[server] Add helpers for running background goroutines.
Such background goroutines will be used to do various maintenance jobs like
rereading settings or flushing metrics.
R=tandrii@chromium.org, jchinlee@chromium.org, nodir@chromium.org
BUG=959427
Change-Id: If8c794c118122cbd2e83145e7167d7a179e77fcc
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1616741
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
diff --git a/server/server.go b/server/server.go
index ad76bc3..e775d4a 100644
--- a/server/server.go
+++ b/server/server.go
@@ -71,6 +71,10 @@
started bool // true inside and after ListenAndServe
stopped bool // true inside and after Shutdown
done chan struct{} // closed after Shutdown returns
+
+ bgrCtx context.Context // root context for background work, canceled in Shutdown
+ bgrCancel context.CancelFunc // cancels bgrCtx
+ bgrWg sync.WaitGroup // waits for runInBackground goroutines to stop
}
// New constructs a new server instance.
@@ -97,6 +101,10 @@
// TODO(vadimsh): Populate admin routes (admin portal, pprof).
srv.RegisterHTTP(opts.AdminAddr)
+ // Prepare the context used for background work. It is canceled as soon as we
+ // enter the shutdown sequence.
+ srv.bgrCtx, srv.bgrCancel = context.WithCancel(srv.ctx)
+
return srv
}
@@ -195,7 +203,10 @@
logging.Infof(s.ctx, "Shutting down the server...")
- // Stop them all in parallel. Each Shutdown call blocks until the
+ // Tell all runInBackground goroutines to stop.
+ s.bgrCancel()
+
+ // Stop all http.Servers in parallel. Each Shutdown call blocks until the
// corresponding server is stopped.
wg := sync.WaitGroup{}
wg.Add(len(s.httpSrv))
@@ -208,6 +219,9 @@
}
wg.Wait()
+ // Wait for all background goroutines to stop.
+ s.bgrWg.Wait()
+
// Notify ListenAndServe that it can exit now.
s.stopped = true
close(s.done)
@@ -228,6 +242,18 @@
return fmt.Errorf("test listener is not set")
}
+// runInBackground starts a goroutine that does some background work.
+//
+// It is expected to exit soon after its context is canceled.
+func (s *Server) runInBackground(activity string, f func(context.Context)) {
+ ctx := logging.SetField(s.bgrCtx, "activity", activity)
+ s.bgrWg.Add(1)
+ go func() {
+ defer s.bgrWg.Done()
+ f(ctx)
+ }()
+}
+
// rootMiddleware prepares the per-request context.
func (s *Server) rootMiddleware(c *router.Context, next router.Handler) {
ctx, cancel := context.WithTimeout(s.ctx, time.Minute)
