Server Event Optimizations (#116)

environment/docker/container.go

@@ -342,10 +342,10 @@ func (e *Environment) followOutput() error {
 func (e *Environment) scanOutput(reader io.ReadCloser) {
 	defer reader.Close()
 
-	events := e.Events()
+	if err := system.ScanReader(reader, func(v []byte) {
-
+		e.logCallbackMx.Lock()
-	if err := system.ScanReader(reader, func(line string) {
+		defer e.logCallbackMx.Unlock()
-		events.Publish(environment.ConsoleOutputEvent, line)
+		e.logCallback(v)
 	}); err != nil && err != io.EOF {
 		log.WithField("error", err).WithField("container_id", e.Id).Warn("error processing scanner line in console output")
 		return

environment/docker/environment.go

@@ -49,7 +49,10 @@ type Environment struct {
 	// Holds the stats stream used by the polling commands so that we can easily close it out.
 	stats io.ReadCloser
 
-	emitter *events.EventBus
+	emitter *events.Bus
+
+	logCallbackMx sync.Mutex
+	logCallback   func([]byte)
 
 	// Tracks the environment state.
 	st *system.AtomicString
@@ -100,9 +103,9 @@ func (e *Environment) IsAttached() bool {
 	return e.stream != nil
 }
 
-func (e *Environment) Events() *events.EventBus {
+func (e *Environment) Events() *events.Bus {
 	e.eventMu.Do(func() {
-		e.emitter = events.New()
+		e.emitter = events.NewBus()
 	})
 
 	return e.emitter
@@ -214,3 +217,10 @@ func (e *Environment) SetState(state string) {
 		e.Events().Publish(environment.StateChangeEvent, state)
 	}
 }
+
+func (e *Environment) SetLogCallback(f func([]byte)) {
+	e.logCallbackMx.Lock()
+	defer e.logCallbackMx.Unlock()
+
+	e.logCallback = f
+}

environment/docker/stats.go

@@ -90,11 +90,7 @@ func (e *Environment) pollResources(ctx context.Context) error {
 				st.Network.TxBytes += nw.TxBytes
 			}
 
-			if b, err := json.Marshal(st); err != nil {
+			e.Events().Publish(environment.ResourceEvent, st)
-				e.log().WithField("error", err).Warn("error while marshaling stats object for environment")
-			} else {
-				e.Events().Publish(environment.ResourceEvent, string(b))
-			}
 		}
 	}
 }

environment/environment.go

@@ -8,7 +8,6 @@ import (
 )
 
 const (
-	ConsoleOutputEvent       = "console output"
 	StateChangeEvent         = "state change"
 	ResourceEvent            = "resources"
 	DockerImagePullStarted   = "docker image pull started"
@@ -35,7 +34,7 @@ type ProcessEnvironment interface {
 	// Returns an event emitter instance that can be hooked into to listen for different
 	// events that are fired by the environment. This should not allow someone to publish
 	// events, only subscribe to them.
-	Events() *events.EventBus
+	Events() *events.Bus
 
 	// Determines if the server instance exists. For example, in a docker environment
 	// this should confirm that the container is created and in a bootable state. In
@@ -108,4 +107,7 @@ type ProcessEnvironment interface {
 	// Uptime returns the current environment uptime in milliseconds. This is
 	// the time that has passed since it was last started.
 	Uptime(ctx context.Context) (int64, error)
+
+	// SetLogCallback sets the callback that the container's log output will be passed to.
+	SetLogCallback(func([]byte))
 }

events/events.go

@@ -1,32 +1,79 @@
 package events
 
 import (
-	"encoding/json"
 	"strings"
 	"sync"
-
-	"github.com/gammazero/workerpool"
 )
 
+type Listener chan Event
+
+// Event represents an Event sent over a Bus.
 type Event struct {
-	Data  string
 	Topic string
+	Data  interface{}
 }
 
-type EventBus struct {
+// Bus represents an Event Bus.
-	mu    sync.RWMutex
+type Bus struct {
-	pools map[string]*CallbackPool
+	listenersMx sync.Mutex
+	listeners   map[string][]Listener
 }
 
-func New() *EventBus {
+// NewBus returns a new empty Event Bus.
-	return &EventBus{
+func NewBus() *Bus {
-		pools: make(map[string]*CallbackPool),
+	return &Bus{
+		listeners: make(map[string][]Listener),
 	}
 }
 
