hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/ECAdmin.java - hadoop - Git at Google

 /**
  * 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 org.apache.hadoop.hdfs.tools;

 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.conf.Configured;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.protocol.AddErasureCodingPolicyResponse;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicyInfo;
 import org.apache.hadoop.hdfs.protocol.NoECPolicySetException;
 import org.apache.hadoop.hdfs.util.ECPolicyLoader;
 import org.apache.hadoop.io.erasurecode.ErasureCodeConstants;
 import org.apache.hadoop.tools.TableListing;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Tool;
 import org.apache.hadoop.util.ToolRunner;

 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;

 /**
  * CLI for the erasure code encoding operations.
  */
 @InterfaceAudience.Private
 public class ECAdmin extends Configured implements Tool {

   public static final String NAME = "ec";

   public static void main(String[] args) throws Exception {
     final ECAdmin admin = new ECAdmin(new Configuration());
     int res = ToolRunner.run(admin, args);
     System.exit(res);
   }

   public ECAdmin(Configuration conf) {
     super(conf);
   }

   @Override
   public int run(String[] args) throws Exception {
     if (args.length == 0) {
       AdminHelper.printUsage(false, NAME, COMMANDS);
       ToolRunner.printGenericCommandUsage(System.err);
       return 1;
     }
     final AdminHelper.Command command = AdminHelper.determineCommand(args[0],
         COMMANDS);
     if (command == null) {
       System.err.println("Can't understand command '" + args[0] + "'");
       if (!args[0].startsWith("-")) {
         System.err.println("Command names must start with dashes.");
       }
       AdminHelper.printUsage(false, NAME, COMMANDS);
       ToolRunner.printGenericCommandUsage(System.err);
       return 1;
     }
     final List<String> argsList = new LinkedList<>();
     argsList.addAll(Arrays.asList(args).subList(1, args.length));
     try {
       return command.run(getConf(), argsList);
     } catch (IllegalArgumentException e) {
       System.err.println(AdminHelper.prettifyException(e));
       return -1;
     }
   }

   /** Command to list the set of enabled erasure coding policies. */
   private static class ListECPoliciesCommand
       implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-listPolicies";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + "]\n";
     }

     @Override
     public String getLongUsage() {
       return getShortUsage() + "\n" +
           "Get the list of all erasure coding policies.\n";
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         final Collection<ErasureCodingPolicyInfo> policies =
             dfs.getAllErasureCodingPolicies();
         if (policies.isEmpty()) {
           System.out.println("There is no erasure coding policies in the " +
               "cluster.");
         } else {
           System.out.println("Erasure Coding Policies:");
           for (ErasureCodingPolicyInfo policy : policies) {
             if (policy != null) {
               System.out.println(policy);
             }
           }
         }
       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to add a set of erasure coding policies. */
   private static class AddECPoliciesCommand
       implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-addPolicies";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -policyFile <file>]\n";
     }

     @Override
     public String getLongUsage() {
       final TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<file>",
           "The path of the xml file which defines the EC policies to add");
       return getShortUsage() + "\n" +
           "Add a list of user defined erasure coding policies.\n" +
           listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String filePath =
           StringUtils.popOptionWithArgument("-policyFile", args);
       if (filePath == null) {
         System.err.println("Please specify the path with -policyFile.\nUsage: "
             + getLongUsage());
         return 1;
       }

       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         List<ErasureCodingPolicy> policies =
             new ECPolicyLoader().loadPolicy(filePath);
         if (policies.size() > 0) {
           AddErasureCodingPolicyResponse[] responses =
               dfs.addErasureCodingPolicies(
             policies.toArray(new ErasureCodingPolicy[policies.size()]));
           for (AddErasureCodingPolicyResponse response : responses) {
             System.out.println(response);
           }
         } else {
           System.out.println("No EC policy parsed out from " + filePath);
         }

       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to get the erasure coding policy for a file or directory. */
   private static class GetECPolicyCommand implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-getPolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -path <path>]\n";
     }

