Performance improvements for pull request list page (#29900)

This PR will avoid load pullrequest.Issue twice in pull request list
page. It will reduce x times database queries for those WIP pull
requests.

Partially fix #29585

---------

Co-authored-by: Giteabot <teabot@gitea.io>

14 files changed, 86 insertions, 50 deletions

diff --git a/models/activities/notification_list.go b/models/activities/notification_list.go
index 957f9456e7..5858933391 100644
--- a/models/activities/notification_list.go
+++ b/models/activities/notification_list.go
@@ -14,6 +14,7 @@ import (
 	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/util"
 
 	"xorm.io/builder"
 )
@@ -470,3 +471,31 @@ func (nl NotificationList) LoadComments(ctx context.Context) ([]int, error) {
 	}
 	return failures, nil
 }
+
+// LoadIssuePullRequests loads all issues' pull requests if possible
+func (nl NotificationList) LoadIssuePullRequests(ctx context.Context) error {
+	issues := make(map[int64]*issues_model.Issue, len(nl))
+	for _, notification := range nl {
+		if notification.Issue != nil && notification.Issue.IsPull && notification.Issue.PullRequest == nil {
+			issues[notification.Issue.ID] = notification.Issue
+		}
+	}
+
+	if len(issues) == 0 {
+		return nil
+	}
+
+	pulls, err := issues_model.GetPullRequestByIssueIDs(ctx, util.KeysOfMap(issues))
+	if err != nil {
+		return err
+	}
+
+	for _, pull := range pulls {
+		if issue := issues[pull.IssueID]; issue != nil {
+			issue.PullRequest = pull
+			issue.PullRequest.Issue = issue
+		}
+	}
+
+	return nil
+}
diff --git a/models/issues/issue.go b/models/issues/issue.go
index 563a780dcb..87c1c86eb1 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -193,20 +193,6 @@ func (issue *Issue) IsTimetrackerEnabled(ctx context.Context) bool {
 	return issue.Repo.IsTimetrackerEnabled(ctx)
 }
 
-// GetPullRequest returns the issue pull request
-func (issue *Issue) GetPullRequest(ctx context.Context) (pr *PullRequest, err error) {
-	if !issue.IsPull {
-		return nil, fmt.Errorf("Issue is not a pull request")
-	}
-
-	pr, err = GetPullRequestByIssueID(ctx, issue.ID)
-	if err != nil {
-		return nil, err
-	}
-	pr.Issue = issue
-	return pr, err
-}
-
 // LoadPoster loads poster
 func (issue *Issue) LoadPoster(ctx context.Context) (err error) {
 	if issue.Poster == nil && issue.PosterID != 0 {
diff --git a/models/issues/issue_list.go b/models/issues/issue_list.go
index 41a90d133d..218891ad35 100644
--- a/models/issues/issue_list.go
+++ b/models/issues/issue_list.go
@@ -370,6 +370,9 @@ func (issues IssueList) LoadPullRequests(ctx context.Context) error {
 
 	for _, issue := range issues {
 		issue.PullRequest = pullRequestMaps[issue.ID]
+		if issue.PullRequest != nil {
+			issue.PullRequest.Issue = issue
+		}
 	}
 	return nil
 }
diff --git a/models/issues/pull_list.go b/models/issues/pull_list.go
index c209386e2e..2ee69cd323 100644
--- a/models/issues/pull_list.go
+++ b/models/issues/pull_list.go
@@ -212,3 +212,12 @@ func HasMergedPullRequestInRepo(ctx context.Context, repoID, posterID int64) (bo
 		Limit(1).
 		Get(new(Issue))
 }
+
+// GetPullRequestByIssueIDs returns all pull requests by issue ids
+func GetPullRequestByIssueIDs(ctx context.Context, issueIDs []int64) (PullRequestList, error) {
+	prs := make([]*PullRequest, 0, len(issueIDs))
+	return prs, db.GetEngine(ctx).
+		Where("issue_id > 0").
+		In("issue_id", issueIDs).
+		Find(&prs)
+}
diff --git a/models/issues/review.go b/models/issues/review.go
index fc110630e0..70aba0f94d 100644
--- a/models/issues/review.go
+++ b/models/issues/review.go
@@ -239,11 +239,11 @@ type CreateReviewOptions struct {
 
 // IsOfficialReviewer check if at least one of the provided reviewers can make official reviews in issue (counts towards required approvals)
 func IsOfficialReviewer(ctx context.Context, issue *Issue, reviewer *user_model.User) (bool, error) {
-	pr, err := GetPullRequestByIssueID(ctx, issue.ID)
-	if err != nil {
+	if err := issue.LoadPullRequest(ctx); err != nil {
 		return false, err
 	}
 
+	pr := issue.PullRequest
 	rule, err := git_model.GetFirstMatchProtectedBranchRule(ctx, pr.BaseRepoID, pr.BaseBranch)
 	if err != nil {
 		return false, err
@@ -271,11 +271,10 @@ func IsOfficialReviewer(ctx context.Context, issue *Issue, reviewer *user_model.
 
