com.cloudera.hadoop.hdfs.nfs.nfs4.handlers.READHandler.java Source code

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/**
 * Copyright 2011 The Apache Software Foundation
 *
 * 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 com.cloudera.hadoop.hdfs.nfs.nfs4.handlers;

import static com.cloudera.hadoop.hdfs.nfs.nfs4.Constants.*;

import java.io.IOException;

import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import com.cloudera.hadoop.hdfs.nfs.nfs4.FileHandle;
import com.cloudera.hadoop.hdfs.nfs.nfs4.NFS4Exception;
import com.cloudera.hadoop.hdfs.nfs.nfs4.NFS4Handler;
import com.cloudera.hadoop.hdfs.nfs.nfs4.Session;
import com.cloudera.hadoop.hdfs.nfs.nfs4.requests.READRequest;
import com.cloudera.hadoop.hdfs.nfs.nfs4.responses.READResponse;
import org.apache.log4j.Logger;

public class READHandler extends OperationRequestHandler<READRequest, READResponse> {

    protected static final Logger LOGGER = Logger.getLogger(READHandler.class);

    @Override
    protected READResponse doHandle(NFS4Handler server, Session session, READRequest request)
            throws NFS4Exception, IOException {
        if (session.getCurrentFileHandle() == null) {
            throw new NFS4Exception(NFS4ERR_NOFILEHANDLE);
        }
        int size = Math.min(request.getCount(), NFS4_MAX_RWSIZE);
        if (size < 0) {
            throw new NFS4Exception(NFS4ERR_INVAL);
        }
        FileHandle fileHandle = session.getCurrentFileHandle();
        Path path = server.getPath(fileHandle);
        FileSystem fs = session.getFileSystem();
        FSDataInputStream inputStream = server.forRead(request.getStateID(), fs, fileHandle);
        synchronized (inputStream) {
            if (inputStream.getPos() != request.getOffset()) {
                try {
                    inputStream.seek(request.getOffset());
                } catch (IOException e) {
                    throw new IOException(e.getMessage() + ": " + inputStream.getPos() + ", " + request.getOffset(),
                            e);
                }
                server.incrementMetric("NFS_RANDOM_READS", 1);
            }
            READResponse response = createResponse();
            byte[] data = new byte[size];
            int count = inputStream.read(data);
            long fileLength = -1;
            if (count > 0 && count != data.length
                    && (request.getOffset() + count) < (fileLength = fs.getFileStatus(path).getLen())) {
                LOGGER.info("Short read " + path + " at pos = " + request.getOffset() + ", wanted " + data.length
                        + " and read " + count + ", fileLength = " + fileLength);
                server.incrementMetric("NFS_SHORT_READS", 1);
            }
            boolean eof = count < 0;
            if (eof) {
                data = new byte[0];
                count = 0;
            }
            server.incrementMetric("HDFS_BYTES_READ", count);
            response.setData(data, 0, count);
            response.setEOF(eof);
            response.setStatus(NFS4_OK);
            return response;
        }
    }

    @Override
    protected READResponse createResponse() {
        return new READResponse();
    }
}