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

//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections;

namespace System.Data.Common
{
	internal class RecordCache
	{
		#region Fields

		const int MIN_CACHE_SIZE = 128;

		Stack _records = new Stack(16);
		int _nextFreeIndex = 0;
		int _currentCapacity = 0;
		DataTable _table;
		DataRow[] _rowsToRecords;

		#endregion // Fields

		#region Constructors

		internal RecordCache(DataTable table)
		{
			_table = table;
			_rowsToRecords = table.NewRowArray(16);
		}

		#endregion //Constructors

		#region Properties

		internal int CurrentCapacity 
		{
			get {
				return _currentCapacity;
			}
		}

		internal DataRow this[int index]
		{
			get {
				return _rowsToRecords[index];
			}

			set {
				if (index >= 0) {
					_rowsToRecords[index] = value;
				}
			}
		}

		#endregion // Properties

		#region Methods

		internal int NewRecord()
		{
			if (_records.Count > 0) {
                                return (int)_records.Pop();
			}
			else {
				DataColumnCollection cols = _table.Columns;
				if (_nextFreeIndex >= _currentCapacity) {
					_currentCapacity *= 2;
					if ( _currentCapacity < MIN_CACHE_SIZE ) {
						_currentCapacity = MIN_CACHE_SIZE;
					}
					foreach(DataColumn col in cols) {
						col.DataContainer.Capacity = _currentCapacity;
					}

					DataRow[] old = _rowsToRecords;
					_rowsToRecords = _table.NewRowArray(_currentCapacity);
					Array.Copy(old,0,_rowsToRecords,0,old.Length);
				}
				return _nextFreeIndex++;
			}
		}

		internal void DisposeRecord(int index)
		{
			if ( index < 0 ) {
				throw new ArgumentException();
			}
                        if (!_records.Contains (index))
                                _records.Push(index);

			this[index] = null;
		}

		internal int CopyRecord(DataTable fromTable,int fromRecordIndex,int toRecordIndex)
		{
			int recordIndex = toRecordIndex;
			if (toRecordIndex == -1) {
				recordIndex = NewRecord();
			}

			try
			{
				foreach(DataColumn fromColumn in fromTable.Columns) 
				{
					DataColumn column = _table.Columns[fromColumn.ColumnName];
					if (column != null) 
					{
						column.DataContainer.CopyValue(fromColumn.DataContainer,fromRecordIndex,recordIndex);
					}
				}

				return recordIndex;
			}
			catch
			{
				if (toRecordIndex == -1)
					DisposeRecord(recordIndex);

				throw;
			}
		}

		internal void ReadIDataRecord(int recordIndex, IDataRecord record, int[] mapping, int length)
		{
			if ( mapping.Length > _table.Columns.Count)
				throw new ArgumentException ();

			int i=0;
			for(; i < length; i++) {
				DataColumn column = _table.Columns[mapping[i]];
				column.DataContainer.SetItemFromDataRecord(recordIndex, record,i);
			}

			for (; i < mapping.Length; i++)
			{
				DataColumn column = _table.Columns[mapping[i]];
				if ( column.AutoIncrement ) 
					column.DataContainer[recordIndex] = column.AutoIncrementValue ();
				else
					column.DataContainer[recordIndex] = column.DefaultValue;
			}
		}

		#endregion // Methods
	}
}