com.cloudera.cdk.data.hcatalog.HCatalogExternalMetadataProvider.java Source code

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Here is the source code for com.cloudera.cdk.data.hcatalog.HCatalogExternalMetadataProvider.java

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/**
 * Copyright 2013 Cloudera Inc.
 *
 * Licensed 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.cloudera.cdk.data.hcatalog;

import com.cloudera.cdk.data.DatasetDescriptor;
import com.cloudera.cdk.data.DatasetExistsException;
import com.cloudera.cdk.data.MetadataProviderException;
import com.cloudera.cdk.data.filesystem.impl.Accessor;
import com.google.common.base.Preconditions;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.metastore.TableType;
import org.apache.hadoop.hive.ql.metadata.Table;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class HCatalogExternalMetadataProvider extends HCatalogMetadataProvider {

    private static final Logger logger = LoggerFactory.getLogger(HCatalogExternalMetadataProvider.class);
    private final Path rootDirectory;
    private final FileSystem rootFileSystem;

    public HCatalogExternalMetadataProvider(Configuration conf, Path rootDirectory) {
        super(conf);
        Preconditions.checkArgument(rootDirectory != null, "Root cannot be null");

        try {
            this.rootFileSystem = rootDirectory.getFileSystem(conf);
            this.rootDirectory = rootFileSystem.makeQualified(rootDirectory);
        } catch (IOException ex) {
            throw new MetadataProviderException("Could not get FileSystem for root path", ex);
        }
    }

    @Override
    public DatasetDescriptor load(String name) {
        Preconditions.checkArgument(name != null, "Name cannot be null");

        final Table table = hcat.getTable(HiveUtils.DEFAULT_DB, name);

        if (!TableType.EXTERNAL_TABLE.equals(table.getTableType())) {
            throw new MetadataProviderException("Table is not external, type:" + table.getTableType());
        }

        return HiveUtils.descriptorForTable(conf, table);
    }

    @Override
    public DatasetDescriptor create(String name, DatasetDescriptor descriptor) {
        Preconditions.checkArgument(name != null, "Name cannot be null");
        Preconditions.checkArgument(descriptor != null, "Descriptor cannot be null");

        if (exists(name)) {
            throw new DatasetExistsException("Metadata already exists for dataset:" + name);
        }

        logger.info("Creating an external Hive table named: " + name);

        // create a new descriptor with the dataset's location
        final DatasetDescriptor newDescriptor = new DatasetDescriptor.Builder(descriptor)
                .location(pathForDataset(name)).build();

        // create the data directory first so it is owned by the current user, not Hive
        Accessor.getDefault().ensureExists(newDescriptor, conf);

        // this object will be the table metadata
        final Table table = HiveUtils.tableForDescriptor(name, newDescriptor, true /* external table */ );

        // assign the location of the the table
        hcat.createTable(table);

        return newDescriptor;
    }

    private Path pathForDataset(String name) {
        Preconditions.checkState(rootDirectory != null, "Dataset repository root directory can not be null");

        return rootFileSystem.makeQualified(HiveUtils.pathForDataset(rootDirectory, name));
    }
}