beagled/Lucene.Net/Store/BufferedIndexOutput.cs

   1 /*
   2  * Copyright 2005 The Apache Software Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 using System;
  17 namespace Lucene.Net.Store
  18 {
  19
  20     /// <summary>Base implementation class for buffered {@link IndexOutput}. </summary>
  21     public abstract class BufferedIndexOutput:IndexOutput
  22     {
  23         internal const int BUFFER_SIZE = 1024;
  24
  25         private byte[] buffer = new byte[BUFFER_SIZE];
  26         private long bufferStart = 0; // position in file of buffer
  27         private int bufferPosition = 0; // position in buffer
  28
  29         /// <summary>Writes a single byte.</summary>
  30         /// <seealso cref="IndexInput#ReadByte()">
  31         /// </seealso>
  32         public override void  WriteByte(byte b)
  33         {
  34             if (bufferPosition >= BUFFER_SIZE)
  35                 Flush();
  36             buffer[bufferPosition++] = b;
  37         }
  38
  39         /// <summary>Writes an array of bytes.</summary>
  40         /// <param name="b">the bytes to write
  41         /// </param>
  42         /// <param name="length">the number of bytes to write
  43         /// </param>
  44         /// <seealso cref="IndexInput#ReadBytes(byte[],int,int)">
  45         /// </seealso>
  46         public override void  WriteBytes(byte[] b, int length)
  47         {
  48             for (int i = 0; i < length; i++)
  49                 WriteByte(b[i]);
  50         }
  51
  52         /// <summary>Forces any buffered output to be written. </summary>
  53         public override void  Flush()
  54         {
  55             FlushBuffer(buffer, bufferPosition);
  56             bufferStart += bufferPosition;
  57             bufferPosition = 0;
  58         }
  59
  60         /// <summary>Expert: implements buffer write.  Writes bytes at the current position in
  61         /// the output.
  62         /// </summary>
  63         /// <param name="b">the bytes to write
  64         /// </param>
  65         /// <param name="len">the number of bytes to write
  66         /// </param>
  67         public abstract void  FlushBuffer(byte[] b, int len);
  68
  69         /// <summary>Closes this stream to further operations. </summary>
  70         public override void  Close()
  71         {
  72             Flush();
  73         }
  74
  75         /// <summary>Returns the current position in this file, where the next write will
  76         /// occur.
  77         /// </summary>
  78         /// <seealso cref="#Seek(long)">
  79         /// </seealso>
  80         public override long GetFilePointer()
  81         {
  82             return bufferStart + bufferPosition;
  83         }
  84
  85         /// <summary>Sets current position in this file, where the next write will occur.</summary>
  86         /// <seealso cref="#GetFilePointer()">
  87         /// </seealso>
  88         public override void  Seek(long pos)
  89         {
  90             Flush();
  91             bufferStart = pos;
  92         }
  93
  94         /// <summary>The number of bytes in the file. </summary>
  95         public abstract override long Length();
  96     }
  97 }