Refactor and enhance issue indexer to support both searching, filtering and paging (#26012)

Fix #24662.

Replace #24822 and #25708 (although it has been merged)


## Background

In the past, Gitea supported issue searching with a keyword and
conditions in a less efficient way. It worked by searching for issues
with the keyword and obtaining limited IDs (as it is heavy to get all)
on the indexer (bleve/elasticsearch/meilisearch), and then querying with
conditions on the database to find a subset of the found IDs. This is
why the results could be incomplete.

To solve this issue, we need to store all fields that could be used as
conditions in the indexer and support both keyword and additional
conditions when searching with the indexer.

## Major changes

- Redefine `IndexerData` to include all fields that could be used as
filter conditions.
- Refactor `Search(ctx context.Context, kw string, repoIDs []int64,
limit, start int, state string)` to `Search(ctx context.Context, options
*SearchOptions)`, so it supports more conditions now.
- Change the data type stored in `issueIndexerQueue`. Use
`IndexerMetadata` instead of `IndexerData` in case the data has been
updated while it is in the queue. This also reduces the storage size of
the queue.
- Enhance searching with Bleve/Elasticsearch/Meilisearch, make them
fully support `SearchOptions`. Also, update the data versions.
- Keep most logic of database indexer, but remove
`issues.SearchIssueIDsByKeyword` in `models` to avoid confusion where is
the entry point to search issues.
- Start a Meilisearch instance to test it in unit tests.
- Add unit tests with almost full coverage to test
Bleve/Elasticsearch/Meilisearch indexer.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

7 files changed, 131 insertions, 78 deletions

diff --git a/models/db/common.go b/models/db/common.go
index af6130c9f2..2a5043a8e7 100644
--- a/models/db/common.go
+++ b/models/db/common.go
@@ -20,3 +20,20 @@ func BuildCaseInsensitiveLike(key, value string) builder.Cond {
 	}
 	return builder.Like{"UPPER(" + key + ")", strings.ToUpper(value)}
 }
+
+// BuildCaseInsensitiveIn returns a condition to check if the given value is in the given values case-insensitively.
+// Handles especially SQLite correctly as UPPER there only transforms ASCII letters.
+func BuildCaseInsensitiveIn(key string, values []string) builder.Cond {
+	uppers := make([]string, 0, len(values))
+	if setting.Database.Type.IsSQLite3() {
+		for _, value := range values {
+			uppers = append(uppers, util.ToUpperASCII(value))
+		}
+	} else {
+		for _, value := range values {
+			uppers = append(uppers, strings.ToUpper(value))
+		}
+	}
+
+	return builder.In("UPPER("+key+")", uppers)
+}
diff --git a/models/issues/issue.go b/models/issues/issue.go
index 9d60d011ed..38726de85a 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -13,6 +13,7 @@ import (
 	project_model "code.gitea.io/gitea/models/project"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
@@ -550,9 +551,30 @@ func GetIssueWithAttrsByID(id int64) (*Issue, error) {
 }
 
 // GetIssuesByIDs return issues with the given IDs.
-func GetIssuesByIDs(ctx context.Context, issueIDs []int64) (IssueList, error) {
+// If keepOrder is true, the order of the returned issues will be the same as the given IDs.
+func GetIssuesByIDs(ctx context.Context, issueIDs []int64, keepOrder ...bool) (IssueList, error) {
 	issues := make([]*Issue, 0, len(issueIDs))
-	return issues, db.GetEngine(ctx).In("id", issueIDs).Find(&issues)
+
+	if err := db.GetEngine(ctx).In("id", issueIDs).Find(&issues); err != nil {
+		return nil, err
+	}
+
+	if len(keepOrder) > 0 && keepOrder[0] {
+		m := make(map[int64]*Issue, len(issues))
+		appended := container.Set[int64]{}
+		for _, issue := range issues {
+			m[issue.ID] = issue
+		}
+		issues = issues[:0]
+		for _, id := range issueIDs {
+			if issue, ok := m[id]; ok && !appended.Contains(id) { // make sure the id is existed and not appended
+				appended.Add(id)
+				issues = append(issues, issue)
+			}
+		}
+	}
+
+	return issues, nil
 }
 
 // GetIssueIDsByRepoID returns all issue ids by repo id
diff --git a/models/issues/issue_search.go b/models/issues/issue_search.go
index 6540ce02c0..f9c1dbb384 100644
--- a/models/issues/issue_search.go
+++ b/models/issues/issue_search.go
@@ -21,7 +21,7 @@ import (
 
