tachyon.shell.TfsShell.java Source code

Introduction

Here is the source code for tachyon.shell.TfsShell.java

Source

/*
 * Licensed to the University of California, Berkeley 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 tachyon.shell;

import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

import javax.annotation.concurrent.NotThreadSafe;

import org.apache.commons.lang.StringUtils;
import org.reflections.Reflections;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Throwables;
import com.google.common.collect.Maps;

import tachyon.Constants;
import tachyon.client.file.FileSystem;
import tachyon.conf.TachyonConf;
import tachyon.shell.command.TfsShellCommand;
import tachyon.util.CommonUtils;

/**
 * Class for handling command line inputs.
 */
@NotThreadSafe
public class TfsShell implements Closeable {
    private static final Logger LOG = LoggerFactory.getLogger(Constants.LOGGER_TYPE);

    /**
     * Main method, starts a new TfsShell.
     *
     * @param argv [] Array of arguments given by the user's input from the terminal
     * @throws IOException if closing the shell fails
     */
    public static void main(String[] argv) throws IOException {
        TfsShell shell = new TfsShell(new TachyonConf());
        int ret;
        try {
            ret = shell.run(argv);
        } finally {
            shell.close();
        }
        System.exit(ret);
    }

    private final Map<String, TfsShellCommand> mCommands = Maps.newHashMap();
    private final TachyonConf mTachyonConf;
    private final FileSystem mTfs;

    /**
     * @param tachyonConf the configuration for Tachyon
     */
    public TfsShell(TachyonConf tachyonConf) {
        mTachyonConf = tachyonConf;
        mTfs = FileSystem.Factory.get();
        loadCommands();
    }

    @Override
    public void close() throws IOException {
    }

    /**
     * Uses reflection to get all the {@link TfsShellCommand} classes and store them in a map.
     */
    private void loadCommands() {
        String pkgName = TfsShellCommand.class.getPackage().getName();
        Reflections reflections = new Reflections(pkgName);
        for (Class<? extends TfsShellCommand> cls : reflections.getSubTypesOf(TfsShellCommand.class)) {
            // Only instantiate a concrete class
            if (!Modifier.isAbstract(cls.getModifiers())) {
                TfsShellCommand cmd;
                try {
                    cmd = CommonUtils.createNewClassInstance(cls,
                            new Class[] { TachyonConf.class, FileSystem.class },
                            new Object[] { mTachyonConf, mTfs });
                } catch (Exception e) {
                    throw Throwables.propagate(e);
                }
                mCommands.put(cmd.getCommandName(), cmd);
            }
        }
    }

    /**
     * Method which prints the method to use all the commands.
     */
    private void printUsage() {
        System.out.println("Usage: java TfsShell");
        SortedSet<String> sortedCmds = new TreeSet<String>(mCommands.keySet());
        for (String cmd : sortedCmds) {
            System.out.format("%-60s%-95s%n", "       [" + mCommands.get(cmd).getUsage() + "]   ",
                    mCommands.get(cmd).getDescription());
        }
    }

    /**
     * Method which determines how to handle the user's request, will display usage help to the user
     * if command format is incorrect.
     *
     * @param argv [] Array of arguments given by the user's input from the terminal
     * @return 0 if command is successful, -1 if an error occurred
     */
    public int run(String... argv) {
        if (argv.length == 0) {
            printUsage();
            return -1;
        }

        // Sanity check on the number of arguments
        String cmd = argv[0];
        TfsShellCommand command = mCommands.get(cmd);

        if (command == null) { // Unknown command (we didn't find the cmd in our dict)
            System.out.println(cmd + " is an unknown command.\n");
            printUsage();
            return -1;
        }

        String[] args = Arrays.copyOfRange(argv, 1, argv.length);
        if (!command.validateArgs(args)) {
            printUsage();
            return -1;
        }

        // Handle the command
        try {
            command.run(args);
            return 0;
        } catch (IOException e) {
            System.out.println(e.getMessage());
            LOG.error("Error running " + StringUtils.join(argv, " "), e);
            return -1;
        }
    }
}