app/vmselect/graphite: apply filter then limit

app/vmselect/graphite/tags_api.go

@@ -3,7 +3,6 @@ package graphite
 import (
 	"fmt"
 	"net/http"
-	"regexp"
 	"strconv"
 	"time"
 
@@ -22,26 +21,16 @@ func TagValuesHandler(startTime time.Time, at *auth.Token, tagName string, w htt
 	if err := r.ParseForm(); err != nil {
 		return fmt.Errorf("cannot parse form values: %w", err)
 	}
-	limit := 0
+	limit, err := getInt(r, "limit")
-	if limitStr := r.FormValue("limit"); len(limitStr) > 0 {
-		var err error
-		limit, err = strconv.Atoi(limitStr)
-		if err != nil {
-			return fmt.Errorf("cannot parse limit=%q: %w", limit, err)
-		}
-	}
-	denyPartialResponse := searchutils.GetDenyPartialResponse(r)
-	tagValues, isPartial, err := netstorage.GetGraphiteTagValues(at, denyPartialResponse, tagName, limit, deadline)
 	if err != nil {
 		return err
 	}
 	filter := r.FormValue("filter")
-	if len(filter) > 0 {
+	denyPartialResponse := searchutils.GetDenyPartialResponse(r)
-		tagValues, err = applyRegexpFilter(filter, tagValues)
+	tagValues, isPartial, err := netstorage.GetGraphiteTagValues(at, denyPartialResponse, tagName, filter, limit, deadline)
 	if err != nil {
 		return err
 	}
-	}
 
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
@@ -64,26 +53,16 @@ func TagsHandler(startTime time.Time, at *auth.Token, w http.ResponseWriter, r *
 	if err := r.ParseForm(); err != nil {
 		return fmt.Errorf("cannot parse form values: %w", err)
 	}
-	limit := 0
+	limit, err := getInt(r, "limit")
-	if limitStr := r.FormValue("limit"); len(limitStr) > 0 {
-		var err error
-		limit, err = strconv.Atoi(limitStr)
-		if err != nil {
-			return fmt.Errorf("cannot parse limit=%q: %w", limit, err)
-		}
-	}
-	denyPartialResponse := searchutils.GetDenyPartialResponse(r)
-	labels, isPartial, err := netstorage.GetGraphiteTags(at, denyPartialResponse, limit, deadline)
 	if err != nil {
 		return err
 	}
 	filter := r.FormValue("filter")
-	if len(filter) > 0 {
+	denyPartialResponse := searchutils.GetDenyPartialResponse(r)
-		labels, err = applyRegexpFilter(filter, labels)
+	labels, isPartial, err := netstorage.GetGraphiteTags(at, denyPartialResponse, filter, limit, deadline)
 	if err != nil {
 		return err
 	}
-	}
 
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
@@ -98,19 +77,14 @@ func TagsHandler(startTime time.Time, at *auth.Token, w http.ResponseWriter, r *
 
 var tagsDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/tags"}`)
 
-func applyRegexpFilter(filter string, ss []string) ([]string, error) {
+func getInt(r *http.Request, argName string) (int, error) {
-	// Anchor filter regexp to the beginning of the string as Graphite does.
+	argValue := r.FormValue(argName)
-	// See https://github.com/graphite-project/graphite-web/blob/3ad279df5cb90b211953e39161df416e54a84948/webapp/graphite/tags/localdatabase.py#L157
+	if len(argValue) == 0 {
-	filter = "^(?:" + filter + ")"
+		return 0, nil
-	re, err := regexp.Compile(filter)
+	}
+	n, err := strconv.Atoi(argValue)
 	if err != nil {
-		return nil, fmt.Errorf("cannot parse regexp filter=%q: %w", filter, err)
+		return 0, fmt.Errorf("cannot parse %q=%q: %w", argName, argValue, err)
 	}
-	dst := ss[:0]
+	return n, nil
-	for _, s := range ss {
-		if re.MatchString(s) {
-			dst = append(dst, s)
-		}
-	}
-	return dst, nil
 }

app/vmselect/netstorage/netstorage.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"regexp"
 	"runtime"
 	"sort"
 	"strings"
@@ -558,22 +559,30 @@ func GetLabelsOnTimeRange(at *auth.Token, denyPartialResponse bool, tr storage.T
 }
 
 // GetGraphiteTags returns Graphite tags until the given deadline.
-func GetGraphiteTags(at *auth.Token, denyPartialResponse bool, limit int, deadline searchutils.Deadline) ([]string, bool, error) {
+func GetGraphiteTags(at *auth.Token, denyPartialResponse bool, filter string, limit int, deadline searchutils.Deadline) ([]string, bool, error) {
+	if deadline.Exceeded() {
+		return nil, false, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
+	}
 	labels, isPartial, err := GetLabels(at, denyPartialResponse, deadline)
 	if err != nil {
 		return nil, false, err
 	}
-	if limit < len(labels) {
+	if len(filter) > 0 {
-		labels = labels[:limit]
+		labels, err = applyGraphiteRegexpFilter(filter, labels)
+		if err != nil {
+			return nil, false, err
 		}
-	// Convert __name__ to name in labels according to Graphite tags specs.
+	}
-	// See https://graphite.readthedocs.io/en/stable/tags.html#querying
+	// Substitute "__name__" with "name" for Graphite compatibility
-	for i, label := range labels {
+	for i := range labels {
-		if label == "__name__" {
+		if labels[i] == "__name__" {
 			labels[i] = "name"
 			break
 		}
 	}
+	if limit > 0 && limit < len(labels) {
+		labels = labels[:limit]
+	}
 	return labels, isPartial, nil
 }
 
@@ -714,7 +723,7 @@ func GetLabelValuesOnTimeRange(at *auth.Token, denyPartialResponse bool, labelNa
 }
 
 // GetGraphiteTagValues returns tag values for the given tagName until the given deadline.
-func GetGraphiteTagValues(at *auth.Token, denyPartialResponse bool, tagName string, limit int, deadline searchutils.Deadline) ([]string, bool, error) {
+func GetGraphiteTagValues(at *auth.Token, denyPartialResponse bool, tagName, filter string, limit int, deadline searchutils.Deadline) ([]string, bool, error) {
 	if deadline.Exceeded() {
 		return nil, false, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -725,7 +734,13 @@ func GetGraphiteTagValues(at *auth.Token, denyPartialResponse bool, tagName stri
 	if err != nil {
 		return nil, false, err
 	}
-	if limit < len(tagValues) {
+	if len(filter) > 0 {
+		tagValues, err = applyGraphiteRegexpFilter(filter, tagValues)
+		if err != nil {
+			return nil, false, err
+		}
+	}
+	if limit > 0 && limit < len(tagValues) {
 		tagValues = tagValues[:limit]
 	}
 	return tagValues, isPartial, nil
@@ -2263,3 +2278,20 @@ var (
 
 // The maximum number of concurrent queries per storageNode.
 const maxConcurrentQueriesPerStorageNode = 100
+
+func applyGraphiteRegexpFilter(filter string, ss []string) ([]string, error) {
+	// Anchor filter regexp to the beginning of the string as Graphite does.
+	// See https://github.com/graphite-project/graphite-web/blob/3ad279df5cb90b211953e39161df416e54a84948/webapp/graphite/tags/localdatabase.py#L157
+	filter = "^(?:" + filter + ")"
+	re, err := regexp.Compile(filter)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse regexp filter=%q: %w", filter, err)
+	}
+	dst := ss[:0]
+	for _, s := range ss {
+		if re.MatchString(s) {
+			dst = append(dst, s)
+		}
+	}
+	return dst, nil
+}