perf(dashboard): UGC page stays fast with tens of thousands of creations

The UGC page ran a CDClient query per distinct car or rocket combination
to find each preset's sample (thousands on a large server), re-read the
car and rocket build types from the CDClient on every list request, and
grouped every build into assemblies again on every page, sort or filter
change of the Cars and rockets list.

The modules and icon kinds are now read once at startup on the main
thread (UgcRoutes::Preload), so the web threads never query the CDClient
(which they must not), a combination's kind comes from that table, and
the grouped assemblies are shared by the requests of 15 seconds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDashboardServer/DashboardServer.cpp

@@ -443,6 +443,7 @@ int main(int argc, char** argv) {
 	{
 		const auto start = std::chrono::steady_clock::now();
 		ClientAssets::Preload();
+		UgcRoutes::Preload();
 		PreloadZoneData();
 		Scenery::Preload();
 		WorldView::Preload();

dDashboardServer/routes/UgcRoutes.cpp

@@ -1,7 +1,9 @@
 #include "UgcRoutes.h"
 
 #include <algorithm>
+#include <chrono>
 #include <memory>
+#include <mutex>
 #include <set>
 
 #include "CDClientDatabase.h"
@@ -70,7 +72,7 @@ namespace {
 
 	// Web thread: the icon kinds: player models, and each car or rocket build type in the client's data
 	// (ModularBuildComponent), named after the object its Assembly LOT is
-	nlohmann::json IconKinds() {
+	nlohmann::json LoadIconKinds() {
 		nlohmann::json kinds = nlohmann::json::array({ { { "kind", UgcIconParams::ModelKind() }, { "label", "Player models" } } });
 		auto result = CDClientDatabase::ExecuteQuery("SELECT buildType, xml FROM ModularBuildComponent GROUP BY buildType ORDER BY buildType;");
 		while (!result.eof()) {
@@ -92,17 +94,24 @@ namespace {
 		return kinds;
 	}
 
-	// Web thread: a car or rocket's kind, from its first module's build type (ModuleComponent)
+	// Client data read once by Preload (main thread), only read after that
+	nlohmann::json g_IconKinds = nlohmann::json::array();
+	std::map<uint32_t, UgcAssemblies::ModuleInfo> g_Modules;
+
+	// The icon kinds: player models, then each car or rocket build type with its name
+	const nlohmann::json& IconKinds() { return g_IconKinds; }
+
+	// Every module in the client's data (ModuleComponent) with its build type and name
+	const std::map<uint32_t, UgcAssemblies::ModuleInfo>& Modules() { return g_Modules; }
+
+	// A car or rocket's kind, from its first module's build type
 	std::optional<std::string> ModularKind(std::string modules) {
 		std::replace(modules.begin(), modules.end(), '-', '+'); // a combination's key too
 		const auto lots = UgcModularKey::Lots(modules);
 		if (lots.empty()) return std::nullopt;
-		auto query = CDClientDatabase::CreatePreppedStmt("SELECT m.buildType FROM ComponentsRegistry cr JOIN ModuleComponent m ON m.id = cr.component_id "
+		const auto it = Modules().find(lots.front());
-			"WHERE cr.id = ? AND cr.component_type = 28 LIMIT 1;");
+		if (it == Modules().end() || it->second.buildType < 0) return std::nullopt;
-		query.bind(1, static_cast<int32_t>(lots.front()));
+		return UgcIconParams::BuildKind(it->second.buildType);
-		auto row = query.execQuery();
-		if (row.eof()) return std::nullopt;
-		return UgcIconParams::BuildKind(row.getIntField("buildType", 0));
 	}
 
 	// Web thread: each kind with something to edit its preset on: the newest made player model, the most used combination of each build type
@@ -132,12 +141,9 @@ namespace {
 		return kinds;
 	}
 
