Broken! Do not execute!

helpers/evmux.go

@@ -0,0 +1,52 @@
+package helpers
+
+import "sync"
+
+type EventMux[T any] struct {
+	// INFO: This is a simple event multiplexer that allows to subscribe to events and to publish them.
+	mu          sync.Mutex
+	subscribers []chan T
+}
+
+func NewEventMux[T any]() *EventMux[T] {
+	return &EventMux[T]{
+		subscribers: make([]chan T, 0),
+	}
+}
+
+func (e *EventMux[T]) Subscribe(size uint) chan T {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	subscriber := make(chan T, size)
+	e.subscribers = append(e.subscribers, subscriber)
+	return subscriber
+}
+
+func (e *EventMux[T]) Unsubscribe(subscriber chan T) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	for i, s := range e.subscribers {
+		if s == subscriber {
+			close(s)
+			e.subscribers = append(e.subscribers[:i], e.subscribers[i+1:]...)
+			return
+		}
+	}
+}
+
+func (e *EventMux[T]) Publish(event T) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	for _, subscriber := range e.subscribers {
+		subscriber <- event
+	}
+}
+
+func (e *EventMux[T]) Close() {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	for _, subscriber := range e.subscribers {
+		close(subscriber)
+	}
+	e.subscribers = make([]chan T, 0)
+}

kgpz_web.go

@@ -42,8 +42,11 @@ func Bootstrap(k *app.KGPZ) {
 }
 
 func Start(k *app.KGPZ, s *server.Server) {
+	s.Start()
+
 	sigs := make(chan os.Signal, 1)
 	done := make(chan bool, 1)
+	serversignals := s.Events.Subscribe(1)
 
 	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
 
@@ -52,17 +55,30 @@ func Start(k *app.KGPZ, s *server.Server) {
 		fmt.Println("Received signal. Cleaning up.")
 		// INFO: here we add cleanup functions
 		s.Kill()
+		s.BreakUntil(serversignals, server.Killed)
+		fmt.Println("Server killed.")
 		k.Shutdown()
 		done <- true
 	}()
 
-	// INFO: if the server fails to start this exits the program
+	// Interactive listening for input
-	// We handle graceful server recovery in the server itself.
+	if k.IsDebug() {
-	go func() {
+		go func() {
-		s.Start()
+			for {
-		<-s.Killed
+				var input string
-		fmt.Println("Server exited. Cleaning up.")
+				fmt.Scanln(&input)
-	}()
+				if input == "r" {
+					fmt.Println("Restarting server.")
+					s.Restart()
+				} else if input == "p" {
+					fmt.Println("Pulling repo.")
+					k.Pull()
+				} else if input == "q" {
+					done <- true
+				}
+			}
+		}()
+	}
 
 	<-done
 	fmt.Println("Cleanup finished. Exiting.")

server/server.go

@@ -6,6 +6,21 @@ import (
 	"net/http"
 
 	"githib.com/Theodor-Springmann-Stiftung/kgpz_web/app"
+	"githib.com/Theodor-Springmann-Stiftung/kgpz_web/helpers"
+)
+
+type ServerState int
+
+const (
+	Created ServerState = iota
+	Running
+	Restarting
+	ShuttingDown
+	ShutDown
+	ShuttedDown
+	Kill
+	Killing
+	Killed
 )
 