-// Publish data to a given topic.
+// Off unregisters a listener from the specified topics on the Bus.
-func (e *EventBus) Publish(topic string, data string) {
+func (b *Bus) Off(listener Listener, topics ...string) {
-	t := topic
+	b.listenersMx.Lock()
+	defer b.listenersMx.Unlock()
+
+	for _, topic := range topics {
+		b.off(topic, listener)
+	}
+}
+
+func (b *Bus) off(topic string, listener Listener) bool {
+	listeners, ok := b.listeners[topic]
+	if !ok {
+		return false
+	}
+	for i, l := range listeners {
+		if l != listener {
+			continue
+		}
+
+		listeners = append(listeners[:i], listeners[i+1:]...)
+		b.listeners[topic] = listeners
+		return true
+	}
+	return false
+}
+
+// On registers a listener to the specified topics on the Bus.
+func (b *Bus) On(listener Listener, topics ...string) {
+	b.listenersMx.Lock()
+	defer b.listenersMx.Unlock()
+
+	for _, topic := range topics {
+		b.on(topic, listener)
+	}
+}
+
+func (b *Bus) on(topic string, listener Listener) {
+	listeners, ok := b.listeners[topic]
+	if !ok {
+		b.listeners[topic] = []Listener{listener}
+	} else {
+		b.listeners[topic] = append(listeners, listener)
+	}
+}
+
+// Publish publishes a message to the Bus.
+func (b *Bus) Publish(topic string, data interface{}) {
 	// Some of our topics for the socket support passing a more specific namespace,
 	// such as "backup completed:1234" to indicate which specific backup was completed.
 	//
@@ -36,87 +83,44 @@ func (e *EventBus) Publish(topic string, data string) {
 		parts := strings.SplitN(topic, ":", 2)
 
 		if len(parts) == 2 {
-			t = parts[0]
+			topic = parts[0]
 		}
 	}
 
-	e.mu.RLock()
+	b.listenersMx.Lock()
-	defer e.mu.RUnlock()
+	defer b.listenersMx.Unlock()
 
-	// Acquire a read lock and loop over all the channels registered for the topic. This
+	listeners, ok := b.listeners[topic]
-	// avoids a panic crash if the process tries to unregister the channel while this routine
+	if !ok {
-	// is running.
+		return
-	if cp, ok := e.pools[t]; ok {
-		for _, callback := range cp.callbacks {
-			c := *callback
-			evt := Event{Data: data, Topic: topic}
-			// Using the workerpool with one worker allows us to execute events in a FIFO manner. Running
-			// this using goroutines would cause things such as console output to just output in random order
-			// if more than one event is fired at the same time.
-			//
-			// However, the pool submission does not block the execution of this function itself, allowing
-			// us to call publish without blocking any of the other pathways.
-			//
-			// @see https://github.com/pterodactyl/panel/issues/2303
-			cp.pool.Submit(func() {
-				c(evt)
-			})
 	}
+	if len(listeners) < 1 {
+		return
 	}
+
+	var wg sync.WaitGroup
+	event := Event{Topic: topic, Data: data}
+	for _, listener := range listeners {
+		l := listener
+		wg.Add(1)
+		go func(l Listener, event Event) {
+			defer wg.Done()
+			l <- event
+		}(l, event)
+	}
+	wg.Wait()
 }
 
-// PublishJson publishes a JSON message to a given topic.
+// Destroy destroys the Event Bus by unregistering and closing all listeners.
-func (e *EventBus) PublishJson(topic string, data interface{}) error {
+func (b *Bus) Destroy() {
-	b, err := json.Marshal(data)
+	b.listenersMx.Lock()
-	if err != nil {
+	defer b.listenersMx.Unlock()
-		return err
+
+	for _, listeners := range b.listeners {
+		for _, listener := range listeners {
+			close(listener)
+		}
 	}
 
-	e.Publish(topic, string(b))
+	b.listeners = make(map[string][]Listener)
-
-	return nil
-}
-
-// On adds a callback function that will be executed each time one of the events using the topic
-// name is called.
-func (e *EventBus) On(topic string, callback *func(Event)) {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-
-	// Check if this topic has been registered at least once for the event listener, and if
-	// not create an empty struct for the topic.
-	if _, exists := e.pools[topic]; !exists {
-		e.pools[topic] = &CallbackPool{
-			callbacks: make([]*func(Event), 0),
-			pool:      workerpool.New(1),
-		}
-	}
-
-	// If this callback is not already registered as an event listener, go ahead and append
-	// it to the array of callbacks for this topic.
-	e.pools[topic].Add(callback)
-}
-
-// Off removes an event listener from the bus.
-func (e *EventBus) Off(topic string, callback *func(Event)) {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-
-	if cp, ok := e.pools[topic]; ok {
-		cp.Remove(callback)
-	}
-}
-
-// Destroy removes all the event listeners that have been registered for any topic. Also stops the worker
-// pool to close that routine.
-func (e *EventBus) Destroy() {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-
-	// Stop every pool that exists for a given callback topic.
-	for _, cp := range e.pools {
-		cp.pool.Stop()
-	}
-
-	e.pools = make(map[string]*CallbackPool)
 }

