helix-rest/src/main/java/org/apache/helix/rest/server/resources/zookeeper/ZooKeeperAccessor.java - helix - Git at Google

 package org.apache.helix.rest.server.resources.zookeeper;

 /*
  * 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.
  */

 import java.util.List;
 import java.util.Map;
 import javax.ws.rs.DELETE;
 import javax.ws.rs.GET;
 import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
 import javax.ws.rs.QueryParam;
 import javax.ws.rs.WebApplicationException;
 import javax.ws.rs.core.Response;

 import com.codahale.metrics.annotation.ResponseMetered;
 import com.codahale.metrics.annotation.Timed;
 import com.google.common.base.Enums;
 import com.google.common.collect.ImmutableMap;
 import org.apache.helix.AccessOption;
 import org.apache.helix.BaseDataAccessor;
 import org.apache.helix.manager.zk.ZKUtil;
 import org.apache.helix.msdcommon.util.ZkValidationUtil;
 import org.apache.helix.rest.common.ContextPropertyKeys;
 import org.apache.helix.rest.common.HttpConstants;
 import org.apache.helix.rest.server.ServerContext;
 import org.apache.helix.rest.server.filters.NamespaceAuth;
 import org.apache.helix.rest.server.resources.AbstractResource;
 import org.apache.zookeeper.data.Stat;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;


 /**
  * ZooKeeperAccessor provides methods for accessing ZooKeeper resources (ZNodes).
  * It provides basic ZooKeeper features supported by ZkClient.
  */
 @NamespaceAuth
 @Path("/zookeeper{path: /.+}")
 public class ZooKeeperAccessor extends AbstractResource {
   private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperAccessor.class.getName());
   private BaseDataAccessor<byte[]> _zkBaseDataAccessor;

   public enum ZooKeeperCommand {
     exists,
     getBinaryData,
     getStringData,
     getChildren,
     getStat
   }

   @ResponseMetered(name = HttpConstants.READ_REQUEST)
   @Timed(name = HttpConstants.READ_REQUEST)
   @GET
   public Response get(@PathParam("path") String path, @QueryParam("command") String commandStr) {
     ZooKeeperCommand cmd = getZooKeeperCommandIfPresent(commandStr);
     if (cmd == null) {
       return badRequest("Invalid ZooKeeper command: " + commandStr);
     }

     // Lazily initialize ZkBaseDataAccessor
     ServerContext _serverContext =
         (ServerContext) _application.getProperties().get(ContextPropertyKeys.SERVER_CONTEXT.name());
     _zkBaseDataAccessor = _serverContext.getByteArrayZkBaseDataAccessor();

     // Check that the path supplied is valid
     if (!ZkValidationUtil.isPathValid(path)) {
       String errMsg = "The given path is not a valid ZooKeeper path: " + path;
       LOG.info(errMsg);
       return badRequest(errMsg);
     }

     switch (cmd) {
       case exists:
         return exists(_zkBaseDataAccessor, path);
       case getBinaryData:
         return getBinaryData(_zkBaseDataAccessor, path);
       case getStringData:
         return getStringData(_zkBaseDataAccessor, path);
       case getChildren:
         return getChildren(_zkBaseDataAccessor, path);
       case getStat:
         return getStat(_zkBaseDataAccessor, path);
       default:
         String errMsg = "Unsupported command: " + commandStr;
         LOG.error(errMsg);
         return badRequest(errMsg);
     }
   }

   @ResponseMetered(name = HttpConstants.WRITE_REQUEST)
   @Timed(name = HttpConstants.WRITE_REQUEST)
   @DELETE
   public Response delete(@PathParam("path") String path) {
     // Lazily initialize ZkBaseDataAccessor
     ServerContext _serverContext =
         (ServerContext) _application.getProperties().get(ContextPropertyKeys.SERVER_CONTEXT.name());
     _zkBaseDataAccessor = _serverContext.getByteArrayZkBaseDataAccessor();

     // Check that the path supplied is valid
     if (!ZkValidationUtil.isPathValid(path)) {
       String errMsg = "The given path is not a valid ZooKeeper path: " + path;
       LOG.info(errMsg);
       return badRequest(errMsg);
     }

     return delete(_zkBaseDataAccessor, path);
   }

   /**
    * Checks if a ZNode exists in the given path.
    * @param zkBaseDataAccessor
    * @param path
    * @return true if a ZNode exists, false otherwise
    */
   private Response exists(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
     Map<String, Boolean> result = ImmutableMap.of(ZooKeeperCommand.exists.name(),
         zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT));
     return JSONRepresentation(result);
   }

