///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   TulipEventRelay.sg
//
//
//  Note:  Right now this interface waits for acks from the receiver.
//         This adds an unnecessary context switch.  At some future point
//         we may be able to have something more akin to a one-way single
//         buffer-slot notification system, but for now we ack.

using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Io.Net;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.V1.Services;

using System;
using System.Threading;

namespace Microsoft.Singularity.Drivers.Network.Tulip
{
    internal struct TulipEvent
    {
        internal const uint NoEvent       = (uint) NicEventType.NoEvent;
        internal const uint ReceiveEvent  = (uint) NicEventType.ReceiveEvent;
        internal const uint TransmitEvent = (uint) NicEventType.TransmitEvent;
        internal const uint LinkEvent     = (uint) NicEventType.LinkEvent;
    }

    internal class TulipEventRelay
    {
        TRef<NicDeviceEventContract.Exp:RUNNING>! channel;
        bool channelClosed;

        internal TulipEventRelay([Claims]
                                 NicDeviceEventContract.Exp:READY! ep)
        {
            channel       = new TRef<NicDeviceEventContract.Exp:RUNNING>(ep);
            channelClosed = false;
        }

        internal void ForwardEvent(uint tulipEvent)
        {
            if (channelClosed)
            {
                return;
            }

            NicDeviceEventContract.Exp! exp = channel.Acquire();
            exp.SendNicDeviceEvent((NicEventType)tulipEvent);
            try
            {
                exp.RecvAckNicDeviceEvent();
            }
            catch (ChannelClosedException)
            {
                channelClosed = true;
            }
            finally
            {
                channel.Release(exp);
            }
        }
    }
}