feat: add constraint for GetCUrsor (#304)

Author: crimson-gao

example/consumer/with_log_id/main.go

@@ -20,6 +20,7 @@ func main() {
 		ConsumerGroupName: "test-consumer",
 		ConsumerName:      "test-consumer-1",
 		CursorPosition:    consumerLibrary.END_CURSOR,
+		Query:             "", // query must be empty string or not initialized, GetCursor only support empty query
 	}
 
 	worker := consumerLibrary.InitConsumerWorkerWithCheckpointTracker(option, process_with_log_id)
@@ -40,6 +41,7 @@ func process_with_log_id(shardId int, logGroupList *sls.LogGroupList, checkpoint
 	// start consume logs
 	for _, logGroup := range logGroupList.LogGroups {
 		// logGroupCursor is empty string if failed
+		// only support consumer without query
 		logGroupCursor := logGroup.GetCursor()
 		fmt.Println("log group cursor: ", logGroupCursor)
 

log_store.go

@@ -642,7 +642,7 @@ func (s *LogStore) PullLogsWithQuery(plr *PullLogRequest) (gl *LogGroupList, plm
 	if err != nil {
 		return nil, nil, err
 	}
-	if plm.Count > 0 && plm.readLastCursor != "" {
+	if plm.Count > 0 && plm.readLastCursor != "" && plr.Query == "" {
 		gl.addCursorIfPossible(plm.readLastCursor)
 	}
 	return

model.go

@@ -380,6 +380,7 @@ type ListStoreViewsResponse struct {
 }
 
 // If cursor is unknown, returns empty string
+// If pullLogs with non-empty query or consumer with non-empty query, returns empty string
 func (l *LogGroup) GetCursor() string {
 	return l.cursor
 }