From ed6b411086c8727d439c76c9ba4146e717a7c23c Mon Sep 17 00:00:00 2001
From: Mauro Servienti <mauro.servienti@gmail.com>
Date: Sun, 13 Dec 2020 15:32:45 +0100
Subject: [PATCH] Use ConcurrentDictionary to track properties and events
 subscriptions (#196)

---
 src/ServiceComposer.AspNetCore/DynamicViewModel.cs | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/ServiceComposer.AspNetCore/DynamicViewModel.cs b/src/ServiceComposer.AspNetCore/DynamicViewModel.cs
index cc01327f..a27748c0 100644
--- a/src/ServiceComposer.AspNetCore/DynamicViewModel.cs
+++ b/src/ServiceComposer.AspNetCore/DynamicViewModel.cs
@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Dynamic;
 using System.Linq;
@@ -13,9 +14,9 @@ class DynamicViewModel : DynamicObject, IPublishCompositionEvents, ICompositionE
         readonly string _requestId;
         readonly RouteData _routeData;
         readonly HttpRequest _httpRequest;
-        readonly IDictionary<Type, List<EventHandler<object>>> _subscriptions = new Dictionary<Type, List<EventHandler<object>>>();
-        readonly IDictionary<Type, List<CompositionEventHandler<object>>> _compositionEventsSubscriptions = new Dictionary<Type, List<CompositionEventHandler<object>>>();
-        readonly IDictionary<string, object> _properties = new Dictionary<string, object>();
+        readonly ConcurrentDictionary<Type, List<EventHandler<object>>> _subscriptions = new ConcurrentDictionary<Type, List<EventHandler<object>>>();
+        readonly ConcurrentDictionary<Type, List<CompositionEventHandler<object>>> _compositionEventsSubscriptions = new ConcurrentDictionary<Type, List<CompositionEventHandler<object>>>();
+        readonly ConcurrentDictionary<string, object> _properties = new ConcurrentDictionary<string, object>();
 
         public DynamicViewModel(string requestId, RouteData routeData, HttpRequest httpRequest)
         {
@@ -31,7 +32,7 @@ public void Subscribe<TEvent>(EventHandler<TEvent> handler)
             if (!_subscriptions.TryGetValue(typeof(TEvent), out var handlers))
             {
                 handlers = new List<EventHandler<object>>();
-                _subscriptions.Add(typeof(TEvent), handlers);
+                _subscriptions.TryAdd(typeof(TEvent), handlers);
             }
 
             handlers.Add((requestId, pageViewModel, @event, routeData, query) => handler(requestId, pageViewModel, (TEvent) @event, routeData, query));
@@ -42,7 +43,7 @@ public void Subscribe<TEvent>(CompositionEventHandler<TEvent> handler)
             if (!_compositionEventsSubscriptions.TryGetValue(typeof(TEvent), out var handlers))
             {
                 handlers = new List<CompositionEventHandler<object>>();
-                _compositionEventsSubscriptions.Add(typeof(TEvent), handlers);
+                _compositionEventsSubscriptions.TryAdd(typeof(TEvent), handlers);
             }
 
             handlers.Add((@event, request) => handler((TEvent) @event, request));
@@ -52,7 +53,7 @@ public void Subscribe<TEvent>(CompositionEventHandler<TEvent> handler)
 
         public override bool TrySetMember(SetMemberBinder binder, object value)
         {
-            _properties[binder.Name] = value;
+            _properties.AddOrUpdate(binder.Name, value, (key, existingValue) => value);
             return true;
         }