1 files changed, 168 insertions, 0 deletions
diff --git a/plugins/ObjectCacheServer/src/Distribution/PeerDiscoveryManager.cs b/plugins/ObjectCacheServer/src/Distribution/PeerDiscoveryManager.cs
new file mode 100644
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+++ b/plugins/ObjectCacheServer/src/Distribution/PeerDiscoveryManager.cs
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+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: ObjectCacheServer
+* File: PeerDiscoveryManager.cs 
+*
+* PeerDiscoveryManager.cs is part of ObjectCacheServer which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* ObjectCacheServer is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* ObjectCacheServer is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+
+using VNLib.Plugins;
+using VNLib.Utils.Logging;
+using VNLib.Data.Caching.Extensions;
+using VNLib.Plugins.Extensions.Loading;
+
+namespace VNLib.Data.Caching.ObjectCache.Server.Distribution
+{
+
+    sealed class PeerDiscoveryManager : IAsyncBackgroundWork, ICachePeerAdapter
+    {
+        private readonly NodeConfig _config;
+        private readonly IPeerMonitor _monitor;        
+        private readonly INodeDiscoveryCollection _peers;
+
+        public PeerDiscoveryManager(PluginBase plugin)
+        {
+            //Get config
+            _config = plugin.GetOrCreateSingleton<NodeConfig>();
+
+            //Get the peer monitor
+            _monitor = plugin.GetOrCreateSingleton<CachePeerMonitor>();
+
+            //Get the node collection
+            _peers = plugin.GetOrCreateSingleton<NodeDiscoveryCollection>();
+            
+            _connectedPeers = new();
+        }
+
+        async Task IAsyncBackgroundWork.DoWorkAsync(ILogProvider pluginLog, CancellationToken exitToken)
+        {
+            pluginLog.Information("Node discovery worker started");
+
+            try
+            {
+                while (true)
+                {
+                    try
+                    {
+                        await DiscoverAllNodesAsync(pluginLog, exitToken);
+                    }
+                    catch(OperationCanceledException)
+                    {
+                        throw;
+                    }
+                    catch (Exception ex)
+                    {
+                        pluginLog.Error(ex, "Failed to discover new peer nodes");
+                    }
+
+                    //Delay the next discovery
+                    await Task.Delay(_config.DiscoveryInterval, exitToken);
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                //Normal exit
+                pluginLog.Information("Node discovery worker exiting");
+            }
+            finally
+            {
+
+            }
+        }
+
+        async Task DiscoverAllNodesAsync(ILogProvider log, CancellationToken cancellation)
+        {
+            //Use the monitor to get the initial peers
+            IEnumerable<ICachePeerAdvertisment> ads = _monitor.GetAllPeers()
+                                                        .Where(static p => p.Advertisment != null)
+                                                        .Select(static p => p.Advertisment!);
+
+            //Init enumerator with initial peers
+            INodeDiscoveryEnumerator enumerator = _peers.BeginDiscovery(ads);
+
+            do
+            {
+                //Load the initial peer
+                ICachePeerAdvertisment? peer = enumerator.GetNextPeer();
+
+                if (peer == null)
+                {
+                    break;
+                }
+
+                log.Verbose("Discovering peer nodes from {Peer}", peer.NodeId);
+
+                //Discover nodes from this peer
+                ICachePeerAdvertisment[]? newNodes = await _config.Config.DiscoverClusterNodesAsync(peer, cancellation);
+
+                //Add nodes to the enumerator
+                if (newNodes != null)
+                {
+                    enumerator.OnPeerDiscoveryComplete(newNodes);
+                }
+
+            } while (true);
+
+            //Commit peer updates
+            _peers.CompleteDiscovery(enumerator);
+        }
+
+
+        private readonly List<ICachePeerAdvertisment> _connectedPeers;
+
+        ///<inheritdoc/>
+        public ICachePeerAdvertisment[] GetNewPeers()
+        {
+            lock (_connectedPeers)
+            {
+                //Get all discovered peers
+                ICachePeerAdvertisment[] peers = _peers.GetAllNodes();
+
+                //Get the difference between the discovered peers and the connected peers
+                return peers.Except(_connectedPeers).ToArray();
+            }
+        }
+
+        ///<inheritdoc/>
+        public void OnPeerListenerAttached(ICachePeerAdvertisment peer)
+        {
+            lock (_connectedPeers)
+            {
+                //Add to connected peers
+                _connectedPeers.Add(peer);
+            }
+        }
+
+        ///<inheritdoc/>
+        public void OnPeerListenerDetatched(ICachePeerAdvertisment peer)
+        {
+            //remove from connected peers
+            lock (_connectedPeers)
+            {
+                _connectedPeers.Remove(peer);
+            }
+        }
+    }
+}