lib/http: implement server auto shutdown when idle

In the `ServerOptions`, we add option `ShutdownIdleDuration` when set to
non-zero value it will start a timer.
When the timer expired, the server will stop accepting new connection and
then shutting down.

This allow de-activating HTTP server when no connections received after
specific duration to reduce the system resources.

5 files changed, 83 insertions, 3 deletions

diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index 666dbaad..3130ddba 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -38,8 +38,8 @@ Legend,
 * 💧: Chores
 
 
-[#v0_61_1]
-== pakakeh.go v0.61.1 (2026-xx-xx)
+[#v0_62_0]
+== pakakeh.go v0.62.0 (2026-xx-xx)
 //{{{
 
 [#v0_61_1_lib_http]
@@ -56,6 +56,15 @@ to redirect URL.
 
 Any trailing slash in the BasePath will be removed.
 
+=== 🌱 Implement server auto shutdown when idle
+
+In the `ServerOptions`, we add option `ShutdownIdleDuration` when set to
+non-zero value it will start a timer.
+When the timer expired, the server will stop accepting new connection and
+then shutting down.
+
+This allow de-activating HTTP server when no connections received after
+specific duration to reduce the system resources.
 
 //}}}
 [#v0_61_0]
diff --git a/lib/http/server.go b/lib/http/server.go
index 4501cb9f..bbd1cf3e 100644
--- a/lib/http/server.go
+++ b/lib/http/server.go
@@ -46,6 +46,8 @@ type Server struct {
 	// Modifying the value of Options after server has been started may
 	// cause undefined effects.
 	Options ServerOptions
+
+	shutdownIdleTimer *time.Timer
 }
 
 // NewServer create and initialize new HTTP server that serve root directory
@@ -323,6 +325,14 @@ func (srv *Server) registerPut(ep *Endpoint) (err error) {
 
 // ServeHTTP handle mapping of client request to registered endpoints.
 func (srv *Server) ServeHTTP(res http.ResponseWriter, req *http.Request) {
+	if srv.shutdownIdleTimer != nil {
+		ok := srv.shutdownIdleTimer.Reset(srv.Options.ShutdownIdleDuration)
+		if !ok {
+			// Timer had expired or been stopped.
+			return
+		}
+	}
+
 	req.URL.Path = strings.TrimPrefix(req.URL.Path, srv.Options.BasePath)
 
 	switch req.Method {
@@ -358,6 +368,31 @@ func (srv *Server) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 
 // Start the HTTP server.
 func (srv *Server) Start() (err error) {
+	if srv.Options.ShutdownIdleDuration == 0 {
+		return srv.serve()
+	}
+
+	srv.shutdownIdleTimer = time.NewTimer(srv.Options.ShutdownIdleDuration)
+	go func() {
+		err = srv.serve()
+	}()
+	ever := true
+	for ever {
+		select {
+		case <-srv.shutdownIdleTimer.C:
+			ever = false
+			ok := srv.shutdownIdleTimer.Stop()
+			if !ok {
+				// Stop has been called manually.
+				break
+			}
+			err = srv.Stop(0)
+		}
+	}
+	return err
+}
+
+func (srv *Server) serve() (err error) {
 	if srv.Server.TLSConfig == nil {
 		if srv.Options.Listener == nil {
 			err = srv.Server.ListenAndServe()
@@ -380,6 +415,13 @@ func (srv *Server) Start() (err error) {
 // Stop the server using Shutdown method. The wait is set default and minimum
 // to five seconds.
 func (srv *Server) Stop(wait time.Duration) (err error) {
+	if srv.shutdownIdleTimer != nil {
+		ok := srv.shutdownIdleTimer.Stop()
+		if !ok {
+			// The timer has been stopped by other goroutine.
+			return nil
+		}
+	}
 	var defWait = 5 * time.Second
 	if wait <= defWait {
 		wait = defWait
diff --git a/lib/http/server_options.go b/lib/http/server_options.go
index 8e168885..61fcff33 100644
--- a/lib/http/server_options.go
+++ b/lib/http/server_options.go
@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"strings"
+	"time"
 
 	"git.sr.ht/~shulhan/pakakeh.go/lib/memfs"
 )
@@ -63,6 +64,11 @@ type ServerOptions struct {
 	// The options for Cross-Origin Resource Sharing.
 	CORS CORSOptions
 
+	// ShutdownIdleDuration define the duration where the server will
+	// automatically stop accepting new connection and then shutting down
+	// the server.
+	ShutdownIdleDuration time.Duration
+
 	// If true, server generate index.html automatically if its not
 	// exist in the directory.
 	// The index.html contains the list of files inside the requested
diff --git a/lib/http/server_test.go b/lib/http/server_test.go
index a333628c..0bdcce36 100644
--- a/lib/http/server_test.go
+++ b/lib/http/server_test.go
@@ -1569,3 +1569,26 @@ func runServerFS(t *testing.T, address, dir string) (srv *Server) {
 
 	return srv
 }
+
+func TestServer_ShutdownIdleDuration(t *testing.T) {
+	opts := ServerOptions{
+		Address:              `127.0.0.1:21000`,
+		ShutdownIdleDuration: 500 * time.Millisecond,
+	}
+	srv, err := NewServer(opts)
+	if err != nil {
+		t.Fatal(err)
+	}
+	waitq := make(chan struct{}, 1)
+	waitTimer := time.NewTimer(time.Second)
+	go func() {
+		err = srv.Start()
+		waitq <- struct{}{}
+	}()
+	select {
+	case <-waitq:
+		// Server shutdown after idle.
+	case <-waitTimer.C:
+		t.Fatalf(`expecting shutdown after %v`, opts.ShutdownIdleDuration)
+	}
+}
diff --git a/pakakeh.go b/pakakeh.go
index 97ad48f2..51c7baa0 100644
--- a/pakakeh.go
+++ b/pakakeh.go
@@ -6,4 +6,4 @@
 package pakakeh
 
 // Version of this module.
-var Version = `0.61.1`
+var Version = `0.62.0`