DBContext is just a Context (#17100)

* DBContext is just a Context

This PR removes some of the specialness from the DBContext and makes it context
This allows us to simplify the GetEngine code to wrap around any context in future
and means that we can change our loadRepo(e Engine) functions to simply take contexts.

Signed-off-by: Andrew Thornton <art27@cantab.net>

* fix unit tests

Signed-off-by: Andrew Thornton <art27@cantab.net>

* another place that needs to set the initial context

Signed-off-by: Andrew Thornton <art27@cantab.net>

* avoid race

Signed-off-by: Andrew Thornton <art27@cantab.net>

* change attachment error

Signed-off-by: Andrew Thornton <art27@cantab.net>

1 files changed, 74 insertions, 73 deletions

diff --git a/models/issue.go b/models/issue.go
index a1f5373583..cafd996ac5 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -6,6 +6,7 @@
 package models
 
 import (
+	"context"
 	"fmt"
 	"regexp"
 	"sort"
@@ -113,7 +114,7 @@ func (issue *Issue) IsOverdue() bool {
 
 // LoadRepo loads issue's repository
 func (issue *Issue) LoadRepo() error {
-	return issue.loadRepo(db.DefaultContext().Engine())
+	return issue.loadRepo(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) loadRepo(e db.Engine) (err error) {
@@ -128,7 +129,7 @@ func (issue *Issue) loadRepo(e db.Engine) (err error) {
 
 // IsTimetrackerEnabled returns true if the repo enables timetracking
 func (issue *Issue) IsTimetrackerEnabled() bool {
-	return issue.isTimetrackerEnabled(db.DefaultContext().Engine())
+	return issue.isTimetrackerEnabled(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) isTimetrackerEnabled(e db.Engine) bool {
@@ -145,7 +146,7 @@ func (issue *Issue) GetPullRequest() (pr *PullRequest, err error) {
 		return nil, fmt.Errorf("Issue is not a pull request")
 	}
 
-	pr, err = getPullRequestByIssueID(db.DefaultContext().Engine(), issue.ID)
+	pr, err = getPullRequestByIssueID(db.GetEngine(db.DefaultContext), issue.ID)
 	if err != nil {
 		return nil, err
 	}
@@ -155,7 +156,7 @@ func (issue *Issue) GetPullRequest() (pr *PullRequest, err error) {
 
 // LoadLabels loads labels
 func (issue *Issue) LoadLabels() error {
-	return issue.loadLabels(db.DefaultContext().Engine())
+	return issue.loadLabels(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) loadLabels(e db.Engine) (err error) {
@@ -170,7 +171,7 @@ func (issue *Issue) loadLabels(e db.Engine) (err error) {
 
 // LoadPoster loads poster
 func (issue *Issue) LoadPoster() error {
-	return issue.loadPoster(db.DefaultContext().Engine())
+	return issue.loadPoster(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) loadPoster(e db.Engine) (err error) {
@@ -205,7 +206,7 @@ func (issue *Issue) loadPullRequest(e db.Engine) (err error) {
 
 // LoadPullRequest loads pull request info
 func (issue *Issue) LoadPullRequest() error {
-	return issue.loadPullRequest(db.DefaultContext().Engine())
+	return issue.loadPullRequest(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) loadComments(e db.Engine) (err error) {
@@ -214,7 +215,7 @@ func (issue *Issue) loadComments(e db.Engine) (err error) {
 
 // LoadDiscussComments loads discuss comments
 func (issue *Issue) LoadDiscussComments() error {
-	return issue.loadCommentsByType(db.DefaultContext().Engine(), CommentTypeComment)
+	return issue.loadCommentsByType(db.GetEngine(db.DefaultContext), CommentTypeComment)
 }
 
 func (issue *Issue) loadCommentsByType(e db.Engine, tp CommentType) (err error) {
@@ -327,18 +328,18 @@ func (issue *Issue) loadAttributes(e db.Engine) (err error) {
 
 // LoadAttributes loads the attribute of this issue.
 func (issue *Issue) LoadAttributes() error {
-	return issue.loadAttributes(db.DefaultContext().Engine())
+	return issue.loadAttributes(db.GetEngine(db.DefaultContext))
 }
 
