From 776d76d299748a79b9cb25593cd8266cb26a6553 Mon Sep 17 00:00:00 2001
From: Dan Engelbrecht <dan.engelbrecht@epicgames.com>
Date: Fri, 27 Mar 2026 11:13:02 +0100
Subject: idle deprovision in hub (#895)

- Feature: Hub watchdog automatically deprovisions inactive provisioned and hibernated instances
- Feature: Added `stats/activity_counters` endpoint to measure server activity
- Feature: Added configuration options for hub watchdog
  - `--hub-watchdog-provisioned-inactivity-timeout-seconds` Inactivity timeout before a provisioned instance is deprovisioned
  - `--hub-watchdog-hibernated-inactivity-timeout-seconds` Inactivity timeout before a hibernated instance is deprovisioned
  - `--hub-watchdog-inactivity-check-margin-seconds` Margin before timeout at which an activity check is issued
  - `--hub-watchdog-cycle-interval-ms` Watchdog poll interval in milliseconds
  - `--hub-watchdog-cycle-processing-budget-ms` Maximum time budget per watchdog cycle in milliseconds
  - `--hub-watchdog-instance-check-throttle-ms` Minimum delay between checks on a single instance
  - `--hub-watchdog-activity-check-connect-timeout-ms` Connect timeout for activity check requests
  - `--hub-watchdog-activity-check-request-timeout-ms` Request timeout for activity check requests
---
 src/zenhttp/httpserver.cpp | 97 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 90 insertions(+), 7 deletions(-)

(limited to 'src/zenhttp/httpserver.cpp')

diff --git a/src/zenhttp/httpserver.cpp b/src/zenhttp/httpserver.cpp
index a46c5b851..9fc42f18c 100644
--- a/src/zenhttp/httpserver.cpp
+++ b/src/zenhttp/httpserver.cpp
@@ -798,7 +798,18 @@ HttpRequestRouter::HandleRequest(zen::HttpServerRequest& Request)
 
 	const HttpVerb Verb = Request.RequestVerb();
 
-	std::string_view  Uri = Request.RelativeUri();
+	std::string_view Uri = Request.RelativeUri();
+
+	// Strip the separator slash left over after the service prefix is removed.
+	// When a service has BaseUri "/foo", the prefix length is set to len("/foo") = 4.
+	// Stripping 4 chars from "/foo/bar" yields "/bar" — the path separator becomes
+	// the first character of the relative URI. Remove it so patterns like "bar" or
+	// "{id}" match without needing to account for the leading slash.
+	if (!Uri.empty() && Uri.front() == '/')
+	{
+		Uri.remove_prefix(1);
+	}
+
 	HttpRouterRequest RouterRequest(Request);
 
 	for (const MatcherEndpoint& Handler : m_MatcherEndpoints)
@@ -974,6 +985,12 @@ HttpServer::SetHttpRequestFilter(IHttpRequestFilter* RequestFilter)
 	OnSetHttpRequestFilter(RequestFilter);
 }
 
+void
+HttpServer::HandleStatsRequest(HttpServerRequest& Request)
+{
+	Request.WriteResponse(HttpResponseCode::OK, CollectStats());
+}
+
 CbObject
 HttpServer::CollectStats()
 {
@@ -1004,12 +1021,6 @@ HttpServer::CollectStats()
 	return Cbo.Save();
 }
 
-void
-HttpServer::HandleStatsRequest(HttpServerRequest& Request)
-{
-	Request.WriteResponse(HttpResponseCode::OK, CollectStats());
-}
-
 //////////////////////////////////////////////////////////////////////////
 
 HttpRpcHandler::HttpRpcHandler()
@@ -1446,6 +1457,78 @@ TEST_CASE("http.common")
 		}
 	}
 
+	SUBCASE("router-leading-slash")
+	{
+		// Verify that HandleRequest strips the leading slash that server implementations
+		// leave in RelativeUri() when the service base URI has no trailing slash.
+		// e.g. BaseUri "/stats" + prefix-strip of "/stats/foo" yields "/foo", not "foo".
+
+		bool					 HandledLiteral = false;
+		bool					 HandledPattern = false;
+		bool					 HandledTwoSeg	= false;
+		std::vector<std::string> Captures;
+		auto					 Reset = [&] {
+			HandledLiteral = HandledPattern = HandledTwoSeg = false;
+			Captures.clear();
+		};
+
+		TestHttpService	  Service;
+		HttpRequestRouter r;
+
+		r.AddMatcher("seg", [](std::string_view In) -> bool { return !In.empty() && In.find('/') == std::string_view::npos; });
+
+		r.RegisterRoute(
+			"activity_counters",
+			[&](auto& /*Req*/) { HandledLiteral = true; },
+			HttpVerb::kGet);
+
+		r.RegisterRoute(
+			"{seg}",
+			[&](auto& Req) {
+				HandledPattern = true;
+				Captures	   = {std::string(Req.GetCapture(1))};
+			},
+			HttpVerb::kGet);
+
+		r.RegisterRoute(
+			"prefix/{seg}",
+			[&](auto& Req) {
+				HandledTwoSeg = true;
+				Captures	  = {std::string(Req.GetCapture(1))};
+			},
+			HttpVerb::kGet);
+
+		// Single-segment literal with leading slash — simulates real server RelativeUri
+		{
+			Reset();
+			TestHttpServerRequest req{Service, "/activity_counters"sv};
+			r.HandleRequest(req);
+			CHECK(HandledLiteral);
+			CHECK(!HandledPattern);
+		}
+
+		// Single-segment pattern with leading slash
+		{
+			Reset();
+			TestHttpServerRequest req{Service, "/hello"sv};
+			r.HandleRequest(req);
+			CHECK(!HandledLiteral);
+			CHECK(HandledPattern);
+			REQUIRE_EQ(Captures.size(), 1);
+			CHECK_EQ(Captures[0], "hello"sv);
+		}
+
+		// Two-segment route with leading slash — first literal segment
+		{
+			Reset();
+			TestHttpServerRequest req{Service, "/prefix/world"sv};
+			r.HandleRequest(req);
+			CHECK(HandledTwoSeg);
+			REQUIRE_EQ(Captures.size(), 1);
+			CHECK_EQ(Captures[0], "world"sv);
+		}
+	}
+
 	SUBCASE("content-type")
 	{
 		for (uint8_t i = 0; i < uint8_t(HttpContentType::kCOUNT); ++i)
-- 
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