Optimized persisting of retained messages to avoid useless writes to the filesystem

2026-10-19 19:13:11 +08:00 · 2017-11-08 14:30:13 +01:00
parent 7e48746944
commit d2e481719c
8 changed files with 155 additions and 28 deletions
@@ -0,0 +1,50 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using MQTTnet.Core;
+using MQTTnet.Core.Server;
+using Newtonsoft.Json;
+
+namespace MQTTnet.TestApp.UniversalWindows
+{
+    public class JsonServerStorage : IMqttServerStorage
+    {
+        private readonly string _filename = Path.Combine(Windows.Storage.ApplicationData.Current.LocalFolder.Path, "Retained.json");
+
+        public async Task SaveRetainedMessagesAsync(IList<MqttApplicationMessage> messages)
+        {
+            await Task.CompletedTask;
+
+            var json = JsonConvert.SerializeObject(messages);
+            File.WriteAllText(_filename, json);
+        }
+
+        public async Task<IList<MqttApplicationMessage>> LoadRetainedMessagesAsync()
+        {
+            await Task.CompletedTask;
+
+            if (!File.Exists(_filename))
+            {
+                return new List<MqttApplicationMessage>();
+            }
+
+            try
+            {
+                var json = File.ReadAllText(_filename);
+                return JsonConvert.DeserializeObject<List<MqttApplicationMessage>>(json);
+            }
+            catch
+            {
+                return new List<MqttApplicationMessage>();
+            }
+        }
+
+        public void Clear()
+        {
+            if (File.Exists(_filename))
+            {
+                File.Delete(_filename);
+            }
+        }
+    }
+}