/*
 * 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.cassandra.io.util;

import java.nio.ByteBuffer;

import org.apache.cassandra.io.compress.BufferType;

RandomFileReader component that reads data from a file into a provided buffer and may have requirements over the
size and alignment of reads.
A caching or buffer-managing rebufferer will reference one of these to do the actual reading.
Note: Implementations of this interface must be thread-safe!
/**
 * RandomFileReader component that reads data from a file into a provided buffer and may have requirements over the
 * size and alignment of reads.
 * A caching or buffer-managing rebufferer will reference one of these to do the actual reading.
 * Note: Implementations of this interface must be thread-safe!
 */
public interface ChunkReader extends RebuffererFactory
{
    
Read the chunk at the given position, attempting to fill the capacity of the given buffer.
The filled buffer must be positioned at 0, with limit set at the size of the available data.
The source may have requirements for the positioning and/or size of the buffer (e.g. chunk-aligned and
chunk-sized). These must be satisfied by the caller. 
/**
     * Read the chunk at the given position, attempting to fill the capacity of the given buffer.
     * The filled buffer must be positioned at 0, with limit set at the size of the available data.
     * The source may have requirements for the positioning and/or size of the buffer (e.g. chunk-aligned and
     * chunk-sized). These must be satisfied by the caller. 
     */
    void readChunk(long position, ByteBuffer buffer);

    
Buffer size required for this rebufferer. Must be power of 2 if alignment is required.
/**
     * Buffer size required for this rebufferer. Must be power of 2 if alignment is required.
     */
    int chunkSize();

    
Specifies type of buffer the caller should attempt to give.
This is not guaranteed to be fulfilled.
/**
     * Specifies type of buffer the caller should attempt to give.
     * This is not guaranteed to be fulfilled.
     */
    BufferType preferredBufferType();
}