 // IssuesOptions represents options of an issue.
 type IssuesOptions struct { //nolint
-	db.ListOptions
+	db.Paginator
 	RepoIDs            []int64 // overwrites RepoCond if the length is not 0
 	RepoCond           builder.Cond
 	AssigneeID         int64
@@ -99,15 +99,28 @@ func applySorts(sess *xorm.Session, sortType string, priorityRepoID int64) {
 }
 
 func applyLimit(sess *xorm.Session, opts *IssuesOptions) *xorm.Session {
-	if opts.Page >= 0 && opts.PageSize > 0 {
-		var start int
-		if opts.Page == 0 {
-			start = 0
-		} else {
-			start = (opts.Page - 1) * opts.PageSize
+	if opts.Paginator == nil || opts.Paginator.IsListAll() {
+		return sess
+	}
+
+	// Warning: Do not use GetSkipTake() for *db.ListOptions
+	// Its implementation could reset the page size with setting.API.MaxResponseItems
+	if listOptions, ok := opts.Paginator.(*db.ListOptions); ok {
+		if listOptions.Page >= 0 && listOptions.PageSize > 0 {
+			var start int
+			if listOptions.Page == 0 {
+				start = 0
+			} else {
+				start = (listOptions.Page - 1) * listOptions.PageSize
+			}
+			sess.Limit(listOptions.PageSize, start)
 		}
-		sess.Limit(opts.PageSize, start)
+		return sess
 	}
+
+	start, limit := opts.Paginator.GetSkipTake()
+	sess.Limit(limit, start)
+
 	return sess
 }
 
@@ -435,7 +448,7 @@ func Issues(ctx context.Context, opts *IssuesOptions) ([]*Issue, error) {
 	applyConditions(sess, opts)
 	applySorts(sess, opts.SortType, opts.PriorityRepoID)
 
-	issues := make(IssueList, 0, opts.ListOptions.PageSize)
+	issues := IssueList{}
 	if err := sess.Find(&issues); err != nil {
 		return nil, fmt.Errorf("unable to query Issues: %w", err)
 	}
@@ -447,45 +460,23 @@ func Issues(ctx context.Context, opts *IssuesOptions) ([]*Issue, error) {
 	return issues, nil
 }
 
-// SearchIssueIDsByKeyword search issues on database
-func SearchIssueIDsByKeyword(ctx context.Context, kw string, repoIDs []int64, limit, start int) (int64, []int64, error) {
-	repoCond := builder.In("repo_id", repoIDs)
-	subQuery := builder.Select("id").From("issue").Where(repoCond)
-	cond := builder.And(
-		repoCond,
-		builder.Or(
-			db.BuildCaseInsensitiveLike("name", kw),
-			db.BuildCaseInsensitiveLike("content", kw),
-			builder.In("id", builder.Select("issue_id").
-				From("comment").
-				Where(builder.And(
-					builder.Eq{"type": CommentTypeComment},
-					builder.In("issue_id", subQuery),
-					db.BuildCaseInsensitiveLike("content", kw),
-				)),
-			),
-		),
-	)
-
-	ids := make([]int64, 0, limit)
-	res := make([]struct {
-		ID          int64
-		UpdatedUnix int64
-	}, 0, limit)
-	err := db.GetEngine(ctx).Distinct("id", "updated_unix").Table("issue").Where(cond).
-		OrderBy("`updated_unix` DESC").Limit(limit, start).
-		Find(&res)
-	if err != nil {
-		return 0, nil, err
-	}
-	for _, r := range res {
-		ids = append(ids, r.ID)
+// IssueIDs returns a list of issue ids by given conditions.
+func IssueIDs(ctx context.Context, opts *IssuesOptions, otherConds ...builder.Cond) ([]int64, int64, error) {
+	sess := db.GetEngine(ctx).
+		Join("INNER", "repository", "`issue`.repo_id = `repository`.id")
+	applyConditions(sess, opts)
+	for _, cond := range otherConds {
+		sess.And(cond)
 	}
 
-	total, err := db.GetEngine(ctx).Distinct("id").Table("issue").Where(cond).Count()
+	applyLimit(sess, opts)
+	applySorts(sess, opts.SortType, opts.PriorityRepoID)
+
+	var res []int64
+	total, err := sess.Select("`issue`.id").Table(&Issue{}).FindAndCount(&res)
 	if err != nil {
-		return 0, nil, err
+		return nil, 0, err
 	}
 
