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

4 files changed, 11 insertions, 3 deletions

diff --git a/src/zenhttp/include/zenhttp/auth/authservice.h b/src/zenhttp/include/zenhttp/auth/authservice.h
index 64b86e21f..ee67c0f5b 100644
--- a/src/zenhttp/include/zenhttp/auth/authservice.h
+++ b/src/zenhttp/include/zenhttp/auth/authservice.h
@@ -8,14 +8,14 @@ namespace zen {
 
 class AuthMgr;
 
-class HttpAuthService final : public zen::HttpService
+class HttpAuthService final : public HttpService
 {
 public:
 	HttpAuthService(AuthMgr& AuthMgr);
 	virtual ~HttpAuthService();
 
 	virtual const char* BaseUri() const override;
-	virtual void		HandleRequest(zen::HttpServerRequest& Request) override;
+	virtual void		HandleRequest(HttpServerRequest& Request) override;
 
 private:
 	AuthMgr&		  m_AuthMgr;
diff --git a/src/zenhttp/include/zenhttp/httpclient.h b/src/zenhttp/include/zenhttp/httpclient.h
index b0d74951e..26d60b9ae 100644
--- a/src/zenhttp/include/zenhttp/httpclient.h
+++ b/src/zenhttp/include/zenhttp/httpclient.h
@@ -364,6 +364,7 @@ public:
 	LoggerRef		 Log() { return m_Log; }
 	std::string_view GetBaseUri() const { return m_BaseUri; }
 	std::string_view GetSessionId() const { return m_SessionId; }
+	void			 SetBaseUri(std::string_view NewBaseUri);
 	void			 SetSessionId(const Oid& SessionId);
 
 	bool Authenticate();
diff --git a/src/zenhttp/include/zenhttp/httpserver.h b/src/zenhttp/include/zenhttp/httpserver.h
index 633eb06be..5eaed6004 100644
--- a/src/zenhttp/include/zenhttp/httpserver.h
+++ b/src/zenhttp/include/zenhttp/httpserver.h
@@ -220,6 +220,12 @@ struct IHttpStatsProvider
 	 *  not override this will be skipped in WebSocket broadcasts.
 	 */
 	virtual CbObject CollectStats() { return {}; }
+
+	/** Return a number indicating activity. Increase the number
+	 *  when activity is detected. Example would be to return the
+	 *  number of received requests
+	 */
+	virtual uint64_t GetActivityCounter() { return 0; }
 };
 
 struct IHttpStatsService
@@ -302,8 +308,8 @@ public:
 	}
 
 	// IHttpStatsProvider
-	virtual CbObject CollectStats() override;
 	virtual void	 HandleStatsRequest(HttpServerRequest& Request) override;
+	virtual CbObject CollectStats() override;
 
 private:
 	std::vector<HttpService*> m_KnownServices;
diff --git a/src/zenhttp/include/zenhttp/httpstats.h b/src/zenhttp/include/zenhttp/httpstats.h
index 460315faf..bce771c75 100644
--- a/src/zenhttp/include/zenhttp/httpstats.h
+++ b/src/zenhttp/include/zenhttp/httpstats.h
@@ -62,6 +62,7 @@ private:
 	std::atomic<bool>					  m_PushEnabled{false};
 
 	void BroadcastStats();
+	void Initialize();
 
 	// Thread-based push (when no io_context is provided)
 	std::thread m_PushThread;