From 262e19b691762eb4fb00c50737c5decd62f35d4a Mon Sep 17 00:00:00 2001
From: David <daullmer@gmail.com>
Date: Tue, 14 Jul 2020 13:26:47 +0200
Subject: Add X-Response-Time-ms header and log slow server response time

---
 .../Middleware/ResponseTimeMiddleware.cs           | 78 ++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 Jellyfin.Server/Middleware/ResponseTimeMiddleware.cs

(limited to 'Jellyfin.Server/Middleware')

diff --git a/Jellyfin.Server/Middleware/ResponseTimeMiddleware.cs b/Jellyfin.Server/Middleware/ResponseTimeMiddleware.cs
new file mode 100644
index 000000000..3122d92cb
--- /dev/null
+++ b/Jellyfin.Server/Middleware/ResponseTimeMiddleware.cs
@@ -0,0 +1,78 @@
+using System.Diagnostics;
+using System.Globalization;
+using System.Threading.Tasks;
+using MediaBrowser.Controller.Configuration;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Extensions;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Server.Middleware
+{
+    /// <summary>
+    /// Response time middleware.
+    /// </summary>
+    public class ResponseTimeMiddleware
+    {
+        private const string ResponseHeaderResponseTime = "X-Response-Time-ms";
+
+        private readonly RequestDelegate _next;
+        private readonly ILogger<ResponseTimeMiddleware> _logger;
+
+        private readonly bool _enableWarning;
+        private readonly long _warningThreshold;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ResponseTimeMiddleware"/> class.
+        /// </summary>
+        /// <param name="next">Next request delegate.</param>
+        /// <param name="logger">Instance of the <see cref="ILogger{ExceptionMiddleware}"/> interface.</param>
+        /// <param name="serverConfigurationManager">Instance of the <see cref="IServerConfigurationManager"/> interface.</param>
+        public ResponseTimeMiddleware(
+            RequestDelegate next,
+            ILogger<ResponseTimeMiddleware> logger,
+            IServerConfigurationManager serverConfigurationManager)
+        {
+            _next = next;
+            _logger = logger;
+
+            _enableWarning = serverConfigurationManager.Configuration.EnableSlowResponseWarning;
+            _warningThreshold = serverConfigurationManager.Configuration.SlowResponseThresholdMs;
+        }
+
+        /// <summary>
+        /// Invoke request.
+        /// </summary>
+        /// <param name="context">Request context.</param>
+        /// <returns>Task.</returns>
+        public async Task Invoke(HttpContext context)
+        {
+            var watch = new Stopwatch();
+            watch.Start();
+
+            context.Response.OnStarting(() =>
+            {
+                watch.Stop();
+                LogWarning(context, watch);
+                var responseTimeForCompleteRequest = watch.ElapsedMilliseconds;
+                context.Response.Headers[ResponseHeaderResponseTime] = responseTimeForCompleteRequest.ToString(CultureInfo.InvariantCulture);
+                return Task.CompletedTask;
+            });
+
+            // Call the next delegate/middleware in the pipeline
+            await this._next(context).ConfigureAwait(false);
+        }
+
+        private void LogWarning(HttpContext context, Stopwatch watch)
+        {
+            if (_enableWarning && watch.ElapsedMilliseconds > _warningThreshold)
+            {
+                _logger.LogWarning(
+                    "Slow HTTP Response from {url} to {remoteIp} in {elapsed:g} with Status Code {statusCode}",
+                    context.Request.GetDisplayUrl(),
+                    context.Connection.RemoteIpAddress,
+                    watch.Elapsed,
+                    context.Response.StatusCode);
+            }
+        }
+    }
+}
-- 
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