 // IsOfficialReviewerTeam check if reviewer in this team can make official reviews in issue (counts towards required approvals)
 func IsOfficialReviewerTeam(ctx context.Context, issue *Issue, team *organization.Team) (bool, error) {
-	pr, err := GetPullRequestByIssueID(ctx, issue.ID)
-	if err != nil {
+	if err := issue.LoadPullRequest(ctx); err != nil {
 		return false, err
 	}
-	pb, err := git_model.GetFirstMatchProtectedBranchRule(ctx, pr.BaseRepoID, pr.BaseBranch)
+	pb, err := git_model.GetFirstMatchProtectedBranchRule(ctx, issue.PullRequest.BaseRepoID, issue.PullRequest.BaseBranch)
 	if err != nil {
 		return false, err
 	}
diff --git a/modules/util/slice.go b/modules/util/slice.go
index f00e84bf06..9c878c24be 100644
--- a/modules/util/slice.go
+++ b/modules/util/slice.go
@@ -54,7 +54,7 @@ func Sorted[S ~[]E, E cmp.Ordered](values S) S {
 	return values
 }
 
-// TODO: Replace with "maps.Values" once available
+// TODO: Replace with "maps.Values" once available, current it only in golang.org/x/exp/maps but not in standard library
 func ValuesOfMap[K comparable, V any](m map[K]V) []V {
 	values := make([]V, 0, len(m))
 	for _, v := range m {
@@ -62,3 +62,12 @@ func ValuesOfMap[K comparable, V any](m map[K]V) []V {
 	}
 	return values
 }
+
+// TODO: Replace with "maps.Keys" once available, current it only in golang.org/x/exp/maps but not in standard library
+func KeysOfMap[K comparable, V any](m map[K]V) []K {
+	keys := make([]K, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	return keys
+}
diff --git a/routers/api/v1/repo/issue.go b/routers/api/v1/repo/issue.go
index 61a318baab..6934b34b24 100644
--- a/routers/api/v1/repo/issue.go
+++ b/routers/api/v1/repo/issue.go
@@ -872,10 +872,11 @@ func EditIssue(ctx *context.APIContext) {
 	}
 	if form.State != nil {
 		if issue.IsPull {
-			if pr, err := issue.GetPullRequest(ctx); err != nil {
+			if err := issue.LoadPullRequest(ctx); err != nil {
 				ctx.Error(http.StatusInternalServerError, "GetPullRequest", err)
 				return
-			} else if pr.HasMerged {
+			}
+			if issue.PullRequest.HasMerged {
 				ctx.Error(http.StatusPreconditionFailed, "MergedPRState", "cannot change state of this pull request, it was already merged")
 				return
 			}
diff --git a/routers/api/v1/repo/issue_pin.go b/routers/api/v1/repo/issue_pin.go
index ff1135862b..8fcf670fd0 100644
--- a/routers/api/v1/repo/issue_pin.go
+++ b/routers/api/v1/repo/issue_pin.go
@@ -240,18 +240,12 @@ func ListPinnedPullRequests(ctx *context.APIContext) {
 	}
 
 	apiPrs := make([]*api.PullRequest, len(issues))
+	if err := issues.LoadPullRequests(ctx); err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadPullRequests", err)
+		return
+	}
 	for i, currentIssue := range issues {
-		pr, err := currentIssue.GetPullRequest(ctx)
-		if err != nil {
-			ctx.Error(http.StatusInternalServerError, "GetPullRequest", err)
-			return
-		}
-
-		if err = pr.LoadIssue(ctx); err != nil {
-			ctx.Error(http.StatusInternalServerError, "LoadIssue", err)
-			return
-		}
-
+		pr := currentIssue.PullRequest
 		if err = pr.LoadAttributes(ctx); err != nil {
 			ctx.Error(http.StatusInternalServerError, "LoadAttributes", err)
 			return
diff --git a/routers/web/user/notification.go b/routers/web/user/notification.go
index 438462371b..28f9846d6b 100644
--- a/routers/web/user/notification.go
+++ b/routers/web/user/notification.go
@@ -144,6 +144,12 @@ func getNotifications(ctx *context.Context) {
 		ctx.ServerError("LoadIssues", err)
 		return
 	}
+
+	if err = notifications.LoadIssuePullRequests(ctx); err != nil {
+		ctx.ServerError("LoadIssuePullRequests", err)
+		return
+	}
+
 	notifications = notifications.Without(failures)
 	failCount += len(failures)
 
diff --git a/services/convert/notification.go b/services/convert/notification.go
index 0b97530d8b..41063cf399 100644
--- a/services/convert/notification.go
+++ b/services/convert/notification.go
@@ -61,8 +61,9 @@ func ToNotificationThread(ctx context.Context, n *activities_model.Notification)
 				result.Subject.LatestCommentHTMLURL = comment.HTMLURL(ctx)
 			}
 
