/// <summary>
/// Starts a new transaction - lock database to garantee that only one processes is in a transaction
/// </summary>
public void Begin()
{
if (_level == 0)
{
// lock (or try to) datafile
_disk.Lock();
// get header page from DISK to check changeID
var header = _disk.ReadPage <HeaderPage>(0);
// if changeID was changed, file was changed by another process
if (header.ChangeID != _cache.Header.ChangeID)
{
_cache.Clear(header);
}
}
_level++;
}
/// <summary>
/// Get a page from cache or from disk (and put on cache)
/// </summary>
public T GetPage <T>(uint pageID)
where T : BasePage, new()
{
var page = _cache.GetPage <T>(pageID);
if (page == null)
{
page = _disk.ReadPage <T>(pageID);
_cache.AddPage(page);
}
return(page);
}