Use ServerSessionChangeListener to bind function handlers to SapServer

README.md

@@ -194,15 +194,20 @@ class SomeFunctionResult
 ```csharp
 string connectionString = "AppServerHost=MY_SERVER_HOST; SystemNumber=00; User=MY_SAP_USER; Password=SECRET; Client=100; Language=EN; PoolSize=5; Trace=8";
 
-var connectionPool = new SapConnectionPool(connectionString);
-
-SapServer.InstallGenericServerFunctionHandler(
-(string functionName, SapAttributes attributes) =>
+SapServer.InstallGenericServerFunctionHandler((string functionName, SapAttributes attributes) =>
 {
-    using var connection = connectionPool.GetConnection();
+    using var connection = new SapConnection(connectionString);
+    connection.Connect();
     return connection.GetFunctionMetadata(functionName);
-},
-(ISapServerConnection connection, ISapServerFunction function) =>
+});
+```
+
+### RFC Server
+
+```csharp
+string connectionString = "GWHOST=MY_GW_HOST; GWSERV=MY_GW_SERV; PROGRAM_ID=MY_PROGRAM_ID; REG_COUNT=1";
+
+using var server = SapServer.Create(connectionString, (ISapServerConnection connection, ISapServerFunction function) =>
 {
     var attributes = connection.GetAttributes();
 
@@ -214,14 +219,6 @@ SapServer.InstallGenericServerFunctionHandler(
         break;
     }
 });
-```
-
-### RFC Server
-
-```csharp
-string connectionString = "GWHOST=MY_GW_HOST; GWSERV=MY_GW_SERV; PROGRAM_ID=MY_PROGRAM_ID; REG_COUNT=1";
-
-using var server = SapServer.Create(connectionString);
 server.Error += (object sender, SapServerErrorEventArgs args) => Console.WriteLine(args.Error.Message);
 server.StateChange += (object sender, SapServerStateChangeEventArgs args) => Console.WriteLine(args.OldState + " -> " + args.NewState);
 server.Launch();

src/SapNwRfc/Internal/Interop/RfcCallType.cs

@@ -0,0 +1,10 @@
+namespace SapNwRfc.Internal.Interop
+{
+    internal enum RfcCallType
+    {
+        RFC_SYNCHRONOUS,
+        RFC_TRANSACTIONAL,
+        RFC_QUEUED,
+        RFC_BACKGROUND_UNIT,
+    }
+}

src/SapNwRfc/Internal/Interop/RfcInterop.cs

@@ -331,6 +331,9 @@ public virtual IntPtr AppendNewRow(IntPtr tableHandle, out RfcErrorInfo errorInf
         [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Unicode)]
         public delegate RfcResultCode RfcFunctionDescriptionCallback(string functionName, RfcAttributes attributes, out IntPtr funcDescHandle);
 
+        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+        public delegate void RfcServerSessionChangeListener(IntPtr serverHandle, in RfcSessionChange sessionChange, in RfcErrorInfo errorInfo);
+
         [UnmanagedFunctionPointer(CallingConvention.StdCall)]
         public delegate void RfcServerErrorListener(IntPtr serverHandle, in RfcAttributes clientInfo, in RfcErrorInfo errorInfo);
 
@@ -367,6 +370,24 @@ public virtual RfcResultCode LaunchServer(IntPtr rfcHandle, out RfcErrorInfo err
         public virtual RfcResultCode ShutdownServer(IntPtr rfcHandle, uint timeout, out RfcErrorInfo errorInfo)
             => RfcShutdownServer(rfcHandle, timeout, out errorInfo);
 
+        [DllImport(SapNwRfcDllName)]
+        private static extern RfcResultCode RfcGetServerContext(IntPtr rfcHandle, out RfcServerContext serverContext, out RfcErrorInfo errorInfo);
+
+        public virtual RfcResultCode GetServerContext(IntPtr rfcHandle, out RfcServerContext serverContext, out RfcErrorInfo errorInfo)
+            => RfcGetServerContext(rfcHandle, out serverContext, out errorInfo);
+
+        [DllImport(SapNwRfcDllName)]
+        private static extern RfcResultCode RfcSetServerStateful(IntPtr rfcHandle, uint isStateful, out RfcErrorInfo errorInfo);
+