events/events_test.go

@@ -0,0 +1,180 @@
+package events
+
+import (
+	"testing"
+	"time"
+
+	. "github.com/franela/goblin"
+)
+
+func TestNewBus(t *testing.T) {
+	g := Goblin(t)
+	bus := NewBus()
+
+	g.Describe("NewBus", func() {
+		g.It("is not nil", func() {
+			g.Assert(bus).IsNotNil("Bus expected to not be nil")
+			g.Assert(bus.listeners).IsNotNil("Bus#listeners expected to not be nil")
+		})
+	})
+}
+
+func TestBus_Off(t *testing.T) {
+	g := Goblin(t)
+
+	const topic = "test"
+
+	g.Describe("Off", func() {
+		g.It("unregisters listener", func() {
+			bus := NewBus()
+
+			g.Assert(bus.listeners[topic]).IsNotNil()
+			g.Assert(len(bus.listeners[topic])).IsZero()
+			listener := make(chan Event)
+			bus.On(listener, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(1, "Listener was not registered")
+
+			bus.Off(listener, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(0, "Topic still has one or more listeners")
+
+			close(listener)
+		})
+
+		g.It("unregisters correct listener", func() {
+			bus := NewBus()
+
+			listener := make(chan Event)
+			listener2 := make(chan Event)
+			listener3 := make(chan Event)
+			bus.On(listener, topic)
+			bus.On(listener2, topic)
+			bus.On(listener3, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(3, "Listeners were not registered")
+
+			bus.Off(listener, topic)
+			bus.Off(listener3, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(1, "Expected 1 listener to remain")
+
+			if bus.listeners[topic][0] != listener2 {
+				// A normal Assert does not properly compare channels.
+				g.Fail("wrong listener unregistered")
+			}
+
+			// Cleanup
+			bus.Off(listener2, topic)
+			close(listener)
+			close(listener2)
+			close(listener3)
+		})
+	})
+}
+
+func TestBus_On(t *testing.T) {
+	g := Goblin(t)
+
+	const topic = "test"
+
+	g.Describe("On", func() {
+		g.It("registers listener", func() {
+			bus := NewBus()
+
+			g.Assert(bus.listeners[topic]).IsNotNil()
+			g.Assert(len(bus.listeners[topic])).IsZero()
+			listener := make(chan Event)
+			bus.On(listener, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(1, "Listener was not registered")
+
+			if bus.listeners[topic][0] != listener {
+				// A normal Assert does not properly compare channels.
+				g.Fail("wrong listener registered")
+			}
+
+			// Cleanup
+			bus.Off(listener, topic)
+			close(listener)
+		})
+	})
+}
+
+func TestBus_Publish(t *testing.T) {
+	g := Goblin(t)
+
+	const topic = "test"
+	const message = "this is a test message!"
+
+	g.Describe("Publish", func() {
+		g.It("publishes message", func() {
+			bus := NewBus()
+
+			g.Assert(bus.listeners[topic]).IsNotNil()
+			g.Assert(len(bus.listeners[topic])).IsZero()
+			listener := make(chan Event)
+			bus.On(listener, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(1, "Listener was not registered")
+
+			done := make(chan struct{}, 1)
+			go func() {
+				select {
+				case m := <-listener:
+					g.Assert(m.Topic).Equal(topic)
+					g.Assert(m.Data).Equal(message)
+				case <-time.After(1 * time.Second):
+					g.Fail("listener did not receive message in time")
+				}
+				done <- struct{}{}
+			}()
+			bus.Publish(topic, message)
+			<-done
+
+			// Cleanup
+			close(listener)
+			bus.Off(listener, topic)
+		})
+
+		g.It("publishes message to all listeners", func() {
+			bus := NewBus()
+
+			g.Assert(bus.listeners[topic]).IsNotNil()
+			g.Assert(len(bus.listeners[topic])).IsZero()
+			listener := make(chan Event)
+			listener2 := make(chan Event)
+			listener3 := make(chan Event)
+			bus.On(listener, topic)
+			bus.On(listener2, topic)
+			bus.On(listener3, topic)
+			g.Assert(len(bus.listeners[topic])).Equal(3, "Listener was not registered")
+
+			done := make(chan struct{}, 1)
+			go func() {
+				for i := 0; i < 3; i++ {
+					select {
+					case m := <-listener:
+						g.Assert(m.Topic).Equal(topic)
+						g.Assert(m.Data).Equal(message)
+					case m := <-listener2:
+						g.Assert(m.Topic).Equal(topic)
+						g.Assert(m.Data).Equal(message)
+					case m := <-listener3:
+						g.Assert(m.Topic).Equal(topic)
+						g.Assert(m.Data).Equal(message)
+					case <-time.After(1 * time.Second):
+						g.Fail("all listeners did not receive the message in time")
+						i = 3
+					}
+				}
+
+				done <- struct{}{}
+			}()
+			bus.Publish(topic, message)
+			<-done
+
+			// Cleanup
+			bus.Off(listener, topic)
+			bus.Off(listener2, topic)
+			bus.Off(listener3, topic)
+			close(listener)
+			close(listener2)
+			close(listener3)
+		})
+	})
+}

