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>

5 files changed, 45 insertions, 19 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
 	}