From 80e977aae6656940f7b48ec7fa24f6cffd47b184 Mon Sep 17 00:00:00 2001
From: zenador <zenador@users.noreply.github.com>
Date: Wed, 25 Oct 2023 00:36:07 +0800
Subject: [PATCH] Remove `NewPossibleNonCounterInfo` and minimise creating
 empty annotations (#13012)

* Remove NewPossibleNonCounterInfo until it can be made more efficient, and avoid creating empty annotations as much as possible

Signed-off-by: Jeanette Tan <jeanette.tan@grafana.com>
---
 CHANGELOG.md                    |  4 ++++
 promql/engine.go                |  2 +-
 promql/functions.go             | 14 +++-----------
 tsdb/db_test.go                 |  3 ++-
 util/annotations/annotations.go |  3 +++
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8a0bb1419..507cf664f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## unreleased
+
+* [ENHANCEMENT] PromQL: Reduce inefficiency introduced by warnings/annotations, and temporarily remove NewPossibleNonCounterInfo. #13012
+
 ## 2.48.0-rc.0 / 2023-10-10
 
 * [CHANGE] Remote-write: respect Retry-After header on 5xx errors. #12677
diff --git a/promql/engine.go b/promql/engine.go
index 161aa85ac..423849567 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -2535,7 +2535,7 @@ type groupedAggregation struct {
 func (ev *evaluator) aggregation(e *parser.AggregateExpr, grouping []string, param interface{}, vec Vector, seriesHelper []EvalSeriesHelper, enh *EvalNodeHelper) (Vector, annotations.Annotations) {
 	op := e.Op
 	without := e.Without
-	annos := annotations.Annotations{}
+	var annos annotations.Annotations
 	result := map[uint64]*groupedAggregation{}
 	orderedResult := []*groupedAggregation{}
 	var k int64
diff --git a/promql/functions.go b/promql/functions.go
index ecd6f7c8b..5fd54f6c7 100644
--- a/promql/functions.go
+++ b/promql/functions.go
@@ -77,7 +77,7 @@ func extrapolatedRate(vals []parser.Value, args parser.Expressions, enh *EvalNod
 		resultHistogram    *histogram.FloatHistogram
 		firstT, lastT      int64
 		numSamplesMinusOne int
-		annos              = annotations.Annotations{}
+		annos              annotations.Annotations
 	)
 
 	// We need either at least two Histograms and no Floats, or at least two
@@ -88,14 +88,6 @@ func extrapolatedRate(vals []parser.Value, args parser.Expressions, enh *EvalNod
 		return enh.Out, annos.Add(annotations.NewMixedFloatsHistogramsWarning(metricName, args[0].PositionRange()))
 	}
 
-	if isCounter && metricName != "" && len(samples.Floats) > 0 &&
-		!strings.HasSuffix(metricName, "_total") &&
-		!strings.HasSuffix(metricName, "_sum") &&
-		!strings.HasSuffix(metricName, "_count") &&
-		!strings.HasSuffix(metricName, "_bucket") {
-		annos.Add(annotations.NewPossibleNonCounterInfo(metricName, args[0].PositionRange()))
-	}
-
 	switch {
 	case len(samples.Histograms) > 1:
 		numSamplesMinusOne = len(samples.Histograms) - 1
@@ -642,7 +634,7 @@ func funcQuantileOverTime(vals []parser.Value, args parser.Expressions, enh *Eva
 		return enh.Out, nil
 	}
 
-	annos := annotations.Annotations{}
+	var annos annotations.Annotations
 	if math.IsNaN(q) || q < 0 || q > 1 {
 		annos.Add(annotations.NewInvalidQuantileWarning(q, args[0].PositionRange()))
 	}
@@ -1105,7 +1097,7 @@ func funcHistogramFraction(vals []parser.Value, args parser.Expressions, enh *Ev
 func funcHistogramQuantile(vals []parser.Value, args parser.Expressions, enh *EvalNodeHelper) (Vector, annotations.Annotations) {
 	q := vals[0].(Vector)[0].F
 	inVec := vals[1].(Vector)
-	annos := annotations.Annotations{}
+	var annos annotations.Annotations
 
 	if math.IsNaN(q) || q < 0 || q > 1 {
 		annos.Add(annotations.NewInvalidQuantileWarning(q, args[0].PositionRange()))
diff --git a/tsdb/db_test.go b/tsdb/db_test.go
index 773561c6c..ec5769077 100644
--- a/tsdb/db_test.go
+++ b/tsdb/db_test.go
@@ -1933,7 +1933,8 @@ func TestQuerierWithBoundaryChunks(t *testing.T) {
 	// The requested interval covers 2 blocks, so the querier's label values for blockID should give us 2 values, one from each block.
 	b, ws, err := q.LabelValues(ctx, "blockID")
 	require.NoError(t, err)
-	require.Equal(t, annotations.Annotations{}, ws)
+	var nilAnnotations annotations.Annotations
+	require.Equal(t, nilAnnotations, ws)
 	require.Equal(t, []string{"1", "2"}, b)
 }
 
diff --git a/util/annotations/annotations.go b/util/annotations/annotations.go
index 9cfbb121f..1d339646e 100644
--- a/util/annotations/annotations.go
+++ b/util/annotations/annotations.go
@@ -50,6 +50,9 @@ func (a *Annotations) Add(err error) Annotations {
 // the first in-place, and returns the merged first Annotation for convenience.
 func (a *Annotations) Merge(aa Annotations) Annotations {
 	if *a == nil {
+		if aa == nil {
+			return nil
+		}
 		*a = Annotations{}
 	}
 	for key, val := range aa {