events/pool.go

@@ -1,50 +0,0 @@
-package events
-
-import (
-	"reflect"
-
-	"github.com/gammazero/workerpool"
-)
-
-type CallbackPool struct {
-	callbacks []*func(Event)
-	pool      *workerpool.WorkerPool
-}
-
-// Pushes a new callback into the array of listeners for the pool.
-func (cp *CallbackPool) Add(callback *func(Event)) {
-	if cp.index(reflect.ValueOf(callback)) < 0 {
-		cp.callbacks = append(cp.callbacks, callback)
-	}
-}
-
-// Removes a callback from the array of registered callbacks if it exists.
-func (cp *CallbackPool) Remove(callback *func(Event)) {
-	i := cp.index(reflect.ValueOf(callback))
-
-	// If i < 0 it means there was no index found for the given callback, meaning it was
-	// never registered or was already unregistered from the listeners. Also double check
-	// that we didn't somehow escape the length of the topic callback (not sure how that
-	// would happen, but lets avoid a panic condition).
-	if i < 0 || i >= len(cp.callbacks) {
-		return
-	}
-
-	// We can assume that the topic still exists at this point since we acquire an exclusive
-	// lock on the process, and the "e.index" function cannot return a value >= 0 if there is
-	// no topic already existing.
-	cp.callbacks = append(cp.callbacks[:i], cp.callbacks[i+1:]...)
-}
-
-// Finds the index of a given callback in the topic by comparing all of the registered callback
-// pointers to the passed function. This function does not aquire a lock as it should only be called
-// within the confines of a function that has already acquired a lock for the duration of the lookup.
-func (cp *CallbackPool) index(v reflect.Value) int {
-	for i, handler := range cp.callbacks {
-		if reflect.ValueOf(handler).Pointer() == v.Pointer() {
-			return i
-		}
-	}
-
-	return -1
-}

router/router_server.go

@@ -188,6 +188,8 @@ func deleteServer(c *gin.Context) {
 	// as well.
 	s.CtxCancel()
 	s.Events().Destroy()
+	s.LogSink().Destroy()
+	s.InstallSink().Destroy()
 	s.Websockets().CancelAll()
 
 	// Remove any pending remote file downloads for the server.

router/websocket/listeners.go

@@ -2,6 +2,7 @@ package websocket
 
 import (
 	"context"
+	"encoding/json"
 	"sync"
 	"time"
 
@@ -53,9 +54,9 @@ func (h *Handler) listenForExpiration(ctx context.Context) {
 			jwt := h.GetJwt()
 			if jwt != nil {
 				if jwt.ExpirationTime.Unix()-time.Now().Unix() <= 0 {
-					_ = h.SendJson(&Message{Event: TokenExpiredEvent})
+					_ = h.SendJson(Message{Event: TokenExpiredEvent})
 				} else if jwt.ExpirationTime.Unix()-time.Now().Unix() <= 60 {
-					_ = h.SendJson(&Message{Event: TokenExpiringEvent})
+					_ = h.SendJson(Message{Event: TokenExpiringEvent})
 				}
 			}
 		}
@@ -79,38 +80,79 @@ var e = []string{
 // ListenForServerEvents will listen for different events happening on a server
 // and send them along to the connected websocket client. This function will
 // block until the context provided to it is canceled.
-func (h *Handler) listenForServerEvents(pctx context.Context) error {
+func (h *Handler) listenForServerEvents(ctx context.Context) error {
 	var o sync.Once
 	var err error
-	ctx, cancel := context.WithCancel(pctx)
 
