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/storage/workspaces/httpworkspaces.cpp b/src/zenserver/storage/workspaces/httpworkspaces.cpp
index 785dd62f0..0119912e9 100644
--- a/src/zenserver/storage/workspaces/httpworkspaces.cpp
+++ b/src/zenserver/storage/workspaces/httpworkspaces.cpp
@@ -110,6 +110,21 @@ HttpWorkspacesService::HandleRequest(HttpServerRequest& Request)
 	}
 }
 
+void
+HttpWorkspacesService::HandleStatusRequest(HttpServerRequest& Request)
+{
+	ZEN_TRACE_CPU("HttpWorkspacesService::Status");
+	CbObjectWriter Cbo;
+	Cbo << "ok" << true;
+	Request.WriteResponse(HttpResponseCode::OK, Cbo.Save());
+}
+
+void
+HttpWorkspacesService::HandleStatsRequest(HttpServerRequest& HttpReq)
+{
+	HttpReq.WriteResponse(HttpResponseCode::OK, CollectStats());
+}
+
 CbObject
 HttpWorkspacesService::CollectStats()
 {
@@ -153,19 +168,10 @@ HttpWorkspacesService::CollectStats()
 	return Cbo.Save();
 }
 
-void
-HttpWorkspacesService::HandleStatsRequest(HttpServerRequest& HttpReq)
+uint64_t
+HttpWorkspacesService::GetActivityCounter()
 {
-	HttpReq.WriteResponse(HttpResponseCode::OK, CollectStats());
-}
-
-void
-HttpWorkspacesService::HandleStatusRequest(HttpServerRequest& Request)
-{
-	ZEN_TRACE_CPU("HttpWorkspacesService::Status");
-	CbObjectWriter Cbo;
-	Cbo << "ok" << true;
-	Request.WriteResponse(HttpResponseCode::OK, Cbo.Save());
+	return m_HttpRequests.Count();
 }
 
 void