Collect webhook response time and shard latency

PluralKit.Bot/Bot.cs

@@ -312,8 +312,8 @@ namespace PluralKit.Bot
 
         public async Task HandleMessage(SocketMessage msg)
         {
-            _metrics.Measure.Meter.Mark(BotMetrics.MessagesReceived);
-            
+            RegisterMessageMetrics(msg);
+
             // _client.CurrentUser will be null if we've connected *some* shards but not shard #0 yet
             // This will cause an error in WebhookCacheServices so we just workaround and don't process any messages
             // until we properly connect. TODO: can we do this without chucking away a bunch of messages?
@@ -347,6 +347,7 @@ namespace PluralKit.Bot
                     system = await conn.QueryFirstOrDefaultAsync<PKSystem>(
                         "select systems.* from systems, accounts where accounts.uid = @Id and systems.id = accounts.system",
                         new {Id = arg.Author.Id});
+                    
                 await _commands.ExecuteAsync(new PKCommandContext(_client, arg, system, _services), argPos,
                     _services);
             }
@@ -357,6 +358,21 @@ namespace PluralKit.Bot
             }
         }
 
+        private void RegisterMessageMetrics(SocketMessage msg)
+        {
+            var guild = (msg.Channel as IGuildChannel)?.Guild;
+            if (guild != null)
+            {
+                var shard = _client.GetShardFor(guild);
+                var latencyMillis = shard.Latency;
+                
+                _metrics.Provider.Timer.Instance(BotMetrics.GatewayLatency, new MetricTags("shard", shard.ShardId.ToString()))
+                    .Record(latencyMillis, TimeUnit.Milliseconds);
+            }
+
+            _metrics.Measure.Meter.Mark(BotMetrics.MessagesReceived);
+        }
+
         public Task HandleReactionAdded(Cacheable<IUserMessage, ulong> message, ISocketMessageChannel channel,
             SocketReaction reaction) => _proxy.HandleReactionAddedAsync(message, channel, reaction);
 

PluralKit.Bot/BotMetrics.cs

@@ -1,6 +1,8 @@
 using App.Metrics;
 using App.Metrics.Gauge;
+using App.Metrics.Histogram;
 using App.Metrics.Meter;
+using App.Metrics.Timer;
 
 namespace PluralKit.Bot
 {
@@ -15,5 +17,7 @@ namespace PluralKit.Bot
         public static GaugeOptions Channels => new GaugeOptions {Name = "Channels", MeasurementUnit = Unit.None, Context = "Bot"};
         public static GaugeOptions ShardsConnected => new GaugeOptions { Name = "Shards Connected", Context = "Bot" };
         public static GaugeOptions WebhookCacheSize => new GaugeOptions { Name = "Webhook Cache Size", Context = "Bot" };
+        public static TimerOptions WebhookResponseTime => new TimerOptions { Name = "Webhook Response Time", Context = "Bot" };
+        public static TimerOptions GatewayLatency => new TimerOptions { Name = "Gateway Latency", Context = "Bot" };
     }
 }

PluralKit.Bot/Services/ProxyService.cs

@@ -117,7 +117,10 @@ namespace PluralKit.Bot
             var webhook = await _webhookCache.GetWebhook(message.Channel as ITextChannel);
             var avatarUrl = match.Member.AvatarUrl ?? match.System.AvatarUrl;
             var proxyName = match.Member.ProxyName(match.System.Tag);
-            var hookMessageId = await ExecuteWebhook(webhook, messageContents, proxyName, avatarUrl, message.Attachments.FirstOrDefault());
+
+            ulong hookMessageId;
+            using (_metrics.Measure.Timer.Time(BotMetrics.WebhookResponseTime))
+                hookMessageId = await ExecuteWebhook(webhook, messageContents, proxyName, avatarUrl, message.Attachments.FirstOrDefault());
 
             // Store the message in the database, and log it in the log channel (if applicable)
             await _messageStorage.Store(message.Author.Id, hookMessageId, message.Channel.Id, message.Id, match.Member);