com.github.dryangkun.hbase.tidx.hive.HBaseTableSnapshotInputFormatUtil.java Source code

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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 com.github.dryangkun.hbase.tidx.hive;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.mapreduce.TableSnapshotInputFormatImpl;
import org.apache.hadoop.mapred.InputSplit;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

/**
 * A helper class to isolate newer HBase features from users running against older versions of
 * HBase that don't provide those features.
 *
 * TODO: remove this class when it's okay to drop support for earlier version of HBase.
 */
public class HBaseTableSnapshotInputFormatUtil {

    private static final Log LOG = LogFactory.getLog(HBaseTableSnapshotInputFormatUtil.class);

    /** The class we look for to determine if hbase snapshots are supported. */
    private static final String TABLESNAPSHOTINPUTFORMAT_CLASS = "org.apache.hadoop.hbase.mapreduce.TableSnapshotInputFormatImpl";

    private static final String TABLESNAPSHOTREGIONSPLIT_CLASS = "org.apache.hadoop.hbase.mapred.TableSnapshotInputFormat$TableSnapshotRegionSplit";

    /** True when {@link #TABLESNAPSHOTINPUTFORMAT_CLASS} is present. */
    private static final boolean SUPPORTS_TABLE_SNAPSHOTS;

    static {
        boolean support = false;
        try {
            Class<?> clazz = Class.forName(TABLESNAPSHOTINPUTFORMAT_CLASS);
            support = clazz != null;
        } catch (ClassNotFoundException e) {
            // pass
        }
        SUPPORTS_TABLE_SNAPSHOTS = support;
    }

    /** Return true when the HBase runtime supports {@link HiveHBaseTableSnapshotInputFormat}. */
    public static void assertSupportsTableSnapshots() {
        if (!SUPPORTS_TABLE_SNAPSHOTS) {
            throw new RuntimeException("This version of HBase does not support Hive over table "
                    + "snapshots. Please upgrade to at least HBase 0.98.3 or later. See HIVE-6584 for details.");
        }
    }

    /**
     * Configures {@code conf} for the snapshot job. Call only when
     * {@link #assertSupportsTableSnapshots()} returns true.
     */
    public static void configureJob(Configuration conf, String snapshotName, Path restoreDir) throws IOException {
        TableSnapshotInputFormatImpl.setInput(conf, snapshotName, restoreDir);
    }

    /**
     * Create a bare TableSnapshotRegionSplit. Needed because Writables require a
     * default-constructed instance to hydrate from the DataInput.
     *
     * TODO: remove once HBASE-11555 is fixed.
     */
    public static InputSplit createTableSnapshotRegionSplit() {
        try {
            assertSupportsTableSnapshots();
        } catch (RuntimeException e) {
            LOG.debug("Probably don't support table snapshots. Returning null instance.", e);
            return null;
        }

        try {
            Class<? extends InputSplit> resultType = (Class<? extends InputSplit>) Class
                    .forName(TABLESNAPSHOTREGIONSPLIT_CLASS);
            Constructor<? extends InputSplit> cxtor = resultType.getDeclaredConstructor(new Class[] {});
            cxtor.setAccessible(true);
            return cxtor.newInstance(new Object[] {});
        } catch (ClassNotFoundException e) {
            throw new UnsupportedOperationException("Unable to find " + TABLESNAPSHOTREGIONSPLIT_CLASS, e);
        } catch (IllegalAccessException e) {
            throw new UnsupportedOperationException(
                    "Unable to access specified class " + TABLESNAPSHOTREGIONSPLIT_CLASS, e);
        } catch (InstantiationException e) {
            throw new UnsupportedOperationException(
                    "Unable to instantiate specified class " + TABLESNAPSHOTREGIONSPLIT_CLASS, e);
        } catch (InvocationTargetException e) {
            throw new UnsupportedOperationException(
                    "Constructor threw an exception for " + TABLESNAPSHOTREGIONSPLIT_CLASS, e);
        } catch (NoSuchMethodException e) {
            throw new UnsupportedOperationException(
                    "Unable to find suitable constructor for class " + TABLESNAPSHOTREGIONSPLIT_CLASS, e);
        }
    }
}