fix: objectManager implementation avoid racy goroutines (#3392)

fixes #3391

api/ws_objects.go

@@ -35,9 +35,11 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 	defer func() {
 		// We close socket at the end of requests
 		wsc.conn.close()
-		cancelContexts.Range(func(_, value interface{}) bool {
+		cancelContexts.Range(func(key, value interface{}) bool {
 			cancelFunc := value.(context.CancelFunc)
 			cancelFunc()
+
+			cancelContexts.Delete(key)
 			return true
 		})
 	}()
@@ -55,6 +57,7 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 	// Read goroutine
 	go func() {
 		defer close(writeChannel)
+
 		for {
 			select {
 			case <-done:
@@ -72,10 +75,9 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 				// We get request data & review information
 				var messageRequest ObjectsRequest
 
-				err := json.Unmarshal(message, &messageRequest)
-				if err != nil {
-					LogInfo("Error on message request unmarshal")
-					return
+				if err := json.Unmarshal(message, &messageRequest); err != nil {
+					LogInfo("Error on message request unmarshal", err)
+					continue
 				}
 
 				// new message, new context
@@ -84,6 +86,21 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 				// We store the cancel func associated with this request
 				cancelContexts.Store(messageRequest.RequestID, cancel)
 
+				switch messageRequest.Mode {
+				case "objects", "rewind":
+					// cancel all previous open objects requests for listing
+					cancelContexts.Range(func(key, value interface{}) bool {
+						rid := key.(int64)
+						if rid < messageRequest.RequestID {
+							cancelFunc := value.(context.CancelFunc)
+							cancelFunc()
+
+							cancelContexts.Delete(key)
+						}
+						return true
+					})
+				}
+
 				const itemsPerBatch = 1000
 				switch messageRequest.Mode {
 				case "close":
@@ -95,18 +112,7 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 						cancelContexts.Delete(messageRequest.RequestID)
 					}
 				case "objects":
-					// cancel all previous open objects requests for listing
-					cancelContexts.Range(func(key, value interface{}) bool {
-						rid := key.(int64)
-						if rid < messageRequest.RequestID {
-							cancelFunc := value.(context.CancelFunc)
-							cancelFunc()
-						}
-						return true
-					})
-
 					// start listing and writing to web socket
-					go func() {
 					objectRqConfigs, err := getObjectsOptionsFromReq(messageRequest)
 					if err != nil {
 						LogInfo(fmt.Sprintf("Error during Objects OptionsParse %s", err.Error()))
@@ -120,12 +126,9 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 
 						return
 					}
+
 					var buffer []ObjectResponse
 					for lsObj := range startObjectsListing(ctx, wsc.client, objectRqConfigs) {
-							if _, ok := cancelContexts.Load(messageRequest.RequestID); !ok {
-								return
-							}
-
 						if lsObj.Err != nil {
 							sendWSResponse(WSResponse{
 								RequestID:  messageRequest.RequestID,
@@ -166,22 +169,13 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 						RequestEnd: true,
 					})
 
-						// remove the cancellation context
+					// if we have that request id, cancel it
+					if cancelFunc, ok := cancelContexts.Load(messageRequest.RequestID); ok {
+						cancelFunc.(context.CancelFunc)()
 						cancelContexts.Delete(messageRequest.RequestID)
-					}()
-				case "rewind":
-					// cancel all previous open objects requests for listing
-					cancelContexts.Range(func(key, value interface{}) bool {
-						rid := key.(int64)
-						if rid < messageRequest.RequestID {
-							cancelFunc := value.(context.CancelFunc)
-							cancelFunc()
 					}
-						return true
-					})
-
+				case "rewind":
 					// start listing and writing to web socket
-					go func() {
 					objectRqConfigs, err := getObjectsOptionsFromReq(messageRequest)
 					if err != nil {
 						LogInfo(fmt.Sprintf("Error during Objects OptionsParse %s", err.Error()))
@@ -206,7 +200,6 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 							BucketName: messageRequest.BucketName,
 						})
 
-							cancel()
 						return
 					}
 
@@ -259,9 +252,11 @@ func (wsc *wsMinioClient) objectManager(session *models.Principal) {
 						RequestEnd: true,
 					})
 
-						// remove the cancellation context
+					// if we have that request id, cancel it
+					if cancelFunc, ok := cancelContexts.Load(messageRequest.RequestID); ok {
+						cancelFunc.(context.CancelFunc)()
 						cancelContexts.Delete(messageRequest.RequestID)
-					}()
+					}
 				}
 			}
 		}