private T FullMode(Func <T> valueFactory, ManualResetEvent waitHandle, ref Thread thread, ref int preIsValueCreated)
{
back:
if (Interlocked.CompareExchange(ref preIsValueCreated, 1, 0) == 0)
{
try
{
thread = Thread.CurrentThread;
GC.KeepAlive(thread);
_target = valueFactory.Invoke();
_valueFactory = FuncHelper.GetReturnFunc(_target);
Thread.VolatileWrite(ref _isValueCreated, 1);
return(_target);
}
catch (Exception)
{
Thread.VolatileWrite(ref preIsValueCreated, 0);
throw;
}
finally
{
waitHandle.Set();
thread = null;
}
}
else
{
if (ReferenceEquals(thread, Thread.CurrentThread))
{
throw new InvalidOperationException();
}
else
{
waitHandle.WaitOne();
if (Thread.VolatileRead(ref _isValueCreated) == 1)
{
return(_valueFactory.Invoke());
}
else
{
goto back;
}
}
}
}
private T NoneMode(Func <T> valueFactory, HashSet <Thread> threads)
{
// NOTICE this method has no null check
var currentThread = Thread.CurrentThread;
if (Thread.VolatileRead(ref _isValueCreated) == 0)
{
try
{
// lock (threads) // This is meant to not be thread-safe
{
if (threads.Contains(currentThread))
{
throw new InvalidOperationException();
}
else
{
threads.Add(currentThread);
}
}
_target = valueFactory();
_valueFactory = FuncHelper.GetReturnFunc(_target);
Thread.VolatileWrite(ref _isValueCreated, 1);
return(_target);
}
catch (Exception)
{
Thread.VolatileWrite(ref _isValueCreated, 0);
throw;
}
finally
{
// lock (threads) // This is meant to not be thread-safe
{
threads.Remove(Thread.CurrentThread);
}
}
}
else
{
return(_valueFactory.Invoke());
}
}
