singrdk/base/Libraries/Resiliency/Journalet.sg

///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   Libraries\Resiliency\Journalet.sg
//
//  Note:   Logging Worker Template
//
using System;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.ServiceManager;
using Microsoft.Singularity.Services;

namespace Microsoft.Singularity.Resiliency
{
    public abstract class Journalet
    {
        protected JournalProducer!  producer;
        protected Thread            serviceThread;

        protected TRef<ServiceContract.Exp:Start> clientRef;

        public Journalet(JournalProducer! producer,
                         [Claims]ServiceContract.Exp:Start! ep)
        {
            this.producer = producer;
            this.clientRef = new TRef<ServiceContract.Exp:Start>(ep);
        }

        public abstract void CreateServerEndpoint(out ServiceContract.Exp:Start! ep);

        protected virtual bool Initialize()
        {
            return true;
        }

        protected virtual bool HandleMessages()
        {
            return true;
        }

        protected virtual bool Recover()
        {
            return true;
        }

        /// <summary>
        /// This thread interposes between the client and the server.
        /// </summary>
        protected virtual void ProxyThread() {
            if (!Initialize()) {
                goto exit;
            }

            for (;;) {
                if (!HandleMessages()) {
                    goto exit;
                }
                try {
                    if (!Recover()) {
                        goto exit;
                    }
                }
                catch (Exception e) {
                    DebugStub.WriteLine("ProxyThread: Exception caught.");
                    DebugStub.WriteLine(e.ToString());
                }
            }
exit:
            producer.DeregisterJournalet(this);
            return;
        }

        public void Start() {
            ThreadTerminationContract.Imp! sender;
            ThreadTerminationContract.Exp! receiver;

            serviceThread = new Thread(new ThreadStart(ProxyThread));
            serviceThread.Start();
        }
    }
}