   /**
    * Returns a response containing the binary data and Stat.
    * @param zkBaseDataAccessor
    * @param path
    * @return
    */
   private Response getBinaryData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
     Stat stat = new Stat();
     byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat);
     Map<String, Object> binaryResult = ImmutableMap
         .of(ZooKeeperCommand.getBinaryData.name(), bytes, ZooKeeperCommand.getStat.name(),
             ZKUtil.fromStatToMap(stat));
     // Note: this serialization (using ObjectMapper) will convert this byte[] into
     // a Base64 String! The REST client (user) must convert the resulting String back into
     // a byte[] using Base64.
     return JSONRepresentation(binaryResult);
   }

   /**
    * Returns a response containing the string data and Stat.
    * @param zkBaseDataAccessor
    * @param path
    * @return
    */
   private Response getStringData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
     Stat stat = new Stat();
     byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat);
     Map<String, Object> stringResult = ImmutableMap
         .of(ZooKeeperCommand.getStringData.name(), new String(bytes),
             ZooKeeperCommand.getStat.name(), ZKUtil.fromStatToMap(stat));
     return JSONRepresentation(stringResult);
   }

   /**
    * Returns byte[] from ZooKeeper.
    * @param zkBaseDataAccessor
    * @param path
    * @return
    */
   private byte[] readBinaryDataFromZK(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path,
       Stat stat) {
     if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) {
       return zkBaseDataAccessor.get(path, stat, AccessOption.PERSISTENT);
     } else {
       throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
           .entity(String.format("The ZNode at path %s does not exist!", path)).build());
     }
   }

   /**
    * Returns a list of children ZNode names given the path for the parent ZNode.
    * @param zkBaseDataAccessor
    * @param path
    * @return list of child ZNodes
    */
   private Response getChildren(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
     if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) {
       Map<String, List<String>> result = ImmutableMap.of(ZooKeeperCommand.getChildren.name(),
           zkBaseDataAccessor.getChildNames(path, AccessOption.PERSISTENT));
       return JSONRepresentation(result);
     } else {
       throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
           .entity(String.format("The ZNode at path %s does not exist", path)).build());
     }
   }

   /**
    * Returns the ZNode Stat object given the path.
    * @param zkBaseDataAccessor
    * @param path
    * @return
    */
   private Response getStat(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
     Stat stat = zkBaseDataAccessor.getStat(path, AccessOption.PERSISTENT);
     if (stat == null) {
       throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
           .entity(String.format("The ZNode at path %s does not exist!", path)).build());
     }
     Map<String, String> result = ZKUtil.fromStatToMap(stat);
     result.put("path", path);
     return JSONRepresentation(result);
   }

   /**
    * Delete the ZNode at the given path if exists.
    * @param zkBaseDataAccessor
    * @param path
    * @return The delete result and the operated path.
    */
   private Response delete(BaseDataAccessor zkBaseDataAccessor, String path) {
     Stat stat = zkBaseDataAccessor.getStat(path, AccessOption.PERSISTENT);
     if (stat == null) {
       return notFound();
     } else if (stat.getEphemeralOwner() <= 0) {
       // TODO: Remove this restriction once we have audit and ACL for the API calls.
       // TODO: This method is added pre-maturely to support removing the live instance of a zombie
       // TODO: instance. It is risky to allow all deleting requests before audit and ACL are done.
       throw new WebApplicationException(Response.status(Response.Status.FORBIDDEN)
           .entity(String.format("Deleting a non-ephemeral node is not allowed.")).build());
     }

     if (zkBaseDataAccessor.remove(path, AccessOption.PERSISTENT)) {
       return OK();
     } else {
       throw new WebApplicationException(Response.status(Response.Status.INTERNAL_SERVER_ERROR)
           .entity(String.format("Failed to delete %s.", path)).build());
     }
   }

   private ZooKeeperCommand getZooKeeperCommandIfPresent(String command) {
     return Enums.getIfPresent(ZooKeeperCommand.class, command).orNull();
   }
 }
	package org.apache.helix.rest.server.resources.zookeeper;

