HintFactory.java

package com.midea.cloudSearch.druid.segment;

import java.util.ArrayList;
import java.util.List;

public class HintFactory {

    public static Hint getHintFromString(String hintAsString){
        if(hintAsString.startsWith("! USE_NESTED_LOOPS") || hintAsString.startsWith("! USE_NL")){
            return new Hint(HintType.USE_NESTED_LOOPS,null);
        }
        if(hintAsString.equals("! HASH_WITH_TERMS_FILTER"))
            return new Hint(HintType.HASH_WITH_TERMS_FILTER,null);
        if(hintAsString.startsWith("! JOIN_TABLES_LIMIT")){
            String[] numbers =  getParamsFromHint(hintAsString, "! JOIN_TABLES_LIMIT");
            //todo: check if numbers etc..
            List<Object> params = new ArrayList<>();
            for (String number : numbers){
                if(number.equals("null") || number.equals("infinity")){
                    params.add(null);
                }
                else {
                    params.add(Integer.parseInt(number));
                }
            }

            return new Hint(HintType.JOIN_LIMIT,params.toArray());
        }
        if(hintAsString.startsWith("! NL_MULTISEARCH_SIZE")) {
            String[] number = getParamsFromHint(hintAsString,"! NL_MULTISEARCH_SIZE");
            //todo: check if numbers etc..
            int multiSearchSize = Integer.parseInt(number[0]);
            return new Hint(HintType.NL_MULTISEARCH_SIZE,new Object[]{multiSearchSize});
        }
        if(hintAsString.startsWith("! USE_SCROLL")){
            String[] scrollParams = getParamsFromHint(hintAsString,"! USE_SCROLL");
            int docsPerShardFetch = 50;
            int timeout = 60000;
            if(scrollParams != null && scrollParams.length ==2) {
                docsPerShardFetch = Integer.parseInt(scrollParams[0]);
                timeout = Integer.parseInt(scrollParams[1]);
            }
            return new Hint(HintType.USE_SCROLL, new Object[]{docsPerShardFetch,timeout});
        }
        if(hintAsString.startsWith("! IGNORE_UNAVAILABLE")){
            return new Hint(HintType.IGNORE_UNAVAILABLE,null);
        }
        if(hintAsString.startsWith("! DOCS_WITH_AGGREGATION")) {
            String[] number = getParamsFromHint(hintAsString,"! DOCS_WITH_AGGREGATION");
            //todo: check if numbers etc..
            int docsWithAggregation = Integer.parseInt(number[0]);
            return new Hint(HintType.DOCS_WITH_AGGREGATION,new Object[]{docsWithAggregation});
        }

        return null;
    }


    private static String[] getParamsFromHint(String hint, String prefix) {
        if(!hint.contains("(")) return null;
        String onlyParams = hint.replace(prefix, "").replaceAll("\\s*\\(\\s*","").replaceAll("\\s*\\,\\s*", ",").replaceAll("\\s*\\)\\s*", "");
        return onlyParams.split(",");
    }


}