public TransactionHead Lock(ITransaction transaction, PageHead pageHead)
{
TransactionHead transactionHead;
lock (_transactions)
if (!_transactions.TryGetValue(transaction.TransactionId, out transactionHead))
{
throw new FileLayerException("You must begin the transaction before you can lock pages with it");
}
transactionHead.Lock(pageHead);
return(transactionHead);
}
/// <summary>
/// Returns the page head for a page number. The page head is the had
/// of a linked list of versions of that page
/// </summary>
/// <returns>Null if the page does not exist in storage</returns>
public PageHead GetPageHead(ulong pageNumber, CacheHints hints)
{
PageHead pageHead;
lock (_pages)
{
if (!_pages.TryGetValue(pageNumber, out pageHead))
{
var page = GetFromFileSet(pageNumber);
if (page == null)
{
return(null);
}
pageHead = new PageHead(pageNumber, page);
_pages.Add(pageNumber, pageHead);
}
}
return(pageHead);
}
public void Unlock(PageHead pageHead)
{
}
public bool Lock(PageHead pageHead)
{
if (Parent == null)
{
EnsureLockedPages();
lock (LockedPages)
{
if (LockedPages.Contains(pageHead))
{
return(false);
}
LockedPages.Add(pageHead);
}
pageHead.Lock(this);
using (var latestVersion = pageHead.GetVersion(null))
{
using (var newPage = _pagePool.Get(pageHead.PageNumber))
{
latestVersion.Data.CopyTo(newPage.Data, 0);
if (Updates != null)
{
lock (Updates)
{
foreach (var update in Updates)
{
if (update.PageNumber == pageHead.PageNumber)
{
update.Data.CopyTo(newPage.Data, update.Offset);
}
}
}
}
SetModifiedPage(newPage);
}
}
return(true);
}
if (!Parent.Lock(pageHead))
{
return(false);
}
using (var parentPage = Parent.GetModifiedPage(pageHead.PageNumber))
{
using (var newPage = _pagePool.Get(pageHead.PageNumber))
{
parentPage.Data.CopyTo(newPage.Data, 0);
if (Updates != null)
{
lock (Updates)
{
foreach (var update in Updates)
{
if (update.PageNumber == pageHead.PageNumber)
{
update.Data.CopyTo(newPage.Data, update.Offset);
}
}
}
}
SetModifiedPage(newPage);
}
}
return(true);
}
/// <summary>
/// This is split out from the constructor to make thread locking more efficient
/// </summary>
public void Added(PageHead pageHead, OwinContainers.LinkedList <PageVersion> .ListElement listElement)
{
_pageHead = pageHead;
_pageVersionsElement = listElement;
}
