/// <summary>
/// Recursive RetrieveColumns method for data pinning. This should pin a buffer and
/// call the inherited RetrieveColumns method.
/// </summary>
/// <param name="sesid">The session to use.</param>
/// <param name="tableid">
/// The table to retrieve the columns from.
/// </param>
/// <param name="columnValues">
/// Column values to retrieve.
/// </param>
internal static void RetrieveColumns(JET_SESID sesid, JET_TABLEID tableid, ColumnValue[] columnValues)
{
const int MaxColumnValues = 1024;
if (columnValues.Length > MaxColumnValues)
{
throw new ArgumentOutOfRangeException("columnValues", columnValues.Length, "Too many column values");
}
unsafe
{
byte[] buffer = null;
NATIVE_RETRIEVECOLUMN *nativeRetrievecolumns = stackalloc NATIVE_RETRIEVECOLUMN[columnValues.Length];
try
{
buffer = Caches.ColumnCache.Allocate();
Debug.Assert(MaxColumnValues * 16 < buffer.Length, "Maximum size of fixed columns could exceed buffer size");
fixed(byte *pinnedBuffer = buffer)
{
byte *currentBuffer = pinnedBuffer;
int numVariableLengthColumns = columnValues.Length;
// First the fixed-size columns
for (int i = 0; i < columnValues.Length; ++i)
{
if (0 != columnValues[i].Size)
{
columnValues[i].MakeNativeRetrieveColumn(ref nativeRetrievecolumns[i]);
nativeRetrievecolumns[i].pvData = new IntPtr(currentBuffer);
nativeRetrievecolumns[i].cbData = checked ((uint)columnValues[i].Size);
currentBuffer += nativeRetrievecolumns[i].cbData;
Debug.Assert(currentBuffer <= pinnedBuffer + buffer.Length, "Moved past end of pinned buffer");
numVariableLengthColumns--;
}
}
// Now the variable-length columns
if (numVariableLengthColumns > 0)
{
int bufferUsed = checked ((int)(currentBuffer - pinnedBuffer));
int bufferRemaining = checked (buffer.Length - bufferUsed);
int bufferPerColumn = bufferRemaining / numVariableLengthColumns;
Debug.Assert(bufferPerColumn > 0, "Not enough buffer left to retrieve variable length columns");
// Now the variable-size columns
for (int i = 0; i < columnValues.Length; ++i)
{
if (0 == columnValues[i].Size)
{
columnValues[i].MakeNativeRetrieveColumn(ref nativeRetrievecolumns[i]);
nativeRetrievecolumns[i].pvData = new IntPtr(currentBuffer);
nativeRetrievecolumns[i].cbData = checked ((uint)bufferPerColumn);
currentBuffer += nativeRetrievecolumns[i].cbData;
Debug.Assert(currentBuffer <= pinnedBuffer + buffer.Length, "Moved past end of pinned buffer");
}
}
}
// Retrieve the columns
Api.Check(Api.Impl.JetRetrieveColumns(sesid, tableid, nativeRetrievecolumns, columnValues.Length));
// Propagate the warnings and output.
for (int i = 0; i < columnValues.Length; ++i)
{
columnValues[i].Error = (JET_wrn)nativeRetrievecolumns[i].err;
columnValues[i].ItagSequence = (int)nativeRetrievecolumns[i].itagSequence;
}
// Now parse out the columns that were retrieved successfully
for (int i = 0; i < columnValues.Length; ++i)
{
if (nativeRetrievecolumns[i].err != (int)JET_wrn.BufferTruncated)
{
byte *columnBuffer = (byte *)nativeRetrievecolumns[i].pvData;
int startIndex = checked ((int)(columnBuffer - pinnedBuffer));
columnValues[i].GetValueFromBytes(
buffer,
startIndex,
checked ((int)nativeRetrievecolumns[i].cbActual),
nativeRetrievecolumns[i].err);
}
}
}
// Finally retrieve the buffers where the columns weren't large enough.
RetrieveTruncatedBuffers(sesid, tableid, columnValues, nativeRetrievecolumns);
}
finally
{
if (buffer != null)
{
Caches.ColumnCache.Free(ref buffer);
}
}
}
}
/// <summary> /// Recursive SetColumns method for data pinning. This should populate the buffer and /// call the inherited SetColumns method. /// </summary> /// <param name="sesid">The session to use.</param> /// <param name="tableid"> /// The table to set the columns in. An update should be prepared. /// </param> /// <param name="columnValues"> /// Column values to set. /// </param> /// <param name="nativeColumns"> /// Structures to put the pinned data in. /// </param> /// <param name="i">Offset of this object in the array.</param> /// <returns>An error code.</returns> internal abstract unsafe int SetColumns(JET_SESID sesid, JET_TABLEID tableid, ColumnValue[] columnValues, NATIVE_SETCOLUMN *nativeColumns, int i);
/// <summary>
/// Recursive SetColumns method for data pinning. This populates the buffer and
/// calls the inherited SetColumns method.
/// </summary>
/// <param name="sesid">The session to use.</param>
/// <param name="tableid">
/// The table to set the columns in. An update should be prepared.
/// </param>
/// <param name="columnValues">
/// Column values to set.
/// </param>
/// <param name="nativeColumns">
/// Structures to put the pinned data in.
/// </param>
/// <param name="i">Offset of this object in the array.</param>
/// <returns>An error code.</returns>
internal override unsafe int SetColumns(JET_SESID sesid, JET_TABLEID tableid, ColumnValue[] columnValues, NATIVE_SETCOLUMN *nativeColumns, int i)
{
var data = this.Value.GetValueOrDefault();
return(this.SetColumns(sesid, tableid, columnValues, nativeColumns, i, &data, sizeof(double), this.Value.HasValue));
}
