TUN-7373: Streaming logs override for same actor

To help accommodate web browser interactions with websockets, when a
streaming logs session is requested for the same actor while already
serving a session for that user in a separate request, the original
request will be closed and the new request start streaming logs
instead. This should help with rogue sessions holding on for too long
with no client on the other side (before idle timeout or connection
close).

management/logger.go

@@ -11,16 +11,9 @@ import (
 
 var json = jsoniter.ConfigFastest
 
-const (
-	// Indicates how many log messages the listener will hold before dropping.
-	// Provides a throttling mechanism to drop latest messages if the sender
-	// can't keep up with the influx of log messages.
-	logWindow = 30
-)
-
 // Logger manages the number of management streaming log sessions
 type Logger struct {
-	sessions []*Session
+	sessions []*session
 	mu       sync.RWMutex
 
 	// Unique logger that isn't a io.Writer of the list of zerolog writers. This helps prevent management log
@@ -40,69 +33,47 @@ func NewLogger() *Logger {
 }
 
 type LoggerListener interface {
-	Listen(*StreamingFilters) *Session
-	Close(*Session)
+	// ActiveSession returns the first active session for the requested actor.
+	ActiveSession(actor) *session
+	// ActiveSession returns the count of active sessions.
+	ActiveSessions() int
+	// Listen appends the session to the list of sessions that receive log events.
+	Listen(*session)
+	// Remove a session from the available sessions that were receiving log events.
+	Remove(*session)
 }
 
-type Session struct {
-	// Buffered channel that holds the recent log events
-	listener chan *Log
-	// Types of log events that this session will provide through the listener
-	filters *StreamingFilters
-}
-
-func newSession(size int, filters *StreamingFilters) *Session {
-	s := &Session{
-		listener: make(chan *Log, size),
-	}
-	if filters != nil {
-		s.filters = filters
-	} else {
-		s.filters = &StreamingFilters{}
-	}
-	return s
-}
-
-// Insert attempts to insert the log to the session. If the log event matches the provided session filters, it
-// will be applied to the listener.
-func (s *Session) Insert(log *Log) {
-	// Level filters are optional
-	if s.filters.Level != nil {
-		if *s.filters.Level > log.Level {
-			return
+func (l *Logger) ActiveSession(actor actor) *session {
+	l.mu.RLock()
+	defer l.mu.RUnlock()
+	for _, session := range l.sessions {
+		if session.actor.ID == actor.ID && session.active.Load() {
+			return session
 		}
 	}
-	// Event filters are optional
-	if len(s.filters.Events) != 0 && !contains(s.filters.Events, log.Event) {
-		return
-	}
-	select {
-	case s.listener <- log:
-	default:
-		// buffer is full, discard
-	}
+	return nil
 }
 
-func contains(array []LogEventType, t LogEventType) bool {
-	for _, v := range array {
-		if v == t {
-			return true
+func (l *Logger) ActiveSessions() int {
+	l.mu.RLock()
+	defer l.mu.RUnlock()
+	count := 0
+	for _, session := range l.sessions {
+		if session.active.Load() {
+			count += 1
 		}
 	}
-	return false
+	return count
 }
 
-// Listen creates a new Session that will append filtered log events as they are created.
-func (l *Logger) Listen(filters *StreamingFilters) *Session {
+func (l *Logger) Listen(session *session) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	listener := newSession(logWindow, filters)
-	l.sessions = append(l.sessions, listener)
-	return listener
+	session.active.Store(true)
+	l.sessions = append(l.sessions, session)
 }
 
-// Close will remove a Session from the available sessions that were receiving log events.
-func (l *Logger) Close(session *Session) {
+func (l *Logger) Remove(session *session) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
 	index := -1