How to retrieve cached data in datanode? (Centralized cache management)

[남윤민 <ro...@dgist.ac.kr>]

 Hello, I have a question about using the cached data in memory via centralized cache management. I cached the data what I want to use through the CLI (hdfs cacheadmin -addDirectives ...).Then, when I write my mapreduce application, how can I read the cached data in memory? Here is the source code from my mapreduce application.    System.out.println("Ready for loading customer table from Centralized Cache in DataNode");   System.out.println("Connecting HDFS... at " + hdfsURI.toString());   DFSClient dfs = new DFSClient(hdfsURI, new Configuration());   CacheDirectiveInfo info =      new CacheDirectiveInfo.Builder().setPath(new Path("path in HDFS for cached data")).setPool("cache").build();   CacheDirectiveEntry cachedFile = dfs.listCacheDirectives(info).next();   System.out.println("We got cachedFile! ID: " +    cachedFile.getInfo().getId() + ", Path: " + cachedFile.getInfo().getPath() + ", CachedPool: " + cachedFile.getInfo().getPool());      System.out.println("Open DFSInputStream t
 o read cachedFile to ByteBuffer");   DFSInputStream in = dfs.open(cachedFile.getInfo().getPath().toString());   ElasticByteBufferPool bufPool = new ElasticByteBufferPool();   ByteBuffer buf = ByteBuffer.allocate(10000);   System.out.println("Generating Off-Heap ByteBuffer! size: " + buf.capacity());   in.read(buf);   buf.flip(); // Flip: ready for reading data after writing data into buffer   System.out.println("Zero-Copying cached file into buffer!");  
Is it right source code for using the centralized cache management feature?
Thanks


// Yoonmin Nam