public IPage GetPage(ITransaction transaction, ulong pageNumber, CacheHints hints, PageHeadCollection pages)
{
PageHead pageHead;
if (transaction == null)
{
pageHead = pages.GetPageHead(pageNumber, hints);
return(pageHead == null ? null : pageHead.GetVersion(null));
}
TransactionHead transactionHead;
lock (_transactions)
if (!_transactions.TryGetValue(transaction.TransactionId, out transactionHead))
{
throw new FileLayerException("You can not get pages for a transaction until you begin the transaction");
}
var modifiedPage = transactionHead.GetModifiedPage(pageNumber);
if (modifiedPage != null)
{
return(modifiedPage);
}
pageHead = pages.GetPageHead(pageNumber, hints);
return(pageHead == null ? null : pageHead.GetVersion(transactionHead.Root.Transaction.BeginVersionNumber));
}
/// <summary>
/// Reads all of the bytes referenced by this location into a buffer and returns it
/// </summary>
public byte[] ReadAll(
ITransaction transaction,
CacheHints hints)
{
var record = new byte[Length];
ReadInto(transaction, hints, record);
return(record);
}
public IPage Get(ITransaction transaction, ulong pageNumber, CacheHints hints)
{
if (!_pages.TryGetValue(pageNumber, out IPage page))
{
return(null);
}
return(page.Reference());
}
/// <summary>
/// Reads all of the bytes referenced by this location into the buffer supplied
/// </summary>
public void ReadInto(
ITransaction transaction,
CacheHints hints,
byte[] record)
{
#if DEBUG
if ((ulong)record.LongLength != Length)
{
throw new FileLayerException("The buffer passed is the wrong length");
}
#endif
if (ContunuationPages == null)
{
using (var page = PageStore.Get(transaction, PageNumber, hints))
Array.Copy(page.Data, Offset, record, 0, record.Length);
}
else
{
var recordOffset = 0UL;
var bytesToCopy = PageStore.PageSize - Offset;
using (var page = PageStore.Get(transaction, PageNumber, hints))
Array.Copy(page.Data, Offset, record, (long)recordOffset, bytesToCopy);
foreach (var pageNumber in ContunuationPages)
{
recordOffset += bytesToCopy;
bytesToCopy = PageStore.PageSize;
if (recordOffset + bytesToCopy > Length)
{
bytesToCopy = (uint)(Length - recordOffset);
}
using (var page = PageStore.Get(transaction, pageNumber, hints))
Array.Copy(page.Data, 0, record, (long)recordOffset, bytesToCopy);
}
}
}
/// <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);
}
IPage IPageCache.Get(ITransaction transaction, ulong pageNumber, CacheHints hints)
{
return(_pageCache.Get(transaction, pageNumber, hints));
}
