refactor(automerge): fix error handling, populate recent automerge tasks on restart (#39001)

* Refactor "automerge" related code, clarify many details (including "unique queue item", start check by pull head or commit)
* Fix automerge queue handler's error handling, clarify error messages
* Populate recent automerge tasks on restart to restore the previous aborted automerge tasks

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/actions/run.go

@@ -8,7 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
-	"strings"
+	"strconv"
 	"time"
 
 	"gitea.dev/models/db"
@@ -123,7 +123,9 @@ func (run *ActionRun) RefLink() string {
 func (run *ActionRun) PrettyRef() string {
 	refName := git.RefName(run.Ref)
 	if refName.IsPull() {
-		return "#" + strings.TrimSuffix(strings.TrimPrefix(run.Ref, git.PullPrefix), "/head")
+		if pullIndex, ok := refName.PullIndex(); ok {
+			return "#" + strconv.FormatInt(pullIndex, 10)
+		}
 	}
 	return refName.ShortName()
 }

models/issues/pull.go

@@ -415,7 +415,7 @@ func (pr *PullRequest) getReviewedByLines(ctx context.Context, writer io.Writer)
 
 // GetGitHeadRefName returns git ref for hidden pull request branch
 func (pr *PullRequest) GetGitHeadRefName() string { // TODO: make it return RefName but not string
-	return fmt.Sprintf("%s%d/head", git.PullPrefix, pr.Index)
+	return git.RefNameFromPullIndex(pr.Index).String()
 }
 
 // GetReviewCommentsCount returns the number of review comments made on the diff of a PR review (not including comments on commits or issues in a PR)

models/pull/automerge.go

@@ -80,6 +80,12 @@ func GetScheduledMergeByPullID(ctx context.Context, pullID int64) (bool, *AutoMe
 	return true, scheduledPRM, err
 }
 
+func GetScheduledMergePullIDsSince(ctx context.Context, since timeutil.TimeStamp) ([]int64, error) {
+	var pullIDs []int64
+	err := db.GetEngine(ctx).Table(&AutoMerge{}).Where("created_unix >= ?", since).Cols("pull_id").Find(&pullIDs)
+	return pullIDs, err
+}
+
 // DeleteScheduledAutoMerge delete a scheduled pull request
 func DeleteScheduledAutoMerge(ctx context.Context, pullID int64) error {
 	exist, scheduledPRM, err := GetScheduledMergeByPullID(ctx, pullID)