/**
* 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.mapreduce.filecache;
import java.io.*;
import java.util.*;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.util.*;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.mapred.DefaultTaskController;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.MRJobConfig;
import java.net.URI;
/**
* Distribute application-specific large, read-only files efficiently.
*
* <p><code>DistributedCache</code> is a facility provided by the Map-Reduce
* framework to cache files (text, archives, jars etc.) needed by applications.
* </p>
*
* <p>Applications specify the files, via urls (hdfs:// or http://) to be cached
* via the {@link org.apache.hadoop.mapred.JobConf}. The
* <code>DistributedCache</code> assumes that the files specified via urls are
* already present on the {@link FileSystem} at the path specified by the url
* and are accessible by every machine in the cluster.</p>
*
* <p>The framework will copy the necessary files on to the slave node before
* any tasks for the job are executed on that node. Its efficiency stems from
* the fact that the files are only copied once per job and the ability to
* cache archives which are un-archived on the slaves.</p>
*
* <p><code>DistributedCache</code> can be used to distribute simple, read-only
* data/text files and/or more complex types such as archives, jars etc.
* Archives (zip, tar and tgz/tar.gz files) are un-archived at the slave nodes.
* Jars may be optionally added to the classpath of the tasks, a rudimentary
* software distribution mechanism. Files have execution permissions.
* Optionally users can also direct it to symlink the distributed cache file(s)
* into the working directory of the task.</p>
*
* <p><code>DistributedCache</code> tracks modification timestamps of the cache
* files. Clearly the cache files should not be modified by the application
* or externally while the job is executing.</p>
*
* <p>Here is an illustrative example on how to use the
* <code>DistributedCache</code>:</p>
* <p><blockquote><pre>
* // Setting up the cache for the application
*
* 1. Copy the requisite files to the <code>FileSystem</code>:
*
* $ bin/hadoop fs -copyFromLocal lookup.dat /myapp/lookup.dat
* $ bin/hadoop fs -copyFromLocal map.zip /myapp/map.zip
* $ bin/hadoop fs -copyFromLocal mylib.jar /myapp/mylib.jar
* $ bin/hadoop fs -copyFromLocal mytar.tar /myapp/mytar.tar
* $ bin/hadoop fs -copyFromLocal mytgz.tgz /myapp/mytgz.tgz
* $ bin/hadoop fs -copyFromLocal mytargz.tar.gz /myapp/mytargz.tar.gz
*
* 2. Setup the application's <code>JobConf</code>:
*
* JobConf job = new JobConf();
* DistributedCache.addCacheFile(new URI("/myapp/lookup.dat#lookup.dat"),
* job);
* DistributedCache.addCacheArchive(new URI("/myapp/map.zip", job);
* DistributedCache.addFileToClassPath(new Path("/myapp/mylib.jar"), job);
* DistributedCache.addCacheArchive(new URI("/myapp/mytar.tar", job);
* DistributedCache.addCacheArchive(new URI("/myapp/mytgz.tgz", job);
* DistributedCache.addCacheArchive(new URI("/myapp/mytargz.tar.gz", job);
*
* 3. Use the cached files in the {@link org.apache.hadoop.mapred.Mapper}
* or {@link org.apache.hadoop.mapred.Reducer}:
*
* public static class MapClass extends MapReduceBase
* implements Mapper<K, V, K, V> {
*
* private Path[] localArchives;
* private Path[] localFiles;
*
* public void configure(JobConf job) {
* // Get the cached archives/files
* localArchives = DistributedCache.getLocalCacheArchives(job);
* localFiles = DistributedCache.getLocalCacheFiles(job);
* }
*
* public void map(K key, V value,
* OutputCollector<K, V> output, Reporter reporter)
* throws IOException {
* // Use data from the cached archives/files here
* // ...
* // ...
* output.collect(k, v);
* }
* }
*
* </pre></blockquote></p>
*
* It is also very common to use the DistributedCache by using
* {@link org.apache.hadoop.util.GenericOptionsParser}.