-	callback := func(e events.Event) {
+	ctx, cancel := context.WithCancel(ctx)
-		if sendErr := h.SendJson(&Message{Event: e.Topic, Args: []string{e.Data}}); sendErr != nil {
+	defer cancel()
-			h.Logger().WithField("event", e.Topic).WithField("error", sendErr).Error("failed to send event over server websocket")
+
+	eventChan := make(chan events.Event)
+	logOutput := make(chan []byte)
+	installOutput := make(chan []byte)
+	h.server.Events().On(eventChan, e...)
+	h.server.LogSink().On(logOutput)
+	h.server.InstallSink().On(installOutput)
+
+	onError := func(evt string, err2 error) {
+		h.Logger().WithField("event", evt).WithField("error", err2).Error("failed to send event over server websocket")
 		// Avoid race conditions by only setting the error once and then canceling
 		// the context. This way if additional processing errors come through due
 		// to a massive flood of things you still only report and stop at the first.
 		o.Do(func() {
-				err = sendErr
+			err = err2
-				cancel()
 		})
+		cancel()
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			break
+		case e := <-logOutput:
+			sendErr := h.SendJson(Message{Event: server.ConsoleOutputEvent, Args: []string{string(e)}})
+			if sendErr == nil {
+				continue
+			}
+			onError(server.ConsoleOutputEvent, sendErr)
+		case e := <-installOutput:
+			sendErr := h.SendJson(Message{Event: server.InstallOutputEvent, Args: []string{string(e)}})
+			if sendErr == nil {
+				continue
+			}
+			onError(server.InstallOutputEvent, sendErr)
+		case e := <-eventChan:
+			var sendErr error
+			message := Message{Event: e.Topic}
+			if str, ok := e.Data.(string); ok {
+				message.Args = []string{str}
+			} else if b, ok := e.Data.([]byte); ok {
+				message.Args = []string{string(b)}
+			} else {
+				b, sendErr = json.Marshal(e.Data)
+				if sendErr == nil {
+					message.Args = []string{string(b)}
 				}
 			}
 
-	// Subscribe to all of the events with the same callback that will push the
+			if sendErr == nil {
-	// data out over the websocket for the server.
+				sendErr = h.SendJson(message)
-	for _, evt := range e {
+				if sendErr == nil {
-		h.server.Events().On(evt, &callback)
+					continue
+				}
+			}
+			onError(message.Event, sendErr)
+		}
+		break
 	}
 
-	// When this function returns de-register all of the event listeners.
+	h.server.Events().Off(eventChan, e...)
-	defer func() {
+	h.server.InstallSink().Off(logOutput)
-		for _, evt := range e {
+	h.server.InstallSink().Off(installOutput)
-			h.server.Events().Off(evt, &callback)
+	close(eventChan)
-		}
+	close(logOutput)
-	}()
+	close(installOutput)
 
-	<-ctx.Done()
 	// If the internal context is stopped it is either because the parent context
 	// got canceled or because we ran into an error. If the "err" variable is nil
 	// we can assume the parent was canceled and need not perform any actions.

router/websocket/websocket.go

@@ -122,18 +122,17 @@ func (h *Handler) Logger() *log.Entry {
 		WithField("server", h.server.ID())
 }
 
-func (h *Handler) SendJson(v *Message) error {
+func (h *Handler) SendJson(v Message) error {
 	// Do not send JSON down the line if the JWT on the connection is not valid!
 	if err := h.TokenValid(); err != nil {
-		h.unsafeSendJson(Message{
+		_ = h.unsafeSendJson(Message{
 			Event: JwtErrorEvent,
 			Args:  []string{err.Error()},
 		})
 		return nil
 	}
 
-	j := h.GetJwt()
+	if j := h.GetJwt(); j != nil {
-	if j != nil {
 		// If we're sending installation output but the user does not have the required
 		// permissions to see the output, don't send it down the line.
 		if v.Event == server.InstallOutputEvent {
@@ -297,7 +296,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 			h.setJwt(token)
 
 			// Tell the client they authenticated successfully.
-			h.unsafeSendJson(Message{Event: AuthenticationSuccessEvent})
+			_ = h.unsafeSendJson(Message{Event: AuthenticationSuccessEvent})
 
