abhishekdas99 commented on a change in pull request #2225: URL: https://github.com/apache/hadoop/pull/2225#discussion_r487493380
########## File path: hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ViewFsOverloadScheme.java ########## @@ -0,0 +1,218 @@ +/** + * 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.fs.viewfs; + +import java.io.IOException; +import java.lang.reflect.Constructor; +import java.lang.reflect.InvocationTargetException; +import java.net.URI; + +import java.net.URISyntaxException; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.AbstractFileSystem; +import org.apache.hadoop.fs.FsConstants; +import org.apache.hadoop.fs.Path; +import org.apache.hadoop.fs.UnsupportedFileSystemException; + +import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_IGNORE_PORT_IN_MOUNT_TABLE_NAME; + +/****************************************************************************** + * This class is AbstractFileSystem implementation corresponding to + * ViewFileSystemOverloadScheme. This class is extended from the ViewFs + * for the overloaded scheme file system. Mount link configurations and + * in-memory mount table building behaviors are inherited from ViewFs. + * Unlike ViewFs scheme (viewfs://), the users would be able to use any scheme. + * + * To use this class, the following configurations need to be added in + * core-site.xml file. + * 1) fs.AbstractFileSystem.<scheme>.impl + * = org.apache.hadoop.fs.viewfs.ViewFsOverloadScheme + * 2) fs.viewfs.overload.scheme.target.abstract.<scheme>.impl + * = <hadoop compatible file system implementation class name for the + * <scheme>" + * + * Here <scheme> can be any scheme, but with that scheme there should be a + * hadoop compatible file system available. Second configuration value should + * be the respective scheme's file system implementation class. + * Example: if scheme is configured with "hdfs", then the 2nd configuration + * class name will be org.apache.hadoop.hdfs.Hdfs. + * + * Use Case 1: + * =========== + * If users want some of their existing cluster (hdfs://Cluster) + * data to mount with other hdfs and object store clusters(hdfs://NN1, + * o3fs://bucket1.volume1/, s3a://bucket1/) + * + * fs.viewfs.mounttable.Cluster.link./user = hdfs://NN1/user + * fs.viewfs.mounttable.Cluster.link./data = o3fs://bucket1.volume1/data + * fs.viewfs.mounttable.Cluster.link./backup = s3a://bucket1/backup/ + * + * Op1: Create file hdfs://Cluster/user/fileA will go to hdfs://NN1/user/fileA + * Op2: Create file hdfs://Cluster/data/datafile will go to + * o3fs://bucket1.volume1/data/datafile + * Op3: Create file hdfs://Cluster/backup/data.zip will go to + * s3a://bucket1/backup/data.zip + * + * Use Case 2: + * =========== + * If users want some of their existing cluster (s3a://bucketA/) + * data to mount with other hdfs and object store clusters + * (hdfs://NN1, o3fs://bucket1.volume1/) + * + * fs.viewfs.mounttable.bucketA.link./user = hdfs://NN1/user + * fs.viewfs.mounttable.bucketA.link./data = o3fs://bucket1.volume1/data + * fs.viewfs.mounttable.bucketA.link./salesDB = s3a://bucketA/salesDB/ + * + * Op1: Create file s3a://bucketA/user/fileA will go to hdfs://NN1/user/fileA + * Op2: Create file s3a://bucketA/data/datafile will go to + * o3fs://bucket1.volume1/data/datafile + * Op3: Create file s3a://bucketA/salesDB/dbfile will go to + * s3a://bucketA/salesDB/dbfile + * + * Note: + * (1) In ViewFileSystemOverloadScheme, by default the mount links will be + * represented as non-symlinks. If you want to change this behavior, please see + * {@link ViewFileSystem#listStatus(Path)} + * (2) In ViewFileSystemOverloadScheme, only the initialized uri's hostname will + * be considered as the mount table name. When the passed uri has hostname:port, + * it will simply ignore the port number and only hostname will be considered as + * the mount table name. + * (3) If there are no mount links configured with the initializing uri's + * hostname as the mount table name, then it will automatically consider the + * current uri as fallback( ex: fs.viewfs.mounttable.<mycluster>.linkFallBack) + * target fs uri. + *****************************************************************************/ + +public class ViewFsOverloadScheme extends ViewFs { + private URI myUri; + private static final Class<?>[] URI_CONFIG_ARGS = + new Class[]{URI.class, Configuration.class}; + + public ViewFsOverloadScheme() throws IOException, URISyntaxException { + super(new Configuration()); + } + + public ViewFsOverloadScheme(final URI theUri, final Configuration conf) + throws IOException, URISyntaxException { + super(theUri, conf); + } + + @Override + void loadMountTable(URI theUri, Configuration conf, + boolean initingUriAsFallbackOnNoMounts) + throws URISyntaxException, IOException { + myUri = theUri; + /* The default value to false in ViewFSOverloadScheme */ + conf.setBoolean(Constants.CONFIG_VIEWFS_MOUNT_LINKS_AS_SYMLINKS, + conf.getBoolean(Constants.CONFIG_VIEWFS_MOUNT_LINKS_AS_SYMLINKS, + false)); + /* the default value to true in ViewFSOverloadScheme */ + conf.setBoolean(CONFIG_VIEWFS_IGNORE_PORT_IN_MOUNT_TABLE_NAME, + conf.getBoolean(Constants.CONFIG_VIEWFS_IGNORE_PORT_IN_MOUNT_TABLE_NAME, + true)); + loadMountTableConfigs(theUri, conf); + super.loadMountTable(theUri, conf, initingUriAsFallbackOnNoMounts); + } + + protected void loadMountTableConfigs(URI uri, Configuration conf) + throws IOException { + String mountTableConfigPath = + conf.get(Constants.CONFIG_VIEWFS_MOUNTTABLE_PATH); + if (null != mountTableConfigPath) { + MountTableConfigLoader loader = new HCFSMountTableConfigLoader(); + loader.load(mountTableConfigPath, conf); + } else { + // TODO: Should we fail here.? + if (LOG.isDebugEnabled()) { + LOG.debug( + "Missing configuration for fs.viewfs.mounttable.path. Proceeding" Review comment: Fixed. Also changed ViewFileSystemOverloadScheme.java ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