     @Override
     public String getLongUsage() {
       final TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<path>",
           "The path of the file/directory for getting the erasure coding " +
               "policy");
       return getShortUsage() + "\n" +
           "Get the erasure coding policy of a file/directory.\n\n" +
           listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String path = StringUtils.popOptionWithArgument("-path", args);
       if (path == null) {
         System.err.println("Please specify the path with -path.\nUsage: " +
             getLongUsage());
         return 1;
       }

       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final Path p = new Path(path);
       final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
       try {
         ErasureCodingPolicy ecPolicy = dfs.getErasureCodingPolicy(p);
         if (ecPolicy != null) {
           System.out.println(ecPolicy.getName());
         } else {
           System.out.println("The erasure coding policy of " + path + " is " +
               "unspecified");
         }
       } catch (Exception e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to remove an erasure coding policy. */
   private static class RemoveECPolicyCommand implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-removePolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -policy <policy>]\n";
     }

     @Override
     public String getLongUsage() {
       TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<policy>", "The name of the erasure coding policy");
       return getShortUsage() + "\n" +
           "Remove an user defined erasure coding policy.\n" +
           listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String ecPolicyName = StringUtils.popOptionWithArgument(
           "-policy", args);
       if (ecPolicyName == null) {
         System.err.println("Please specify the policy name.\nUsage: " +
             getLongUsage());
         return 1;
       }
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }
       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         dfs.removeErasureCodingPolicy(ecPolicyName);
         System.out.println("Erasure coding policy " + ecPolicyName +
             "is removed");
       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to set the erasure coding policy to a file/directory. */
   private static class SetECPolicyCommand implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-setPolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() +
           " -path <path> [-policy <policy>] [-replicate]]\n";
     }

     @Override
     public String getLongUsage() {
       TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<path>", "The path of the file/directory to set " +
           "the erasure coding policy");
       listing.addRow("<policy>", "The name of the erasure coding policy");
       listing.addRow("-replicate",
           "force 3x replication scheme on the directory");
       return getShortUsage() + "\n" +
           "Set the erasure coding policy for a file/directory.\n\n" +
           listing.toString() + "\n" +
           "-replicate and -policy are optional arguments. They cannot been " +
           "used at the same time";
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String path = StringUtils.popOptionWithArgument("-path", args);
       if (path == null) {
         System.err.println("Please specify the path for setting the EC " +
             "policy.\nUsage: " + getLongUsage());
         return 1;
       }

       String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
           args);
       final boolean replicate = StringUtils.popOption("-replicate", args);

       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       if (replicate) {
         if (ecPolicyName != null) {
           System.err.println(getName() +
               ": -replicate and -policy cannot been used at the same time");
           return 2;
         }
         ecPolicyName = ErasureCodeConstants.REPLICATION_POLICY_NAME;
       }

       final Path p = new Path(path);
       final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
       try {
         dfs.setErasureCodingPolicy(p, ecPolicyName);

         String actualECPolicyName = dfs.getErasureCodingPolicy(p).getName();

         System.out.println("Set " + actualECPolicyName +
             " erasure coding policy on "+ path);
         RemoteIterator<FileStatus> dirIt = dfs.listStatusIterator(p);
         if (dirIt.hasNext()) {
           System.out.println("Warning: setting erasure coding policy on a " +
               "non-empty directory will not automatically convert existing " +
               "files to " + actualECPolicyName + " erasure coding policy");
         }
       } catch (Exception e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 3;
       }
       return 0;
     }
   }

   /** Command to unset the erasure coding policy set for a file/directory. */
   private static class UnsetECPolicyCommand
       implements AdminHelper.Command {

     @Override
     public String getName() {
       return "-unsetPolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -path <path>]\n";
     }

     @Override
     public String getLongUsage() {
       TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<path>", "The path of the directory "
           + "from which the erasure coding policy will be unset.");
       return getShortUsage() + "\n"
           + "Unset the erasure coding policy for a directory.\n\n"
           + listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String path = StringUtils.popOptionWithArgument("-path", args);
       if (path == null) {
         System.err.println("Please specify a path.\nUsage: " + getLongUsage());
         return 1;
       }

