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

   1 //
   2 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   3 //
   4 // Permission is hereby granted, free of charge, to any person obtaining
   5 // a copy of this software and associated documentation files (the
   6 // "Software"), to deal in the Software without restriction, including
   7 // without limitation the rights to use, copy, modify, merge, publish,
   8 // distribute, sublicense, and/or sell copies of the Software, and to
   9 // permit persons to whom the Software is furnished to do so, subject to
  10 // the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be
  13 // included in all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  19 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  20 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  21 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  22 //
  23 using System;
  24 using System.Collections;
  25
  26 namespace System.Data.Common
  27 {
  28         internal class RecordCache {
  29                 #region Fields
  30
  31                 const int MIN_CACHE_SIZE = 128;
  32
  33                 Stack _records = new Stack (16);
  34                 int _nextFreeIndex = 0;
  35                 int _currentCapacity = 0;
  36                 DataTable _table;
  37                 DataRow [] _rowsToRecords;
  38
  39                 #endregion // Fields
  40
  41                 #region Constructors
  42
  43                 internal RecordCache (DataTable table)
  44                 {
  45                         _table = table;
  46                         _rowsToRecords = table.NewRowArray (16);
  47                 }
  48
  49                 #endregion //Constructors
  50
  51                 #region Properties
  52
  53                 internal int CurrentCapacity {
  54                         get { return _currentCapacity; }
  55                 }
  56
  57                 internal DataRow this [int index] {
  58                         get { return _rowsToRecords [index]; }
  59                         set {
  60                                 if (index >= 0)
  61                                         _rowsToRecords [index] = value;
  62                         }
  63                 }
  64
  65                 #endregion // Properties
  66
  67                 #region Methods
  68
  69                 internal int NewRecord ()
  70                 {
  71                         if (_records.Count > 0)
  72                                 return (int) _records.Pop ();
  73
  74                         DataColumnCollection cols = _table.Columns;
  75                         if (_nextFreeIndex >= _currentCapacity) {
  76                                 _currentCapacity *= 2;
  77                                 if (_currentCapacity < MIN_CACHE_SIZE)
  78                                         _currentCapacity = MIN_CACHE_SIZE;
  79
  80                                 for (int i = 0; i < cols.Count; ++i)
  81                                         cols [i].DataContainer.Capacity = _currentCapacity;
  82
  83                                 DataRow [] old = _rowsToRecords;
  84                                 _rowsToRecords = _table.NewRowArray (_currentCapacity);
  85                                 Array.Copy (old, 0, _rowsToRecords, 0, old.Length);
  86                         }
  87                         return _nextFreeIndex++;
  88                 }
  89
  90                 internal void DisposeRecord (int index)
  91                 {
  92                         if (index < 0)
  93                                 throw new ArgumentException ();
  94
  95                         if (!_records.Contains (index))
  96                                 _records.Push (index);
  97
  98                         this [index] = null;
  99                 }
 100
 101                 // FIXME: This doesn't seem to be the right class to have this method
 102                 internal int CopyRecord (DataTable fromTable, int fromRecordIndex, int toRecordIndex)
 103                 {
 104                         int recordIndex = toRecordIndex;
 105                         if (toRecordIndex == -1)
 106                                 recordIndex = NewRecord ();
 107
 108                         try {
 109                                 foreach (DataColumn toColumn in _table.Columns) {
 110                                         DataColumn fromColumn = fromTable.Columns [toColumn.ColumnName];
 111                                         if (fromColumn != null)
 112                                                 toColumn.DataContainer.CopyValue (fromColumn.DataContainer, fromRecordIndex, recordIndex);
 113                                         else
 114                                                 toColumn.DataContainer.CopyValue (_table.DefaultValuesRowIndex, recordIndex);
 115                                 }
 116                                 return recordIndex;
 117                         } catch {
 118                                 if (toRecordIndex == -1)
 119                                         DisposeRecord (recordIndex);
 120
 121                                 throw;
 122                         }
 123                 }
 124
 125                 // FIXME: This doesn't seem to be the right class to have this method
 126                 internal void ReadIDataRecord (int recordIndex, IDataRecord record, int [] mapping, int length)
 127                 {
 128                         if (mapping.Length > _table.Columns.Count)
 129                                 throw new ArgumentException ();
 130
 131                         int i = 0;
 132                         for(; i < length; i++) {
 133                                 DataColumn column = _table.Columns [mapping [i]];
 134                                 column.DataContainer.SetItemFromDataRecord (recordIndex, record, i);
 135                         }
 136
 137                         for (; i < mapping.Length; i++) {
 138                                 DataColumn column = _table.Columns [mapping [i]];
 139                                 if (column.AutoIncrement)
 140                                         column.DataContainer [recordIndex] = column.AutoIncrementValue ();
 141                                 else
 142                                         column.DataContainer [recordIndex] = column.DefaultValue;
 143                         }
 144                 }
 145
 146                 #endregion // Methods
 147         }
 148 }