mcs/class/System.Data/System.Data.Common/RecordCache.cs

   1
   2 //
   3 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining
   6 // a copy of this software and associated documentation files (the
   7 // "Software"), to deal in the Software without restriction, including
   8 // without limitation the rights to use, copy, modify, merge, publish,
   9 // distribute, sublicense, and/or sell copies of the Software, and to
  10 // permit persons to whom the Software is furnished to do so, subject to
  11 // the following conditions:
  12 //
  13 // The above copyright notice and this permission notice shall be
  14 // included in all copies or substantial portions of the Software.
  15 //
  16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  18 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  20 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  21 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  22 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23 //
  24 using System;
  25 using System.Collections;
  26
  27 namespace System.Data.Common
  28 {
  29         internal class RecordCache
  30         {
  31                 #region Fields
  32
  33                 const int MIN_CACHE_SIZE = 128;
  34
  35                 Stack _records = new Stack(16);
  36                 int _nextFreeIndex = 0;
  37                 int _currentCapacity = 0;
  38                 DataTable _table;
  39
  40                 #endregion // Fields
  41
  42                 #region Constructors
  43
  44                 internal RecordCache(DataTable table)
  45                 {
  46                         _table = table;
  47                 }
  48
  49                 #endregion //Constructors
  50
  51                 #region Properties
  52
  53                 internal int CurrentCapacity
  54                 {
  55                         get {
  56                                 return _currentCapacity;
  57                         }
  58                 }
  59
  60                 #endregion // Properties
  61
  62                 #region Methods
  63
  64                 internal int NewRecord()
  65                 {
  66                         if (_records.Count > 0) {
  67                                 return (int)_records.Pop();
  68                         }
  69                         else {
  70                                 DataColumnCollection cols = _table.Columns;
  71                                 if (_nextFreeIndex >= _currentCapacity) {
  72                                         _currentCapacity *= 2;
  73                                         if ( _currentCapacity < MIN_CACHE_SIZE ) {
  74                                                 _currentCapacity = MIN_CACHE_SIZE;
  75                                         }
  76                                         foreach(DataColumn col in cols) {
  77                                                 col.DataContainer.Capacity = _currentCapacity;
  78                                         }
  79                                 }
  80                                 return _nextFreeIndex++;
  81                         }
  82                 }
  83
  84                 internal void DisposeRecord(int index)
  85                 {
  86                         if ( index < 0 ) {
  87                                 throw new ArgumentException();
  88                         }
  89                         _records.Push(index);
  90                 }
  91
  92                 internal int CopyRecord(DataTable fromTable,int fromRecordIndex,int toRecordIndex)
  93                 {
  94                         int recordIndex = toRecordIndex;
  95                         if (toRecordIndex == -1) {
  96                                 recordIndex = NewRecord();
  97                         }
  98
  99                         foreach(DataColumn fromColumn in fromTable.Columns) {
 100                                 DataColumn column = _table.Columns[fromColumn.ColumnName];
 101                                 if (column != null) {
 102                                         column.DataContainer.CopyValue(fromColumn.DataContainer,fromRecordIndex,recordIndex);
 103                                 }
 104                         }
 105
 106                         return recordIndex;
 107                 }
 108
 109                 #endregion // Methods
 110
 111         }
 112 }