+        public virtual RfcResultCode SetServerStateful(IntPtr rfcHandle, uint isStateful, out RfcErrorInfo errorInfo)
+            => RfcSetServerStateful(rfcHandle, isStateful, out errorInfo);
+
+        [DllImport(SapNwRfcDllName)]
+        private static extern RfcResultCode RfcAddServerSessionChangedListener(IntPtr rfcHandle, RfcServerSessionChangeListener sessionChangeListener, out RfcErrorInfo errorInfo);
+
+        public virtual RfcResultCode AddServerSessionChangedListener(IntPtr rfcHandle, RfcServerSessionChangeListener sessionChangeListener, out RfcErrorInfo errorInfo)
+            => RfcAddServerSessionChangedListener(rfcHandle, sessionChangeListener, out errorInfo);
+
         [DllImport(SapNwRfcDllName)]
         private static extern RfcResultCode RfcAddServerErrorListener(IntPtr rfcHandle, RfcServerErrorListener errorListener, out RfcErrorInfo errorInfo);
 

src/SapNwRfc/Internal/Interop/RfcServerContext.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace SapNwRfc.Internal.Interop
+{
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+    internal struct RfcServerContext
+    {
+        [MarshalAs(UnmanagedType.I4)]
+        public RfcCallType CallType;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 24 + 1)]
+        public string Tid;
+
+        public IntPtr UnitIdentifier;
+
+        public IntPtr UnitAttributes;
+
+        [MarshalAs(UnmanagedType.U4)]
+        public uint IsStateful;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32 + 1)]
+        public string SessionId;
+    }
+}

src/SapNwRfc/Internal/Interop/RfcSessionChange.cs

@@ -0,0 +1,14 @@
+using System.Runtime.InteropServices;
+
+namespace SapNwRfc.Internal.Interop
+{
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+    internal struct RfcSessionChange
+    {
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 30 + 1)]
+        public string SessionId;
+
+        [MarshalAs(UnmanagedType.I4)]
+        public RfcSessionEvent Event;
+    }
+}

src/SapNwRfc/Internal/Interop/RfcSessionEvent.cs

@@ -0,0 +1,10 @@
+namespace SapNwRfc.Internal.Interop
+{
+    internal enum RfcSessionEvent
+    {
+        RFC_SESSION_CREATED,
+        RFC_SESSION_ACTIVATED,
+        RFC_SESSION_PASSIVATED,
+        RFC_SESSION_DESTROYED,
+    }
+}

src/SapNwRfc/Pooling/SapPooledConnection.cs

@@ -83,9 +83,10 @@ public void InvokeFunction(string name, CancellationToken cancellationToken = de
         /// <inheritdoc cref="ISapPooledConnection"/>
         public void InvokeFunction(string name, object input, CancellationToken cancellationToken = default)
         {
+            _connection = _connection ?? _pool.GetConnection(cancellationToken);
+
             try
             {
-                _connection = _connection ?? _pool.GetConnection(cancellationToken);
                 using (ISapFunction function = _connection.CreateFunction(name))
                     function.Invoke(input);
             }
@@ -104,6 +105,8 @@ public void InvokeFunction(string name, object input, CancellationToken cancella
         /// <inheritdoc cref="ISapPooledConnection"/>
         public TOutput InvokeFunction<TOutput>(string name, CancellationToken cancellationToken = default)
         {
+            _connection = _connection ?? _pool.GetConnection(cancellationToken);
+
             try
             {
                 // no using here to prevent function from being disposed
@@ -132,10 +135,17 @@ public TOutput InvokeFunction<TOutput>(string name, CancellationToken cancellati
         /// <inheritdoc cref="ISapPooledConnection"/>
         public TOutput InvokeFunction<TOutput>(string name, object input, CancellationToken cancellationToken = default)
         {