       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final Path p = new Path(path);
       final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
       try {
         dfs.unsetErasureCodingPolicy(p);
         System.out.println("Unset erasure coding policy from " + path);
         RemoteIterator<FileStatus> dirIt = dfs.listStatusIterator(p);
         if (dirIt.hasNext()) {
           System.out.println("Warning: unsetting erasure coding policy on a " +
               "non-empty directory will not automatically convert existing" +
               " files to replicated data.");
         }
       } catch (NoECPolicySetException e) {
         System.err.println(AdminHelper.prettifyException(e));
         System.err.println("Use '-setPolicy -path <PATH> -replicate' to enforce"
             + " default replication policy irrespective of EC policy"
             + " defined on parent.");
         return 2;
       } catch (Exception e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to list the set of supported erasure coding codecs and coders. */
   private static class ListECCodecsCommand
       implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-listCodecs";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + "]\n";
     }

     @Override
     public String getLongUsage() {
       return getShortUsage() + "\n" +
           "Get the list of supported erasure coding codecs and coders.\n" +
           "A coder is an implementation of a codec. A codec can have " +
           "different implementations, thus different coders.\n" +
           "The coders for a codec are listed in a fall back order.\n";
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         Map<String, String> codecs =
             dfs.getAllErasureCodingCodecs();
         if (codecs.isEmpty()) {
           System.out.println("No erasure coding codecs are supported on the " +
               "cluster.");
         } else {
           System.out.println("Erasure Coding Codecs: Codec [Coder List]");
           for (Map.Entry<String, String> codec : codecs.entrySet()) {
             if (codec != null) {
               System.out.println("\t" + codec.getKey().toUpperCase() + " ["
                   + codec.getValue().toUpperCase() +"]");
             }
           }
         }
       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to enable an existing erasure coding policy. */
   private static class EnableECPolicyCommand implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-enablePolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -policy <policy>]\n";
     }

     @Override
     public String getLongUsage() {
       TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<policy>", "The name of the erasure coding policy");
       return getShortUsage() + "\n" +
           "Enable the erasure coding policy.\n\n" +
           listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
           args);
       if (ecPolicyName == null) {
         System.err.println("Please specify the policy name.\nUsage: " +
             getLongUsage());
         return 1;
       }
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         dfs.enableErasureCodingPolicy(ecPolicyName);
         System.out.println("Erasure coding policy " + ecPolicyName +
             " is enabled");
       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   /** Command to disable an existing erasure coding policy. */
   private static class DisableECPolicyCommand implements AdminHelper.Command {
     @Override
     public String getName() {
       return "-disablePolicy";
     }

     @Override
     public String getShortUsage() {
       return "[" + getName() + " -policy <policy>]\n";
     }

     @Override
     public String getLongUsage() {
       TableListing listing = AdminHelper.getOptionDescriptionListing();
       listing.addRow("<policy>", "The name of the erasure coding policy");
       return getShortUsage() + "\n" +
           "Disable the erasure coding policy.\n\n" +
           listing.toString();
     }

     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
       final String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
           args);
       if (ecPolicyName == null) {
         System.err.println("Please specify the policy name.\nUsage: " +
             getLongUsage());
         return 1;
       }
       if (args.size() > 0) {
         System.err.println(getName() + ": Too many arguments");
         return 1;
       }

       final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
       try {
         dfs.disableErasureCodingPolicy(ecPolicyName);
         System.out.println("Erasure coding policy " + ecPolicyName +
             " is disabled");
       } catch (IOException e) {
         System.err.println(AdminHelper.prettifyException(e));
         return 2;
       }
       return 0;
     }
   }

   private static final AdminHelper.Command[] COMMANDS = {
       new ListECPoliciesCommand(),
       new AddECPoliciesCommand(),
       new GetECPolicyCommand(),
       new RemoveECPolicyCommand(),
       new SetECPolicyCommand(),
       new UnsetECPolicyCommand(),
       new ListECCodecsCommand(),
       new EnableECPolicyCommand(),
       new DisableECPolicyCommand()
   };
 }
	/**
	* 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 org.apache.hadoop.hdfs.tools;

