Add Shutdown() and ShutdownWithContext() (#103)

* Add Shutdown() and ShutdownWithContext()

* reformat comments

* check nil

* fix lint

atreugo.go

@@ -1,6 +1,7 @@
 package atreugo
 
 import (
+	"context"
 	"log"
 	"net"
 	"os"
@@ -272,3 +273,38 @@ func (s *Atreugo) NewVirtualHost(hostnames ...string) *Router {
 
 	return vHost
 }
+
+// Shutdown gracefully shuts down the server without interrupting any active connections.
+// Shutdown works by first closing all open listeners and then waiting indefinitely for
+// all connections to return to idle and then shut down.
+//
+// When Shutdown is called, Serve, ListenAndServe, and ListenAndServeTLS immediately return
+// nil. Make sure the program doesn't exit and waits instead for Shutdown to return.
+//
+// Shutdown does not close keepalive connections so it's recommended to set ReadTimeout
+// and IdleTimeout to something else than 0.
+func (s *Atreugo) Shutdown() (err error) {
+	if s.engine != nil {
+		err = s.engine.ShutdownWithContext(context.Background())
+	}
+
+	return
+}
+
+// ShutdownWithContext gracefully shuts down the server without interrupting any active
+// connections. ShutdownWithContext works by first closing all open listeners and then
+// waiting for all connections to return to idle or context timeout and then shut down.
+//
+// When ShutdownWithContext is called, Serve, ListenAndServe, and ListenAndServeTLS
+// immediately return nil. Make sure the program doesn't exit and waits instead for
+// Shutdown to return.
+//
+// ShutdownWithContext does not close keepalive connections so it's recommended to set
+// ReadTimeout and IdleTimeout to something else than 0.
+func (s *Atreugo) ShutdownWithContext(ctx context.Context) (err error) {
+	if s.engine != nil {
+		err = s.engine.ShutdownWithContext(ctx)
+	}
+
+	return
+}

atreugo_test.go

@@ -1,6 +1,7 @@
 package atreugo
 
 import (
+	"context"
 	"crypto/tls"
 	"errors"
 	"fmt"
@@ -591,6 +592,77 @@ func TestAtreugo_NewVirtualHost(t *testing.T) { //nolint:funlen
 	}
 }
 
+func TestAtreugo_Shutdown(t *testing.T) {
+	s := New(testConfig)
+
+	ln := fasthttputil.NewInmemoryListener()
+	errCh := make(chan error, 1)
+
+	go func() {
+		errCh <- s.Serve(ln)
+	}()
+
+	time.Sleep(500 * time.Millisecond)
+
+	if err := s.Shutdown(); err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if err := <-errCh; err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if lnAddr := ln.Addr().String(); s.cfg.Addr != lnAddr {
+		t.Errorf("Atreugo.Config.Addr = %s, want %s", s.cfg.Addr, lnAddr)
+	}
+
+	lnNetwork := ln.Addr().Network()
+	if s.cfg.Network != lnNetwork {
+		t.Errorf("Atreugo.Config.Network = %s, want %s", s.cfg.Network, lnNetwork)
+	}
+
+	if s.engine.Handler == nil {
+		t.Error("Atreugo.engine.Handler is nil")
+	}
+}
+
+func TestAtreugo_ShutdownWithContext(t *testing.T) {
+	s := New(testConfig)
+
+	ln := fasthttputil.NewInmemoryListener()
+	errCh := make(chan error, 1)
+
+	go func() {
+		errCh <- s.Serve(ln)
+	}()
+
+	time.Sleep(500 * time.Millisecond)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+	defer cancel()
+
+	if err := s.ShutdownWithContext(ctx); err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if err := <-errCh; err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if lnAddr := ln.Addr().String(); s.cfg.Addr != lnAddr {
+		t.Errorf("Atreugo.Config.Addr = %s, want %s", s.cfg.Addr, lnAddr)
+	}
+
+	lnNetwork := ln.Addr().Network()
+	if s.cfg.Network != lnNetwork {
+		t.Errorf("Atreugo.Config.Network = %s, want %s", s.cfg.Network, lnNetwork)
+	}
+
+	if s.engine.Handler == nil {
+		t.Error("Atreugo.engine.Handler is nil")
+	}
+}
+
 // Benchmarks.
 func Benchmark_Handler(b *testing.B) {
 	s := New(testConfig)