Akka.Streams.Implementation.Fusing.GraphInterpreter.ProcessEvent C# (CSharp) Method

        private void ProcessEvent(int connection)
        {
            // this must be the state after returning without delivering any signals, to avoid double-finalization of some unlucky stage
            // (this can happen if a stage completes voluntarily while connection close events are still queued)
            ActiveStage = null;
            var code = PortStates[connection];

            // Manual fast decoding, fast paths are PUSH and PULL
            if ((code & (Pushing | InClosed | OutClosed)) == Pushing)
            {
                // PUSH
                ProcessElement(connection);
            }
            else if ((code & (Pulling | OutClosed | InClosed)) == Pulling)
            {
                // PULL
                if (IsDebug) Console.WriteLine($"{Name} PULL {InOwnerName(connection)} -> {OutOwnerName(connection)} ({OutHandlers[connection]}) [{OutLogicName(connection)}]");
                PortStates[connection] ^= PullEndFlip;
                ActiveStage = SafeLogics(Assembly.OutletOwners[connection]);
                OutHandlers[connection].OnPull();
            }
            else if ((code & (OutClosed | InClosed)) == InClosed)
            {
                // CANCEL
                var stageId = Assembly.OutletOwners[connection];
                ActiveStage = SafeLogics(stageId);
                if (IsDebug) Console.WriteLine($"{Name} CANCEL {InOwnerName(connection)} -> {OutOwnerName(connection)} ({OutHandlers[connection]}) [{OutLogicName(connection)}]");
                PortStates[connection] |= OutClosed;
                CompleteConnection(stageId);
                OutHandlers[connection].OnDownstreamFinish();
            }
            else if ((code & (OutClosed | InClosed)) == OutClosed)
            {
                // COMPLETIONS
                if ((code & Pushing) == 0)
                {
                    // Normal completion (no push pending)
                    if (IsDebug) Console.WriteLine($"{Name} COMPLETE {OutOwnerName(connection)} -> {InOwnerName(connection)} ({InHandlers[connection]}) [{InLogicName(connection)}]");
                    PortStates[connection] |= InClosed;
                    var stageId = Assembly.InletOwners[connection];
                    ActiveStage = SafeLogics(stageId);
                    CompleteConnection(stageId);

                    if ((PortStates[connection] & InFailed) == 0)
                        InHandlers[connection].OnUpstreamFinish();
                    else
                        InHandlers[connection].OnUpstreamFailure(((Failed)ConnectionSlots[connection]).Reason);
                }
                else
                {
                    // Push is pending, first process push, then re-enqueue closing event
                    ProcessElement(connection);
                    Enqueue(connection);
                }
            }
        }