	/*
	* 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.
	*/

	import java.util.List;
	import java.util.Map;
	import javax.ws.rs.DELETE;
	import javax.ws.rs.GET;
	import javax.ws.rs.Path;
	import javax.ws.rs.PathParam;
	import javax.ws.rs.QueryParam;
	import javax.ws.rs.WebApplicationException;
	import javax.ws.rs.core.Response;

	import com.codahale.metrics.annotation.ResponseMetered;
	import com.codahale.metrics.annotation.Timed;
	import com.google.common.base.Enums;
	import com.google.common.collect.ImmutableMap;
	import org.apache.helix.AccessOption;
	import org.apache.helix.BaseDataAccessor;
	import org.apache.helix.manager.zk.ZKUtil;
	import org.apache.helix.msdcommon.util.ZkValidationUtil;
	import org.apache.helix.rest.common.ContextPropertyKeys;
	import org.apache.helix.rest.common.HttpConstants;
	import org.apache.helix.rest.server.ServerContext;
	import org.apache.helix.rest.server.filters.NamespaceAuth;
	import org.apache.helix.rest.server.resources.AbstractResource;
	import org.apache.zookeeper.data.Stat;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;


	/**
	* ZooKeeperAccessor provides methods for accessing ZooKeeper resources (ZNodes).
	* It provides basic ZooKeeper features supported by ZkClient.
	*/
	@NamespaceAuth
	@Path("/zookeeper{path: /.+}")
	public class ZooKeeperAccessor extends AbstractResource {
	private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperAccessor.class.getName());
	private BaseDataAccessor<byte[]> _zkBaseDataAccessor;

	public enum ZooKeeperCommand {
	exists,
	getBinaryData,
	getStringData,
	getChildren,
	getStat
	}

	@ResponseMetered(name = HttpConstants.READ_REQUEST)
	@Timed(name = HttpConstants.READ_REQUEST)
	@GET
	public Response get(@PathParam("path") String path, @QueryParam("command") String commandStr) {
	ZooKeeperCommand cmd = getZooKeeperCommandIfPresent(commandStr);
	if (cmd == null) {
	return badRequest("Invalid ZooKeeper command: " + commandStr);
	}

	// Lazily initialize ZkBaseDataAccessor
	ServerContext _serverContext =
	(ServerContext) _application.getProperties().get(ContextPropertyKeys.SERVER_CONTEXT.name());
	_zkBaseDataAccessor = _serverContext.getByteArrayZkBaseDataAccessor();

	// Check that the path supplied is valid
	if (!ZkValidationUtil.isPathValid(path)) {
	String errMsg = "The given path is not a valid ZooKeeper path: " + path;
	LOG.info(errMsg);
	return badRequest(errMsg);
	}

	switch (cmd) {
	case exists:
	return exists(_zkBaseDataAccessor, path);
	case getBinaryData:
	return getBinaryData(_zkBaseDataAccessor, path);
	case getStringData:
	return getStringData(_zkBaseDataAccessor, path);
	case getChildren:
	return getChildren(_zkBaseDataAccessor, path);
	case getStat:
	return getStat(_zkBaseDataAccessor, path);
	default:
	String errMsg = "Unsupported command: " + commandStr;
	LOG.error(errMsg);
	return badRequest(errMsg);
	}
	}

	@ResponseMetered(name = HttpConstants.WRITE_REQUEST)
	@Timed(name = HttpConstants.WRITE_REQUEST)
	@DELETE
	public Response delete(@PathParam("path") String path) {
	// Lazily initialize ZkBaseDataAccessor
	ServerContext _serverContext =
	(ServerContext) _application.getProperties().get(ContextPropertyKeys.SERVER_CONTEXT.name());
	_zkBaseDataAccessor = _serverContext.getByteArrayZkBaseDataAccessor();

	// Check that the path supplied is valid
	if (!ZkValidationUtil.isPathValid(path)) {
	String errMsg = "The given path is not a valid ZooKeeper path: " + path;
	LOG.info(errMsg);
	return badRequest(errMsg);
	}

	return delete(_zkBaseDataAccessor, path);
	}

	/**
	* Checks if a ZNode exists in the given path.
	* @param zkBaseDataAccessor
	* @param path
	* @return true if a ZNode exists, false otherwise
	*/
	private Response exists(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
	Map<String, Boolean> result = ImmutableMap.of(ZooKeeperCommand.exists.name(),
	zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT));
	return JSONRepresentation(result);
	}

