Java tutorial
/** * This file is part of Graylog. * * Graylog is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Graylog is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Graylog. If not, see <http://www.gnu.org/licenses/>. */ package org.graylog2.lookup; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Maps; import com.google.inject.assistedinject.Assisted; import org.graylog2.lookup.dto.CacheDto; import org.graylog2.lookup.dto.DataAdapterDto; import org.graylog2.lookup.dto.LookupTableDto; import javax.inject.Inject; import java.util.Collection; import java.util.Map; import java.util.Optional; /** * Loads and caches lookup table related DTOs to avoid hammering the database when loading all lookup tables for the * first time during server startup. */ public class DtoLoader { interface Factory { DtoLoader create(Collection<LookupTableDto> lookupTableDtos); } private final Map<String, CacheDto> caches; private final Map<String, DataAdapterDto> dataAdapters; @Inject DtoLoader(@Assisted Collection<LookupTableDto> lookupTableDtos, MongoLutCacheService cacheService, MongoLutDataAdapterService dataAdapterService) { final ImmutableSet.Builder<String> cacheIds = ImmutableSet.builder(); final ImmutableSet.Builder<String> adapterIds = ImmutableSet.builder(); lookupTableDtos.forEach(dto -> { cacheIds.add(dto.cacheId()); adapterIds.add(dto.dataAdapterId()); }); this.caches = Maps.uniqueIndex(cacheService.findByIds(cacheIds.build()), CacheDto::id); this.dataAdapters = Maps.uniqueIndex(dataAdapterService.findByIds(adapterIds.build()), DataAdapterDto::id); } Optional<CacheDto> getCacheDto(String id) { return Optional.ofNullable(caches.get(id)); } Optional<DataAdapterDto> getDataAdapterDto(String id) { return Optional.ofNullable(dataAdapters.get(id)); } }