*
* This class includes methods that should be used by users
* (specifically those mentioned in the example above, as well
* as {@link DistributedCache#addArchiveToClassPath(Path, Configuration)}),
* as well as methods intended for use by the MapReduce framework
* (e.g., {@link org.apache.hadoop.mapred.JobClient}). For implementation
* details, see {@link TrackerDistributedCacheManager} and
* {@link TaskDistributedCacheManager}.
*
* @see TrackerDistributedCacheManager
* @see TaskDistributedCacheManager
* @see org.apache.hadoop.mapred.JobConf
* @see org.apache.hadoop.mapred.JobClient
*/
@Deprecated
@InterfaceAudience.Private
public class DistributedCache {
/**
* Get the locally cached file or archive; it could either be
* previously cached (and valid) or copy it from the {@link FileSystem} now.
*
* @param cache the cache to be localized, this should be specified as
* new URI(scheme://scheme-specific-part/absolute_path_to_file#LINKNAME).
* @param conf The Confguration file which contains the filesystem
* @param baseDir The base cache Dir where you wnat to localize the files/archives
* @param fileStatus The file status on the dfs.
* @param isArchive if the cache is an archive or a file. In case it is an
* archive with a .zip or .jar or .tar or .tgz or .tar.gz extension it will
* be unzipped/unjarred/untarred automatically
* and the directory where the archive is unzipped/unjarred/untarred is
* returned as the Path.
* In case of a file, the path to the file is returned
* @param confFileStamp this is the hdfs file modification timestamp to verify that the
* file to be cached hasn't changed since the job started
* @param currentWorkDir this is the directory where you would want to create symlinks
* for the locally cached files/archives
* @return the path to directory where the archives are unjarred in case of archives,
* the path to the file where the file is copied locally
* @throws IOException
* @deprecated Internal to MapReduce framework.
* Use TrackerDistributedCacheManager instead.
*/
@Deprecated
public static Path getLocalCache(URI cache, Configuration conf,
Path baseDir, FileStatus fileStatus,
boolean isArchive, long confFileStamp,
Path currentWorkDir)
throws IOException {
return getLocalCache(cache, conf, baseDir, fileStatus, isArchive,
confFileStamp, currentWorkDir, true);
}
/**
* Get the locally cached file or archive; it could either be
* previously cached (and valid) or copy it from the {@link FileSystem} now.
*
* @param cache the cache to be localized, this should be specified as
* new URI(scheme://scheme-specific-part/absolute_path_to_file#LINKNAME).
* @param conf The Confguration file which contains the filesystem
* @param baseDir The base cache Dir where you wnat to localize the files/archives
* @param fileStatus The file status on the dfs.
* @param isArchive if the cache is an archive or a file. In case it is an
* archive with a .zip or .jar or .tar or .tgz or .tar.gz extension it will
* be unzipped/unjarred/untarred automatically
* and the directory where the archive is unzipped/unjarred/untarred is
* returned as the Path.
* In case of a file, the path to the file is returned
* @param confFileStamp this is the hdfs file modification timestamp to verify that the
* file to be cached hasn't changed since the job started
* @param currentWorkDir this is the directory where you would want to create symlinks
* for the locally cached files/archives
* @param honorSymLinkConf if this is false, then the symlinks are not
* created even if conf says so (this is required for an optimization in task
* launches
* @return the path to directory where the archives are unjarred in case of archives,
* the path to the file where the file is copied locally
* @throws IOException
* @deprecated Internal to MapReduce framework.
* Use TrackerDistributedCacheManager instead.
*/
@Deprecated
public static Path getLocalCache(URI cache, Configuration conf,
Path baseDir, FileStatus fileStatus,
boolean isArchive, long confFileStamp,
Path currentWorkDir, boolean honorSymLinkConf) throws IOException {
return new TrackerDistributedCacheManager(conf, new DefaultTaskController())
.getLocalCache(cache, conf, baseDir.toString(), fileStatus, isArchive,
confFileStamp, currentWorkDir, honorSymLinkConf, false);
}
/**
* Get the locally cached file or archive; it could either be
* previously cached (and valid) or copy it from the {@link FileSystem} now.
