1 files changed, 83 insertions, 0 deletions
diff --git a/VNLib.Data.Caching/src/ClientRetryManager.cs b/VNLib.Data.Caching/src/ClientRetryManager.cs
new file mode 100644
index 0000000..97d3d3a
--- /dev/null
+++ b/VNLib.Data.Caching/src/ClientRetryManager.cs
@@ -0,0 +1,83 @@
+using System;
+using System.Threading.Tasks;
+using System.Security.Cryptography;
+
+using VNLib.Utils;
+using VNLib.Net.Messaging.FBM.Client;
+
+namespace VNLib.Data.Caching
+{
+    /// <summary>
+    /// Manages a <see cref="FBMClientWorkerBase"/> reconnect policy
+    /// </summary>
+    public class ClientRetryManager<T> : VnDisposeable where T: IStatefulConnection
+    {
+        const int RetryRandMaxMsDelay = 1000;
+
+        private readonly TimeSpan RetryDelay;
+        private readonly T Client;
+        private readonly Uri ServerUri;
+
+        internal ClientRetryManager(T worker, TimeSpan delay, Uri serverUri)
+        {
+            this.Client = worker;
+            this.RetryDelay = delay;
+            this.ServerUri = serverUri;
+            //Register disconnect listener
+            worker.ConnectionClosed += Worker_Disconnected;
+        }
+
+        private void Worker_Disconnected(object? sender, EventArgs args)
+        {
+            //Exec retry on exit
+            _ = RetryAsync().ConfigureAwait(false);
+        }
+       
+
+        /// <summary>
+        /// Raised before client is to be reconnected
+        /// </summary>
+        public event Action<T>? OnBeforeReconnect;
+        /// <summary>
+        /// Raised when the client fails to reconnect. Should return a value that instructs the 
+        /// manager to reconnect
+        /// </summary>
+        public event Func<T, Exception, bool>? OnReconnectFailed;
+
+        async Task RetryAsync()
+        {
+            
+            //Begin random delay with retry ms
+            int randomDelayMs = (int)RetryDelay.TotalMilliseconds;
+            //random delay to add to prevent retry-storm
+            randomDelayMs += RandomNumberGenerator.GetInt32(RetryRandMaxMsDelay);
+            //Retry loop
+            bool retry = true;
+            while (retry)
+            {
+                try
+                {
+                    //Inform Listener for the retry
+                    OnBeforeReconnect?.Invoke(Client);
+                    //wait for delay before reconnecting
+                    await Task.Delay(randomDelayMs);
+                    //Reconnect async
+                    await Client.ConnectAsync(ServerUri).ConfigureAwait(false);
+                    break;
+                }
+                catch (Exception Ex)
+                {
+                    //Invoke error handler, may be null, incase exit
+                    retry = OnReconnectFailed?.Invoke(Client, Ex) ?? false;
+                }
+            }
+        }
+
+        ///<inheritdoc/>
+        protected override void Free()
+        {
+            //Unregister the event listener
+            Client.ConnectionClosed -= Worker_Disconnected;
+        }
+    }
+}