io.questdb.griffin.engine.functions.rnd.RndIntCCFunctionFactory Maven / Gradle / Ivy

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 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
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 *  http://www.apache.org/licenses/LICENSE-2.0
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 *  distributed under the License is distributed on an "AS IS" BASIS,
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package io.questdb.griffin.engine.functions.rnd;

import io.questdb.cairo.CairoConfiguration;
import io.questdb.cairo.sql.Function;
import io.questdb.cairo.sql.Record;
import io.questdb.cairo.sql.SymbolTableSource;
import io.questdb.griffin.FunctionFactory;
import io.questdb.griffin.SqlException;
import io.questdb.griffin.SqlExecutionContext;
import io.questdb.griffin.engine.functions.IntFunction;
import io.questdb.std.Numbers;
import io.questdb.std.ObjList;
import io.questdb.std.Rnd;

public class RndIntCCFunctionFactory implements FunctionFactory {

    @Override
    public String getSignature() {
        return "rnd_int(iii)";
    }

    @Override
    public Function newInstance(ObjList args, int position, CairoConfiguration configuration, SqlExecutionContext sqlExecutionContext) throws SqlException {

        int lo = args.getQuick(0).getInt(null);
        int hi = args.getQuick(1).getInt(null);
        int nanRate = args.getQuick(2).getInt(null);

        if (nanRate < 0) {
            throw SqlException.$(args.getQuick(2).getPosition(), "invalid NaN rate");
        }

        if (lo < hi) {
            return new RndFunction(position, lo, hi, nanRate);
        }

        throw SqlException.position(position).put("invalid range");
    }

    private static class RndFunction extends IntFunction implements Function {
        private final int lo;
        private final int range;
        private final int nanRate;
        private Rnd rnd;

        public RndFunction(int position, int lo, int hi, int nanRate) {
            super(position);
            this.lo = lo;
            this.range = hi - lo + 1;
            this.nanRate = nanRate + 1;
        }

        @Override
        public int getInt(Record rec) {
            if ((rnd.nextInt() % nanRate) == 1) {
                return Numbers.INT_NaN;
            }
            return lo + rnd.nextPositiveInt() % range;
        }

        @Override
        public void init(SymbolTableSource symbolTableSource, SqlExecutionContext executionContext) {
            this.rnd = executionContext.getRandom();
        }
    }
}