Optimization of labels handling in issue_search (#26460)

This PR enhances the labels handling in issue_search by optimizing the
SQL query and de-duplicate the IDs when generating the query string.

---------

Co-authored-by: techknowlogick <techknowlogick@gitea.com>

models/issues/issue_search.go

@@ -6,6 +6,7 @@ package issues
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"strings"
 
 	"code.gitea.io/gitea/models/db"
@@ -13,6 +14,7 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unit"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/optional"
 
 	"xorm.io/builder"
@@ -116,13 +118,29 @@ func applyLabelsCondition(sess *xorm.Session, opts *IssuesOptions) {
 		if opts.LabelIDs[0] == 0 {
 			sess.Where("issue.id NOT IN (SELECT issue_id FROM issue_label)")
 		} else {
-			for i, labelID := range opts.LabelIDs {
+			// We sort and deduplicate the labels' ids
+			IncludedLabelIDs := make(container.Set[int64])
+			ExcludedLabelIDs := make(container.Set[int64])
+			for _, labelID := range opts.LabelIDs {
 				if labelID > 0 {
-					sess.Join("INNER", fmt.Sprintf("issue_label il%d", i),
-						fmt.Sprintf("issue.id = il%[1]d.issue_id AND il%[1]d.label_id = %[2]d", i, labelID))
+					IncludedLabelIDs.Add(labelID)
 				} else if labelID < 0 { // 0 is not supported here, so just ignore it
-					sess.Where("issue.id not in (select issue_id from issue_label where label_id = ?)", -labelID)
-				}
+					ExcludedLabelIDs.Add(-labelID)
+				}
+			}
+			// ... and use them in a subquery of the form :
+			//  where (select count(*) from issue_label where issue_id=issue.id and label_id in (2, 4, 6)) = 3
+			// This equality is guaranteed thanks to unique index (issue_id,label_id) on table issue_label.
+			if len(IncludedLabelIDs) > 0 {
+				subquery := builder.Select("count(*)").From("issue_label").Where(builder.Expr("issue_id = issue.id")).
+					And(builder.In("label_id", IncludedLabelIDs.Values()))
+				sess.Where(builder.Eq{strconv.Itoa(len(IncludedLabelIDs)): subquery})
+			}
+			// or (select count(*)...) = 0 for excluded labels
+			if len(ExcludedLabelIDs) > 0 {
+				subquery := builder.Select("count(*)").From("issue_label").Where(builder.Expr("issue_id = issue.id")).
+					And(builder.In("label_id", ExcludedLabelIDs.Values()))
+				sess.Where(builder.Eq{"0": subquery})
 			}
 		}
 	}

models/issues/label.go

@@ -7,6 +7,7 @@ package issues
 import (
 	"context"
 	"fmt"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -142,9 +143,8 @@ func (l *Label) CalOpenOrgIssues(ctx context.Context, repoID, labelID int64) {
 
 // LoadSelectedLabelsAfterClick calculates the set of selected labels when a label is clicked
 func (l *Label) LoadSelectedLabelsAfterClick(currentSelectedLabels []int64, currentSelectedExclusiveScopes []string) {
-	var labelQuerySlice []string
+	labelQuerySlice := []int64{}
 	labelSelected := false
-	labelID := strconv.FormatInt(l.ID, 10)
 	labelScope := l.ExclusiveScope()
 	for i, s := range currentSelectedLabels {
 		if s == l.ID {
@@ -155,15 +155,26 @@ func (l *Label) LoadSelectedLabelsAfterClick(currentSelectedLabels []int64, curr
 		} else if s != 0 {
 			// Exclude other labels in the same scope from selection
 			if s < 0 || labelScope == "" || labelScope != currentSelectedExclusiveScopes[i] {
-				labelQuerySlice = append(labelQuerySlice, strconv.FormatInt(s, 10))
+				labelQuerySlice = append(labelQuerySlice, s)
 			}
 		}
 	}
+
 	if !labelSelected {
-		labelQuerySlice = append(labelQuerySlice, labelID)
+		labelQuerySlice = append(labelQuerySlice, l.ID)
 	}
 	l.IsSelected = labelSelected
-	l.QueryString = strings.Join(labelQuerySlice, ",")
+
+	// Sort and deduplicate the ids to avoid the crawlers asking for the
+	// same thing with simply a different order of parameters
+	slices.Sort(labelQuerySlice)
+	labelQuerySlice = slices.Compact(labelQuerySlice)
+	// Quick conversion (strings.Join() doesn't accept slices of Int64)
+	labelQuerySliceStrings := make([]string, len(labelQuerySlice))
+	for i, x := range labelQuerySlice {
+		labelQuerySliceStrings[i] = strconv.FormatInt(x, 10)
+	}
+	l.QueryString = strings.Join(labelQuerySliceStrings, ",")
 }
 
 // BelongsToOrg returns true if label is an organization label

models/issues/label_test.go

@@ -23,6 +23,27 @@ func TestLabel_CalOpenIssues(t *testing.T) {
 	assert.EqualValues(t, 2, label.NumOpenIssues)
 }
 
+func TestLabel_LoadSelectedLabelsAfterClick(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	// Loading the label id:8 which have a scope and an exclusivity
+	label := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 8})
+
+	// First test : with negative and scope
+	label.LoadSelectedLabelsAfterClick([]int64{1, -8}, []string{"", "scope"})
+	assert.Equal(t, "1", label.QueryString)
+	assert.Equal(t, true, label.IsSelected)
+
+	// Second test : with duplicates
+	label.LoadSelectedLabelsAfterClick([]int64{1, 7, 1, 7, 7}, []string{"", "scope", "", "scope", "scope"})
+	assert.Equal(t, "1,8", label.QueryString)
+	assert.Equal(t, false, label.IsSelected)
+
+	// Third test : empty set
+	label.LoadSelectedLabelsAfterClick([]int64{}, []string{})
+	assert.False(t, label.IsSelected)
+	assert.Equal(t, "8", label.QueryString)
+}
+
 func TestLabel_ExclusiveScope(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	label := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 7})