separate dispose from close and configure socket to allow rapid connect

Author: vazois

benchmark/BDN.benchmark/Embedded/GarnetServerEmbedded.cs

@@ -110,6 +110,11 @@ public override void Start()
         {
         }
 
+        /// <inheritdoc />
+        public override void Close()
+        {
+        }
+
         public bool TryCreateMessageConsumer(Span<byte> bytes, INetworkSender networkSender, out IMessageConsumer session)
         {
             session = null;

libs/host/GarnetServer.cs

@@ -478,7 +478,14 @@ public void Dispose(bool deleteDir = true)
 
         private void InternalDispose()
         {
+            // Phase 1: Stop listening on all servers to free ports immediately.
+            for (var i = 0; i < servers.Length; i++)
+                servers[i]?.Close();
+
+            // Phase 2: Dispose the provider (storage engine shutdown — may take time).
             Provider?.Dispose();
+
+            // Phase 3: Drain active handlers and clean up remaining resources.
             for (var i = 0; i < servers.Length; i++)
                 servers[i]?.Dispose();
             subscribeBroker?.Dispose();

libs/server/Servers/GarnetServerBase.cs

@@ -154,6 +154,9 @@ public bool AddSession(WireFormat protocol, ref ISessionProvider provider, INetw
         /// <inheritdoc />
         public abstract void Start();
 
+        /// <inheritdoc />
+        public abstract void Close();
+
         /// <inheritdoc />
         public virtual void Dispose()
         {

libs/server/Servers/GarnetServerTcp.cs

@@ -82,24 +82,47 @@ public GarnetServerTcp(
             this.unixSocketPath = unixSocketPath;
             this.unixSocketPermission = unixSocketPermission;
 
-            listenSocket = endpoint switch
+            if (endpoint is UnixDomainSocketEndPoint unix)
             {
-                UnixDomainSocketEndPoint unix => new Socket(unix.AddressFamily, SocketType.Stream, ProtocolType.Unspecified),
+                // UDS Initialization & Cleanup
+                listenSocket = new Socket(unix.AddressFamily, SocketType.Stream, ProtocolType.Unspecified);
+                var socketPath = unix.ToString();
+                if (File.Exists(socketPath))
+                {
+                    File.Delete(socketPath);
+                }
+            }
+            else
+            {
+                // TCP Initialization & Port Reuse
+                listenSocket = new Socket(endpoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
 
-                _ => new Socket(endpoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp)
-            };
+                // Set reuse BEFORE Bind to handle TIME_WAIT states
+                listenSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+            }
 
             acceptEventArg = new SocketAsyncEventArgs();
             acceptEventArg.Completed += AcceptEventArg_Completed;
         }
 
+        /// <summary>
+        /// Stop listening for new connections. Frees the listening port
+        /// without waiting for active connections to drain.
+        /// </summary>
+        public override void Close()
+        {
+            listenSocket.Close();
+        }
+
         /// <summary>
         /// Dispose
         /// </summary>
         public override void Dispose()
         {
-            base.Dispose();
+            // Close listening socket to free the port and stop accepting new connections.
+            // This also prevents new connections from arriving while DisposeActiveHandlers drains existing ones.
             listenSocket.Dispose();
+            base.Dispose();
             acceptEventArg.UserToken = null;
             acceptEventArg.Dispose();
             networkPool?.Dispose();

libs/server/Servers/IGarnetServer.cs

@@ -46,5 +46,11 @@ public interface IGarnetServer : IDisposable
         /// Start server
         /// </summary>
         public void Start();
+
+        /// <summary>
+        /// Stop listening for new connections. Frees the listening port
+        /// without waiting for active connections to drain.
+        /// </summary>
+        public void Close();
     }
 }