 			// Check if the client was refreshing their authentication token
 			// instead of authenticating for the first time.
@@ -315,7 +314,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 			// On every authentication event, send the current server status back
 			// to the client. :)
 			state := h.server.Environment.State()
-			h.SendJson(&Message{
+			_ = h.SendJson(Message{
 				Event: server.StatusEvent,
 				Args:  []string{state},
 			})
@@ -327,7 +326,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 					_ = h.server.Filesystem().HasSpaceAvailable(false)
 
 					b, _ := json.Marshal(h.server.Proc())
-					h.SendJson(&Message{
+					_ = h.SendJson(Message{
 						Event: server.StatsEvent,
 						Args:  []string{string(b)},
 					})
@@ -357,7 +356,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 			if errors.Is(err, context.DeadlineExceeded) {
 				m, _ := h.GetErrorMessage("another power action is currently being processed for this server, please try again later")
 
-				h.SendJson(&Message{
+				_ = h.SendJson(Message{
 					Event: ErrorEvent,
 					Args:  []string{m},
 				})
@@ -381,7 +380,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 			}
 
 			for _, line := range logs {
-				h.SendJson(&Message{
+				_ = h.SendJson(Message{
 					Event: server.ConsoleOutputEvent,
 					Args:  []string{line},
 				})
@@ -392,7 +391,7 @@ func (h *Handler) HandleInbound(ctx context.Context, m Message) error {
 	case SendStatsEvent:
 		{
 			b, _ := json.Marshal(h.server.Proc())
-			h.SendJson(&Message{
+			_ = h.SendJson(Message{
 				Event: server.StatsEvent,
 				Args:  []string{string(b)},
 			})

server/backup.go

@@ -79,7 +79,7 @@ func (s *Server) Backup(b backup.BackupInterface) error {
 			s.Log().WithField("backup", b.Identifier()).Info("notified panel of failed backup state")
 		}
 
-		_ = s.Events().PublishJson(BackupCompletedEvent+":"+b.Identifier(), map[string]interface{}{
+		s.Events().Publish(BackupCompletedEvent+":"+b.Identifier(), map[string]interface{}{
 			"uuid":          b.Identifier(),
 			"is_successful": false,
 			"checksum":      "",
@@ -103,7 +103,7 @@ func (s *Server) Backup(b backup.BackupInterface) error {
 
 	// Emit an event over the socket so we can update the backup in realtime on
 	// the frontend for the server.
-	_ = s.Events().PublishJson(BackupCompletedEvent+":"+b.Identifier(), map[string]interface{}{
+	s.Events().Publish(BackupCompletedEvent+":"+b.Identifier(), map[string]interface{}{
 		"uuid":          b.Identifier(),
 		"is_successful": true,
 		"checksum":      ad.Checksum,

server/events.go

@@ -21,12 +21,12 @@ const (
 )
 
 // Returns the server's emitter instance.
-func (s *Server) Events() *events.EventBus {
+func (s *Server) Events() *events.Bus {
 	s.emitterLock.Lock()
 	defer s.emitterLock.Unlock()
 
 	if s.emitter == nil {
-		s.emitter = events.New()
+		s.emitter = events.NewBus()
 	}
 
 	return s.emitter

server/install.go

@@ -521,10 +521,7 @@ func (ip *InstallationProcess) StreamOutput(ctx context.Context, id string) erro
 	}
 	defer reader.Close()
 
-	evts := ip.Server.Events()
+	err = system.ScanReader(reader, ip.Server.InstallSink().Push)
-	err = system.ScanReader(reader, func(line string) {
-		evts.Publish(InstallOutputEvent, line)
-	})
 	if err != nil {
 		ip.Server.Log().WithFields(log.Fields{"container_id": id, "error": err}).Warn("error processing install output lines")
 	}

server/listeners.go

@@ -1,7 +1,6 @@
 package server
 
 import (
-	"encoding/json"
 	"regexp"
 	"strconv"
 	"sync"
@@ -51,10 +50,7 @@ func (dsl *diskSpaceLimiter) Trigger() {
 	})
 }
 
-// StartEventListeners adds all the internal event listeners we want to use for a server. These listeners can only be
+func (s *Server) processConsoleOutputEvent(v []byte) {
-// removed by deleting the server as they should last for the duration of the process' lifetime.
-func (s *Server) StartEventListeners() {
-	console := func(e events.Event) {
 	t := s.Throttler()
 	err := t.Increment(func() {
 		s.PublishConsoleOutputFromDaemon("Your server is outputting too much data and is being throttled.")
@@ -87,15 +83,27 @@ func (s *Server) StartEventListeners() {
 