	/**
	* Returns a response containing the binary data and Stat.
	* @param zkBaseDataAccessor
	* @param path
	* @return
	*/
	private Response getBinaryData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
	Stat stat = new Stat();
	byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat);
	Map<String, Object> binaryResult = ImmutableMap
	.of(ZooKeeperCommand.getBinaryData.name(), bytes, ZooKeeperCommand.getStat.name(),
	ZKUtil.fromStatToMap(stat));
	// Note: this serialization (using ObjectMapper) will convert this byte[] into
	// a Base64 String! The REST client (user) must convert the resulting String back into
	// a byte[] using Base64.
	return JSONRepresentation(binaryResult);
	}

	/**
	* Returns a response containing the string data and Stat.
	* @param zkBaseDataAccessor
	* @param path
	* @return
	*/
	private Response getStringData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
	Stat stat = new Stat();
	byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat);
	Map<String, Object> stringResult = ImmutableMap
	.of(ZooKeeperCommand.getStringData.name(), new String(bytes),
	ZooKeeperCommand.getStat.name(), ZKUtil.fromStatToMap(stat));
	return JSONRepresentation(stringResult);
	}

	/**
	* Returns byte[] from ZooKeeper.
	* @param zkBaseDataAccessor
	* @param path
	* @return
	*/
	private byte[] readBinaryDataFromZK(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path,
	Stat stat) {
	if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) {
	return zkBaseDataAccessor.get(path, stat, AccessOption.PERSISTENT);
	} else {
	throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
	.entity(String.format("The ZNode at path %s does not exist!", path)).build());
	}
	}

	/**
	* Returns a list of children ZNode names given the path for the parent ZNode.
	* @param zkBaseDataAccessor
	* @param path
	* @return list of child ZNodes
	*/
	private Response getChildren(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
	if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) {
	Map<String, List<String>> result = ImmutableMap.of(ZooKeeperCommand.getChildren.name(),
	zkBaseDataAccessor.getChildNames(path, AccessOption.PERSISTENT));
	return JSONRepresentation(result);
	} else {
	throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
	.entity(String.format("The ZNode at path %s does not exist", path)).build());
	}
	}

	/**
	* Returns the ZNode Stat object given the path.
	* @param zkBaseDataAccessor
	* @param path
	* @return
	*/
	private Response getStat(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) {
	Stat stat = zkBaseDataAccessor.getStat(path, AccessOption.PERSISTENT);
	if (stat == null) {
	throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND)
	.entity(String.format("The ZNode at path %s does not exist!", path)).build());
	}
	Map<String, String> result = ZKUtil.fromStatToMap(stat);
	result.put("path", path);
	return JSONRepresentation(result);
	}

	/**
	* Delete the ZNode at the given path if exists.
	* @param zkBaseDataAccessor
	* @param path
	* @return The delete result and the operated path.
	*/
	private Response delete(BaseDataAccessor zkBaseDataAccessor, String path) {
	Stat stat = zkBaseDataAccessor.getStat(path, AccessOption.PERSISTENT);
	if (stat == null) {
	return notFound();
	} else if (stat.getEphemeralOwner() <= 0) {
	// TODO: Remove this restriction once we have audit and ACL for the API calls.
	// TODO: This method is added pre-maturely to support removing the live instance of a zombie
	// TODO: instance. It is risky to allow all deleting requests before audit and ACL are done.
	throw new WebApplicationException(Response.status(Response.Status.FORBIDDEN)
	.entity(String.format("Deleting a non-ephemeral node is not allowed.")).build());
	}

	if (zkBaseDataAccessor.remove(path, AccessOption.PERSISTENT)) {
	return OK();
	} else {
	throw new WebApplicationException(Response.status(Response.Status.INTERNAL_SERVER_ERROR)
	.entity(String.format("Failed to delete %s.", path)).build());
	}
	}

	private ZooKeeperCommand getZooKeeperCommandIfPresent(String command) {
	return Enums.getIfPresent(ZooKeeperCommand.class, command).orNull();
	}
	}