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                 DataRow[] _rowsToRecords;
  40
  41                 #endregion // Fields
  42
  43                 #region Constructors
  44
  45                 internal RecordCache(DataTable table)
  46                 {
  47                         _table = table;
  48                         _rowsToRecords = table.NewRowArray(16);
  49                 }
  50
  51                 #endregion //Constructors
  52
  53                 #region Properties
  54
  55                 internal int CurrentCapacity
  56                 {
  57                         get {
  58                                 return _currentCapacity;
  59                         }
  60                 }
  61
  62                 internal DataRow this[int index]
  63                 {
  64                         get {
  65                                 return _rowsToRecords[index];
  66                         }
  67
  68                         set {
  69                                 if (index >= 0) {
  70                                         _rowsToRecords[index] = value;
  71                                 }
  72                         }
  73                 }
  74
  75                 #endregion // Properties
  76
  77                 #region Methods
  78
  79                 internal int NewRecord()
  80                 {
  81                         if (_records.Count > 0) {
  82                                 return (int)_records.Pop();
  83                         }
  84                         else {
  85                                 DataColumnCollection cols = _table.Columns;
  86                                 if (_nextFreeIndex >= _currentCapacity) {
  87                                         _currentCapacity *= 2;
  88                                         if ( _currentCapacity < MIN_CACHE_SIZE ) {
  89                                                 _currentCapacity = MIN_CACHE_SIZE;
  90                                         }
  91                                         foreach(DataColumn col in cols) {
  92                                                 col.DataContainer.Capacity = _currentCapacity;
  93                                         }
  94
  95                                         DataRow[] old = _rowsToRecords;
  96                                         _rowsToRecords = _table.NewRowArray(_currentCapacity);
  97                                         Array.Copy(old,0,_rowsToRecords,0,old.Length);
  98                                 }
  99                                 return _nextFreeIndex++;
 100                         }
 101                 }
 102
 103                 internal void DisposeRecord(int index)
 104                 {
 105                         if ( index < 0 ) {
 106                                 throw new ArgumentException();
 107                         }
 108                         _records.Push(index);
 109                         this[index] = null;
 110                 }
 111
 112                 internal int CopyRecord(DataTable fromTable,int fromRecordIndex,int toRecordIndex)
 113                 {
 114                         int recordIndex = toRecordIndex;
 115                         if (toRecordIndex == -1) {
 116                                 recordIndex = NewRecord();
 117                         }
 118
 119                         try
 120                         {
 121                                 foreach(DataColumn fromColumn in fromTable.Columns)
 122                                 {
 123                                         DataColumn column = _table.Columns[fromColumn.ColumnName];
 124                                         if (column != null)
 125                                         {
 126                                                 column.DataContainer.CopyValue(fromColumn.DataContainer,fromRecordIndex,recordIndex);
 127                                         }
 128                                 }
 129
 130                                 return recordIndex;
 131                         }
 132                         catch
 133                         {
 134                                 if (toRecordIndex == -1)
 135                                         DisposeRecord(recordIndex);
 136
 137                                 throw;
 138                         }
 139                 }
 140
 141                 internal void ReadIDataRecord(int recordIndex, IDataRecord record, int[] mapping, int length)
 142                 {
 143                         if ( mapping.Length > _table.Columns.Count)
 144                                 throw new ArgumentException ();
 145
 146                         int i=0;
 147                         for(; i < length; i++) {
 148                                 DataColumn column = _table.Columns[mapping[i]];
 149                                 column.DataContainer.SetItemFromDataRecord(recordIndex, record,i);
 150                         }
 151
 152                         for (; i < mapping.Length; i++)
 153                         {
 154                                 DataColumn column = _table.Columns[mapping[i]];
 155                                 if ( column.AutoIncrement )
 156                                         column.DataContainer[recordIndex] = column.AutoIncrementValue ();
 157                                 else
 158                                         column.DataContainer[recordIndex] = column.DefaultValue;
 159                         }
 160                 }
 161
 162                 #endregion // Methods
 163         }
 164 }