 // LoadMilestone load milestone of this issue.
 func (issue *Issue) LoadMilestone() error {
-	return issue.loadMilestone(db.DefaultContext().Engine())
+	return issue.loadMilestone(db.GetEngine(db.DefaultContext))
 }
 
 // GetIsRead load the `IsRead` field of the issue
 func (issue *Issue) GetIsRead(userID int64) error {
 	issueUser := &IssueUser{IssueID: issue.ID, UID: userID}
-	if has, err := db.DefaultContext().Engine().Get(issueUser); err != nil {
+	if has, err := db.GetEngine(db.DefaultContext).Get(issueUser); err != nil {
 		return err
 	} else if !has {
 		issue.IsRead = false
@@ -411,7 +412,7 @@ func (issue *Issue) hasLabel(e db.Engine, labelID int64) bool {
 
 // HasLabel returns true if issue has been labeled by given ID.
 func (issue *Issue) HasLabel(labelID int64) bool {
-	return issue.hasLabel(db.DefaultContext().Engine(), labelID)
+	return issue.hasLabel(db.GetEngine(db.DefaultContext), labelID)
 }
 
 // ReplyReference returns tokenized address to use for email reply headers
@@ -473,13 +474,13 @@ func (issue *Issue) ClearLabels(doer *User) (err error) {
 	}
 	defer committer.Close()
 
-	if err := issue.loadRepo(ctx.Engine()); err != nil {
+	if err := issue.loadRepo(db.GetEngine(ctx)); err != nil {
 		return err
-	} else if err = issue.loadPullRequest(ctx.Engine()); err != nil {
+	} else if err = issue.loadPullRequest(db.GetEngine(ctx)); err != nil {
 		return err
 	}
 
-	perm, err := getUserRepoPermission(ctx.Engine(), issue.Repo, doer)
+	perm, err := getUserRepoPermission(db.GetEngine(ctx), issue.Repo, doer)
 	if err != nil {
 		return err
 	}
@@ -487,7 +488,7 @@ func (issue *Issue) ClearLabels(doer *User) (err error) {
 		return ErrRepoLabelNotExist{}
 	}
 
-	if err = issue.clearLabels(ctx.Engine(), doer); err != nil {
+	if err = issue.clearLabels(db.GetEngine(ctx), doer); err != nil {
 		return err
 	}
 
@@ -521,11 +522,11 @@ func (issue *Issue) ReplaceLabels(labels []*Label, doer *User) (err error) {
 	}
 	defer committer.Close()
 
-	if err = issue.loadRepo(ctx.Engine()); err != nil {
+	if err = issue.loadRepo(db.GetEngine(ctx)); err != nil {
 		return err
 	}
 
-	if err = issue.loadLabels(ctx.Engine()); err != nil {
+	if err = issue.loadLabels(db.GetEngine(ctx)); err != nil {
 		return err
 	}
 
@@ -561,19 +562,19 @@ func (issue *Issue) ReplaceLabels(labels []*Label, doer *User) (err error) {
 	toRemove = append(toRemove, issue.Labels[removeIndex:]...)
 
 	if len(toAdd) > 0 {
-		if err = issue.addLabels(ctx.Engine(), toAdd, doer); err != nil {
+		if err = issue.addLabels(db.GetEngine(ctx), toAdd, doer); err != nil {
 			return fmt.Errorf("addLabels: %v", err)
 		}
 	}
 
 	for _, l := range toRemove {
-		if err = issue.removeLabel(ctx.Engine(), doer, l); err != nil {
+		if err = issue.removeLabel(db.GetEngine(ctx), doer, l); err != nil {
 			return fmt.Errorf("removeLabel: %v", err)
 		}
 	}
 
 	issue.Labels = nil
-	if err = issue.loadLabels(ctx.Engine()); err != nil {
+	if err = issue.loadLabels(db.GetEngine(ctx)); err != nil {
 		return err
 	}
 
@@ -586,7 +587,7 @@ func (issue *Issue) ReadBy(userID int64) error {
 		return err
 	}
 
