MetaData.java

/**
 * Copyright 2013 Netflix, 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.netflix.priam.backup;

import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.json.simple.JSONArray;
import org.json.simple.parser.JSONParser;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.name.Named;
import com.netflix.priam.IConfiguration;
import com.netflix.priam.backup.AbstractBackupPath.BackupFileType;
import com.netflix.priam.backup.IMessageObserver.BACKUP_MESSAGE_TYPE;
import com.netflix.priam.utils.RetryableCallable;

/**
 * Class to create a meta data file with a list of snapshot files. Also list the
 * contents of a meta data file.
 */
public class MetaData
{
    private static final Logger logger = LoggerFactory.getLogger(MetaData.class);
    private final Provider<AbstractBackupPath> pathFactory;
    static List<IMessageObserver> observers = new ArrayList<IMessageObserver>();
    private final List<String> metaRemotePaths = new ArrayList<String>();
    private final IBackupFileSystem fs;

    @Inject
    public MetaData(Provider<AbstractBackupPath> pathFactory, @Named("backup") IFileSystemContext backupFileSystemCtx, IConfiguration config)

    {
        this.pathFactory = pathFactory;
        this.fs = backupFileSystemCtx.getFileStrategy(config);
    }

    @SuppressWarnings("unchecked")
    public void set(List<AbstractBackupPath> bps, String snapshotName) throws Exception
    {
        File metafile = createTmpMetaFile();
        FileWriter fr = new FileWriter(metafile);
        try
        {
            JSONArray jsonObj = new JSONArray();
            for (AbstractBackupPath filePath : bps)
                jsonObj.add(filePath.getRemotePath());
            fr.write(jsonObj.toJSONString());
        }
        finally
        {
            IOUtils.closeQuietly(fr);
        }
        AbstractBackupPath backupfile = pathFactory.get();
        backupfile.parseLocal(metafile, BackupFileType.META);
        backupfile.time = backupfile.parseDate(snapshotName);
        try
        {
			upload(backupfile);

			addToRemotePath(backupfile.getRemotePath());
			if (metaRemotePaths.size() > 0) {
				notifyObservers();
			}          
        }
        finally
        {
            FileUtils.deleteQuietly(metafile);
        }
    }

    public List<AbstractBackupPath> get(final AbstractBackupPath meta)
    {
        List<AbstractBackupPath> files = Lists.newArrayList();
        try
        {
            new RetryableCallable<Void>()
            {
                @Override
                public Void retriableCall() throws Exception
                {
                    fs.download(meta, new FileOutputStream(meta.newRestoreFile()));
                    return null;
                }
            }.call();

            File file = meta.newRestoreFile();
            JSONArray jsonObj = (JSONArray) new JSONParser().parse(new FileReader(file));
            for (int i = 0; i < jsonObj.size(); i++)
            {
                AbstractBackupPath p = pathFactory.get();
                p.parseRemote((String) jsonObj.get(i));
                files.add(p);
            }
        }
        catch (Exception ex)
        {
            logger.error("Error downloading the Meta data try with a diffrent date...", ex);
        }
        return files;
    }

    private void upload(final AbstractBackupPath bp) throws Exception
    {
        new RetryableCallable<Void>()
        {
            @Override
            public Void retriableCall() throws Exception
            {
                fs.upload(bp, bp.localReader());
                return null;
            }
        }.call();
    }
    
    public File createTmpMetaFile() throws IOException{
        File metafile = File.createTempFile("meta", ".json");
        File destFile = new File(metafile.getParent(), "meta.json");
        if(destFile.exists())
            destFile.delete();
        FileUtils.moveFile(metafile, destFile);
        return destFile;
    }

	public static void addObserver(IMessageObserver observer) {
		observers.add(observer);
	}

	public static void removeObserver(IMessageObserver observer) {
		observers.remove(observer);
	}

	public void notifyObservers() {
		for (IMessageObserver observer : observers) {
			if (observer != null) {
				logger.debug("Updating snapshot observers now ...");
				observer.update(BACKUP_MESSAGE_TYPE.META, metaRemotePaths);
			} else
				logger.info("Observer is Null, hence can not notify ...");
		}
	}

	protected void addToRemotePath(String remotePath) {
		metaRemotePaths.add(remotePath);
	}
	
    public List<AbstractBackupPath> toJson(File input) {
    	List<AbstractBackupPath> files = Lists.newArrayList();
    	try{
    		
            JSONArray jsonObj = (JSONArray) new JSONParser().parse(new FileReader(input));
            for (int i = 0; i < jsonObj.size(); i++)
            {
                AbstractBackupPath p = pathFactory.get();
                p.parseRemote((String) jsonObj.get(i));
                files.add(p);
            }
            
    	} catch (Exception ex) {
    		throw new RuntimeException("Error transforming file " + input.getAbsolutePath() + " to JSON format.  Msg:" + ex.getLocalizedMessage(), ex);
    	}

        logger.debug("Transformed file " + input.getAbsolutePath() + " to JSON.  Number of JSON elements: " + files.size());
        return files;
    }	

}