Improve proxy cache behavior and diagnostics

src/Jellyfin.Plugin.Multilang/Api/MultilangController.cs

@@ -49,6 +49,8 @@ public sealed class MultilangController : ControllerBase
     private readonly RefreshService _refreshService;
     private readonly FanartClient _fanartClient;
     private readonly ItemsProxyCache _itemsProxyCache;
+    private readonly ItemsProxyRequestCoalescer _itemsProxyRequestCoalescer;
+    private readonly ItemsProxyPrecacheService _itemsProxyPrecacheService;
     private readonly ItemsProxyTransformer _itemsProxyTransformer;
     private readonly AssetStorageService _assetStorage;
     private readonly MultilangBackupService _backupService;
@@ -67,6 +69,8 @@ public sealed class MultilangController : ControllerBase
         RefreshService refreshService,
         FanartClient fanartClient,
         ItemsProxyCache itemsProxyCache,
+        ItemsProxyRequestCoalescer itemsProxyRequestCoalescer,
+        ItemsProxyPrecacheService itemsProxyPrecacheService,
         ItemsProxyTransformer itemsProxyTransformer,
         AssetStorageService assetStorage,
         MultilangBackupService backupService)
@@ -84,6 +88,8 @@ public sealed class MultilangController : ControllerBase
         _refreshService = refreshService;
         _fanartClient = fanartClient;
         _itemsProxyCache = itemsProxyCache;
+        _itemsProxyRequestCoalescer = itemsProxyRequestCoalescer;
+        _itemsProxyPrecacheService = itemsProxyPrecacheService;
         _itemsProxyTransformer = itemsProxyTransformer;
         _assetStorage = assetStorage;
         _backupService = backupService;
@@ -264,7 +270,7 @@ public sealed class MultilangController : ControllerBase
     }
 
     [HttpGet("ItemsProxy")]
-    public async Task<IActionResult> ItemsProxy([FromQuery] string url, CancellationToken cancellationToken)
+    public async Task<IActionResult> ItemsProxy([FromQuery] string url, [FromQuery] bool precache, CancellationToken cancellationToken)
     {
         if (string.IsNullOrWhiteSpace(url))
             return BadRequest(new { Error = "MissingUrl" });
@@ -286,6 +292,18 @@ public sealed class MultilangController : ControllerBase
         var cfg = Plugin.Instance?.Configuration ?? new PluginConfiguration();
         var cacheAllowed = rules.Enabled && cfg.ItemsProxyCacheTtlMinutes > 0 && cfg.ItemsProxyCacheMaxMiB > 0;
         var cacheTtl = TimeSpan.FromMinutes(Math.Max(1, cfg.ItemsProxyCacheTtlMinutes));
+        if (!precache && cacheAllowed)
+        {
+            var baseUri = new Uri($"{Request.Scheme}://{Request.Host}{Request.PathBase}/");
+            _itemsProxyPrecacheService.ObserveUserActivity(
+                baseUri,
+                userId,
+                token,
+                proxyRequest.Controls.ClientLocale,
+                cfg.PrecacheMovieLibraries,
+                cfg.PrecacheTvShowLibraries);
+        }
+
         if (cacheAllowed && _itemsProxyCache.TryGet(proxyRequest.CacheKey, cacheTtl, out var cached))
         {
             totalSw.Stop();
@@ -320,16 +338,27 @@ public sealed class MultilangController : ControllerBase
         }
 
         var upstreamSw = Stopwatch.StartNew();
-        var http = _httpClientFactory.CreateClient();
-        using var request = new HttpRequestMessage(HttpMethod.Get, proxyRequest.Upstream);
-        request.Headers.TryAddWithoutValidation("X-Emby-Token", token);
-        request.Headers.TryAddWithoutValidation("X-MediaBrowser-Token", token);
-        using var response = await http.SendAsync(request, cancellationToken).ConfigureAwait(false);
-        var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+        var upstream = await _itemsProxyRequestCoalescer.GetOrFetchAsync(
+            proxyRequest.NormalizedUrlForCache,
+            async sharedCancellationToken =>
+            {
+                var http = _httpClientFactory.CreateClient();
+                using var request = new HttpRequestMessage(HttpMethod.Get, proxyRequest.Upstream);
+                request.Headers.TryAddWithoutValidation("X-Emby-Token", token);
+                request.Headers.TryAddWithoutValidation("X-MediaBrowser-Token", token);
+                using var response = await http.SendAsync(request, sharedCancellationToken).ConfigureAwait(false);
+                var body = await response.Content.ReadAsStringAsync(sharedCancellationToken).ConfigureAwait(false);
+                return new ItemsProxyUpstreamResponse(
+                    (int)response.StatusCode,
+                    body,
+                    response.Content.Headers.ContentType?.ToString() ?? "application/json");
+            },
+            cancellationToken).ConfigureAwait(false);
         upstreamSw.Stop();
+        var body = upstream.Response.Body;
         string[] responseItemIds = [];
         var transformMs = 0L;
-        if (response.IsSuccessStatusCode && rules.Enabled)
+        if (upstream.Response.IsSuccessStatusCode && rules.Enabled)
         {
             var transformSw = Stopwatch.StartNew();
             var transformed = _itemsProxyTransformer.TransformItemsResponse(body, rules, proxyRequest.Controls);
@@ -340,11 +369,11 @@ public sealed class MultilangController : ControllerBase
         }
         totalSw.Stop();
 
