Fix crash in console logger and also handle bucket DNS updates (#8654)

Also fix listenBucketNotification bugs seen by minio-js
listen bucket notification API.

cmd/consolelogger.go

@@ -34,31 +34,40 @@ const defaultLogBufferCount = 10000
 
 //HTTPConsoleLoggerSys holds global console logger state
 type HTTPConsoleLoggerSys struct {
+	sync.RWMutex
 	pubsub   *pubsub.PubSub
 	console  *console.Target
 	nodeName string
-	// To protect ring buffer.
-	logBufLk sync.RWMutex
 	logBuf   *ring.Ring
 }
 
-// NewConsoleLogger - creates new HTTPConsoleLoggerSys with all nodes subscribed to
-// the console logging pub sub system
-func NewConsoleLogger(ctx context.Context, endpointZones EndpointZones) *HTTPConsoleLoggerSys {
+func mustGetNodeName(endpointZones EndpointZones) (nodeName string) {
 	host, err := xnet.ParseHost(GetLocalPeer(endpointZones))
 	if err != nil {
 		logger.FatalIf(err, "Unable to start console logging subsystem")
 	}
-	var nodeName string
 	if globalIsDistXL {
 		nodeName = host.Name
 	}
+	return nodeName
+}
+
+// NewConsoleLogger - creates new HTTPConsoleLoggerSys with all nodes subscribed to
+// the console logging pub sub system
+func NewConsoleLogger(ctx context.Context) *HTTPConsoleLoggerSys {
 	ps := pubsub.New()
 	return &HTTPConsoleLoggerSys{
-		ps, nil, nodeName, sync.RWMutex{}, ring.New(defaultLogBufferCount),
+		pubsub:  ps,
+		console: console.New(),
+		logBuf:  ring.New(defaultLogBufferCount),
 	}
 }
 
+// SetNodeName - sets the node name if any after distributed setup has initialized
+func (sys *HTTPConsoleLoggerSys) SetNodeName(endpointZones EndpointZones) {
+	sys.nodeName = mustGetNodeName(endpointZones)
+}
+
 // HasLogListeners returns true if console log listeners are registered
 // for this node or peers
 func (sys *HTTPConsoleLoggerSys) HasLogListeners() bool {
@@ -67,9 +76,9 @@ func (sys *HTTPConsoleLoggerSys) HasLogListeners() bool {
 
 // Subscribe starts console logging for this node.
 func (sys *HTTPConsoleLoggerSys) Subscribe(subCh chan interface{}, doneCh chan struct{}, node string, last int, logKind string, filter func(entry interface{}) bool) {
-	// Enable console logging for remote client even if local console logging is disabled in the config.
-	if !sys.pubsub.HasSubscribers() {
-		logger.AddTarget(globalConsoleSys.Console())
+	// Enable console logging for remote client.
+	if !sys.HasLogListeners() {
+		logger.AddTarget(sys)
 	}
 
 	cnt := 0
@@ -81,14 +90,14 @@ func (sys *HTTPConsoleLoggerSys) Subscribe(subCh chan interface{}, doneCh chan s
 	}
 
 	lastN = make([]madmin.LogInfo, last)
-	sys.logBufLk.RLock()
+	sys.RLock()
 	sys.logBuf.Do(func(p interface{}) {
 		if p != nil && (p.(madmin.LogInfo)).SendLog(node, logKind) {
 			lastN[cnt%last] = p.(madmin.LogInfo)
 			cnt++
 		}
 	})
-	sys.logBufLk.RUnlock()
+	sys.RUnlock()
 	// send last n console log messages in order filtered by node
 	if cnt > 0 {
 		for i := 0; i < last; i++ {
@@ -106,17 +115,6 @@ func (sys *HTTPConsoleLoggerSys) Subscribe(subCh chan interface{}, doneCh chan s
 	sys.pubsub.Subscribe(subCh, doneCh, filter)
 }
 
-// Console returns a console target
-func (sys *HTTPConsoleLoggerSys) Console() *HTTPConsoleLoggerSys {
-	if sys == nil {
-		return sys
-	}
-	if sys.console == nil {
-		sys.console = console.New()
-	}
-	return sys
-}
-
 // Send log message 'e' to console and publish to console
 // log pubsub system
 func (sys *HTTPConsoleLoggerSys) Send(e interface{}, logKind string) error {
@@ -129,11 +127,11 @@ func (sys *HTTPConsoleLoggerSys) Send(e interface{}, logKind string) error {
 	}
 
 	sys.pubsub.Publish(lg)
-	sys.logBufLk.Lock()
+	sys.Lock()
 	// add log to ring buffer
 	sys.logBuf.Value = lg
 	sys.logBuf = sys.logBuf.Next()
-	sys.logBufLk.Unlock()
+	sys.Unlock()
 
 	return sys.console.Send(e, string(logger.All))
 }