public Page EnterLatch(BufferEntry buffer, LatchFlags flags)
{
if (LatchLocks.TryGetValue(buffer.Position, out var latchLock))
{
if (flags != latchLock.Flags)
{
throw new InvalidOperationException($"has hold a {flags} lactch of the buffer:{buffer.Position}!");
}
return(buffer.Page);
}
switch (flags)
{
case LatchFlags.Read:
LatchLocks[buffer.Position] = buffer.Latch.EnterReadScope();
break;
case LatchFlags.RWRead:
LatchLocks[buffer.Position] = buffer.Latch.EnterReadWriteScope();
break;
case LatchFlags.Write:
LatchLocks[buffer.Position] = buffer.Latch.EnterWriteScope();
break;
}
return(buffer.Page);
}
public bool CheckLatch(BufferEntry buffer, LatchFlags flags)
{
if (!LatchLocks.TryGetValue(buffer.Position, out var latch))
{
return(false);
}
switch (flags)
{
case LatchFlags.Write:
return(latch.Flags == LatchFlags.Write || latch.Flags == LatchFlags.RWWrite);
default:
return(true);
}
}
public Page EnterLatch(PagePosition page, LatchFlags flags)
{
if (LatchLocks.TryGetValue(page, out var latchLock))
{
if (flags != latchLock.Flags)
{
throw new InvalidOperationException($"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);
}