 	// If we are not throttled, go ahead and output the data.
 	if !t.Throttled() {
-			s.Events().Publish(ConsoleOutputEvent, e.Data)
+		s.LogSink().Push(v)
 	}
 
 	// Also pass the data along to the console output channel.
-		s.onConsoleOutput(e.Data)
+	s.onConsoleOutput(string(v))
-	}
+}
 
+// StartEventListeners adds all the internal event listeners we want to use for a server. These listeners can only be
+// removed by deleting the server as they should last for the duration of the process' lifetime.
+func (s *Server) StartEventListeners() {
+	state := make(chan events.Event)
+	stats := make(chan events.Event)
+	docker := make(chan events.Event)
+
+	go func() {
 		l := newDiskLimiter(s)
-	state := func(e events.Event) {
+
+		for {
+			select {
+			case e := <-state:
+				go func() {
 					// Reset the throttler when the process is started.
 					if e.Data == environment.ProcessStartingState {
 						l.Reset()
@@ -103,18 +111,12 @@ func (s *Server) StartEventListeners() {
 					}
 
 					s.OnStateChange()
-	}
+				}()
-
+			case e := <-stats:
-	stats := func(e events.Event) {
+				go func() {
-		var st environment.Stats
-		if err := json.Unmarshal([]byte(e.Data), &st); err != nil {
-			s.Log().WithField("error", err).Warn("failed to unmarshal server environment stats")
-			return
-		}
-
 					// Update the server resource tracking object with the resources we got here.
 					s.resources.mu.Lock()
-		s.resources.Stats = st
+					s.resources.Stats = e.Data.(environment.Stats)
 					s.resources.mu.Unlock()
 
 					// If there is no disk space available at this point, trigger the server disk limiter logic
@@ -124,25 +126,27 @@ func (s *Server) StartEventListeners() {
 					}
 
 					s.emitProcUsage()
-	}
+				}()
-
+			case e := <-docker:
-	docker := func(e events.Event) {
+				go func() {
-		if e.Topic == environment.DockerImagePullStatus {
+					switch e.Topic {
+					case environment.DockerImagePullStatus:
 						s.Events().Publish(InstallOutputEvent, e.Data)
-		} else if e.Topic == environment.DockerImagePullStarted {
+					case environment.DockerImagePullStarted:
 						s.PublishConsoleOutputFromDaemon("Pulling Docker container image, this could take a few minutes to complete...")
-		} else {
+					default:
 						s.PublishConsoleOutputFromDaemon("Finished pulling Docker container image")
 					}
+				}()
 			}
+		}
+	}()
 
 	s.Log().Debug("registering event listeners: console, state, resources...")
-	s.Environment.Events().On(environment.ConsoleOutputEvent, &console)
+	s.Environment.SetLogCallback(s.processConsoleOutputEvent)
-	s.Environment.Events().On(environment.StateChangeEvent, &state)
+	s.Environment.Events().On(state, environment.StateChangeEvent)
-	s.Environment.Events().On(environment.ResourceEvent, &stats)
+	s.Environment.Events().On(stats, environment.ResourceEvent)
-	for _, evt := range dockerEvents {
+	s.Environment.Events().On(docker, dockerEvents...)
-		s.Environment.Events().On(evt, &docker)
-	}
 }
 
 var stripAnsiRegex = regexp.MustCompile("[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\u0007)|(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))")

server/resources.go

@@ -52,7 +52,5 @@ func (ru *ResourceUsage) Reset() {
 }
 
 func (s *Server) emitProcUsage() {
-	if err := s.Events().PublishJson(StatsEvent, s.Proc()); err != nil {
+	s.Events().Publish(StatsEvent, s.Proc())
-		s.Log().WithField("error", err).Warn("error while emitting server resource usage to listeners")
-	}
 }

server/server.go

@@ -49,7 +49,7 @@ type Server struct {
 	fs *filesystem.Filesystem
 
 	// Events emitted by the server instance.
-	emitter *events.EventBus
+	emitter *events.Bus
 
 	// Defines the process configuration for the server instance. This is dynamically
 	// fetched from the Pterodactyl Server instance each time the server process is
@@ -70,6 +70,9 @@ type Server struct {
 	// Tracks open websocket connections for the server.
 	wsBag       *WebsocketBag
 	wsBagLocker sync.Mutex
+
+	logSink     *sinkPool
+	installSink *sinkPool
 }
 