*
* @param cache the cache to be localized, this should be specified as
* new URI(scheme://scheme-specific-part/absolute_path_to_file#LINKNAME).
* @param conf The Confguration file which contains the filesystem
* @param baseDir The base cache Dir where you wnat to localize the files/archives
* @param isArchive if the cache is an archive or a file. In case it is an
* archive with a .zip or .jar or .tar or .tgz or .tar.gz extension it will
* be unzipped/unjarred/untarred automatically
* and the directory where the archive is unzipped/unjarred/untarred
* is returned as the Path.
* In case of a file, the path to the file is returned
* @param confFileStamp this is the hdfs file modification timestamp to verify that the
* file to be cached hasn't changed since the job started
* @param currentWorkDir this is the directory where you would want to create symlinks
* for the locally cached files/archives
* @return the path to directory where the archives are unjarred in case of archives,
* the path to the file where the file is copied locally
* @throws IOException
* @deprecated Internal to MapReduce framework.
* Use TrackerDistributedCacheManager instead.
*/
@Deprecated
public static Path getLocalCache(URI cache, Configuration conf,
Path baseDir, boolean isArchive,
long confFileStamp, Path currentWorkDir)
throws IOException {
return getLocalCache(cache, conf,
baseDir, null, isArchive,
confFileStamp, currentWorkDir);
}
/**
* This is the opposite of getlocalcache. When you are done with
* using the cache, you need to release the cache
* @param cache The cache URI to be released
* @param conf configuration which contains the filesystem the cache
* is contained in.
* @throws IOException
* @deprecated Internal to MapReduce framework.
* Use TrackerDistributedCacheManager instead.
*/
@Deprecated
public static void releaseCache(URI cache, Configuration conf)
throws IOException {
// find the timestamp of the uri
URI[] archives = DistributedCache.getCacheArchives(conf);
URI[] files = DistributedCache.getCacheFiles(conf);
String[] archivesTimestamps =
DistributedCache.getArchiveTimestamps(conf);
String[] filesTimestamps =
DistributedCache.getFileTimestamps(conf);
String timestamp = null;
if (archives != null) {
for (int i = 0; i < archives.length; i++) {
if (archives[i].equals(cache)) {
timestamp = archivesTimestamps[i];
break;
}
}
}
if (timestamp == null && files != null) {
for (int i = 0; i < files.length; i++) {
if (files[i].equals(cache)) {
timestamp = filesTimestamps[i];
break;
}
}
}
if (timestamp == null) {
throw new IOException("TimeStamp of the uri couldnot be found");
}
new TrackerDistributedCacheManager(conf, new DefaultTaskController())
.releaseCache(cache, conf, Long.parseLong(timestamp));
}
/**
* Returns the relative path of the dir this cache will be localized in
* relative path that this cache will be localized in. For
* hdfs://hostname:port/absolute_path -- the relative path is
* hostname/absolute path -- if it is just /absolute_path -- then the
* relative path is hostname of DFS this mapred cluster is running
* on/absolute_path
* @deprecated Internal to MapReduce framework. Use DistributedCacheManager
* instead.
*/
@Deprecated
public static String makeRelative(URI cache, Configuration conf)
throws IOException {
return new TrackerDistributedCacheManager(conf, new DefaultTaskController())
.makeRelative(cache, conf);
}
/**
* Returns mtime of a given cache file on hdfs.
*
* @param conf configuration
* @param cache cache file
* @return mtime of a given cache file on hdfs
* @throws IOException
* @deprecated Internal to MapReduce framework.
* Use {@link TrackerDistributedCacheManager} instead.
