////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   IoMemoryNode.sg
//
//  Note: internal node type used to support IoMemory images
//

using System;
using System.Collections;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using SharedHeap = Microsoft.Singularity.Memory.SharedHeap;

using Microsoft.Singularity.Security;
using Microsoft.Singularity.Security.AccessControl;

namespace Microsoft.Singularity.Directory
{
    contract IoMemFSContract
    {
        in  message Connect(FileContract.Exp:Start!ep,UIntPtr addr, int length);
        out message AckConnect();
        out message NakConnect(FileContract.Exp:Start! ep);

        state Ready: one
        {
            Connect?  -> (AckConnect! or NakConnect!) -> Ready;
        }
    }

    public class IoMemoryFS
    {
        private TRef<IoMemFSContract.Exp:Ready> ioRef;

        public IoMemFSContract.Imp Start ()
        {
            IoMemFSContract.Imp! imp;
            IoMemFSContract.Exp! sp;
            IoMemFSContract.NewChannel(out imp, out sp);

            ioRef = new TRef<IoMemFSContract.Exp:Ready>(sp);

            // create the service thread to manage all requests for IoMemory objects
            Thread thread = Thread.CreateThread(DirectoryService.processForWorkerThreads,
                                                new ThreadStart(IoFSPump));
            if (thread != null) {
                thread.Start();
            }
            else {
                // make sure caller does not hang
                sp = ioRef.Acquire();
                delete sp;
            }
            return imp;
        }

        private void IoFSPump()
        {
            bool success;
            int code;
            char[] in ExHeap path;
            EMap<FileContract.Exp:Ready,IoMemory> clients;

            assert ioRef != null;
            IoMemFSContract.Exp io = ioRef.Acquire();
            clients = new EMap<FileContract.Exp:Ready,IoMemory>();

            for (bool run = true; run;) {
                switch receive  {
                    case io.Connect(ep,UIntPtr addr, int len):
                        Kernel.Waypoint(3310);
                        // TODO: this must be mapped into *user* space
                        IoMemory ioMem = IoMemory.Wrap(addr, (uint)len, true, true);
                        ep.SendSuccess();
                        Kernel.Waypoint(3311);
                        clients.Add(ep,ioMem);
                        Kernel.Waypoint(3312);
                        io.SendAckConnect();
                        Kernel.Waypoint(3313);
                        break;
                    case ep.Read(i_buffer, i_bufferOffset, fileOffset, count)in clients~>ioMem:
                        Kernel.Waypoint(3300);
                        int ioLength = 0;
                        if (ioMem != null) {
                            ioLength = ioMem.Length;
                        }
                        int offset = (int) fileOffset;
                        //DebugStub.Print(" NS read. fileOff="+
                        if (offset >= ioLength) {
                            ep.SendAckRead(i_buffer,0,1); //error
                            clients.Add(ep,ioMem);
                            Kernel.Waypoint(3301);
                            break;
                        }
                        int readLen = Math.Min((int) count,  Math.Max(0,ioLength - (int)fileOffset) );
                        Bitter.FromIoMemory(i_buffer, (int) i_bufferOffset, readLen,
                                            ioMem, (int)fileOffset);
                        ep.SendAckRead(i_buffer,readLen,0);
                        clients.Add(ep,ioMem);
                        Kernel.Waypoint(3302);
                        break;
                    case ep.ChannelClosed() in clients~>ioMem :
                        delete ep;
                        break;
                    case unsatisfiable :
                        run = false;
                        break;
                }
            }
            clients.Dispose(); //delete ep;
            delete io;
        }
    } //IoMemory Service
}