1 files changed, 162 insertions, 0 deletions
diff --git a/Libs/VNLib.Plugins.Essentials.Sessions.Runtime/VnCacheClient.cs b/Libs/VNLib.Plugins.Essentials.Sessions.Runtime/VnCacheClient.cs
new file mode 100644
index 0000000..a6979ef
--- /dev/null
+++ b/Libs/VNLib.Plugins.Essentials.Sessions.Runtime/VnCacheClient.cs
@@ -0,0 +1,162 @@
+using System;
+using System.Text.Json;
+using System.Net.Sockets;
+using System.Net.WebSockets;
+using System.Security.Cryptography;
+
+using VNLib.Utils;
+using VNLib.Utils.Memory;
+using VNLib.Utils.Logging;
+using VNLib.Utils.Extensions;
+using VNLib.Data.Caching.Extensions;
+using VNLib.Net.Messaging.FBM.Client;
+using VNLib.Plugins.Extensions.Loading;
+
+namespace VNLib.Plugins.Essentials.Sessions
+{
+    /// <summary>
+    /// A wrapper to simplify a cache client object
+    /// </summary>
+    public sealed class VnCacheClient : OpenResourceHandle<FBMClient?>
+    {
+        FBMClient? _client;
+
+        /// <summary>
+        /// The wrapped client
+        /// </summary>
+        public override FBMClient? Resource => _client;
+
+
+        private TimeSpan RetryInterval;
+        
+        private readonly ILogProvider? DebugLog;
+        private readonly IUnmangedHeap? ClientHeap;
+
+        /// <summary>
+        /// Initializes an emtpy client wrapper that still requires 
+        /// configuration loading
+        /// </summary>
+        /// <param name="debugLog">An optional debugging log</param>
+        /// <param name="heap">An optional <see cref="IUnmangedHeap"/> for <see cref="FBMClient"/> buffers</param>
+        public VnCacheClient(ILogProvider? debugLog, IUnmangedHeap? heap = null)
+        {
+            DebugLog = debugLog;
+            //Default to 10 seconds
+            RetryInterval = TimeSpan.FromSeconds(10);
+
+            ClientHeap = heap;
+        }
+
+        protected override void Free()
+        {
+            _client?.Dispose();
+            _client = null;
+        }
+
+        /// <summary>
+        /// Loads required configuration variables from the config store and 
+        /// intializes the interal client
+        /// </summary>
+        /// <param name="config">A dictionary of configuration varables</param>
+        /// <exception cref="KeyNotFoundException"></exception>
+        public async Task LoadConfigAsync(PluginBase pbase, IReadOnlyDictionary<string, JsonElement> config)
+        {
+            int maxMessageSize = config["max_message_size"].GetInt32();
+            string? brokerAddress = config["broker_address"].GetString() ?? throw new KeyNotFoundException("Missing required configuration variable broker_address");
+
+            //Get keys async
+            Task<string?> clientPrivTask = pbase.TryGetSecretAsync("client_private_key");
+            Task<string?> brokerPubTask = pbase.TryGetSecretAsync("broker_public_key");
+
+            //Wait for all tasks to complete
+            string?[] keys = await Task.WhenAll(clientPrivTask, brokerPubTask);
+
+            byte[] privKey = Convert.FromBase64String(keys[0] ?? throw new KeyNotFoundException("Missing required secret client_private_key"));
+            byte[] brokerPub = Convert.FromBase64String(keys[1] ?? throw new KeyNotFoundException("Missing required secret broker_public_key"));
+            
+            RetryInterval = config["retry_interval_sec"].GetTimeSpan(TimeParseType.Seconds);
+
+            Uri brokerUri = new(brokerAddress);
+
+            //Init the client with default settings
+            FBMClientConfig conf = FBMDataCacheExtensions.GetDefaultConfig(ClientHeap ?? Memory.Shared, maxMessageSize, DebugLog);
+
+            _client = new(conf);
+            //Add the configuration
+            _client.UseBroker(brokerUri)
+                .ImportBrokerPublicKey(brokerPub)
+                .ImportClientPrivateKey(privKey)
+                .UseTls(brokerUri.Scheme == Uri.UriSchemeHttps);
+
+            //Zero the key memory
+            Memory.InitializeBlock(privKey.AsSpan());
+            Memory.InitializeBlock(brokerPub.AsSpan());
+        }
+
+        /// <summary>
+        /// Discovers nodes in the configured cluster and connects to a random node
+        /// </summary>
+        /// <param name="Log">A <see cref="ILogProvider"/> to write log events to</param>
+        /// <param name="cancellationToken">A token to cancel the operation</param>
+        /// <returns>A task that completes when the operation has been cancelled or an unrecoverable error occured</returns>
+        /// <exception cref="InvalidOperationException"></exception>
+        /// <exception cref="OperationCanceledException"></exception>
+        public async Task RunAsync(ILogProvider Log, CancellationToken cancellationToken)
+        {
+            _ = Resource ?? throw new InvalidOperationException("Client configuration not loaded, cannot connect to cache servers");
+
+            while (true)
+            {
+                //Load the server list
+                ActiveServer[]? servers;
+                while (true)
+                {
+                    try
+                    {
+                        Log.Debug("Discovering cluster nodes in broker");
+                        //Get server list
+                        servers = await Resource.DiscoverNodesAsync(cancellationToken);
+                        break;
+                    }
+                    catch (HttpRequestException re) when (re.InnerException is SocketException)
+                    {
+                        Log.Warn("Broker server is unreachable");
+                    }
+                    catch (Exception ex)
+                    {
+                        Log.Warn("Failed to get server list from broker, reason {r}", ex.Message);
+                    }
+                    //Gen random ms delay
+                    int randomMsDelay = RandomNumberGenerator.GetInt32(1000, 2000);
+                    await Task.Delay(randomMsDelay, cancellationToken);
+                }
+                if (servers?.Length == 0)
+                {
+                    Log.Warn("No cluster nodes found, retrying");
+                    await Task.Delay(RetryInterval, cancellationToken);
+                    continue;
+                }
+                //select random server from the list of servers
+                ActiveServer selected = servers!.SelectRandom();
+                try
+                {
+                    Log.Debug("Connecting to server {server}", selected.ServerId);
+                    //Try to connect to server
+                    await Resource.ConnectAndWaitForExitAsync(selected, cancellationToken);
+                    Log.Debug("Cache server disconnected");
+                }
+                catch (WebSocketException wse)
+                {
+                    Log.Warn("Failed to connect to cache server {reason}", wse.Message);
+                    continue;
+                }
+                catch (HttpRequestException he) when (he.InnerException is SocketException)
+                {
+                    Log.Debug("Failed to connect to recommended server {server}", selected.ServerId);
+                    //Continue next loop
+                    continue;
+                }
+            }
+        }
+    }
+}