com.cloudera.nav.plugin.client.writer.MetadataWriterFactory.java Source code

Introduction

Here is the source code for com.cloudera.nav.plugin.client.writer.MetadataWriterFactory.java

Source

/*
 * Copyright (c) 2015 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.nav.plugin.client.writer;

import com.cloudera.nav.plugin.client.PluginConfigurations;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Throwables;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URL;

import org.apache.commons.net.util.Base64;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

/**
 * A factory that returns the appropriate MetadataWriter given a set of
 * configurations
 */
public class MetadataWriterFactory {

    public static final String HDFS = "hdfs";
    public static final String LOCAL = "file";
    public static final String HTTP = "http";

    /**
     * Return lower cased metadata parent uri scheme. If null then empty
     * string is returned (for easier string comparisons).
     *
     * @param config
     * @return
     */
    @VisibleForTesting
    static String getScheme(PluginConfigurations config) {
        URI uri = config.getMetadataParentUri();
        String scheme = uri.getScheme();
        return scheme == null ? "" : scheme.toLowerCase();
    }

    /**
     * Create a new metadata writer based on the given configurations.
     * The configurations should determine the file format and the underlying
     * storage mechanism.
     *
     * @param config
     * @return
     */
    public MetadataWriter newWriter(PluginConfigurations config) {
        String scheme = getScheme(config);
        if (scheme.equals(HDFS)) {
            throw new UnsupportedOperationException();
        } else if (scheme.equals(LOCAL)) {
            throw new UnsupportedOperationException();
        } else {
            try {
                HttpURLConnection conn = createHttpStream(config);
                Writer dataWriter = null;
                dataWriter = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream()));
                return new HttpJsonMetadataWriter(config, dataWriter, conn);
            } catch (IOException e) {
                throw Throwables.propagate(e);
            }
        }
    }

    private HttpURLConnection createHttpStream(PluginConfigurations config) throws IOException {
        URL url = new URL(config.getMetadataParentUri().toASCIIString());
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        String userpass = config.getUsername() + ":" + config.getPassword();
        String basicAuth = "Basic " + new String(Base64.encodeBase64(userpass.getBytes()));
        conn.addRequestProperty("Authorization", basicAuth);
        conn.addRequestProperty("Content-Type", "application/json");
        conn.setDoOutput(true);
        config.setProperty("conn", conn);
        return conn;
    }

    private OutputStream createLocalFileStream(PluginConfigurations config) {
        String fileName = getFilePath(config.getMetadataParentUri().getPath());
        File file = new File(fileName);
        try {
            file.createNewFile();
        } catch (IOException e) {
            throw Throwables.propagate(e);
        }
        try {
            return new FileOutputStream(file);
        } catch (FileNotFoundException e) {
            throw Throwables.propagate(e);
        }
    }

    private OutputStream createHdfsStream(PluginConfigurations config) {
        try {
            FileSystem fs = FileSystem.get(config.getHadoopConfigurations());
            Path path = new Path(getFilePath(config.getMetadataParentUriString()));
            if (fs.exists(path)) {
                return fs.append(path);
            }
            // TODO block sizes, replication counts etc
            return fs.create(path);
        } catch (IOException e) {
            throw Throwables.propagate(e);
        }
    }

    private String getFilePath(String path) {
        // TODO file rotation
        if (!path.endsWith("/")) {
            path += "/";
        }
        return path + ".metadata";
    }

}