-	return total, ids, nil
+	return res, total, nil
 }
diff --git a/models/issues/issue_test.go b/models/issues/issue_test.go
index 44e59f5cc4..0f2ceadc6b 100644
--- a/models/issues/issue_test.go
+++ b/models/issues/issue_test.go
@@ -73,7 +73,7 @@ func TestIssueAPIURL(t *testing.T) {
 func TestGetIssuesByIDs(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	testSuccess := func(expectedIssueIDs, nonExistentIssueIDs []int64) {
-		issues, err := issues_model.GetIssuesByIDs(db.DefaultContext, append(expectedIssueIDs, nonExistentIssueIDs...))
+		issues, err := issues_model.GetIssuesByIDs(db.DefaultContext, append(expectedIssueIDs, nonExistentIssueIDs...), true)
 		assert.NoError(t, err)
 		actualIssueIDs := make([]int64, len(issues))
 		for i, issue := range issues {
@@ -83,6 +83,7 @@ func TestGetIssuesByIDs(t *testing.T) {
 	}
 	testSuccess([]int64{1, 2, 3}, []int64{})
 	testSuccess([]int64{1, 2, 3}, []int64{unittest.NonexistentID})
+	testSuccess([]int64{3, 2, 1}, []int64{})
 }
 
 func TestGetParticipantIDsByIssue(t *testing.T) {
@@ -165,7 +166,7 @@ func TestIssues(t *testing.T) {
 			issues_model.IssuesOptions{
 				RepoCond: builder.In("repo_id", 1, 3),
 				SortType: "oldest",
-				ListOptions: db.ListOptions{
+				Paginator: &db.ListOptions{
 					Page:     1,
 					PageSize: 4,
 				},
@@ -175,7 +176,7 @@ func TestIssues(t *testing.T) {
 		{
 			issues_model.IssuesOptions{
 				LabelIDs: []int64{1},
-				ListOptions: db.ListOptions{
+				Paginator: &db.ListOptions{
 					Page:     1,
 					PageSize: 4,
 				},
@@ -185,7 +186,7 @@ func TestIssues(t *testing.T) {
 		{
 			issues_model.IssuesOptions{
 				LabelIDs: []int64{1, 2},
-				ListOptions: db.ListOptions{
+				Paginator: &db.ListOptions{
 					Page:     1,
 					PageSize: 4,
 				},
@@ -333,30 +334,6 @@ func TestIssue_loadTotalTimes(t *testing.T) {
 	assert.Equal(t, int64(3682), ms.TotalTrackedTime)
 }
 
-func TestIssue_SearchIssueIDsByKeyword(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-	total, ids, err := issues_model.SearchIssueIDsByKeyword(context.TODO(), "issue2", []int64{1}, 10, 0)
-	assert.NoError(t, err)
-	assert.EqualValues(t, 1, total)
-	assert.EqualValues(t, []int64{2}, ids)
-
-	total, ids, err = issues_model.SearchIssueIDsByKeyword(context.TODO(), "first", []int64{1}, 10, 0)
-	assert.NoError(t, err)
-	assert.EqualValues(t, 1, total)
-	assert.EqualValues(t, []int64{1}, ids)
-
-	total, ids, err = issues_model.SearchIssueIDsByKeyword(context.TODO(), "for", []int64{1}, 10, 0)
-	assert.NoError(t, err)
-	assert.EqualValues(t, 5, total)
-	assert.ElementsMatch(t, []int64{1, 2, 3, 5, 11}, ids)
-
-	// issue1's comment id 2
-	total, ids, err = issues_model.SearchIssueIDsByKeyword(context.TODO(), "good", []int64{1}, 10, 0)
-	assert.NoError(t, err)
-	assert.EqualValues(t, 1, total)
-	assert.EqualValues(t, []int64{1}, ids)
-}
-
 func TestGetRepoIDsForIssuesOptions(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
@@ -496,7 +473,19 @@ func TestCorrectIssueStats(t *testing.T) {
 	wg.Wait()
 
