org.apache.kylin.metadata.realization.RealizationRegistry Maven / Gradle / Ivy

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/*
 * 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.kylin.metadata.realization;

import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.kylin.common.KylinConfig;
import org.reflections.Reflections;
import org.reflections.scanners.SubTypesScanner;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/**
 * Created by Hongbin Ma(Binmahone) on 12/18/14.
 */
public class RealizationRegistry {

    private static final Logger logger = LoggerFactory.getLogger(RealizationRegistry.class);
    private static final ConcurrentHashMap CACHE = new ConcurrentHashMap();

    public static RealizationRegistry getInstance(KylinConfig config) {
        RealizationRegistry r = CACHE.get(config);
        if (r != null) {
            return r;
        }

        synchronized (RealizationRegistry.class) {
            r = CACHE.get(config);
            if (r != null) {
                return r;
            }
            try {
                r = new RealizationRegistry(config);
                CACHE.put(config, r);
                return r;
            } catch (IOException e) {
                throw new IllegalStateException("Failed to init CubeManager from " + config, e);
            }
        }
    }

    public static void clearCache() {
        CACHE.clear();
    }

    // ============================================================================

    private Map providers;
    private KylinConfig config;

    private RealizationRegistry(KylinConfig config) throws IOException {
        logger.info("Initializing RealizationRegistry with metadata url " + config);
        this.config = config;
        init();
    }

    private void init() {
        providers = Maps.newConcurrentMap();

        // use reflection to load providers
        final Set> realizationProviders = new Reflections("org.apache.kylin", new SubTypesScanner()).getSubTypesOf(IRealizationProvider.class);
        List es = Lists.newArrayList();
        for (Class cls : realizationProviders) {
            try {
                IRealizationProvider p = (IRealizationProvider) cls.getMethod("getInstance", KylinConfig.class).invoke(null, config);
                providers.put(p.getRealizationType(), p);

            } catch (Exception | NoClassDefFoundError e) {
                es.add(e);
            }

            if (es.size() > 0) {
                for (Throwable exceptionOrError : es) {
                    logger.error("Create new store instance failed ", exceptionOrError);
                }
                throw new IllegalArgumentException("Failed to find metadata store by url: " + config.getMetadataUrl());
            }
        }

        logger.info("RealizationRegistry is " + providers);
    }

    public Set getRealizationTypes() {
        return Collections.unmodifiableSet(providers.keySet());
    }

    public IRealization getRealization(RealizationType type, String name) {
        IRealizationProvider p = providers.get(type);
        if (p == null) {
            logger.warn("No provider for realization type " + type);
            return null;
        }

        try {
            return p.getRealization(name);
        } catch (Exception ex) {
            // exception is possible if e.g. cube metadata is wrong
            logger.warn("Failed to load realization " + type + ":" + name, ex);
            return null;
        }
    }

}