MetastoreEventFactory.java

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package org.apache.doris.datasource.hive.event;

import org.apache.doris.catalog.Env;
import org.apache.doris.datasource.MetaIdMappingsLog;
import org.apache.doris.datasource.hive.HMSExternalCatalog;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.apache.hadoop.hive.metastore.api.NotificationEvent;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;

/**
 * Factory class to create various MetastoreEvents.
 */
public class MetastoreEventFactory implements EventFactory {
    private static final Logger LOG = LogManager.getLogger(MetastoreEventFactory.class);

    @Override
    public List<MetastoreEvent> transferNotificationEventToMetastoreEvents(NotificationEvent event,
                                                                           String catalogName) {
        Preconditions.checkNotNull(event.getEventType());
        MetastoreEventType metastoreEventType = MetastoreEventType.from(event.getEventType());
        if (LOG.isDebugEnabled()) {
            LOG.debug("catalogName = {}, Event = {}", catalogName, event.toString());
        }
        switch (metastoreEventType) {
            case CREATE_TABLE:
                return CreateTableEvent.getEvents(event, catalogName);
            case DROP_TABLE:
                return DropTableEvent.getEvents(event, catalogName);
            case ALTER_TABLE:
                return AlterTableEvent.getEvents(event, catalogName);
            case CREATE_DATABASE:
                return CreateDatabaseEvent.getEvents(event, catalogName);
            case DROP_DATABASE:
                return DropDatabaseEvent.getEvents(event, catalogName);
            case ALTER_DATABASE:
                return AlterDatabaseEvent.getEvents(event, catalogName);
            case ADD_PARTITION:
                return AddPartitionEvent.getEvents(event, catalogName);
            case DROP_PARTITION:
                return DropPartitionEvent.getEvents(event, catalogName);
            case ALTER_PARTITION:
                return AlterPartitionEvent.getEvents(event, catalogName);
            case INSERT:
                return InsertEvent.getEvents(event, catalogName);
            default:
                // ignore all the unknown events by creating a IgnoredEvent
                return IgnoredEvent.getEvents(event, catalogName);
        }
    }

    List<MetastoreEvent> getMetastoreEvents(List<NotificationEvent> events, HMSExternalCatalog hmsExternalCatalog) {
        List<MetastoreEvent> metastoreEvents = Lists.newArrayList();
        String catalogName = hmsExternalCatalog.getName();
        for (NotificationEvent event : events) {
            metastoreEvents.addAll(transferNotificationEventToMetastoreEvents(event, catalogName));
        }
        List<MetastoreEvent> mergedEvents = mergeEvents(catalogName, metastoreEvents);
        if (Env.getCurrentEnv().isMaster()) {
            logMetaIdMappings(hmsExternalCatalog.getId(), events.get(events.size() - 1).getEventId(), mergedEvents);
        }
        return mergedEvents;
    }

    private void logMetaIdMappings(long catalogId, long lastSyncedEventId, List<MetastoreEvent> mergedEvents) {
        MetaIdMappingsLog log = new MetaIdMappingsLog();
        log.setCatalogId(catalogId);
        log.setFromHmsEvent(true);
        log.setLastSyncedEventId(lastSyncedEventId);
        for (MetastoreEvent event : mergedEvents) {
            log.addMetaIdMappings(event.transferToMetaIdMappings());
        }
        Env.getCurrentEnv().getExternalMetaIdMgr().replayMetaIdMappingsLog(log);
        Env.getCurrentEnv().getEditLog().logMetaIdMappingsLog(log);
    }

    /**
     * Merge events to reduce the cost time on event processing, currently mainly handles MetastoreTableEvent
     * because merge MetastoreTableEvent is simple and cost-effective.
     * For example, consider there are some events as following:
     * <pre>
     *    event1: alter table db1.t1 add partition p1;
     *    event2: alter table db1.t1 drop partition p2;
     *    event3: alter table db1.t2 add partition p3;
     *    event4: alter table db2.t3 rename to t4;
     *    event5: drop table db1.t1;
     * </pre>
     * Only `event3 event4 event5` will be reserved and other events will be skipped.
     * */
    public List<MetastoreEvent> mergeEvents(String catalogName, List<MetastoreEvent> events) {
        List<MetastoreEvent> eventsCopy = Lists.newArrayList(events);
        Map<MetastoreTableEvent.TableKey, List<Integer>> indexMap = Maps.newLinkedHashMap();
        for (int i = 0; i < events.size(); i++) {
            MetastoreEvent event = events.get(i);

            // if the event is a rename db event, just clear indexMap
            // to make sure the table references of these events in indexMap will not change
            if (event instanceof AlterDatabaseEvent && ((AlterDatabaseEvent) event).isRename()) {
                indexMap.clear();
                continue;
            }

            // Only check MetastoreTableEvent
            if (!(event instanceof MetastoreTableEvent)) {
                continue;
            }

            // Divide events into multi groups to reduce check count
            MetastoreTableEvent.TableKey groupKey = ((MetastoreTableEvent) event).getTableKey();
            if (!indexMap.containsKey(groupKey)) {
                List<Integer> indexList = Lists.newLinkedList();
                indexList.add(i);
                indexMap.put(groupKey, indexList);
                continue;
            }

            List<Integer> indexList = indexMap.get(groupKey);
            for (int j = 0; j < indexList.size(); j++) {
                int candidateIndex = indexList.get(j);
                if (candidateIndex == -1) {
                    continue;
                }
                if (event.canBeBatched(events.get(candidateIndex))) {
                    eventsCopy.set(candidateIndex, null);
                    indexList.set(j, -1);
                }
            }
            indexList = indexList.stream().filter(index -> index != -1)
                        .collect(Collectors.toList());
            indexList.add(i);
            indexMap.put(groupKey, indexList);
        }

        List<MetastoreEvent> filteredEvents = eventsCopy.stream().filter(Objects::nonNull)
                    .collect(Collectors.toList());
        LOG.info("Event size on catalog [{}] before merge is [{}], after merge is [{}]",
                    catalogName, events.size(), filteredEvents.size());
        return ImmutableList.copyOf(filteredEvents);
    }
}