/// <summary>
/// Set a page as dirty and ensure page are in cache. Should be used after any change on page
/// Do not use on end of method because page can be deleted/change type
/// Always remove from clean list and add in dirty list
/// [ThreadSafe]
/// </summary>
public void SetDirty(BasePage page)
{
_clean.Remove(page.PageID);
page.IsDirty = true;
_dirty[page.PageID] = page;
}
/// <summary>
/// Save all dirty pages to disk
/// </summary>
public void PersistDirtyPages()
{
// get header page
var header = _pager.GetPage <HeaderPage>(0);
// increase file changeID (back to 0 when overflow)
header.ChangeID = header.ChangeID == ushort.MaxValue ? (ushort)0 : (ushort)(header.ChangeID + (ushort)1);
// mark header as dirty
_pager.SetDirty(header);
_log.Write(Logger.DISK, "begin disk operations - changeID: {0}", header.ChangeID);
// write journal file in desc order to header be last page in disk
if (_disk.IsJournalEnabled)
{
_disk.WriteJournal(_cache.GetDirtyPages()
.OrderByDescending(x => x.PageID)
.Select(x => x.DiskData)
.Where(x => x.Length > 0)
.ToList(), header.LastPageID);
// mark header as recovery before start writing (in journal, must keep recovery = false)
header.Recovery = true;
// flush to disk to ensure journal is committed to disk before proceeding
_disk.Flush();
}
else
{
// if no journal extend, resize file here to fast writes
_disk.SetLength(BasePage.GetSizeOfPages(header.LastPageID + 1));
}
// write header page first. if header.Recovery == true, this ensures it's written to disk *before* we start changing pages
var headerPage = _cache.GetPage(0);
var headerBuffer = headerPage.WritePage();
_disk.WritePage(0, headerBuffer);
_disk.Flush();
// get all dirty page stating from Header page (SortedList)
// header page (id=0) always must be first page to write on disk because it's will mark disk as "in recovery"
foreach (var page in _cache.GetDirtyPages())
{
// we've already written the header, so skip it
if (page.PageID == 0)
{
continue;
}
// page.WritePage() updated DiskData with new rendered buffer
var buffer = _crypto == null || page.PageID == 0 ?
page.WritePage() :
_crypto.Encrypt(page.WritePage());
_disk.WritePage(page.PageID, buffer);
}
if (_disk.IsJournalEnabled)
{
// ensure changed pages are persisted to disk *before* we change header.Recovery to false
_disk.Flush();
// re-write header page but now with recovery=false
header.Recovery = false;
_log.Write(Logger.DISK, "re-write header page now with recovery = false");
_disk.WritePage(0, header.WritePage());
}
// mark all dirty pages as clean pages (all are persisted in disk and are valid pages)
_cache.MarkDirtyAsClean();
// flush all data direct to disk
_disk.Flush();
// discard journal file
_disk.ClearJournal(header.LastPageID);
}
/// <summary>
/// Shrink datafile to crop journal area
/// </summary>
public void ClearJournal(uint lastPageID)
{
_log.Write(Logger.JOURNAL, "shrink datafile to remove journal area");
this.SetLength(BasePage.GetSizeOfPages(lastPageID + 1));
}
