1);

                    jdbcResults.add(jdbcRes);
                }

                return resultToResonse(new JdbcQueryExecuteMultipleStatementsResult(jdbcResults, items, last, txId));
            }
        }
        catch (Exception e) {
            // Trying to close all cursors of current request.
            clearCursors(req.requestId());

            unregisterReq = true;

            if (X.cause(e, QueryCancelledException.class) != null) {
                if (log.isDebugEnabled()) {
                    log.debug("Failed to execute SQL query " +
                        "[reqId=" + req.requestId() +
                        ", req=" + req +
                        "]. Error:" + X.getFullStackTrace(e));
                }

                return exceptionToResult(new QueryCancelledException());
            }
            else if (X.cause(e, IgniteSQLException.class) != null) {
                IgniteSQLException e0 = X.cause(e, IgniteSQLException.class);

                if (isNeedToNodeLog(e0))
                    U.warn(log, "Failed to execute SQL query [reqId=" + req.requestId() + ", req=" + req + ']', e);

                return exceptionToResult(e0);
            }
            else {
                U.warn(log, "Failed to execute SQL query [reqId=" + req.requestId() + ", req=" + req + ']', e);

                return exceptionToResult(e);
            }
        }
        finally {
            cleanupQueryCancellationMeta(unregisterReq, req.requestId());
        }
    }