org.apache.lens.server.api.util.LensUtil.java Source code

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Here is the source code for org.apache.lens.server.api.util.LensUtil.java

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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.lens.server.api.util;

import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.util.HashMap;
import java.util.Set;

import org.apache.lens.server.api.common.ConfigBasedObjectCreationFactory;

import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;

import lombok.NonNull;

/**
 * Utility methods for Lens
 */
public final class LensUtil {

    private LensUtil() {

    }

    /**
     * Get the message corresponding to base cause. If no cause is available or no message is available
     *  parent's message is returned.
     *
     * @param e
     * @return message
     */
    public static String getCauseMessage(@NonNull Throwable e) {
        String expMsg = null;
        if (e.getCause() != null) {
            expMsg = getCauseMessage(e.getCause());
        }
        if (StringUtils.isBlank(expMsg)) {
            expMsg = e.getLocalizedMessage();
        }
        return expMsg;
    }

    public static Throwable getCause(@NonNull Throwable e) {
        if (e.getCause() != null) {
            return getCause(e.getCause());
        }
        return e;
    }

    public static boolean isSocketException(@NonNull Throwable e) {
        Throwable cause = getCause(e);
        return cause instanceof SocketException || cause instanceof SocketTimeoutException;
    }

    public static <T> Set<T> getImplementationsMutable(final String factoriesKey, final Configuration conf) {
        Set<T> implSet = Sets.newLinkedHashSet();
        final String[] factoryNames = conf.getStrings(factoriesKey);
        if (factoryNames != null) {
            for (String factoryName : factoryNames) {
                if (StringUtils.isNotBlank(factoryName)) {
                    final T implementation = getImplementation(factoryName.trim(), conf);
                    implSet.add(implementation);
                }
            }
        }
        return implSet;
    }

    public static <T> ImmutableSet<T> getImplementations(final String factoriesKey, final Configuration conf) {
        Set<T> implSet = getImplementationsMutable(factoriesKey, conf);
        return ImmutableSet.copyOf(implSet);
    }

    public static <T> T getImplementation(final String factoryName, final Configuration conf) {

        try {
            ConfigBasedObjectCreationFactory<T> factory = (ConfigBasedObjectCreationFactory<T>) Class
                    .forName(factoryName).newInstance();
            T ret = factory.create(conf);
            if (ret instanceof Configurable) {
                ((Configurable) ret).setConf(conf);
            }
            return ret;
        } catch (final ReflectiveOperationException e) {
            throw new IllegalStateException(e);
        }
    }

    public static <K, V> HashMap<K, V> getHashMap(Object... args) {
        assert (args.length % 2 == 0);
        HashMap<K, V> map = new HashMap<>();
        for (int i = 0; i < args.length; i += 2) {
            map.put((K) args[i], (V) args[i + 1]);
        }
        return map;
    }
}