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/*
* 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.
*/
using System;
namespace Lucene.Net.Store
{
/// <summary>Base implementation class for buffered {@link IndexOutput}. </summary>
public abstract class BufferedIndexOutput : IndexOutput
{
internal const int BUFFER_SIZE = 16384;
private byte[] buffer = new byte[BUFFER_SIZE];
private long bufferStart = 0; // position in file of buffer
private int bufferPosition = 0; // position in buffer
/// <summary>Writes a single byte.</summary>
/// <seealso cref="IndexInput.ReadByte()">
/// </seealso>
public override void WriteByte(byte b)
{
if (bufferPosition >= BUFFER_SIZE)
Flush();
buffer[bufferPosition++] = b;
}
/// <summary>Writes an array of bytes.</summary>
/// <param name="b">the bytes to write
/// </param>
/// <param name="length">the number of bytes to write
/// </param>
/// <seealso cref="IndexInput.ReadBytes(byte[],int,int)">
/// </seealso>
public override void WriteBytes(byte[] b, int offset, int length)
{
int bytesLeft = BUFFER_SIZE - bufferPosition;
// is there enough space in the buffer?
if (bytesLeft >= length)
{
// we add the data to the end of the buffer
Array.Copy(b, offset, buffer, bufferPosition, length);
bufferPosition += length;
// if the buffer is full, flush it
if (BUFFER_SIZE - bufferPosition == 0)
Flush();
}
else
{
// is data larger then buffer?
if (length > BUFFER_SIZE)
{
// we flush the buffer
if (bufferPosition > 0)
Flush();
// and write data at once
FlushBuffer(b, offset, length);
bufferStart += length;
}
else
{
// we fill/flush the buffer (until the input is written)
int pos = 0; // position in the input data
int pieceLength;
while (pos < length)
{
pieceLength = (length - pos < bytesLeft)?length - pos:bytesLeft;
Array.Copy(b, pos + offset, buffer, bufferPosition, pieceLength);
pos += pieceLength;
bufferPosition += pieceLength;
// if the buffer is full, flush it
bytesLeft = BUFFER_SIZE - bufferPosition;
if (bytesLeft == 0)
{
Flush();
bytesLeft = BUFFER_SIZE;
}
}
}
}
}
/// <summary>Forces any buffered output to be written. </summary>
public override void Flush()
{
FlushBuffer(buffer, bufferPosition);
bufferStart += bufferPosition;
bufferPosition = 0;
}
/// <summary>Expert: implements buffer write. Writes bytes at the current position in
/// the output.
/// </summary>
/// <param name="b">the bytes to write
/// </param>
/// <param name="len">the number of bytes to write
/// </param>
private void FlushBuffer(byte[] b, int len)
{
FlushBuffer(b, 0, len);
}
/// <summary>Expert: implements buffer write. Writes bytes at the current position in
/// the output.
/// </summary>
/// <param name="b">the bytes to write
/// </param>
/// <param name="offset">the offset in the byte array
/// </param>
/// <param name="len">the number of bytes to write
/// </param>
public abstract void FlushBuffer(byte[] b, int offset, int len);
/// <summary>Closes this stream to further operations. </summary>
public override void Close()
{
Flush();
}
/// <summary>Returns the current position in this file, where the next write will
/// occur.
/// </summary>
/// <seealso cref="Seek(long)">
/// </seealso>
public override long GetFilePointer()
{
return bufferStart + bufferPosition;
}
/// <summary>Sets current position in this file, where the next write will occur.</summary>
/// <seealso cref="GetFilePointer()">
/// </seealso>
public override void Seek(long pos)
{
Flush();
bufferStart = pos;
}
/// <summary>The number of bytes in the file. </summary>
public abstract override long Length();
}
}
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