private bool IsValidStateTransition(StableConnectionState oldState, StableConnectionState newState)
{
switch (oldState)
{
case StableConnectionState.Created:
return newState == StableConnectionState.Opening || newState == StableConnectionState.Closed;
case StableConnectionState.Opening:
return newState == StableConnectionState.Opened || newState == StableConnectionState.Closed;
case StableConnectionState.Opened:
return newState == StableConnectionState.Closed;
case StableConnectionState.Closed:
return newState == StableConnectionState.Invalid;
case StableConnectionState.Invalid:
return false;
default:
throw new InvalidProgramException("Unknown StableConnectionState value: " + oldState.ToString());
}
}
private StableConnectionState ChangeStateSafe(StableConnectionState newState)
{
var curState = _state;
if (!IsValidStateTransition((StableConnectionState)curState, newState))
return (StableConnectionState)curState;
if (Interlocked.CompareExchange(ref _state, (int)newState, curState) == curState)
return (StableConnectionState)curState;
SpinWait sw = new SpinWait();
while (Interlocked.CompareExchange(ref _state, (int)newState, curState) != curState)
{
sw.SpinOnce();
curState = _state;
if (!IsValidStateTransition((StableConnectionState)curState, newState))
return (StableConnectionState)curState;
}
return (StableConnectionState)curState;
}