*/
@Deprecated
public static long getTimestamp(Configuration conf, URI cache)
throws IOException {
return TrackerDistributedCacheManager.getTimestamp(conf, cache);
}
/**
* This method create symlinks for all files in a given dir in another directory
* @param conf the configuration
* @param jobCacheDir the target directory for creating symlinks
* @param workDir the directory in which the symlinks are created
* @throws IOException
* @deprecated Internal to MapReduce framework. Use DistributedCacheManager
* instead.
*/
@Deprecated
public static void createAllSymlink(Configuration conf, File jobCacheDir, File workDir)
throws IOException{
TrackerDistributedCacheManager.createAllSymlink(conf, jobCacheDir, workDir);
}
/**
* Set the configuration with the given set of archives. Intended
* to be used by user code.
* @param archives The list of archives that need to be localized
* @param conf Configuration which will be changed
* @deprecated Use {@link Job#setCacheArchives(URI[])} instead
*/
@Deprecated
public static void setCacheArchives(URI[] archives, Configuration conf) {
String sarchives = StringUtils.uriToString(archives);
conf.set(MRJobConfig.CACHE_ARCHIVES, sarchives);
}
/**
* Set the configuration with the given set of files. Intended to be
* used by user code.
* @param files The list of files that need to be localized
* @param conf Configuration which will be changed
* @deprecated Use {@link Job#setCacheFiles(URI[])} instead
*/
@Deprecated
public static void setCacheFiles(URI[] files, Configuration conf) {
String sfiles = StringUtils.uriToString(files);
conf.set(MRJobConfig.CACHE_FILES, sfiles);
}
/**
* Get cache archives set in the Configuration. Used by
* internal DistributedCache and MapReduce code.
* @param conf The configuration which contains the archives
* @return A URI array of the caches set in the Configuration
* @throws IOException
* @deprecated Use {@link JobContext#getCacheArchives()} instead
*/
@Deprecated
public static URI[] getCacheArchives(Configuration conf) throws IOException {
return StringUtils.stringToURI(conf.getStrings(MRJobConfig.CACHE_ARCHIVES));
}
/**
* Get cache files set in the Configuration. Used by internal
* DistributedCache and MapReduce code.
* @param conf The configuration which contains the files
* @return A URI array of the files set in the Configuration
* @throws IOException
* @deprecated Use {@link JobContext#getCacheFiles()} instead
*/
@Deprecated
public static URI[] getCacheFiles(Configuration conf) throws IOException {
return StringUtils.stringToURI(conf.getStrings(MRJobConfig.CACHE_FILES));
}
/**
* Return the path array of the localized caches. Intended to be used
* by user code.
* @param conf Configuration that contains the localized archives
* @return A path array of localized caches
* @throws IOException
* @deprecated Use {@link JobContext#getLocalCacheArchives()} instead
*/
@Deprecated
public static Path[] getLocalCacheArchives(Configuration conf)
throws IOException {
return StringUtils.stringToPath(conf
.getStrings(MRJobConfig.CACHE_LOCALARCHIVES));
}
/**
* Return the path array of the localized files. Intended to be used
* by user code.
* @param conf Configuration that contains the localized files
* @return A path array of localized files
* @throws IOException
* @deprecated Use {@link JobContext#getLocalCacheFiles()} instead
*/
@Deprecated
public static Path[] getLocalCacheFiles(Configuration conf)
throws IOException {
return StringUtils.stringToPath(conf.getStrings(MRJobConfig.CACHE_LOCALFILES));
}
/**
* Get the timestamps of the archives. Used by internal
* DistributedCache and MapReduce code.
* @param conf The configuration which stored the timestamps
* @return a string array of timestamps
* @throws IOException
* @deprecated Use {@link JobContext#getArchiveTimestamps()} instead
*/
@Deprecated
public static String[] getArchiveTimestamps(Configuration conf) {
return conf.getStrings(MRJobConfig.CACHE_ARCHIVES_TIMESTAMPS);
}
/**
* Get the timestamps of the files. Used by internal
* DistributedCache and MapReduce code.
