internal/frontend: recycle database connections every 5m

In order to avoid imbalance between pkgsite's two database instances,
recycle connections every 5 minutes.

Change-Id: I9ca1e686a90f8c61619fd76454ec66163e501ee1
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/680175
kokoro-CI: kokoro <noreply+kokoro@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/internal/frontend/server.go b/internal/frontend/server.go
index a5e5e533..3e63f69b 100644
--- a/internal/frontend/server.go
+++ b/internal/frontend/server.go
@@ -42,7 +42,7 @@ import (
 type Server struct {
 	fetchServer FetchServerInterface
 	// getDataSource should never be called from a handler. It is called only in Server.errorHandler.
-	getDataSource      func(context.Context) internal.DataSource
+	getDataSource      func(context.Context) (internal.DataSource, func())
 	queue              queue.Queue
 	templateFS         template.TrustedFS
 	staticFS           fs.FS
@@ -82,9 +82,9 @@ type ServerConfig struct {
 	Config *config.Config
 	// Note that FetchServer may be nil.
 	FetchServer FetchServerInterface
-	// DataSourceGetter should return a DataSource on each call.
+	// DataSourceGetter should return a DataSource and a release function on each call.
 	// It should be goroutine-safe.
-	DataSourceGetter  func(context.Context) internal.DataSource
+	DataSourceGetter  func(context.Context) (internal.DataSource, func())
 	Queue             queue.Queue
 	TemplateFS        template.TrustedFS // for loading templates safely
 	StaticFS          fs.FS              // for static/ directory
@@ -503,7 +503,8 @@ func (s *Server) PanicHandler() (_ http.HandlerFunc, err error) {
 func (s *Server) errorHandler(f func(w http.ResponseWriter, r *http.Request, ds internal.DataSource) error) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		// Obtain a DataSource to use for this request.
-		ds := s.getDataSource(r.Context())
+		ds, release := s.getDataSource(r.Context())
+		defer release()
 		if err := f(w, r, ds); err != nil {
 			s.serveError(w, r, err)
 		}