public Page EnterLatch(BufferEntry buffer, LatchFlags flags)
{
if (LatchLocks.TryGetValue(buffer.Position, out var latchLock))
{
if (flags != latchLock.Flags)
{
throw new InvalidOperationException($"has hold a {flags} lactch of the buffer:{buffer.Position}!");
}
return(buffer.Page);
}
switch (flags)
{
case LatchFlags.Read:
LatchLocks[buffer.Position] = buffer.Latch.EnterReadScope();
break;
case LatchFlags.RWRead:
LatchLocks[buffer.Position] = buffer.Latch.EnterReadWriteScope();
break;
case LatchFlags.Write:
LatchLocks[buffer.Position] = buffer.Latch.EnterWriteScope();
break;
}
return(buffer.Page);
}
public bool CheckLatch(BufferEntry buffer, LatchFlags flags)
{
if (!LatchLocks.TryGetValue(buffer.Position, out var latch))
{
return(false);
}
switch (flags)
{
case LatchFlags.Write:
return(latch.Flags == LatchFlags.Write || latch.Flags == LatchFlags.RWWrite);
default:
return(true);
}
}
/// <summary>
/// thread unsafe
/// </summary>
public bool UpgrateWrite()
{
if (_release == UnReleased)
{
switch (Flags)
{
case LatchFlags.Write:
case LatchFlags.RWWrite:
return(true);
case LatchFlags.RWRead:
//don't wait
var ok = Latch._internalLock.TryEnterWriteLock(0);
Flags = ok ? LatchFlags.RWWrite : Flags;
return(ok);
default:
throw new InvalidOperationException();
}
}
return(false);
}
public Page EnterLatch(PagePosition page, LatchFlags flags)
{
if (LatchLocks.TryGetValue(page, out var latchLock))
{
if (flags != latchLock.Flags)
{
throw new InvalidOperationException($"has hold a {flags} lactch of the buffer:{page}!");
}
return((latchLock.Latch.Target as BufferEntry)?.Page);
}
var buffer = Buffers.GetEntry(page);
if (buffer == null)
{
throw new NullReferenceException(nameof(buffer));
}
switch (flags)
{
case LatchFlags.Read:
LatchLocks[page] = buffer.Latch.EnterReadScope();
break;
case LatchFlags.Write:
LatchLocks[page] = buffer.Latch.EnterWriteScope();
break;
case LatchFlags.RWRead:
LatchLocks[page] = buffer.Latch.EnterReadWriteScope();
break;
}
return(buffer.Page);
}
public Page EnterLatch(int fileId, long pageNumber, LatchFlags flags)
{
return(EnterLatch(new PagePosition(fileId, pageNumber), flags));
}
private Stack <TreePage> GetPagePathForKey(LowLevelTransaction lltx, Span <byte> key, ushort size, LatchFlags latchFlags = LatchFlags.Write)
{
var path = new Stack <TreePage>();
var buffer = lltx.Buffers.GetEntry(_root.FileId, _root.PageNumber);
while (true)
{
var page = lltx.EnterLatch(buffer, latchFlags).AsTree();
ref var th = ref page.TreeHeader;
if (th.IsLeaf)
{
if (th.FreeSize > size)
{
while (path.Count != 0)
{
lltx.ExitLatch(path.Pop().Position);
}
}
path.Push(page);
break;
}
else if (th.FreeSize > MaxBranchEntrySize)
{
while (path.Count != 0)
{
lltx.ExitLatch(path.Pop().Position);
}
}
path.Push(page);
buffer = lltx.Buffers.GetEntry(page.FindPage(key));
}
public LatchScope(LatchEntry latch, LatchFlags flags)
{
Flags = flags;
Latch = latch ?? throw new ArgumentNullException(nameof(latch));
}
