Transaction-aware retry create issue to cope with duplicate keys (#8307)

* Revert #7898

* Transaction-aware retry create issue to cope with duplicate keys

* Restore INSERT ... WHERE usage

* Rearrange code for clarity

* Fix error return in newIssue()

* Fix error message

1 files changed, 19 insertions, 1 deletions

diff --git a/models/pull.go b/models/pull.go
index b41fb004e1..ff1f7b773b 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -657,6 +657,24 @@ func (pr *PullRequest) testPatch(e Engine) (err error) {
 
 // NewPullRequest creates new pull request with labels for repository.
 func NewPullRequest(repo *Repository, pull *Issue, labelIDs []int64, uuids []string, pr *PullRequest, patch []byte, assigneeIDs []int64) (err error) {
+	// Retry several times in case INSERT fails due to duplicate key for (repo_id, index); see #7887
+	i := 0
+	for {
+		if err = newPullRequestAttempt(repo, pull, labelIDs, uuids, pr, patch, assigneeIDs); err == nil {
+			return nil
+		}
+		if !IsErrNewIssueInsert(err) {
+			return err
+		}
+		if i++; i == issueMaxDupIndexAttempts {
+			break
+		}
+		log.Error("NewPullRequest: error attempting to insert the new issue; will retry. Original error: %v", err)
+	}
+	return fmt.Errorf("NewPullRequest: too many errors attempting to insert the new issue. Last error was: %v", err)
+}
+
+func newPullRequestAttempt(repo *Repository, pull *Issue, labelIDs []int64, uuids []string, pr *PullRequest, patch []byte, assigneeIDs []int64) (err error) {
 	sess := x.NewSession()
 	defer sess.Close()
 	if err = sess.Begin(); err != nil {
@@ -671,7 +689,7 @@ func NewPullRequest(repo *Repository, pull *Issue, labelIDs []int64, uuids []str
 		IsPull:      true,
 		AssigneeIDs: assigneeIDs,
 	}); err != nil {
-		if IsErrUserDoesNotHaveAccessToRepo(err) {
+		if IsErrUserDoesNotHaveAccessToRepo(err) || IsErrNewIssueInsert(err) {
 			return err
 		}
 		return fmt.Errorf("newIssue: %v", err)