From 42601acfdeda9422d6941f29efddcdb84acc8dff Mon Sep 17 00:00:00 2001
From: Julius Volz <julius.volz@gmail.com>
Date: Sat, 21 Feb 2015 17:45:47 +0100
Subject: [PATCH] Replace labelsToKey() with metric Fingerprint (fixes grouping
 bug).

---
 rules/ast/ast.go    | 32 ++++-------------------
 rules/rules_test.go | 64 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 27 deletions(-)

diff --git a/rules/ast/ast.go b/rules/ast/ast.go
index 8eae7359a..a3eb25788 100644
--- a/rules/ast/ast.go
+++ b/rules/ast/ast.go
@@ -19,7 +19,6 @@ import (
 	"fmt"
 	"hash/fnv"
 	"math"
-	"sort"
 	"time"
 
 	clientmodel "github.com/prometheus/client_golang/model"
@@ -382,27 +381,6 @@ func (node *VectorAggregation) labelsToGroupingKey(labels clientmodel.Metric) ui
 	return summer.Sum64()
 }
 
-func labelsToKey(labels clientmodel.Metric) uint64 {
-	pairs := metric.LabelPairs{}
-
-	for label, value := range labels {
-		pairs = append(pairs, &metric.LabelPair{
-			Name:  label,
-			Value: value,
-		})
-	}
-
-	sort.Sort(pairs)
-
-	summer := fnv.New64a()
-
-	for _, pair := range pairs {
-		fmt.Fprint(summer, pair.Name, pair.Value)
-	}
-
-	return summer.Sum64()
-}
-
 // EvalVectorInstant evaluates a VectorNode with an instant query.
 func EvalVectorInstant(node VectorNode, timestamp clientmodel.Timestamp, storage local.Storage, queryStats *stats.TimerGroup) (Vector, error) {
 	totalEvalTimer := queryStats.GetTimer(stats.TotalEvalTime).Start()
@@ -436,7 +414,7 @@ func EvalVectorRange(node VectorNode, start clientmodel.Timestamp, end clientmod
 	defer closer.Close()
 
 	evalTimer := queryStats.GetTimer(stats.InnerEvalTime).Start()
-	sampleStreams := map[uint64]*SampleStream{}
+	sampleStreams := map[clientmodel.Fingerprint]*SampleStream{}
 	for t := start; !t.After(end); t = t.Add(interval) {
 		if et := totalEvalTimer.ElapsedTime(); et > *queryTimeout {
 			evalTimer.Stop()
@@ -448,14 +426,14 @@ func EvalVectorRange(node VectorNode, start clientmodel.Timestamp, end clientmod
 				Value:     sample.Value,
 				Timestamp: sample.Timestamp,
 			}
-			groupingKey := labelsToKey(sample.Metric.Metric)
-			if sampleStreams[groupingKey] == nil {
-				sampleStreams[groupingKey] = &SampleStream{
+			fp := sample.Metric.Metric.Fingerprint()
+			if sampleStreams[fp] == nil {
+				sampleStreams[fp] = &SampleStream{
 					Metric: sample.Metric,
 					Values: metric.Values{samplePair},
 				}
 			} else {
-				sampleStreams[groupingKey].Values = append(sampleStreams[groupingKey].Values, samplePair)
+				sampleStreams[fp].Values = append(sampleStreams[fp].Values, samplePair)
 			}
 		}
 	}
diff --git a/rules/rules_test.go b/rules/rules_test.go
index 61f3b9c4e..d25cd2501 100644
--- a/rules/rules_test.go
+++ b/rules/rules_test.go
@@ -860,6 +860,70 @@ func TestRangedEvaluationRegressions(t *testing.T) {
 			},
 			expr: "sum(testmetric) keeping_extra",
 		},
+		{
+			// Testing metric fingerprint grouping behavior.
+			in: ast.Matrix{
+				{
+					Metric: clientmodel.COWMetric{
+						Metric: clientmodel.Metric{
+							clientmodel.MetricNameLabel: "testmetric",
+							"aa": "bb",
+						},
+					},
+					Values: metric.Values{
+						{
+							Timestamp: testStartTime,
+							Value:     1,
+						},
+					},
+				},
+				{
+					Metric: clientmodel.COWMetric{
+						Metric: clientmodel.Metric{
+							clientmodel.MetricNameLabel: "testmetric",
+							"a": "abb",
+						},
+					},
+					Values: metric.Values{
+						{
+							Timestamp: testStartTime,
+							Value:     2,
+						},
+					},
+				},
+			},
+			out: ast.Matrix{
+				{
+					Metric: clientmodel.COWMetric{
+						Metric: clientmodel.Metric{
+							clientmodel.MetricNameLabel: "testmetric",
+							"aa": "bb",
+						},
+					},
+					Values: metric.Values{
+						{
+							Timestamp: testStartTime,
+							Value:     1,
+						},
+					},
+				},
+				{
+					Metric: clientmodel.COWMetric{
+						Metric: clientmodel.Metric{
+							clientmodel.MetricNameLabel: "testmetric",
+							"a": "abb",
+						},
+					},
+					Values: metric.Values{
+						{
+							Timestamp: testStartTime,
+							Value:     2,
+						},
+					},
+				},
+			},
+			expr: "testmetric",
+		},
 	}
 
 	for i, s := range scenarios {