-	// Web thread: every module in the client's data (ModuleComponent) with its build type and name, read once
+	// Main thread (Preload): every module in the client's data (ModuleComponent) with its build type and name
-	const std::map<uint32_t, UgcAssemblies::ModuleInfo>& Modules() {
+	std::map<uint32_t, UgcAssemblies::ModuleInfo> LoadModules() {
-		static std::map<uint32_t, UgcAssemblies::ModuleInfo> modules;
+		std::map<uint32_t, UgcAssemblies::ModuleInfo> modules;
-		static bool loaded = false;
-		if (loaded) return modules;
-		loaded = true;
 		auto result = CDClientDatabase::ExecuteQuery("SELECT cr.id AS lot, m.buildType AS buildType, o.name AS name, o.displayName AS displayName FROM ComponentsRegistry cr "
 			"JOIN ModuleComponent m ON m.id = cr.component_id LEFT JOIN Objects o ON o.id = cr.id WHERE cr.component_type = 28;");
 		while (!result.eof()) {
@@ -194,6 +200,24 @@ namespace {
 			{ "detail", entry.detail }, { "bricks", entry.bricks }, { "triangles", entry.triangles }, { "processMs", entry.processMs }, { "processCpuMs", entry.processCpuMs }, { "processMemoryKb", entry.processMemoryKb }, { "modelName", entry.modelName } };
 	}
 
+	// Web thread: the cars and rockets grouped into assemblies (one per combination of modules), from every build.
+	// Grouping all builds is the slow part of the Cars and rockets list, so the result is kept for a short while and
+	// shared by the requests in that time (it follows new builds and makes within ASSEMBLY_CACHE_TIME).
+	constexpr auto ASSEMBLY_CACHE_TIME = std::chrono::seconds(15);
+	std::vector<IUgcLookup::UgcEntry> AllBuilds(const IUgcLookup::UgcSearch& search);
+	std::shared_ptr<const std::vector<UgcAssemblies::Assembly>> CachedAssemblies() {
+		static std::mutex mutex;
+		static std::shared_ptr<const std::vector<UgcAssemblies::Assembly>> cached;
+		static std::chrono::steady_clock::time_point at;
+		std::lock_guard lock(mutex);
+		const auto now = std::chrono::steady_clock::now();
+		if (!cached || now - at > ASSEMBLY_CACHE_TIME) {
+			cached = std::make_shared<const std::vector<UgcAssemblies::Assembly>>(UgcAssemblies::Group(AllBuilds({}), Modules()));
+			at = now;
+		}
+		return cached;
+	}
+
 	// Web thread: every car and rocket build (the assemblies are made from them)
 	std::vector<IUgcLookup::UgcEntry> AllBuilds(const IUgcLookup::UgcSearch& search = {}) {
 		IUgcLookup::UgcListQuery query;
@@ -233,6 +257,11 @@ namespace {
 }
 
 namespace UgcRoutes {
+	void Preload() {
+		g_Modules = LoadModules();
+		g_IconKinds = LoadIconKinds();
+	}
+
 	void RegisterRoutes() {
 		Route(eHTTPMethod::GET, "/ugc", Perm("properties_view"), "What the UGC server made of players' models",
 			[](HTTPReply& reply, const HTTPContext& context) { RenderPage(reply, context, "ugc.jinja2", "ugc"); });
@@ -294,7 +323,7 @@ namespace UgcRoutes {
 							if (parsed.search.number) filter.moduleLot = static_cast<uint32_t>(*parsed.search.number);
 						}
 					}
-					auto assemblies = UgcAssemblies::Group(AllBuilds(), modules);
+					auto assemblies = *CachedAssemblies();
 					std::erase_if(assemblies, [&](const auto& a) { return !UgcAssemblies::Matches(a, filter, modules); });
 					UgcAssemblies::Sort(assemblies, UgcAssemblies::ParseSort(sortText).value_or(UgcAssemblies::eSort::NEWEST), modules, reverse);
 					total = assemblies.size();

dDashboardServer/routes/UgcRoutes.h

@@ -3,4 +3,8 @@
 // The UGC page: what the UGC server has made of players' models and modular builds, and making them again
 namespace UgcRoutes {
 	void RegisterRoutes();
+
+	// Reads the client data the UGC page needs (modules, build types) once, on the main thread at startup, so the web
+	// threads never query the CDClient
+	void Preload();
 }