Fix query engine not goroutine safe issue.

tsdb/mapper.go

@@ -216,7 +216,7 @@ func (lm *LocalMapper) Open() error {
 					// No data exists for this key.
 					continue
 				}
-				seriesTags := lm.shard.index.series[key].Tags
+				seriesTags := lm.shard.index.TagsForSeries(key)
 				cm := newSeriesCursor(c, t.Filters[i], seriesTags)
 				cursors = append(cursors, cm)
 			}

tsdb/meta.go

@@ -112,6 +112,17 @@ func (s *DatabaseIndex) CreateMeasurementIndexIfNotExists(name string) *Measurem
 	return m
 }
 
+// TagsForSeries returns the tag map for the passed in series
+func (s *DatabaseIndex) TagsForSeries(key string) map[string]string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	ss := s.series[key]
+	if ss == nil {
+		return nil
+	}
+	return ss.Tags
+}
+
 // measurementsByExpr takes and expression containing only tags and returns
 // a list of matching *Measurement.
 func (db *DatabaseIndex) measurementsByExpr(expr influxql.Expr) (Measurements, error) {