+            _connection = _connection ?? _pool.GetConnection(cancellationToken);
+
             try
             {
-                using (ISapFunction function = _connection.CreateFunction(name))
-                    return function.Invoke<TOutput>(input);
+                // no using here to prevent function from being disposed
+                // when possibly an IEnumerable is used in TOutput
+                // and rows are accessed after InvokeFunction
+                ISapFunction function = _connection.CreateFunction(name);
+                _functions.Add(function);
+
+                return function.Invoke<TOutput>(input);
             }
             catch (SapCommunicationFailedException)
             {

src/SapNwRfc/SapServer.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using SapNwRfc.Internal.Interop;
 
 namespace SapNwRfc
@@ -12,35 +13,65 @@ public sealed class SapServer : ISapServer
         private readonly RfcInterop _interop;
         private readonly IntPtr _rfcServerHandle;
         private readonly SapConnectionParameters _parameters;
+        private readonly Action<ISapServerConnection, ISapServerFunction> _action;
 
-        private SapServer(RfcInterop interop, IntPtr rfcServerHandle, SapConnectionParameters parameters)
+        // Keep a reference to the server function delegates so they don't get GCed
+        private readonly RfcInterop.RfcServerSessionChangeListener _serverSessionChangeListener;
+        private readonly RfcInterop.RfcServerErrorListener _serverErrorListener;
+        private readonly RfcInterop.RfcServerStateChangeListener _serverStateChangeListener;
+
+        private SapServer(RfcInterop interop, IntPtr rfcServerHandle, SapConnectionParameters parameters, Action<ISapServerConnection, ISapServerFunction> action)
         {
             _interop = interop;
             _rfcServerHandle = rfcServerHandle;
             _parameters = parameters;
+            _action = action;
+
+            _serverSessionChangeListener = ServerSessionChangeListener;
+            _serverErrorListener = ServerErrorListener;
+            _serverStateChangeListener = ServerStateChangeListener;
+
+            RfcResultCode resultCode = _interop.AddServerSessionChangedListener(
+                rfcHandle: rfcServerHandle,
+                sessionChangeListener: _serverSessionChangeListener,
+                errorInfo: out RfcErrorInfo errorInfo);
+        }
+
+        private void ServerSessionChangeListener(IntPtr serverHandle, in RfcSessionChange sessionChange, in RfcErrorInfo errorInfo)
+        {
+            if (sessionChange.Event == RfcSessionEvent.RFC_SESSION_CREATED)
+            {
+                Servers.TryAdd(sessionChange.SessionId, this);
+            }
+            else if (sessionChange.Event == RfcSessionEvent.RFC_SESSION_DESTROYED)
+            {
+                Servers.TryRemove(sessionChange.SessionId, out _);
+            }
         }
 
         /// <summary>
         /// Creates and connects a new RFC Server.
         /// </summary>
         /// <param name="connectionString">The connection string.</param>
+        /// <param name="action">The RFC server function handler.</param>
         /// <returns>The SAP RFC Server.</returns>
-        public static ISapServer Create(string connectionString)
+        public static ISapServer Create(string connectionString, Action<ISapServerConnection, ISapServerFunction> action)
         {
-            return Create(SapConnectionParameters.Parse(connectionString));
+            return Create(SapConnectionParameters.Parse(connectionString), action);
         }
 
         /// <summary>
         /// Creates and connects a new RFC Server.
