LimitUtils.java

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package org.apache.doris.qe;

import org.apache.doris.common.Status;
import org.apache.doris.thrift.TStatusCode;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.function.Consumer;

/**
 * This is a utility class for limit related operations.
 * Because current there are 2 places need to check limit rows, so put the logic here for unification.
 *  - Coordinator.getNext();
 *  - QueryProcessor.getNext();
 */
public class LimitUtils {
    private static final Logger LOG = LogManager.getLogger(LimitUtils.class);
    private static final Status LIMIT_REACH_STATUS = new Status(TStatusCode.LIMIT_REACH, "query reach limit");

    // if reached limit rows, cancel this query immediately
    // to avoid BE from reading more data.
    public static boolean cancelIfReachLimit(RowBatch resultBatch, long limitRows, long numReceivedRows,
            Consumer<Status> cancelFunc) {
        boolean reachedLimit = false;
        if (limitRows > 0 && numReceivedRows >= limitRows) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("reach limit rows: {}, received rows: {}, cancel query", limitRows, numReceivedRows);
            }
            cancelFunc.accept(LIMIT_REACH_STATUS);
            // set this
            resultBatch.setEos(true);
            reachedLimit = true;
        }
        return reachedLimit;
    }
}