-	return setIssueNotificationStatusReadIfUnread(db.DefaultContext().Engine(), userID, issue.ID)
+	return setIssueNotificationStatusReadIfUnread(db.GetEngine(db.DefaultContext), userID, issue.ID)
 }
 
 func updateIssueCols(e db.Engine, issue *Issue, cols ...string) error {
@@ -688,14 +689,14 @@ func (issue *Issue) ChangeStatus(doer *User, isClosed bool) (*Comment, error) {
 	}
 	defer committer.Close()
 
-	if err := issue.loadRepo(ctx.Engine()); err != nil {
+	if err := issue.loadRepo(db.GetEngine(ctx)); err != nil {
 		return nil, err
 	}
-	if err := issue.loadPoster(ctx.Engine()); err != nil {
+	if err := issue.loadPoster(db.GetEngine(ctx)); err != nil {
 		return nil, err
 	}
 
-	comment, err := issue.changeStatus(ctx.Engine(), doer, isClosed, false)
+	comment, err := issue.changeStatus(db.GetEngine(ctx), doer, isClosed, false)
 	if err != nil {
 		return nil, err
 	}
@@ -715,11 +716,11 @@ func (issue *Issue) ChangeTitle(doer *User, oldTitle string) (err error) {
 	}
 	defer committer.Close()
 
-	if err = updateIssueCols(ctx.Engine(), issue, "name"); err != nil {
+	if err = updateIssueCols(db.GetEngine(ctx), issue, "name"); err != nil {
 		return fmt.Errorf("updateIssueCols: %v", err)
 	}
 
-	if err = issue.loadRepo(ctx.Engine()); err != nil {
+	if err = issue.loadRepo(db.GetEngine(ctx)); err != nil {
 		return fmt.Errorf("loadRepo: %v", err)
 	}
 
@@ -731,10 +732,10 @@ func (issue *Issue) ChangeTitle(doer *User, oldTitle string) (err error) {
 		OldTitle: oldTitle,
 		NewTitle: issue.Title,
 	}
-	if _, err = createComment(ctx.Engine(), opts); err != nil {
+	if _, err = createComment(db.GetEngine(ctx), opts); err != nil {
 		return fmt.Errorf("createComment: %v", err)
 	}
-	if err = issue.addCrossReferences(ctx.Engine(), doer, true); err != nil {
+	if err = issue.addCrossReferences(db.GetEngine(ctx), doer, true); err != nil {
 		return err
 	}
 
@@ -749,7 +750,7 @@ func (issue *Issue) ChangeRef(doer *User, oldRef string) (err error) {
 	}
 	defer committer.Close()
 
-	if err = updateIssueCols(ctx.Engine(), issue, "ref"); err != nil {
+	if err = updateIssueCols(db.GetEngine(ctx), issue, "ref"); err != nil {
 		return fmt.Errorf("updateIssueCols: %v", err)
 	}
 
@@ -758,7 +759,7 @@ func (issue *Issue) ChangeRef(doer *User, oldRef string) (err error) {
 
 // AddDeletePRBranchComment adds delete branch comment for pull request issue
 func AddDeletePRBranchComment(doer *User, repo *Repository, issueID int64, branchName string) error {
-	issue, err := getIssueByID(db.DefaultContext().Engine(), issueID)
+	issue, err := getIssueByID(db.GetEngine(db.DefaultContext), issueID)
 	if err != nil {
 		return err
 	}
@@ -774,7 +775,7 @@ func AddDeletePRBranchComment(doer *User, repo *Repository, issueID int64, branc
 		Issue:  issue,
 		OldRef: branchName,
 	}
-	if _, err = createComment(ctx.Engine(), opts); err != nil {
+	if _, err = createComment(db.GetEngine(ctx), opts); err != nil {
 		return err
 	}
 
