eagle-core/eagle-query/eagle-query-base/src/main/java/org/apache/eagle/query/aggregate/Aggregator.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.eagle.query.aggregate;

import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.eagle.log.base.taggedlog.TaggedLogAPIEntity;

public class Aggregator {
    private static final Logger LOG = LoggerFactory.getLogger(Aggregator.class);
    public static final String GROUPBY_ROOT_FIELD_NAME = "site";
    public static final String GROUPBY_ROOT_FIELD_VALUE = "xyz";
    public static final String UNASSIGNED_GROUPBY_ROOT_FIELD_NAME = "unassigned";

    private final AggregateAPIEntityFactory factory;
    private final AggregateAPIEntity root;
    private final List<String> groupbys;
    private final List<String> sumFunctionFields;
    private final boolean counting;

    public Aggregator(AggregateAPIEntityFactory factory, AggregateAPIEntity root, List<String> groupbys, boolean counting, List<String> sumFunctionFields) {
        this.factory = factory;
        this.root = root;
        this.groupbys = groupbys;
        this.sumFunctionFields = sumFunctionFields;
        this.counting = counting;
    }

    /**
     * this locate result can be cached? we don't need check if it's TaggedLogAPIEntity each time when iterating entities
     * @param groupby
     * @param obj
     * @return
     * @throws Exception
     */
    private String locateGroupbyField(String groupby, TaggedLogAPIEntity obj) {
        if (groupby.equals(GROUPBY_ROOT_FIELD_NAME)) {
            return GROUPBY_ROOT_FIELD_VALUE;
        }
        // check tag first
        String tagv = obj.getTags().get(groupby);
        if (tagv != null) {
            return tagv;
        }
        // check against pojo, or qualifierValues
        String fn = groupby.substring(0,1).toUpperCase() + groupby.substring(1, groupby.length());
        try {
            Method getM = obj.getClass().getMethod("get" + fn);
            Object value = getM.invoke(obj);
            return (String)value;
        } catch (Exception ex) {
            LOG.warn(groupby + " field is in neither tags nor fields, " + ex.getMessage());
            return null;
        }
    }

    /**
     * accumulate a list of entities
     * @param entities
     * @throws Exception
     */
    public void accumulateAll(List<TaggedLogAPIEntity> entities) throws Exception {
        for (TaggedLogAPIEntity entity : entities) {
            accumulate(entity);
        }
    }

    /**
     * currently only group by tags
     * groupbys' first item always is site, which is a reserved field
     */
    public void accumulate(TaggedLogAPIEntity entity) throws Exception {
        AggregateAPIEntity current = root;
        for (String groupby : groupbys) {
            // TODO tagv is empty, so what to do? use a reserved field_name "unassigned" ?
            // TODO we should support all Pojo with java bean style object
            String tagv = locateGroupbyField(groupby, entity);
            if (tagv == null || tagv.isEmpty()) {
                tagv = UNASSIGNED_GROUPBY_ROOT_FIELD_NAME;
            }
            Map<String, AggregateAPIEntity> children = current.getEntityList();
            if (children.get(tagv) == null) {
                children.put(tagv, factory.create());
                current.setNumDirectDescendants(current.getNumDirectDescendants() + 1);
            }
            AggregateAPIEntity child = children.get(tagv);
            // go through all aggregate functions including count, summary etc.
            if (counting) {
                count(child);
            }
            for (String sumFunctionField : sumFunctionFields) {
                sum(child, entity, sumFunctionField);
            }

            current = child;
        }

    }


    /**
     * use java bean specifications?
     * reflection is not efficient, let us find out solutions
     */
    private void sum(Object targetObj, TaggedLogAPIEntity srcObj, String fieldName) throws Exception {
        try {
            String fn = fieldName.substring(0,1).toUpperCase() + fieldName.substring(1, fieldName.length());
            Method srcGetMethod = srcObj.getClass().getMethod("get" + fn);
            Object srcValue = srcGetMethod.invoke(srcObj);
            if (srcValue == null) {
                return;  // silently don't count this source object
            }
            Method targetGetMethod = targetObj.getClass().getMethod("get" + fn);
            Object targetValue = targetGetMethod.invoke(targetObj);
            if (targetValue instanceof Long) {
                Method setM = targetObj.getClass().getMethod("set" + fn, long.class);
                Long tmp1 = (Long)targetValue;
                // TODO, now source object always have type "java.lang.String", later on we should support various type including integer type
                Long tmp2 = null;
                if (srcValue instanceof String) {
                    tmp2 = Long.valueOf((String)srcValue);
                } else if (srcValue instanceof Long) {
                    tmp2 = (Long)srcValue;
                } else {
                    throw new IllegalAggregateFieldTypeException(srcValue.getClass().toString() + " type is not support. The source type must be Long or String");
                }
                setM.invoke(targetObj, tmp1.longValue() + tmp2.longValue());
            } else if (targetValue instanceof Double) {
                Method setM = targetObj.getClass().getMethod("set" + fn, double.class);
                Double tmp1 = (Double)targetValue;
                String src = (String) srcValue;
                Double tmp2 = Double.valueOf(src);
                setM.invoke(targetObj, tmp1.doubleValue() + tmp2.doubleValue());
            } else {
                throw new IllegalAggregateFieldTypeException(targetValue.getClass().toString() + " type is not support. The target type must be long or double");
            }
        } catch (Exception ex) {
            LOG.error("Cannot do sum aggregation for field " + fieldName, ex);
            throw ex;
        }
    }

    /**
     * count possible not only count for number of descendants but also count for not-null fields
     * @param targetObj
     * @throws Exception
     */
    private void count(AggregateAPIEntity targetObj) throws Exception {
        targetObj.setNumTotalDescendants(targetObj.getNumTotalDescendants() + 1);
    }
}