source: branches/thasling/DistributedGA/DistributedGA.ContactServer/ContactServiceImpl.cs @ 13537

using DistributedGA.Core.Domain;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;
using System.Timers;

namespace DistributedGA.ContactServer
{

    [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
    public class ContactServiceImpl : IContactService
    {

        private ConcurrentDictionary<PeerInfo, DateTime> allPeers = null;

        private Timer timer = null;

        public ContactServiceImpl()
        {
            allPeers = new ConcurrentDictionary<PeerInfo, DateTime>();

            timer = new Timer(60 * 1000); //each hour
            timer.Elapsed += CleanUpContactTable;
            timer.Start();
        }

        public void RegisterPeer(PeerInfo source)
        {
            try
            {
                UpdateHeartbeat(source);
            }
            catch (Exception ex)
            {
                AddError("ContactServiceImpl.RegisterPeer", ex);
            }
        }

        public List<PeerInfo> GetPeerList(PeerInfo source)
        {
            try
            {
                UpdateHeartbeat(source);
                //only return peers of the same work group and not the sender itself
                return allPeers.Keys.Where(x =>
                {
                    if (source.ProblemInstance.Equals(x.ProblemInstance) &&
                        (!(x.IpAddress.Equals(source.IpAddress) && (x.Port.Equals(source.Port)))))
                        return true;
                    else
                        return false;
                }).ToList();
            }
            catch (Exception ex)
            {
                AddError("ContactServiceImpl.GetPeerList", ex);
                return null;
            }
        }

        public void MakeLog(PeerInfo source, string msg)
        {
            try
            {
                // TODO 

            }
            catch (Exception ex)
            {
                AddError("ContactServiceImpl.GetPeerList", ex);
            }
        }

        private void UpdateHeartbeat(PeerInfo source)
        {
            DateTime now = DateTime.Now;
            allPeers.AddOrUpdate(source, now, (k, v) => v = now);
        }

        private void CleanUpContactTable(object sender, ElapsedEventArgs e)
        {
            DateTime deadline = DateTime.Now;
            //collect items to remove
            List<PeerInfo> itemsToDelete = new List<PeerInfo>();
            foreach (PeerInfo pi in allPeers.Keys)
            {
                DateTime tmp;
                if (allPeers.TryGetValue(pi, out tmp))
                {
                    //if (tmp.AddHours(1f) < deadline)
                    if (tmp < deadline.AddHours(1f))
                    {
                        itemsToDelete.Add(pi);
                    }
                }
            }
            //remove items
            foreach (PeerInfo pi in itemsToDelete)
            {
                DateTime tmp;
                allPeers.TryRemove(pi, out tmp);
            }
        }

        private void AddError(string source, Exception ex)
        {
            MakeLog(new PeerInfo() { ProblemInstance = "ContactServer  Error at " + source }, ex.Message);
        }

    }
}