 // INFO: Server is a meta-package that handles the current router, which it starts in a goroutine.
@@ -16,9 +31,7 @@ import (
 // - we reload all clients
 // - if data validity catastrophically fails, we restart the router to map error pages.
 type Server struct {
-	running chan bool
+	Events helpers.EventMux[ServerState]
-	alive   chan bool
-	Killed  chan bool
 }
 
 func Start(k *app.KGPZ) *Server {
@@ -26,81 +39,102 @@ func Start(k *app.KGPZ) *Server {
 }
 
 func (s *Server) Start() {
-	srv := &http.Server{Addr: ":8080"}
+	srv := &http.Server{Addr: ":8081"}
-	s.running = make(chan bool, 1)
+	s.killHandler(srv)
-	s.alive = make(chan bool, 1)
+	s.shutdownHandler(srv)
-	s.Killed = s.killHandler(srv, s.alive)
+	s.runnerHandler(srv)
-	shuttingdown := s.shutdownHandler(srv, s.running)
+	s.restartHandler()
-	shutdown := s.runnerHandler(srv, shuttingdown)
-	s.restartHandler(shutdown)
 }
 
 func (s *Server) Restart() {
-	s.running <- false
+	s.Events.Publish(ShutDown)
 }
 
 func (s *Server) Kill() {
-	s.alive <- false
+	s.Events.Publish(Kill)
 }
 
-func (s *Server) killHandler(srv *http.Server, alive chan bool) chan bool {
+func (s *Server) restartHandler() {
-	kill := make(chan bool, 1)
+	shutdown := s.Events.Subscribe(1)
-
 	go func() {
-		<-alive
+		s.BreakUntil(shutdown, ShuttedDown)
-
+		s.Events.Publish(Restarting)
-		if err := srv.Shutdown(nil); err != nil {
-			fmt.Println("Error shutting down server")
-		}
-
-		kill <- true
-	}()
-
-	return kill
-}
-
-func (s *Server) restartHandler(shutdown chan bool) {
-	go func() {
-		<-shutdown
 		s.Start()
 	}()
 }
 
-func (s *Server) runnerHandler(srv *http.Server, shuttingdown chan bool) chan bool {
+func (s *Server) runnerHandler(srv *http.Server) {
-	shutdown := make(chan bool, 1)
 
+	shutttingdown := s.Events.Subscribe(1)
 	go func() {
+		s.Events.Publish(Running)
 		// EXAMPLE:
-		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		mux := http.NewServeMux()
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 			io.WriteString(w, "hello world\n")
 		})
 
+		srv.Handler = mux
+
 		if err := srv.ListenAndServe(); err != http.ErrServerClosed {
 			fmt.Println("Error starting server")
+			return
 		}
 
-		<-shuttingdown
+	loop:
-		shutdown <- true
+		for {
+			msg := <-shutttingdown
+			if msg == ShuttingDown {
+				s.Events.Publish(ShuttedDown)
+				break loop
+			}
+			if msg == Killing {
+				s.Events.Publish(Killed)
+				break loop
+			}
+		}
 	}()
 
-	return shutdown
 }
 
-func (s *Server) shutdownHandler(srv *http.Server, running chan bool) chan bool {
+func (s *Server) shutdownHandler(srv *http.Server) {
-	shuttingdown := make(chan bool, 1)
 
+	shutdown := s.Events.Subscribe(1)
 	go func() {
-		<-running
+		s.BreakUntil(shutdown, ShutDown)
-
+		fmt.Println("Shutting down server")
 		if err := srv.Shutdown(nil); err != nil {
 			fmt.Println("Error shutting down server")
 		}
 
-		shuttingdown <- true
+		s.Events.Publish(ShuttingDown)
 	}()
 
-	return shuttingdown
 }
 
-func (s *Server) Shutdown() {
+func (s *Server) killHandler(srv *http.Server) {
+
+	kill := s.Events.Subscribe(1)
+	go func() {
+		s.BreakUntil(kill, Kill)
+		fmt.Println("Killing server")
+		if err := srv.Shutdown(nil); err != nil {
+			fmt.Println("Error shutting down server")
+		}
+
+		s.Events.Publish(Killing)
+	}()
+
+}
+
+func (s *Server) BreakUntil(c chan ServerState, state ServerState) {
+loop:
+	for {
+		msg := <-c
+		if msg == state {
+			break loop
+		}
+	}
+
+	s.Events.Unsubscribe(c)
 }