 	// Now we will get all issueID's that match the "Bugs are nasty" query.
-	total, ids, err := issues_model.SearchIssueIDsByKeyword(context.TODO(), "Bugs are nasty", []int64{1}, issueAmount, 0)
+	issues, err := issues_model.Issues(context.TODO(), &issues_model.IssuesOptions{
+		Paginator: &db.ListOptions{
+			PageSize: issueAmount,
+		},
+		RepoIDs: []int64{1},
+	})
+	total := int64(len(issues))
+	var ids []int64
+	for _, issue := range issues {
+		if issue.Content == "Bugs are nasty" {
+			ids = append(ids, issue.ID)
+		}
+	}
 
 	// Just to be sure.
 	assert.NoError(t, err)
diff --git a/models/issues/issue_user.go b/models/issues/issue_user.go
index 4a537752a2..47da5c62c4 100644
--- a/models/issues/issue_user.go
+++ b/models/issues/issue_user.go
@@ -84,3 +84,13 @@ func UpdateIssueUsersByMentions(ctx context.Context, issueID int64, uids []int64
 	}
 	return nil
 }
+
+// GetIssueMentionIDs returns all mentioned user IDs of an issue.
+func GetIssueMentionIDs(ctx context.Context, issueID int64) ([]int64, error) {
+	var ids []int64
+	return ids, db.GetEngine(ctx).Table(IssueUser{}).
+		Where("issue_id=?", issueID).
+		And("is_mentioned=?", true).
+		Select("uid").
+		Find(&ids)
+}
diff --git a/models/issues/label.go b/models/issues/label.go
index 8f2cf05a28..57a2e67f8c 100644
--- a/models/issues/label.go
+++ b/models/issues/label.go
@@ -272,12 +272,12 @@ func GetLabelByID(ctx context.Context, labelID int64) (*Label, error) {
 }
 
 // GetLabelsByIDs returns a list of labels by IDs
-func GetLabelsByIDs(labelIDs []int64) ([]*Label, error) {
+func GetLabelsByIDs(labelIDs []int64, cols ...string) ([]*Label, error) {
 	labels := make([]*Label, 0, len(labelIDs))
 	return labels, db.GetEngine(db.DefaultContext).Table("label").
 		In("id", labelIDs).
 		Asc("name").
-		Cols("id", "repo_id", "org_id").
+		Cols(cols...).
 		Find(&labels)
 }
 
@@ -476,6 +476,18 @@ func GetLabelsByOrgID(ctx context.Context, orgID int64, sortType string, listOpt
 	return labels, sess.Find(&labels)
 }
 
+// GetLabelIDsByNames returns a list of labelIDs by names.
+// It doesn't filter them by repo or org, so it could return labels belonging to different repos/orgs.
+// It's used for filtering issues via indexer, otherwise it would be useless.
+// Since it could return labels with the same name, so the length of returned ids could be more than the length of names.
+func GetLabelIDsByNames(ctx context.Context, labelNames []string) ([]int64, error) {
+	labelIDs := make([]int64, 0, len(labelNames))
+	return labelIDs, db.GetEngine(ctx).Table("label").
+		In("name", labelNames).
+		Cols("id").
+		Find(&labelIDs)
+}
+
 // CountLabelsByOrgID count all labels that belong to given organization by ID.
 func CountLabelsByOrgID(orgID int64) (int64, error) {
 	return db.GetEngine(db.DefaultContext).Where("org_id = ?", orgID).Count(&Label{})
diff --git a/models/issues/milestone.go b/models/issues/milestone.go
index ffe5c8eb50..1418e0869d 100644
--- a/models/issues/milestone.go
+++ b/models/issues/milestone.go
@@ -396,6 +396,18 @@ func GetMilestones(opts GetMilestonesOption) (MilestoneList, int64, error) {
 	return miles, total, err
 }
 
+// GetMilestoneIDsByNames returns a list of milestone ids by given names.
+// It doesn't filter them by repo, so it could return milestones belonging to different repos.
+// It's used for filtering issues via indexer, otherwise it would be useless.
+// Since it could return milestones with the same name, so the length of returned ids could be more than the length of names.
+func GetMilestoneIDsByNames(ctx context.Context, names []string) ([]int64, error) {
+	var ids []int64
+	return ids, db.GetEngine(ctx).Table("milestone").
+		Where(db.BuildCaseInsensitiveIn("name", names)).
+		Cols("id").
+		Find(&ids)
+}
+
 // SearchMilestones search milestones
 func SearchMilestones(repoCond builder.Cond, page int, isClosed bool, sortType, keyword string) (MilestoneList, error) {
 	miles := make([]*Milestone, 0, setting.UI.IssuePagingNum)