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

1 files changed, 18 insertions, 12 deletions

diff --git a/src/zenserver/sessions/httpsessions.cpp b/src/zenserver/sessions/httpsessions.cpp
index 429ba98cf..fdf2e1f21 100644
--- a/src/zenserver/sessions/httpsessions.cpp
+++ b/src/zenserver/sessions/httpsessions.cpp
@@ -49,6 +49,21 @@ HttpSessionsService::HandleRequest(HttpServerRequest& Request)
 	}
 }
 
+void
+HttpSessionsService::HandleStatusRequest(HttpServerRequest& Request)
+{
+	ZEN_TRACE_CPU("HttpSessionsService::Status");
+	CbObjectWriter Cbo;
+	Cbo << "ok" << true;
+	Request.WriteResponse(HttpResponseCode::OK, Cbo.Save());
+}
+
+void
+HttpSessionsService::HandleStatsRequest(HttpServerRequest& HttpReq)
+{
+	HttpReq.WriteResponse(HttpResponseCode::OK, CollectStats());
+}
+
 CbObject
 HttpSessionsService::CollectStats()
 {
@@ -72,19 +87,10 @@ HttpSessionsService::CollectStats()
 	return Cbo.Save();
 }
 
-void
-HttpSessionsService::HandleStatsRequest(HttpServerRequest& HttpReq)
+uint64_t
+HttpSessionsService::GetActivityCounter()
 {
-	HttpReq.WriteResponse(HttpResponseCode::OK, CollectStats());
-}
-
-void
-HttpSessionsService::HandleStatusRequest(HttpServerRequest& Request)
-{
-	ZEN_TRACE_CPU("HttpSessionsService::Status");
-	CbObjectWriter Cbo;
-	Cbo << "ok" << true;
-	Request.WriteResponse(HttpResponseCode::OK, Cbo.Save());
+	return m_HttpRequests.Count();
 }
 
 void