IFileWriter.java

/**
 * 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.facebook.infrastructure.io;

import java.io.File;
import java.io.IOException;

/**
 * An interface for writing into the SequenceFile abstraction.
 * Author : Avinash Lakshman ( alakshman@facebook.com) & Prashant Malik ( pmalik@facebook.com )
 */

public interface IFileWriter
{
    /**
     * Get the current position of the file pointer.
     * @return current file pointer position
     * @throws IOException
     */
    public long getCurrentPosition() throws IOException;
    
    /**
     * @return the last file modification time.
     */
    public long lastModified();
    
    /**
     * Seeks the file pointer to the specified position.
     * @param position position within the file to seek to.
     * @throws IOException
     */
    public void seek(long position) throws IOException;
    
    /**
     * Appends the key and the value to the the underlying SequenceFile.
     * @param keyBuffer buffer which contains the serialized key.
     * @param buffer buffer which contains the serialized data.
     * @throws IOException
     */
    public void append(DataOutputBuffer keyBuffer, DataOutputBuffer buffer) throws IOException;
    
    /**
     * Appends the key and the value to the the underlying SequenceFile.
     * @param key key associated with this peice of data.
     * @param buffer buffer containing the serialized data.
     * @throws IOException
     */
    public void append(String key, DataOutputBuffer buffer) throws IOException;
    
    /**
     * Appends the key and the value to the the underlying SequenceFile.
     * @param key key associated with this peice of data.
     * @param value byte array containing the serialized data.
     * @throws IOException
     */
    public void append(String key, byte[] value) throws IOException;
    
    /**
     * Appends the key and the long value to the the underlying SequenceFile.
     * This is used in the contruction of the index file associated with a 
     * SSTable.
     * @param key key associated with this peice of data.
     * @param value value associated with this key.
     * @throws IOException
     */
    public void append(String key, long value) throws IOException;
    
    /**
     * Be extremely careful while using this API. This currently
     * used to write the commit log header in the commit logs.
     * If not used carefully it could completely screw up reads
     * of other key/value pairs that are written. 
     * 
     * @param bytes serialized version of the commit log header.
     * @throws IOException
    */
    public long writeDirect(byte[] bytes) throws IOException;
      
    /**
     * Close the file which is being used for the write.
     * @throws IOException
     */
    public void close() throws IOException;  
    
    /**
     * Close the file after appending the passed in footer information.
     * @param footer footer information.
     * @param size size of the footer.
     * @throws IOException
     */
    public void close(byte[] footer, int size) throws IOException;
    
    /**
     * @return the name of the file.
     */
    public String getFileName();    
    
    /**
     * @return the size of the file.
     * @throws IOException
     */
    public long getFileSize() throws IOException;    
}