-        var contentType = response.Content.Headers.ContentType?.ToString() ?? "application/json";
+        var contentType = upstream.Response.ContentType;
         var bodySizeBytes = System.Text.Encoding.UTF8.GetByteCount(body);
         var cacheStored = false;
         if (cacheAllowed &&
-            response.IsSuccessStatusCode &&
+            upstream.Response.IsSuccessStatusCode &&
             responseItemIds.Length > 0 &&
             totalSw.ElapsedMilliseconds >= Math.Max(0, cfg.ItemsProxyCacheThresholdMs))
         {
@@ -362,7 +391,7 @@ public sealed class MultilangController : ControllerBase
 
         if (cacheAllowed &&
             !cacheStored &&
-            response.IsSuccessStatusCode &&
+            upstream.Response.IsSuccessStatusCode &&
             responseItemIds.Length > 0)
         {
             _itemsProxyCache.StoreMicro(
@@ -380,16 +409,17 @@ public sealed class MultilangController : ControllerBase
             proxyRequest.NormalizedUrlForCache,
             cacheHit: false,
             cacheStored: cacheStored,
-            statusCode: (int)response.StatusCode,
+            statusCode: upstream.Response.StatusCode,
             itemCount: responseItemIds.Length,
             totalMs: totalSw.ElapsedMilliseconds,
             upstreamMs: upstreamSw.ElapsedMilliseconds,
             transformMs: transformMs,
-            sizeBytes: bodySizeBytes);
+            sizeBytes: bodySizeBytes,
+            inFlightCoalesced: upstream.JoinedExistingRequest);
 
         return new ContentResult
         {
-            StatusCode = (int)response.StatusCode,
+            StatusCode = upstream.Response.StatusCode,
             Content = body,
             ContentType = contentType
         };
@@ -1443,6 +1473,10 @@ public sealed class AdminConfigDto
 
     public int ItemsProxyCacheMaxMiB { get; set; }
 
+    public bool PrecacheMovieLibraries { get; set; } = true;
+
+    public bool PrecacheTvShowLibraries { get; set; } = true;
+
     public string AssetStorageMode { get; set; } = "url";
 
     public bool IgnoreArticlesWhenSorting { get; set; } = true;
@@ -1469,6 +1503,8 @@ public sealed class AdminConfigDto
             ItemsProxyCacheThresholdMs = cfg.ItemsProxyCacheThresholdMs,
             ItemsProxyCacheTtlMinutes = cfg.ItemsProxyCacheTtlMinutes,
             ItemsProxyCacheMaxMiB = cfg.ItemsProxyCacheMaxMiB,
+            PrecacheMovieLibraries = cfg.PrecacheMovieLibraries,
+            PrecacheTvShowLibraries = cfg.PrecacheTvShowLibraries,
             AssetStorageMode = NormalizeAssetStorageMode(cfg.AssetStorageMode),
             IgnoreArticlesWhenSorting = cfg.IgnoreArticlesWhenSorting,
             JellyfinTitleLanguageFallback = cfg.JellyfinTitleLanguageFallback,
@@ -1493,6 +1529,8 @@ public sealed class AdminConfigDto
             ItemsProxyCacheThresholdMs = Math.Max(0, ItemsProxyCacheThresholdMs),
             ItemsProxyCacheTtlMinutes = Math.Max(1, ItemsProxyCacheTtlMinutes),
             ItemsProxyCacheMaxMiB = Math.Max(1, ItemsProxyCacheMaxMiB),
+            PrecacheMovieLibraries = PrecacheMovieLibraries,
+            PrecacheTvShowLibraries = PrecacheTvShowLibraries,
             AssetStorageMode = NormalizeAssetStorageMode(AssetStorageMode),
             IgnoreArticlesWhenSorting = IgnoreArticlesWhenSorting,
             JellyfinTitleLanguageFallback = JellyfinTitleLanguageFallback?.Trim() ?? string.Empty,