	import org.apache.hadoop.classification.InterfaceAudience;
	import org.apache.hadoop.conf.Configuration;
	import org.apache.hadoop.conf.Configured;
	import org.apache.hadoop.fs.FileStatus;
	import org.apache.hadoop.fs.Path;
	import org.apache.hadoop.fs.RemoteIterator;
	import org.apache.hadoop.hdfs.DistributedFileSystem;
	import org.apache.hadoop.hdfs.protocol.AddErasureCodingPolicyResponse;
	import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
	import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicyInfo;
	import org.apache.hadoop.hdfs.protocol.NoECPolicySetException;
	import org.apache.hadoop.hdfs.util.ECPolicyLoader;
	import org.apache.hadoop.io.erasurecode.ErasureCodeConstants;
	import org.apache.hadoop.tools.TableListing;
	import org.apache.hadoop.util.StringUtils;
	import org.apache.hadoop.util.Tool;
	import org.apache.hadoop.util.ToolRunner;

	import java.io.IOException;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Map;

	/**
	* CLI for the erasure code encoding operations.
	*/
	@InterfaceAudience.Private
	public class ECAdmin extends Configured implements Tool {

	public static final String NAME = "ec";

	public static void main(String[] args) throws Exception {
	final ECAdmin admin = new ECAdmin(new Configuration());
	int res = ToolRunner.run(admin, args);
	System.exit(res);
	}

	public ECAdmin(Configuration conf) {
	super(conf);
	}

	@Override
	public int run(String[] args) throws Exception {
	if (args.length == 0) {
	AdminHelper.printUsage(false, NAME, COMMANDS);
	ToolRunner.printGenericCommandUsage(System.err);
	return 1;
	}
	final AdminHelper.Command command = AdminHelper.determineCommand(args[0],
	COMMANDS);
	if (command == null) {
	System.err.println("Can't understand command '" + args[0] + "'");
	if (!args[0].startsWith("-")) {
	System.err.println("Command names must start with dashes.");
	}
	AdminHelper.printUsage(false, NAME, COMMANDS);
	ToolRunner.printGenericCommandUsage(System.err);
	return 1;
	}
	final List<String> argsList = new LinkedList<>();
	argsList.addAll(Arrays.asList(args).subList(1, args.length));
	try {
	return command.run(getConf(), argsList);
	} catch (IllegalArgumentException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return -1;
	}
	}

	/** Command to list the set of enabled erasure coding policies. */
	private static class ListECPoliciesCommand
	implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-listPolicies";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + "]\n";
	}

	@Override
	public String getLongUsage() {
	return getShortUsage() + "\n" +
	"Get the list of all erasure coding policies.\n";
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	final Collection<ErasureCodingPolicyInfo> policies =
	dfs.getAllErasureCodingPolicies();
	if (policies.isEmpty()) {
	System.out.println("There is no erasure coding policies in the " +
	"cluster.");
	} else {
	System.out.println("Erasure Coding Policies:");
	for (ErasureCodingPolicyInfo policy : policies) {
	if (policy != null) {
	System.out.println(policy);
	}
	}
	}
	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to add a set of erasure coding policies. */
	private static class AddECPoliciesCommand
	implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-addPolicies";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -policyFile <file>]\n";
	}

	@Override
	public String getLongUsage() {
	final TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<file>",
	"The path of the xml file which defines the EC policies to add");
	return getShortUsage() + "\n" +
	"Add a list of user defined erasure coding policies.\n" +
	listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String filePath =
	StringUtils.popOptionWithArgument("-policyFile", args);
	if (filePath == null) {
	System.err.println("Please specify the path with -policyFile.\nUsage: "
	+ getLongUsage());
	return 1;
	}

	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	List<ErasureCodingPolicy> policies =
	new ECPolicyLoader().loadPolicy(filePath);
	if (policies.size() > 0) {
	AddErasureCodingPolicyResponse[] responses =
	dfs.addErasureCodingPolicies(
	policies.toArray(new ErasureCodingPolicy[policies.size()]));
	for (AddErasureCodingPolicyResponse response : responses) {
	System.out.println(response);
	}
	} else {
	System.out.println("No EC policy parsed out from " + filePath);
	}

	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to get the erasure coding policy for a file or directory. */
	private static class GetECPolicyCommand implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-getPolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -path <path>]\n";
	}