* @param conf The configuration which stored the timestamps
* @return a string array of timestamps
* @throws IOException
* @deprecated Use {@link JobContext#getFileTimestamps()} instead
*/
@Deprecated
public static String[] getFileTimestamps(Configuration conf) {
return conf.getStrings(MRJobConfig.CACHE_FILE_TIMESTAMPS);
}
/**
* This is to check the timestamp of the archives to be localized.
* Used by internal MapReduce code.
* @param conf Configuration which stores the timestamp's
* @param timestamps comma separated list of timestamps of archives.
* The order should be the same as the order in which the archives are added.
* @deprecated Use
* {@link TrackerDistributedCacheManager#setArchiveTimestamps(Configuration, String)}
* instead
*/
@Deprecated
public static void setArchiveTimestamps(Configuration conf, String timestamps) {
TrackerDistributedCacheManager.setArchiveTimestamps(conf, timestamps);
}
/**
* This is to check the timestamp of the files to be localized.
* Used by internal MapReduce code.
* @param conf Configuration which stores the timestamp's
* @param timestamps comma separated list of timestamps of files.
* The order should be the same as the order in which the files are added.
* @deprecated Use
* {@link TrackerDistributedCacheManager#setFileTimestamps(Configuration, String)}
* instead
*/
@Deprecated
public static void setFileTimestamps(Configuration conf, String timestamps) {
TrackerDistributedCacheManager.setFileTimestamps(conf, timestamps);
}
/**
* Set the conf to contain the location for localized archives. Used
* by internal DistributedCache code.
* @param conf The conf to modify to contain the localized caches
* @param str a comma separated list of local archives
* @deprecated Use
* {@link TrackerDistributedCacheManager#setLocalArchives(Configuration, String)}
* instead
*/
@Deprecated
public static void setLocalArchives(Configuration conf, String str) {
TrackerDistributedCacheManager.setLocalArchives(conf, str);
}
/**
* Set the conf to contain the location for localized files. Used
* by internal DistributedCache code.
* @param conf The conf to modify to contain the localized caches
* @param str a comma separated list of local files
* @deprecated Use
* {@link TrackerDistributedCacheManager#setLocalFiles(Configuration, String)}
* instead
*/
@Deprecated
public static void setLocalFiles(Configuration conf, String str) {
TrackerDistributedCacheManager.setLocalFiles(conf, str);
}
/**
* Add a archives to be localized to the conf. Intended to
* be used by user code.
* @param uri The uri of the cache to be localized
* @param conf Configuration to add the cache to
* @deprecated Use {@link Job#addCacheArchive(URI)} instead
*/
@Deprecated
public static void addCacheArchive(URI uri, Configuration conf) {
String archives = conf.get(MRJobConfig.CACHE_ARCHIVES);
conf.set(MRJobConfig.CACHE_ARCHIVES, archives == null ? uri.toString()
: archives + "," + uri.toString());
}
/**
* Add a file to be localized to the conf. Intended
* to be used by user code.
* @param uri The uri of the cache to be localized
* @param conf Configuration to add the cache to
* @deprecated Use {@link Job#addCacheFile(URI)} instead
*/
@Deprecated
public static void addCacheFile(URI uri, Configuration conf) {
String files = conf.get(MRJobConfig.CACHE_FILES);
conf.set(MRJobConfig.CACHE_FILES, files == null ? uri.toString() : files + ","
+ uri.toString());
}
/**
* Add an file path to the current set of classpath entries It adds the file
* to cache as well. Intended to be used by user code.
*
* @param file Path of the file to be added
* @param conf Configuration that contains the classpath setting
* @deprecated Use {@link Job#addFileToClassPath(Path)} instead
*/
@Deprecated
public static void addFileToClassPath(Path file, Configuration conf)
throws IOException {
String classpath = conf.get(MRJobConfig.CLASSPATH_FILES);
conf.set(MRJobConfig.CLASSPATH_FILES, classpath == null ? file.toString()
: classpath + "," + file.toString());
FileSystem fs = FileSystem.get(conf);
URI uri = fs.makeQualified(file).toUri();
addCacheFile(uri, conf);
}
/**
* Get the file entries in classpath as an array of Path.
