Add support for retained application messages

2026-10-17 17:53:03 +08:00 · 2017-09-30 18:42:41 +02:00
parent 3cce33415d
commit 862f76fea2
24 changed files with 454 additions and 235 deletions
@@ -0,0 +1,104 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using MQTTnet.Core.Diagnostics;
+using MQTTnet.Core.Internal;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Server
+{
+    public sealed class MqttClientRetainedMessagesManager
+    {
+        private readonly Dictionary<string, MqttPublishPacket> _retainedMessages = new Dictionary<string, MqttPublishPacket>();
+        private readonly MqttServerOptions _options;
+
+        public MqttClientRetainedMessagesManager(MqttServerOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        public async Task LoadMessagesAsync()
+        {
+            try
+            {
+                var retainedMessages = await _options.Storage.LoadRetainedMessagesAsync();
+                lock (_retainedMessages)
+                {
+                    _retainedMessages.Clear();
+                    foreach (var retainedMessage in retainedMessages)
+                    {
+                        _retainedMessages[retainedMessage.Topic] = retainedMessage.ToPublishPacket();
+                    }
+                }
+            }
+            catch (Exception exception)
+            {
+                MqttTrace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while loading retained messages.");
+            }
+        }
+
+        public async Task HandleMessageAsync(string clientId, MqttPublishPacket publishPacket)
+        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+
+            List<MqttPublishPacket> allRetainedMessages;
+            lock (_retainedMessages)
+            {
+                if (publishPacket.Payload?.Any() == false)
+                {
+                    _retainedMessages.Remove(publishPacket.Topic);
+                    MqttTrace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' cleared retained message for topic '{1}'.", clientId, publishPacket.Topic);
+                }
+                else
+                {
+                    _retainedMessages[publishPacket.Topic] = publishPacket;
+                    MqttTrace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' updated retained message for topic '{1}'.", clientId, publishPacket.Topic);
+                }
+
+                allRetainedMessages = new List<MqttPublishPacket>(_retainedMessages.Values);
+            }
+
+            try
+            {
+                // ReSharper disable once UseNullPropagation
+                if (_options.Storage != null)
+                {
+                    await _options.Storage.SaveRetainedMessagesAsync(allRetainedMessages.Select(p => p.ToApplicationMessage()).ToList());
+                }
+            }
+            catch (Exception exception)
+            {
+                MqttTrace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while saving retained messages.");
+            }
+        }
+
+        public List<MqttPublishPacket> GetMessages(MqttSubscribePacket subscribePacket)
+        {
+            var retainedMessages = new List<MqttPublishPacket>();
+            lock (_retainedMessages)
+            {
+                foreach (var retainedMessage in _retainedMessages.Values)
+                {
+                    foreach (var topicFilter in subscribePacket.TopicFilters)
+                    {
+                        if (retainedMessage.QualityOfServiceLevel < topicFilter.QualityOfServiceLevel)
+                        {
+                            continue;
+                        }
+
+                        if (!MqttTopicFilterComparer.IsMatch(retainedMessage.Topic, topicFilter.Topic))
+                        {
+                            continue;
+                        }
+
+                        retainedMessages.Add(retainedMessage);
+                        break;
+                    }
+                }
+            }
+
+            return retainedMessages;
+        }
+    }
+}