/// <summary>
/// Load all confirmed transactions from log file (used only when open datafile)
/// Don't need lock because it's called on ctor of LiteEngine
/// Update _disk instance with last log position
/// </summary>
public void RestoreIndex(HeaderPage header)
{
// get all page positions
var positions = new Dictionary <long, List <PagePosition> >();
var last = 0L;
// read all pages to get confirmed transactions (do not read page content, only page header)
foreach (var buffer in _disk.ReadLog(true))
{
// read direct from buffer to avoid create BasePage structure
var pageID = buffer.ReadUInt32(BasePage.P_PAGE_ID);
var isConfirmed = buffer.ReadBool(BasePage.P_IS_CONFIRMED);
var transactionID = buffer.ReadUInt32(BasePage.P_TRANSACTION_ID);
if (transactionID == 0 || transactionID == uint.MaxValue)
{
continue;
}
var position = new PagePosition(pageID, buffer.Position);
if (positions.TryGetValue(transactionID, out var list))
{
list.Add(position);
}
else
{
positions[transactionID] = new List <PagePosition> {
position
};
}
if (isConfirmed)
{
// update last IsConfirmed page
last = buffer.Position;
this.ConfirmTransaction(transactionID, positions[transactionID]);
var pageType = (PageType)buffer.ReadByte(BasePage.P_PAGE_TYPE);
// when a header is modified in transaction, must always be the last page inside log file (per transaction)
if (pageType == PageType.Header)
{
// copy this buffer block into original header block
Buffer.BlockCopy(buffer.Array, buffer.Offset, header.Buffer.Array, header.Buffer.Offset, PAGE_SIZE);
header.LoadPage();
}
}
// update last transaction ID
_lastTransactionID = (int)transactionID;
}
// update last log position acording with last IsConfirmed on log
if (last > 0)
{
_disk.LogEndPosition = last + PAGE_SIZE;
}
}
