From 515890ec5307a4e8448c50589ac3fc442e0e4671 Mon Sep 17 00:00:00 2001
From: Marco Pracucci <marco@pracucci.com>
Date: Fri, 26 Jan 2024 06:26:52 +0100
Subject: [PATCH] Use Matcher.SetMatches()

Signed-off-by: Marco Pracucci <marco@pracucci.com>
---
 tsdb/querier.go      | 54 ++-----------------------------------
 tsdb/querier_test.go | 63 --------------------------------------------
 2 files changed, 2 insertions(+), 115 deletions(-)

diff --git a/tsdb/querier.go b/tsdb/querier.go
index a692c98f1..447332341 100644
--- a/tsdb/querier.go
+++ b/tsdb/querier.go
@@ -18,7 +18,6 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"strings"
 	"unicode/utf8"
 
 	"github.com/oklog/ulid"
@@ -186,55 +185,6 @@ func (q *blockChunkQuerier) Select(ctx context.Context, sortSeries bool, hints *
 	return NewBlockChunkSeriesSet(q.blockID, q.index, q.chunks, q.tombstones, p, mint, maxt, disableTrimming)
 }
 
-func findSetMatches(pattern string) []string {
-	// Return empty matches if the wrapper from Prometheus is missing.
-	if len(pattern) < 6 || pattern[:4] != "^(?:" || pattern[len(pattern)-2:] != ")$" {
-		return nil
-	}
-	escaped := false
-	sets := []*strings.Builder{{}}
-	init := 4
-	end := len(pattern) - 2
-	// If the regex is wrapped in a group we can remove the first and last parentheses
-	if pattern[init] == '(' && pattern[end-1] == ')' {
-		init++
-		end--
-	}
-	for i := init; i < end; i++ {
-		if escaped {
-			switch {
-			case isRegexMetaCharacter(pattern[i]):
-				sets[len(sets)-1].WriteByte(pattern[i])
-			case pattern[i] == '\\':
-				sets[len(sets)-1].WriteByte('\\')
-			default:
-				return nil
-			}
-			escaped = false
-		} else {
-			switch {
-			case isRegexMetaCharacter(pattern[i]):
-				if pattern[i] == '|' {
-					sets = append(sets, &strings.Builder{})
-				} else {
-					return nil
-				}
-			case pattern[i] == '\\':
-				escaped = true
-			default:
-				sets[len(sets)-1].WriteByte(pattern[i])
-			}
-		}
-	}
-	matches := make([]string, 0, len(sets))
-	for _, s := range sets {
-		if s.Len() > 0 {
-			matches = append(matches, s.String())
-		}
-	}
-	return matches
-}
-
 // PostingsForMatchers assembles a single postings iterator against the index reader
 // based on the given matchers. The resulting postings are not ordered by series.
 func PostingsForMatchers(ctx context.Context, ix IndexReader, ms ...*labels.Matcher) (index.Postings, error) {
@@ -376,7 +326,7 @@ func postingsForMatcher(ctx context.Context, ix IndexReader, m *labels.Matcher)
 
 	// Fast-path for set matching.
 	if m.Type == labels.MatchRegexp {
-		setMatches := findSetMatches(m.GetRegexString())
+		setMatches := m.SetMatches()
 		if len(setMatches) > 0 {
 			return ix.Postings(ctx, m.Name, setMatches...)
 		}
@@ -407,7 +357,7 @@ func inversePostingsForMatcher(ctx context.Context, ix IndexReader, m *labels.Ma
 	// Inverse of a MatchNotRegexp is MatchRegexp (double negation).
 	// Fast-path for set matching.
 	if m.Type == labels.MatchNotRegexp {
-		setMatches := findSetMatches(m.GetRegexString())
+		setMatches := m.SetMatches()
 		if len(setMatches) > 0 {
 			return ix.Postings(ctx, m.Name, setMatches...)
 		}
diff --git a/tsdb/querier_test.go b/tsdb/querier_test.go
index ce59c0ee7..ed7e4e340 100644
--- a/tsdb/querier_test.go
+++ b/tsdb/querier_test.go
@@ -2637,69 +2637,6 @@ func BenchmarkSetMatcher(b *testing.B) {
 	}
 }
 
-// Refer to https://github.com/prometheus/prometheus/issues/2651.
-func TestFindSetMatches(t *testing.T) {
-	cases := []struct {
-		pattern string
-		exp     []string
-	}{
-		// Single value, coming from a `bar=~"foo"` selector.
-		{
-			pattern: "^(?:foo)$",
-			exp: []string{
-				"foo",
-			},
-		},
-		// Simple sets.
-		{
-			pattern: "^(?:foo|bar|baz)$",
-			exp: []string{
-				"foo",
-				"bar",
-				"baz",
-			},
-		},
-		// Simple sets containing escaped characters.
-		{
-			pattern: "^(?:fo\\.o|bar\\?|\\^baz)$",
-			exp: []string{
-				"fo.o",
-				"bar?",
-				"^baz",
-			},
-		},
-		// Simple sets containing special characters without escaping.
-		{
-			pattern: "^(?:fo.o|bar?|^baz)$",
-			exp:     nil,
-		},
-		// Missing wrapper.
-		{
-			pattern: "foo|bar|baz",
-			exp:     nil,
-		},
-	}
-
-	for _, c := range cases {
-		matches := findSetMatches(c.pattern)
-		if len(c.exp) == 0 {
-			if len(matches) != 0 {
-				t.Errorf("Evaluating %s, unexpected result %v", c.pattern, matches)
-			}
-		} else {
-			if len(matches) != len(c.exp) {
-				t.Errorf("Evaluating %s, length of result not equal to exp", c.pattern)
-			} else {
-				for i := 0; i < len(c.exp); i++ {
-					if c.exp[i] != matches[i] {
-						t.Errorf("Evaluating %s, unexpected result %s", c.pattern, matches[i])
-					}
-				}
-			}
-		}
-	}
-}
-
 func TestPostingsForMatchers(t *testing.T) {
 	ctx := context.Background()