Fixup management of managed and unmanaged resources

nng.NET/AsyncContext.cs

@@ -174,10 +174,24 @@ protected void HandleFailedSend()
         protected object sync = new object();
 
         #region IDisposable
-        public void Dispose()
+        public void Dispose() => Dispose(true);
+
+        protected virtual void Dispose(bool disposing)
         {
-            Aio?.Dispose();
+            if (disposed)
+                return;
+
+            if (disposing)
+            {
+                Aio?.Dispose();
+            }
+
+            // No unmanaged resources to cleanup
+
+            disposed = true;
         }
+
+        bool disposed = false;
         #endregion
     }
 
@@ -253,12 +267,19 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposed)
                 return;
+
             if (disposing)
             {
-                var _ = nng_ctx_close(NativeNngStruct);
+                // No managed resources to dispose
             }
+
+            var _ = nng_ctx_close(NativeNngStruct);
+
             disposed = true;
         }
+
+        ~NngCtx() => Dispose(false);
+
         bool disposed = false;
         #endregion
     }

nng.NET/Dialer.cs

@@ -82,12 +82,19 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposed)
                 return;
+
             if (disposing)
             {
-                int _ = nng_dialer_close(NativeNngStruct);
+                // No managed resources to dispose
             }
+
+            int _ = nng_dialer_close(NativeNngStruct);
+
             disposed = true;
         }
+
+        ~NngDialer() => Dispose(false);
+
         bool disposed = false;
         #endregion
 

nng.NET/Listener.cs

@@ -84,12 +84,19 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposed)
                 return;
+
             if (disposing)
             {
-                int _ = nng_listener_close(NativeNngStruct);
+                // No managed resources to dispose
             }
+
+            int _ = nng_listener_close(NativeNngStruct);
+
             disposed = true;
         }
+
+        ~NngListener() => Dispose(false);
+
         bool disposed = false;
         #endregion
 

nng.NET/Memory.cs

@@ -40,7 +40,7 @@ public void Take()
             Ptr = default;
             Length = default;
         }
-        
+
         #region IDisposable
         public void Dispose()
         {
@@ -52,13 +52,20 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposed)
                 return;
+
             if (disposing)
             {
-                if (Ptr != IntPtr.Zero)
-                    nng_free(Ptr, Length);
+                // No managed resources to dispose
             }
+
+            if (Ptr != IntPtr.Zero)
+                nng_free(Ptr, Length);
+
             disposed = true;
         }
+
+        ~NngAlloc() => Dispose(false);
+
         bool disposed = false;
         #endregion
     }

nng.NET/Socket.cs

@@ -175,12 +175,19 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposed)
                 return;
+
             if (disposing)
             {
-                int _ = nng_close(NativeNngStruct);
+                // No managed resources to dispose
             }
+
+            int _ = nng_close(NativeNngStruct);
+
             disposed = true;
         }
+
+        ~NngSocket() => Dispose(false);
+
         bool disposed = false;
         #endregion
     }

nng.NET/Stats.cs

@@ -35,10 +35,7 @@ public static NngResult<IStatRoot> GetStatSnapshot()
             var res = nng_stats_get(out nng_stat statsp);
             return NngResult<IStatRoot>.OkThen(res, () => new StatRoot { NativeNngStruct = statsp });
         }
-    }
 
-    public class StatRoot : NngStat, IStatRoot
-    {
         #region IDisposable
         public void Dispose()
         {
@@ -52,14 +49,23 @@ protected virtual void Dispose(bool disposing)
                 return;
             if (disposing)
             {
-                nng_stats_free(NativeNngStruct);
+                // No managed resources to dispose
             }
+            nng_stats_free(NativeNngStruct);
             disposed = true;
         }
+
+        ~NngStat() => Dispose(false);
+
         bool disposed = false;
         #endregion
     }
 
+    public class StatRoot : NngStat, IStatRoot
+    {
+
+    }
+
     public class StatChild : NngStat, IStatChild
     {
         public static IStatChild Create(nng_stat stat)

nng.NET/String.cs

@@ -40,11 +40,13 @@ protected virtual void Dispose(bool disposing)
                 return;
             if (disposing)
             {
-                if (Ptr != IntPtr.Zero)
-                    nng_strfree(Ptr);
+                // No managed resources to dispose
             }
+            if (Ptr != IntPtr.Zero)
+                nng_strfree(Ptr);
             disposed = true;
         }
+        ~NngString() => Dispose(false);
         bool disposed = false;
         #endregion
     }