	@Override
	public String getLongUsage() {
	final TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<path>",
	"The path of the file/directory for getting the erasure coding " +
	"policy");
	return getShortUsage() + "\n" +
	"Get the erasure coding policy of a file/directory.\n\n" +
	listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String path = StringUtils.popOptionWithArgument("-path", args);
	if (path == null) {
	System.err.println("Please specify the path with -path.\nUsage: " +
	getLongUsage());
	return 1;
	}

	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final Path p = new Path(path);
	final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
	try {
	ErasureCodingPolicy ecPolicy = dfs.getErasureCodingPolicy(p);
	if (ecPolicy != null) {
	System.out.println(ecPolicy.getName());
	} else {
	System.out.println("The erasure coding policy of " + path + " is " +
	"unspecified");
	}
	} catch (Exception e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to remove an erasure coding policy. */
	private static class RemoveECPolicyCommand implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-removePolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -policy <policy>]\n";
	}

	@Override
	public String getLongUsage() {
	TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<policy>", "The name of the erasure coding policy");
	return getShortUsage() + "\n" +
	"Remove an user defined erasure coding policy.\n" +
	listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String ecPolicyName = StringUtils.popOptionWithArgument(
	"-policy", args);
	if (ecPolicyName == null) {
	System.err.println("Please specify the policy name.\nUsage: " +
	getLongUsage());
	return 1;
	}
	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}
	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	dfs.removeErasureCodingPolicy(ecPolicyName);
	System.out.println("Erasure coding policy " + ecPolicyName +
	"is removed");
	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to set the erasure coding policy to a file/directory. */
	private static class SetECPolicyCommand implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-setPolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() +
	" -path <path> [-policy <policy>] [-replicate]]\n";
	}

	@Override
	public String getLongUsage() {
	TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<path>", "The path of the file/directory to set " +
	"the erasure coding policy");
	listing.addRow("<policy>", "The name of the erasure coding policy");
	listing.addRow("-replicate",
	"force 3x replication scheme on the directory");
	return getShortUsage() + "\n" +
	"Set the erasure coding policy for a file/directory.\n\n" +
	listing.toString() + "\n" +
	"-replicate and -policy are optional arguments. They cannot been " +
	"used at the same time";
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String path = StringUtils.popOptionWithArgument("-path", args);
	if (path == null) {
	System.err.println("Please specify the path for setting the EC " +
	"policy.\nUsage: " + getLongUsage());
	return 1;
	}

	String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
	args);
	final boolean replicate = StringUtils.popOption("-replicate", args);

	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	if (replicate) {
	if (ecPolicyName != null) {
	System.err.println(getName() +
	": -replicate and -policy cannot been used at the same time");
	return 2;
	}
	ecPolicyName = ErasureCodeConstants.REPLICATION_POLICY_NAME;
	}

	final Path p = new Path(path);
	final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
	try {
	dfs.setErasureCodingPolicy(p, ecPolicyName);

	String actualECPolicyName = dfs.getErasureCodingPolicy(p).getName();

	System.out.println("Set " + actualECPolicyName +
	" erasure coding policy on "+ path);
	RemoteIterator<FileStatus> dirIt = dfs.listStatusIterator(p);
	if (dirIt.hasNext()) {
	System.out.println("Warning: setting erasure coding policy on a " +
	"non-empty directory will not automatically convert existing " +
	"files to " + actualECPolicyName + " erasure coding policy");
	}
	} catch (Exception e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 3;
	}
	return 0;
	}
	}

	/** Command to unset the erasure coding policy set for a file/directory. */
	private static class UnsetECPolicyCommand
	implements AdminHelper.Command {

	@Override
	public String getName() {
	return "-unsetPolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -path <path>]\n";
	}

	@Override
	public String getLongUsage() {
	TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<path>", "The path of the directory "
	+ "from which the erasure coding policy will be unset.");
	return getShortUsage() + "\n"
	+ "Unset the erasure coding policy for a directory.\n\n"
	+ listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String path = StringUtils.popOptionWithArgument("-path", args);
	if (path == null) {
	System.err.println("Please specify a path.\nUsage: " + getLongUsage());
	return 1;
	}

