symmetrize Find() and FindByTag; comments

Author: Dieterbe

idx/memory/memory.go

@@ -836,8 +836,9 @@ func (m *MemoryIdx) FindByTag(orgId uint32, expressions []string, from int64) ([
 	m.RLock()
 	defer m.RUnlock()
 
+	// construct the output slice of idx.Node's such that there is only 1 idx.Node for each path
 	ids := m.idsByTagQuery(orgId, query)
-	nodesByPath := make(map[string]idx.Node)
+	byPath := make(map[string]idx.Node)
 	for id := range ids {
 		def, ok := m.defById[id]
 		if !ok {
@@ -846,8 +847,8 @@ func (m *MemoryIdx) FindByTag(orgId uint32, expressions []string, from int64) ([
 			continue
 		}
 
-		if existing, ok := nodesByPath[def.NameWithTags()]; !ok {
-			nodesByPath[def.NameWithTags()] = idx.Node{
+		if existing, ok := byPath[def.NameWithTags()]; !ok {
+			byPath[def.NameWithTags()] = idx.Node{
 				Path:        def.NameWithTags(),
 				Leaf:        true,
 				HasChildren: false,
@@ -858,13 +859,13 @@ func (m *MemoryIdx) FindByTag(orgId uint32, expressions []string, from int64) ([
 		}
 	}
 
-	res := make([]idx.Node, 0, len(nodesByPath))
+	results := make([]idx.Node, 0, len(byPath))
 
-	for _, v := range nodesByPath {
-		res = append(res, v)
+	for _, v := range byPath {
+		results = append(results, v)
 	}
 
-	return res, nil
+	return results, nil
 }
 
 func (m *MemoryIdx) idsByTagQuery(orgId uint32, query TagQuery) IdSet {
@@ -893,11 +894,13 @@ func (m *MemoryIdx) Find(orgId uint32, pattern string, from int64) ([]idx.Node,
 	}
 	log.Debug("memory-idx: %d nodes matching pattern %s found", len(matchedNodes), pattern)
 	results := make([]idx.Node, 0)
-	seen := make(map[string]struct{})
+	byPath := make(map[string]struct{})
+	// construct the output slice of idx.Node's such that there is only 1 idx.Node
+	// for each path, and it holds all defs that the Node refers too.
 	// if there are public (orgId OrgIdPublic) and private leaf nodes with the same series
 	// path, then the public metricDefs will be excluded.
 	for _, n := range matchedNodes {
-		if _, ok := seen[n.Path]; !ok {
+		if _, ok := byPath[n.Path]; !ok {
 			idxNode := idx.Node{
 				Path:        n.Path,
 				Leaf:        n.Leaf(),
@@ -920,7 +923,7 @@ func (m *MemoryIdx) Find(orgId uint32, pattern string, from int64) ([]idx.Node,
 				}
 			}
 			results = append(results, idxNode)
-			seen[n.Path] = struct{}{}
+			byPath[n.Path] = struct{}{}
 		} else {
 			log.Debug("memory-idx: path %s already seen", n.Path)
 		}
@@ -930,6 +933,7 @@ func (m *MemoryIdx) Find(orgId uint32, pattern string, from int64) ([]idx.Node,
 	return results, nil
 }
 
+// find returns all Nodes matching the pattern for the given orgId
 func (m *MemoryIdx) find(orgId uint32, pattern string) ([]*Node, error) {
 	tree, ok := m.tree[orgId]
 	if !ok {