Fix possible pull request broken when leave the page immediately after clicking the update button (go-gitea#34509)

If user leaves the page, the context will become cancelled, so that the
update process maybe terminal in an unexpected status. This PR haven't
resolve the problem totally. It uses a background context to not cancel
the update process even if the user leaved the pull request view page.

Fix go-gitea#31779

Author: lunny

routers/api/v1/repo/pull.go

@@ -23,6 +23,7 @@ import (
 	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/graceful"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
@@ -1301,7 +1302,7 @@ func UpdatePullRequest(ctx *context.APIContext) {
 	// default merge commit message
 	message := fmt.Sprintf("Merge branch '%s' into %s", pr.BaseBranch, pr.HeadBranch)
 
-	if err = pull_service.Update(ctx, pr, ctx.Doer, message, rebase); err != nil {
+	if err = pull_service.Update(graceful.GetManager().ShutdownContext(), pr, ctx.Doer, message, rebase); err != nil {
 		if pull_service.IsErrMergeConflicts(err) {
 			ctx.APIError(http.StatusConflict, "merge failed because of conflict")
 			return

routers/web/repo/pull.go

@@ -26,6 +26,7 @@ import (
 	"code.gitea.io/gitea/modules/emoji"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/graceful"
 	issue_template "code.gitea.io/gitea/modules/issue/template"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
@@ -980,7 +981,9 @@ func UpdatePullRequest(ctx *context.Context) {
 	// default merge commit message
 	message := fmt.Sprintf("Merge branch '%s' into %s", issue.PullRequest.BaseBranch, issue.PullRequest.HeadBranch)
 
-	if err = pull_service.Update(ctx, issue.PullRequest, ctx.Doer, message, rebase); err != nil {
+	// The update process should not be cancelled by the user
+	// so we set the context to be a background context
+	if err = pull_service.Update(graceful.GetManager().ShutdownContext(), issue.PullRequest, ctx.Doer, message, rebase); err != nil {
 		if pull_service.IsErrMergeConflicts(err) {
 			conflictError := err.(pull_service.ErrMergeConflicts)
 			flashError, err := ctx.RenderToHTML(tplAlertDetails, map[string]any{

services/pull/update.go

@@ -41,22 +41,6 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 		return fmt.Errorf("HeadBranch of PR %d is up to date", pr.Index)
 	}
 
-	if rebase {
-		defer func() {
-			go AddTestPullRequestTask(TestPullRequestOptions{
-				RepoID:      pr.BaseRepo.ID,
-				Doer:        doer,
-				Branch:      pr.BaseBranch,
-				IsSync:      false,
-				IsForcePush: false,
-				OldCommitID: "",
-				NewCommitID: "",
-			})
-		}()
-
-		return updateHeadByRebaseOnToBase(ctx, pr, doer)
-	}
-
 	if err := pr.LoadBaseRepo(ctx); err != nil {
 		log.Error("unable to load BaseRepo for %-v during update-by-merge: %v", pr, err)
 		return fmt.Errorf("unable to load BaseRepo for PR[%d] during update-by-merge: %w", pr.ID, err)
@@ -74,6 +58,22 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 		return fmt.Errorf("unable to load HeadRepo for PR[%d] during update-by-merge: %w", pr.ID, err)
 	}
 
+	defer func() {
+		go AddTestPullRequestTask(TestPullRequestOptions{
+			RepoID:      pr.BaseRepo.ID,
+			Doer:        doer,
+			Branch:      pr.BaseBranch,
+			IsSync:      false,
+			IsForcePush: false,
+			OldCommitID: "",
+			NewCommitID: "",
+		})
+	}()
+
+	if rebase {
+		return updateHeadByRebaseOnToBase(ctx, pr, doer)
+	}
+
 	// TODO: FakePR: it is somewhat hacky, but it is the only way to "merge" at the moment
 	// ideally in the future the "merge" functions should be refactored to decouple from the PullRequest
 	// now use a fake reverse PR to switch head&base repos/branches
@@ -90,19 +90,6 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 	}
 
 	_, err = doMergeAndPush(ctx, reversePR, doer, repo_model.MergeStyleMerge, "", message, repository.PushTriggerPRUpdateWithBase)
-
-	defer func() {
-		go AddTestPullRequestTask(TestPullRequestOptions{
-			RepoID:      reversePR.HeadRepo.ID,
-			Doer:        doer,
-			Branch:      reversePR.HeadBranch,
-			IsSync:      false,
-			IsForcePush: false,
-			OldCommitID: "",
-			NewCommitID: "",
-		})
-	}()
-
 	return err
 }