         /// </summary>
         /// <param name="parameters">The connection parameters.</param>
+        /// <param name="action">The RFC server function handler.</param>
         /// <returns>The SAP RFC Server.</returns>
-        public static ISapServer Create(SapConnectionParameters parameters)
+        public static ISapServer Create(SapConnectionParameters parameters, Action<ISapServerConnection, ISapServerFunction> action)
         {
-            return Create(new RfcInterop(), parameters);
+            return Create(new RfcInterop(), parameters, action);
         }
 
-        private static ISapServer Create(RfcInterop rfcInterop, SapConnectionParameters parameters)
+        private static ISapServer Create(RfcInterop rfcInterop, SapConnectionParameters parameters, Action<ISapServerConnection, ISapServerFunction> action)
         {
             RfcConnectionParameter[] interopParameters = parameters.ToInterop();
 
@@ -51,7 +82,7 @@ private static ISapServer Create(RfcInterop rfcInterop, SapConnectionParameters
 
             errorInfo.ThrowOnError();
 
-            return new SapServer(rfcInterop, rfcServerHandle, parameters);
+            return new SapServer(rfcInterop, rfcServerHandle, parameters, action);
         }
 
         private EventHandler<SapServerErrorEventArgs> _error;
@@ -65,7 +96,7 @@ public event EventHandler<SapServerErrorEventArgs> Error
                 {
                     RfcResultCode resultCode = _interop.AddServerErrorListener(
                         rfcHandle: _rfcServerHandle,
-                        errorListener: ServerErrorListener,
+                        errorListener: _serverErrorListener,
                         errorInfo: out RfcErrorInfo errorInfo);
 
                     resultCode.ThrowOnError(errorInfo);
@@ -96,7 +127,7 @@ public event EventHandler<SapServerStateChangeEventArgs> StateChange
                 {
                     RfcResultCode resultCode = _interop.AddServerStateChangedListener(
                         rfcHandle: _rfcServerHandle,
-                        stateChangeListener: ServerStateChangeListener,
+                        stateChangeListener: _serverStateChangeListener,
                         errorInfo: out RfcErrorInfo errorInfo);
 
                     resultCode.ThrowOnError(errorInfo);
@@ -145,6 +176,14 @@ public void Dispose()
             _interop.DestroyServer(
                 rfcHandle: _rfcServerHandle,
                 errorInfo: out RfcErrorInfo _);
+
+            foreach (KeyValuePair<string, SapServer> kv in Servers)
+            {
+                if (kv.Value == this)
+                {
+                    Servers.TryRemove(kv.Key, out _);
+                }
+            }
         }
 
         /// <summary>
@@ -196,16 +235,6 @@ private static RfcResultCode HandleGenericFunction(IntPtr connectionHandle, IntP
                 return RfcResultCode.RFC_EXTERNAL_FAILURE;
             }
 
-            IntPtr functionDesc = interop.DescribeFunction(
-                rfcHandle: functionHandle,
-                errorInfo: out RfcErrorInfo functionDescErrorInfo);
-
-            if (functionDescErrorInfo.Code != RfcResultCode.RFC_OK)
-            {
-                errorInfo = functionDescErrorInfo;
-                return functionDescErrorInfo.Code;
-            }
-
             RfcResultCode serverContextResultCode = interop.GetServerContext(
                 rfcHandle: connectionHandle,
                 serverContext: out RfcServerContext serverContext,
@@ -233,6 +262,16 @@ private static RfcResultCode HandleGenericFunction(IntPtr connectionHandle, IntP
 
             if (Servers.TryGetValue(serverContext.SessionId, out SapServer sapServer))
             {
+                IntPtr functionDesc = interop.DescribeFunction(
+                    rfcHandle: functionHandle,
+                    errorInfo: out RfcErrorInfo functionDescErrorInfo);
+
+                if (functionDescErrorInfo.Code != RfcResultCode.RFC_OK)
+                {
+                    errorInfo = functionDescErrorInfo;
+                    return functionDescErrorInfo.Code;
+                }
+
                 var connection = new SapServerConnection(interop, connectionHandle);
                 var function = new SapServerFunction(interop, functionHandle, functionDesc);