* Used by internal DistributedCache code.
*
* @param conf Configuration that contains the classpath setting
* @deprecated Use {@link JobContext#getFileClassPaths()} instead
*/
@Deprecated
public static Path[] getFileClassPaths(Configuration conf) {
ArrayList<String> list = (ArrayList<String>)conf.getStringCollection(
MRJobConfig.CLASSPATH_FILES);
if (list.size() == 0) {
return null;
}
Path[] paths = new Path[list.size()];
for (int i = 0; i < list.size(); i++) {
paths[i] = new Path(list.get(i));
}
return paths;
}
/**
* Add an archive path to the current set of classpath entries. It adds the
* archive to cache as well. Intended to be used by user code.
*
* @param archive Path of the archive to be added
* @param conf Configuration that contains the classpath setting
* @deprecated Use {@link Job#addArchiveToClassPath(Path)} instead
*/
@Deprecated
public static void addArchiveToClassPath(Path archive, Configuration conf)
throws IOException {
String classpath = conf.get(MRJobConfig.CLASSPATH_ARCHIVES);
conf.set(MRJobConfig.CLASSPATH_ARCHIVES, classpath == null ? archive
.toString() : classpath + "," + archive.toString());
FileSystem fs = FileSystem.get(conf);
URI uri = fs.makeQualified(archive).toUri();
addCacheArchive(uri, conf);
}
/**
* Get the archive entries in classpath as an array of Path.
* Used by internal DistributedCache code.
*
* @param conf Configuration that contains the classpath setting
* @deprecated Use {@link JobContext#getArchiveClassPaths()} instead
*/
@Deprecated
public static Path[] getArchiveClassPaths(Configuration conf) {
ArrayList<String> list = (ArrayList<String>)conf.getStringCollection(
MRJobConfig.CLASSPATH_ARCHIVES);
if (list.size() == 0) {
return null;
}
Path[] paths = new Path[list.size()];
for (int i = 0; i < list.size(); i++) {
paths[i] = new Path(list.get(i));
}
return paths;
}
/**
* This method allows you to create symlinks in the current working directory
* of the task to all the cache files/archives.
* Intended to be used by user code.
* @param conf the jobconf
* @deprecated Use {@link Job#createSymlink()} instead
*/
@Deprecated
public static void createSymlink(Configuration conf){
conf.set(MRJobConfig.CACHE_SYMLINK, "yes");
}
/**
* This method checks to see if symlinks are to be create for the
* localized cache files in the current working directory
* Used by internal DistributedCache code.
* @param conf the jobconf
* @return true if symlinks are to be created- else return false
* @deprecated Use {@link JobContext#getSymlink()} instead
*/
@Deprecated
public static boolean getSymlink(Configuration conf){
String result = conf.get(MRJobConfig.CACHE_SYMLINK);
if ("yes".equals(result)){
return true;
}
return false;
}
/**
* This method checks if there is a conflict in the fragment names
* of the uris. Also makes sure that each uri has a fragment. It
* is only to be called if you want to create symlinks for
* the various archives and files. May be used by user code.
* @param uriFiles The uri array of urifiles
* @param uriArchives the uri array of uri archives
* @deprecated Use
* {@link TrackerDistributedCacheManager#checkURIs(URI[], URI[])} instead
*/
@Deprecated
public static boolean checkURIs(URI[] uriFiles, URI[] uriArchives){
return TrackerDistributedCacheManager.checkURIs(uriFiles, uriArchives);
}
/**
* Clear the entire contents of the cache and delete the backing files. This
* should only be used when the server is reinitializing, because the users
* are going to lose their files.
* @deprecated Internal to MapReduce framework.
* Use TrackerDistributedCacheManager instead.
*/
@Deprecated
public static void purgeCache(Configuration conf) throws IOException {
new TrackerDistributedCacheManager(conf, new DefaultTaskController())
.purgeCache();
}
}