public void Dispose()
{
// release lock
switch (_status)
{
case ReadWriteLockStatus.Write:
{
var oldCounter =
Concurrency.Atomic(
ref _lockable._counter,
counter => counter.SetWriterCount(counter.WriterCount() - 1).SetReaderCount(counter.ReaderCount()));
Debug.Assert(oldCounter.WriterCount() > 0);
if (oldCounter.WriterCount() > 0)
{
#if READWRITELOCK_TRACE
Debug.Print("{0} #{1} release WriteLock", GetHashCode(), Thread.CurrentThread.ManagedThreadId);
#endif
_lockable._writeThreadID = 0;
}
else
throw new InvalidOperationException("No write lock is held");
_status = ReadWriteLockStatus.None;
}
break;
case ReadWriteLockStatus.Read:
{
var oldCounter =
Concurrency.Atomic(
ref _lockable._counter,
counter => counter.SetReaderCount(counter.ReaderCount() - 1).SetWriterCount(counter.WriterCount()));
if (oldCounter.ReaderCount() > 0)
{
#if READWRITELOCK_TRACE
Debug.Print("{0} #{1} release ReadLock", GetHashCode(), Thread.CurrentThread.ManagedThreadId);
#endif
}
else
throw new InvalidOperationException("No read lock is held");
}
break;
default:
throw new InvalidOperationException("No lock is held");
}
GC.SuppressFinalize(this);
}
public void Downgrade()
{
// update status
switch (_status)
{
case ReadWriteLockStatus.Read:
// already downgraded
return;
case ReadWriteLockStatus.None:
throw new InvalidOperationException("Cannot downgrade lock that has been released");
}
// switch write lock to read lock
_lockable._writeThreadID = 0;
Concurrency.Atomic(ref _lockable._counter, counter => 0.SetReaderCount(counter.ReaderCount() + 1).SetWriterCount(counter.WriterCount() - 1));
_status = ReadWriteLockStatus.Read;
}
internal Lock(ReadWriteLockable lockable, ReadWriteLockStatus status)
{
_lockable = lockable;
_status = status;
}
