/// <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
/// </summary>
public void RestoreIndex(ref HeaderPage header)
{
// get all page positions
var positions = new Dictionary <long, List <PagePosition> >();
var current = 0L;
// read all pages to get confirmed transactions (do not read page content, only page header)
foreach (var buffer in _disk.ReadFull(FileOrigin.Log))
{
// 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);
var position = new PagePosition(pageID, current);
if (positions.TryGetValue(transactionID, out var list))
{
list.Add(position);
}
else
{
positions[transactionID] = new List <PagePosition> {
position
};
}
if (isConfirmed)
{
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)
{
// page buffer instance can't change
var headerBuffer = header.Buffer;
// copy this buffer block into original header block
Buffer.BlockCopy(buffer.Array, buffer.Offset, headerBuffer.Array, headerBuffer.Offset, PAGE_SIZE);
// re-load header (using new buffer data)
header = new HeaderPage(headerBuffer);
header.TransactionID = uint.MaxValue;
header.IsConfirmed = false;
}
}
// update last transaction ID
_lastTransactionID = (int)transactionID;
current += PAGE_SIZE;
}
}
/// <summary>
/// Initialize LiteEngine using initial engine settings
/// </summary>
public LiteEngine(EngineSettings settings)
{
_settings = settings ?? throw new ArgumentNullException(nameof(settings));
// clear checkpoint if database is readonly
if (_settings.ReadOnly)
{
_settings.Checkpoint = 0;
}
LOG($"start initializing{(_settings.ReadOnly ? " (readonly)" : "")}", "ENGINE");
try
{
// initialize locker service (no dependency)
_locker = new LockService(settings.Timeout, settings.ReadOnly);
// initialize disk service (will create database if needed)
_disk = new DiskService(settings);
// read page with no cache ref (has a own PageBuffer) - do not Release() support
var buffer = _disk.ReadFull(FileOrigin.Data).First();
// if first byte are 1 this datafile are encrypted but has do defined password to open
if (buffer[0] == 1)
{
throw new LiteException(0, "This data file is encrypted and needs a password to open");
}
_header = new HeaderPage(buffer);
// initialize wal-index service
_walIndex = new WalIndexService(_disk, _locker);
// if exists log file, restore wal index references (can update full _header instance)
if (_disk.GetLength(FileOrigin.Log) > 0)
{
_walIndex.RestoreIndex(ref _header);
}
// initialize sort temp disk
_sortDisk = new SortDisk(settings.CreateTempFactory(), CONTAINER_SORT_SIZE, settings.UtcDate);
// initialize transaction monitor as last service
_monitor = new TransactionMonitor(_header, _locker, _disk, _walIndex, _settings);
// register system collections
this.InitializeSystemCollections();
LOG("initialization completed", "ENGINE");
}
catch (Exception ex)
{
LOG(ex.Message, "ERROR");
// explicit dispose (but do not run shutdown operation)
this.Dispose(true);
throw;
}
}
/// <summary>
/// Get all pages from datafile based only in Page Position (get from disk - not from cache)
/// </summary>
private IEnumerable <BsonDocument> DumpPages()
{
var collections = _header.GetCollections().ToDictionary(x => x.Value, x => x.Key);
foreach (var buffer in _disk.ReadFull())
{
var page = new BasePage(buffer);
var doc = new BsonDocument
{
["position"] = Number(buffer.Position),
["origin"] = page.PageID == 0 && page.TransactionID == 0 && page.PageType == PageType.Empty ? "blank" :
buffer.Position < _disk.LogStartPosition ? "data" : "log",
["pageID"] = (int)page.PageID,
["pageType"] = page.PageType.ToString(),
["nextPageID"] = (int)page.NextPageID,
["prevPageID"] = (int)page.PrevPageID,
["collection"] = collections.GetOrDefault(page.ColID, "-"),
["transactionID"] = (int)page.TransactionID,
["isConfirmed"] = page.IsConfirmed,
["itemsCount"] = (int)page.ItemsCount,
["freeBytes"] = page.FreeBytes,
["usedBytes"] = (int)page.UsedBytes,
["fragmentedBytes"] = (int)page.FragmentedBytes,
["nextFreePosition"] = (int)page.NextFreePosition,
["highestIndex"] = (int)page.HighestIndex
};
yield return(doc);
}
}