/// <summary>
/// Encapsulate all operations in a single write transaction
/// </summary>
private T Transaction <T>(string collection, bool addIfNotExists, Func <CollectionPage, T> action)
{
// always starts write operation locking database
using (_locker.Write())
{
try
{
var col = this.GetCollectionPage(collection, addIfNotExists);
var result = action(col);
_trans.PersistDirtyPages();
return(result);
}
catch (Exception ex)
{
_log.Write(Logger.ERROR, ex.Message);
// if an error occurs during an operation, rollback must be called to avoid datafile inconsistent
_cache.DiscardDirtyPages();
throw;
}
}
}
/// <summary>
/// Get journal pages and override all into datafile
/// </summary>
public void Recovery()
{
_log.Write(Logger.RECOVERY, "initializing recovery mode");
using (_locker.Write())
{
// double check in header need recovery (could be already recover from another thread)
var header = BasePage.ReadPage(_disk.ReadPage(0)) as HeaderPage;
if (header.Recovery == false)
{
return;
}
// read all journal pages
foreach (var buffer in _disk.ReadJournal(header.LastPageID))
{
// read pageID (first 4 bytes)
var pageID = BitConverter.ToUInt32(buffer, 0);
_log.Write(Logger.RECOVERY, "recover page #{0:0000}", pageID);
// write in stream (encrypt if datafile is encrypted)
_disk.WritePage(pageID, _crypto == null || pageID == 0 ? buffer : _crypto.Encrypt(buffer));
}
// shrink datafile
_disk.ClearJournal(header.LastPageID);
}
}
