lib/{storage,uint64set}: add Set.Union() function and use it

lib/storage/index_db.go

@@ -264,8 +264,7 @@ func (db *indexDB) SetExtDB(extDB *indexDB) {
 	// Add deleted metricIDs from extDB to db.
 	if extDB != nil {
 		dmisExt := extDB.getDeletedMetricIDs()
-		metricIDs := dmisExt.AppendTo(nil)
-		db.updateDeletedMetricIDs(metricIDs)
+		db.updateDeletedMetricIDs(dmisExt)
 	}
 
 	db.extDBLock.Lock()
@@ -900,7 +899,11 @@ func (db *indexDB) DeleteTSIDs(tfss []*TagFilters) (int, error) {
 	deletedCount := len(metricIDs)
 
 	// atomically add deleted metricIDs to an inmemory map.
-	db.updateDeletedMetricIDs(metricIDs)
+	dmis := &uint64set.Set{}
+	for _, metricID := range metricIDs {
+		dmis.Add(metricID)
+	}
+	db.updateDeletedMetricIDs(dmis)
 
 	// Reset TagFilters -> TSIDS cache, since it may contain deleted TSIDs.
 	invalidateTagCache()
@@ -929,13 +932,11 @@ func (db *indexDB) setDeletedMetricIDs(dmis *uint64set.Set) {
 	db.deletedMetricIDs.Store(dmis)
 }
 
-func (db *indexDB) updateDeletedMetricIDs(metricIDs []uint64) {
+func (db *indexDB) updateDeletedMetricIDs(metricIDs *uint64set.Set) {
 	db.deletedMetricIDsUpdateLock.Lock()
 	dmisOld := db.getDeletedMetricIDs()
 	dmisNew := dmisOld.Clone()
-	for _, metricID := range metricIDs {
-		dmisNew.Add(metricID)
-	}
+	dmisNew.Union(metricIDs)
 	db.setDeletedMetricIDs(dmisNew)
 	db.deletedMetricIDsUpdateLock.Unlock()
 }
@@ -1601,9 +1602,7 @@ func (is *indexSearch) updateMetricIDsForTagFilters(metricIDs *uint64set.Set, tf
 		}
 		minMetricIDs = mIDs
 	}
-	for _, metricID := range minMetricIDs.AppendTo(nil) {
-		metricIDs.Add(metricID)
-	}
+	metricIDs.Union(minMetricIDs)
 	return nil
 }
 
@@ -1947,9 +1946,7 @@ func (is *indexSearch) getMetricIDsForRecentHours(tr TimeRange, maxMetrics int,
 			return nil, false
 		}
 		metricIDs := mCurr.Clone()
-		for _, metricID := range mPrev.AppendTo(nil) {
-			metricIDs.Add(metricID)
-		}
+		metricIDs.Union(mPrev)
 		return metricIDs, true
 	}
 	return nil, false

lib/uint64set/uint64set.go

@@ -126,6 +126,14 @@ func (s *Set) AppendTo(dst []uint64) []uint64 {
 	return dst
 }
 
+// Union adds all the items from a to s.
+func (s *Set) Union(a *Set) {
+	// TODO: optimize it
+	for _, x := range a.AppendTo(nil) {
+		s.Add(x)
+	}
+}
+
 type bucket32 struct {
 	hi      uint32
 	b16his  []uint16

lib/uint64set/uint64set_test.go

@@ -88,6 +88,22 @@ func testSetBasicOps(t *testing.T, itemsCount int) {
 		}
 	}
 
+	// Verify union
+	const unionOffset = 12345
+	var s1, s2 Set
+	for i := 0; i < itemsCount; i++ {
+		s1.Add(uint64(i) + offset)
+		s2.Add(uint64(i) + offset + unionOffset)
+	}
+	s1.Union(&s2)
+	expectedLen := 2 * itemsCount
+	if itemsCount > unionOffset {
+		expectedLen = itemsCount + unionOffset
+	}
+	if n := s1.Len(); n != expectedLen {
+		t.Fatalf("unexpected s1.Len() after union; got %d; want %d", n, expectedLen)
+	}
+
 	// Verify Del
 	for i := itemsCount / 2; i < itemsCount-itemsCount/4; i++ {
 		s.Del(uint64(i) + offset)