kfsoutputstream.java

nandflash文件系统源代码

/**
 *
 * Licensed 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.
 *
 * @author: Sriram Rao (Kosmix Corp.)
 * 
 * Implements the Hadoop FSOutputStream interfaces to allow applications to write to
 * files in Kosmos File System (KFS).
 */

package org.apache.hadoop.fs.kfs;

import java.io.*;
import java.net.*;
import java.util.*;
import java.nio.ByteBuffer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.util.Progressable;

import org.kosmix.kosmosfs.access.KfsAccess;
import org.kosmix.kosmosfs.access.KfsOutputChannel;

class KFSOutputStream extends OutputStream {

    private String path;
    private KfsOutputChannel kfsChannel;

    public KFSOutputStream(KfsAccess kfsAccess, String path, short replication) {
        this.path = path;

        this.kfsChannel = kfsAccess.kfs_create(path, replication);
    }

    public long getPos() throws IOException {
        if (kfsChannel == null) {
            throw new IOException("File closed");
        }
        return kfsChannel.tell();
    }

    public void write(int v) throws IOException {
        if (kfsChannel == null) {
            throw new IOException("File closed");
        }
        byte[] b = new byte[1];

        b[0] = (byte) v;
        write(b, 0, 1);
    }

    public void write(byte b[], int off, int len) throws IOException {
        if (kfsChannel == null) {
            throw new IOException("File closed");
        }

        kfsChannel.write(ByteBuffer.wrap(b, off, len));
    }

    public void flush() throws IOException {
        if (kfsChannel == null) {
            throw new IOException("File closed");
        }
        kfsChannel.sync();
    }

    public synchronized void close() throws IOException {
        if (kfsChannel == null) {
            return;
        }
        flush();
        kfsChannel.close();
        kfsChannel = null;
    }
}