	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final Path p = new Path(path);
	final DistributedFileSystem dfs = AdminHelper.getDFS(p.toUri(), conf);
	try {
	dfs.unsetErasureCodingPolicy(p);
	System.out.println("Unset erasure coding policy from " + path);
	RemoteIterator<FileStatus> dirIt = dfs.listStatusIterator(p);
	if (dirIt.hasNext()) {
	System.out.println("Warning: unsetting erasure coding policy on a " +
	"non-empty directory will not automatically convert existing" +
	" files to replicated data.");
	}
	} catch (NoECPolicySetException e) {
	System.err.println(AdminHelper.prettifyException(e));
	System.err.println("Use '-setPolicy -path <PATH> -replicate' to enforce"
	+ " default replication policy irrespective of EC policy"
	+ " defined on parent.");
	return 2;
	} catch (Exception e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to list the set of supported erasure coding codecs and coders. */
	private static class ListECCodecsCommand
	implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-listCodecs";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + "]\n";
	}

	@Override
	public String getLongUsage() {
	return getShortUsage() + "\n" +
	"Get the list of supported erasure coding codecs and coders.\n" +
	"A coder is an implementation of a codec. A codec can have " +
	"different implementations, thus different coders.\n" +
	"The coders for a codec are listed in a fall back order.\n";
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	Map<String, String> codecs =
	dfs.getAllErasureCodingCodecs();
	if (codecs.isEmpty()) {
	System.out.println("No erasure coding codecs are supported on the " +
	"cluster.");
	} else {
	System.out.println("Erasure Coding Codecs: Codec [Coder List]");
	for (Map.Entry<String, String> codec : codecs.entrySet()) {
	if (codec != null) {
	System.out.println("\t" + codec.getKey().toUpperCase() + " ["
	+ codec.getValue().toUpperCase() +"]");
	}
	}
	}
	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to enable an existing erasure coding policy. */
	private static class EnableECPolicyCommand implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-enablePolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -policy <policy>]\n";
	}

	@Override
	public String getLongUsage() {
	TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<policy>", "The name of the erasure coding policy");
	return getShortUsage() + "\n" +
	"Enable the erasure coding policy.\n\n" +
	listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
	args);
	if (ecPolicyName == null) {
	System.err.println("Please specify the policy name.\nUsage: " +
	getLongUsage());
	return 1;
	}
	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	dfs.enableErasureCodingPolicy(ecPolicyName);
	System.out.println("Erasure coding policy " + ecPolicyName +
	" is enabled");
	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	/** Command to disable an existing erasure coding policy. */
	private static class DisableECPolicyCommand implements AdminHelper.Command {
	@Override
	public String getName() {
	return "-disablePolicy";
	}

	@Override
	public String getShortUsage() {
	return "[" + getName() + " -policy <policy>]\n";
	}

	@Override
	public String getLongUsage() {
	TableListing listing = AdminHelper.getOptionDescriptionListing();
	listing.addRow("<policy>", "The name of the erasure coding policy");
	return getShortUsage() + "\n" +
	"Disable the erasure coding policy.\n\n" +
	listing.toString();
	}

	@Override
	public int run(Configuration conf, List<String> args) throws IOException {
	final String ecPolicyName = StringUtils.popOptionWithArgument("-policy",
	args);
	if (ecPolicyName == null) {
	System.err.println("Please specify the policy name.\nUsage: " +
	getLongUsage());
	return 1;
	}
	if (args.size() > 0) {
	System.err.println(getName() + ": Too many arguments");
	return 1;
	}

	final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
	try {
	dfs.disableErasureCodingPolicy(ecPolicyName);
	System.out.println("Erasure coding policy " + ecPolicyName +
	" is disabled");
	} catch (IOException e) {
	System.err.println(AdminHelper.prettifyException(e));
	return 2;
	}
	return 0;
	}
	}

	private static final AdminHelper.Command[] COMMANDS = {
	new ListECPoliciesCommand(),
	new AddECPoliciesCommand(),
	new GetECPolicyCommand(),
	new RemoveECPolicyCommand(),
	new SetECPolicyCommand(),
	new UnsetECPolicyCommand(),
	new ListECCodecsCommand(),
	new EnableECPolicyCommand(),
	new DisableECPolicyCommand()
	};
	}