 // New returns a new server instance with a context and all of the default
@@ -83,6 +86,9 @@ func New(client remote.Client) (*Server, error) {
 		installing:   system.NewAtomicBool(false),
 		transferring: system.NewAtomicBool(false),
 		restoring:    system.NewAtomicBool(false),
+
+		logSink:     newSinkPool(),
+		installSink: newSinkPool(),
 	}
 	if err := defaults.Set(&s); err != nil {
 		return nil, errors.Wrap(err, "server: could not set default values for struct")
@@ -349,3 +355,11 @@ func (s *Server) ToAPIResponse() APIResponse {
 		Configuration: *s.Config(),
 	}
 }
+
+func (s *Server) LogSink() *sinkPool {
+	return s.logSink
+}
+
+func (s *Server) InstallSink() *sinkPool {
+	return s.installSink
+}

server/sink.go

@@ -0,0 +1,71 @@
+package server
+
+import (
+	"sync"
+	"time"
+)
+
+// sinkPool represents a pool with sinks.
+type sinkPool struct {
+	mx    sync.RWMutex
+	sinks []chan []byte
+}
+
+// newSinkPool returns a new empty sinkPool.
+func newSinkPool() *sinkPool {
+	return &sinkPool{}
+}
+
+// On adds a sink on the pool.
+func (p *sinkPool) On(c chan []byte) {
+	p.mx.Lock()
+	defer p.mx.Unlock()
+
+	p.sinks = append(p.sinks, c)
+}
+
+// Off removes a sink from the pool.
+func (p *sinkPool) Off(c chan []byte) {
+	p.mx.Lock()
+	defer p.mx.Unlock()
+
+	sinks := p.sinks
+
+	for i, sink := range sinks {
+		if c != sink {
+			continue
+		}
+		copy(sinks[i:], sinks[i+1:])
+		sinks[len(sinks)-1] = nil
+		sinks = sinks[:len(sinks)-1]
+		p.sinks = sinks
+		return
+	}
+}
+
+// Destroy destroys the pool by removing and closing all sinks.
+func (p *sinkPool) Destroy() {
+	p.mx.Lock()
+	defer p.mx.Unlock()
+
+	for _, c := range p.sinks {
+		close(c)
+	}
+
+	p.sinks = nil
+}
+
+// Push pushes a message to all registered sinks.
+func (p *sinkPool) Push(v []byte) {
+	p.mx.RLock()
+	for _, c := range p.sinks {
+		// TODO: should this be done in parallel?
+		select {
+		// Send the log output to the channel
+		case c <- v:
+		// Timeout after 100 milliseconds, this will cause the write to the channel to be cancelled.
+		case <-time.After(100 * time.Millisecond):
+		}
+	}
+	p.mx.RUnlock()
+}

system/utils.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"io"
 	"strconv"
-	"strings"
 	"sync"
 	"time"
 
@@ -38,14 +37,14 @@ func MustInt(v string) int {
 	return i
 }
 
-func ScanReader(r io.Reader, callback func(line string)) error {
+func ScanReader(r io.Reader, callback func(line []byte)) error {
 	br := bufio.NewReader(r)
 	// Avoid constantly re-allocating memory when we're flooding lines through this
 	// function by using the same buffer for the duration of the call and just truncating
 	// the value back to 0 every loop.
-	var str strings.Builder
+	buf := &bytes.Buffer{}
 	for {
-		str.Reset()
+		buf.Reset()
 		var err error
 		var line []byte
 		var isPrefix bool
@@ -57,7 +56,7 @@ func ScanReader(r io.Reader, callback func(line string)) error {
 			// in line with that it thinks is the terminal size. Those returns break a lot of output handling,
 			// so we'll just replace them with proper new-lines and then split it later and send each line as
 			// its own event in the response.
-			str.Write(bytes.Replace(line, cr, crr, -1))
+			buf.Write(bytes.Replace(line, cr, crr, -1))
 			// Finish this loop and begin outputting the line if there is no prefix (the line fit into
 			// the default buffer), or if we hit the end of the line.
 			if !isPrefix || err == io.EOF {
@@ -71,8 +70,9 @@ func ScanReader(r io.Reader, callback func(line string)) error {
 		}
 		// Publish the line for this loop. Break on new-line characters so every line is sent as a single
 		// output event, otherwise you get funky handling in the browser console.
-		for _, line := range strings.Split(str.String(), "\r\n") {
+		s := bufio.NewScanner(buf)
-			callback(line)
+		for s.Scan() {
+			callback(s.Bytes())
 		}
 		// If the error we got previously that lead to the line being output is an io.EOF we want to
 		// exit the entire looping process.