-			pr, _ := n.Issue.GetPullRequest(ctx)
-			if pr != nil && pr.HasMerged {
+			if err := n.Issue.LoadPullRequest(ctx); err == nil &&
+				n.Issue.PullRequest != nil &&
+				n.Issue.PullRequest.HasMerged {
 				result.Subject.State = "merged"
 			}
 		}
diff --git a/services/pull/review.go b/services/pull/review.go
index 90d07c8358..8900ae2ab1 100644
--- a/services/pull/review.go
+++ b/services/pull/review.go
@@ -268,11 +268,11 @@ func createCodeComment(ctx context.Context, doer *user_model.User, repo *repo_mo
 
 // SubmitReview creates a review out of the existing pending review or creates a new one if no pending review exist
 func SubmitReview(ctx context.Context, doer *user_model.User, gitRepo *git.Repository, issue *issues_model.Issue, reviewType issues_model.ReviewType, content, commitID string, attachmentUUIDs []string) (*issues_model.Review, *issues_model.Comment, error) {
-	pr, err := issue.GetPullRequest(ctx)
-	if err != nil {
+	if err := issue.LoadPullRequest(ctx); err != nil {
 		return nil, nil, err
 	}
 
+	pr := issue.PullRequest
 	var stale bool
 	if reviewType != issues_model.ReviewTypeApprove && reviewType != issues_model.ReviewTypeReject {
 		stale = false
diff --git a/templates/shared/issueicon.tmpl b/templates/shared/issueicon.tmpl
index 089e80bd8b..a62714e988 100644
--- a/templates/shared/issueicon.tmpl
+++ b/templates/shared/issueicon.tmpl
@@ -1,15 +1,15 @@
 {{if .IsPull}}
-	{{if and .PullRequest .PullRequest.HasMerged}}
-		{{svg "octicon-git-merge" 16 "text purple"}}
-	{{else if and (.GetPullRequest ctx) (.GetPullRequest ctx).HasMerged}}
-		{{svg "octicon-git-merge" 16 "text purple"}}
+	{{if not .PullRequest}}
+		No PullRequest
 	{{else}}
 		{{if .IsClosed}}
-			{{svg "octicon-git-pull-request" 16 "text red"}}
+			{{if .PullRequest.HasMerged}}
+				{{svg "octicon-git-merge" 16 "text purple"}}
+			{{else}}
+				{{svg "octicon-git-pull-request" 16 "text red"}}
+			{{end}}
 		{{else}}
-			{{if and .PullRequest (.PullRequest.IsWorkInProgress ctx)}}
-				{{svg "octicon-git-pull-request-draft" 16 "text grey"}}
-			{{else if and (.GetPullRequest ctx) ((.GetPullRequest ctx).IsWorkInProgress ctx)}}
+			{{if .PullRequest.IsWorkInProgress ctx}}
 				{{svg "octicon-git-pull-request-draft" 16 "text grey"}}
 			{{else}}
 				{{svg "octicon-git-pull-request" 16 "text green"}}
diff --git a/tests/integration/pull_merge_test.go b/tests/integration/pull_merge_test.go
index a04b4c98cd..daf411f452 100644
--- a/tests/integration/pull_merge_test.go
+++ b/tests/integration/pull_merge_test.go
@@ -516,8 +516,8 @@ func TestConflictChecking(t *testing.T) {
 		assert.NoError(t, err)
 
 		issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{Title: "PR with conflict!"})
-		conflictingPR, err := issues_model.GetPullRequestByIssueID(db.DefaultContext, issue.ID)
-		assert.NoError(t, err)
+		assert.NoError(t, issue.LoadPullRequest(db.DefaultContext))
+		conflictingPR := issue.PullRequest
 
 		// Ensure conflictedFiles is populated.
 		assert.Len(t, conflictingPR.ConflictedFiles, 1)
diff --git a/tests/integration/pull_update_test.go b/tests/integration/pull_update_test.go
index 078253ffb0..5ae241f3af 100644
--- a/tests/integration/pull_update_test.go
+++ b/tests/integration/pull_update_test.go
@@ -177,8 +177,7 @@ func createOutdatedPR(t *testing.T, actor, forkOrg *user_model.User) *issues_mod
 	assert.NoError(t, err)
 
 	issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{Title: "Test Pull -to-update-"})
-	pr, err := issues_model.GetPullRequestByIssueID(db.DefaultContext, issue.ID)
-	assert.NoError(t, err)
+	assert.NoError(t, issue.LoadPullRequest(db.DefaultContext))
 
-	return pr
+	return issue.PullRequest
 }