@@ -788,13 +789,13 @@ func (issue *Issue) UpdateAttachments(uuids []string) (err error) {
 		return err
 	}
 	defer committer.Close()
-	attachments, err := getAttachmentsByUUIDs(ctx.Engine(), uuids)
+	attachments, err := getAttachmentsByUUIDs(db.GetEngine(ctx), uuids)
 	if err != nil {
 		return fmt.Errorf("getAttachmentsByUUIDs [uuids: %v]: %v", uuids, err)
 	}
 	for i := 0; i < len(attachments); i++ {
 		attachments[i].IssueID = issue.ID
-		if err := updateAttachment(ctx.Engine(), attachments[i]); err != nil {
+		if err := updateAttachment(db.GetEngine(ctx), attachments[i]); err != nil {
 			return fmt.Errorf("update attachment [id: %d]: %v", attachments[i].ID, err)
 		}
 	}
@@ -811,11 +812,11 @@ func (issue *Issue) ChangeContent(doer *User, content string) (err error) {
 	}
 	defer committer.Close()
 
-	if err = updateIssueCols(ctx.Engine(), issue, "content"); err != nil {
+	if err = updateIssueCols(db.GetEngine(ctx), issue, "content"); err != nil {
 		return fmt.Errorf("UpdateIssueCols: %v", err)
 	}
 
-	if err = issue.addCrossReferences(ctx.Engine(), doer, true); err != nil {
+	if err = issue.addCrossReferences(db.GetEngine(ctx), doer, true); err != nil {
 		return err
 	}
 
@@ -854,7 +855,7 @@ func (issue *Issue) GetLastEventLabel() string {
 // GetLastComment return last comment for the current issue.
 func (issue *Issue) GetLastComment() (*Comment, error) {
 	var c Comment
-	exist, err := db.DefaultContext().Engine().Where("type = ?", CommentTypeComment).
+	exist, err := db.GetEngine(db.DefaultContext).Where("type = ?", CommentTypeComment).
 		And("issue_id = ?", issue.ID).Desc("id").Get(&c)
 	if err != nil {
 		return nil, err
@@ -996,16 +997,16 @@ func RecalculateIssueIndexForRepo(repoID int64) error {
 	}
 	defer committer.Close()
 
-	if err := db.UpsertResourceIndex(ctx.Engine(), "issue_index", repoID); err != nil {
+	if err := db.UpsertResourceIndex(db.GetEngine(ctx), "issue_index", repoID); err != nil {
 		return err
 	}
 
 	var max int64
-	if _, err := ctx.Engine().Select(" MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
+	if _, err := db.GetEngine(ctx).Select(" MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
 		return err
 	}
 
-	if _, err := ctx.Engine().Exec("UPDATE `issue_index` SET max_index=? WHERE group_id=?", max, repoID); err != nil {
+	if _, err := db.GetEngine(ctx).Exec("UPDATE `issue_index` SET max_index=? WHERE group_id=?", max, repoID); err != nil {
 		return err
 	}
 
@@ -1027,7 +1028,7 @@ func NewIssue(repo *Repository, issue *Issue, labelIDs []int64, uuids []string)
 	}
 	defer committer.Close()
 
-	if err = newIssue(ctx.Engine(), issue.Poster, NewIssueOptions{
+	if err = newIssue(db.GetEngine(ctx), issue.Poster, NewIssueOptions{
 		Repo:        repo,
 		Issue:       issue,
 		LabelIDs:    labelIDs,
@@ -1055,7 +1056,7 @@ func GetIssueByIndex(repoID, index int64) (*Issue, error) {
 		RepoID: repoID,
 		Index:  index,
 	}
-	has, err := db.DefaultContext().Engine().Get(issue)
+	has, err := db.GetEngine(db.DefaultContext).Get(issue)
 	if err != nil {
 		return nil, err
 	} else if !has {
@@ -1086,16 +1087,16 @@ func getIssueByID(e db.Engine, id int64) (*Issue, error) {
 
 // GetIssueWithAttrsByID returns an issue with attributes by given ID.
 func GetIssueWithAttrsByID(id int64) (*Issue, error) {
-	issue, err := getIssueByID(db.DefaultContext().Engine(), id)
+	issue, err := getIssueByID(db.GetEngine(db.DefaultContext), id)
 	if err != nil {
 		return nil, err
 	}
-	return issue, issue.loadAttributes(db.DefaultContext().Engine())
+	return issue, issue.loadAttributes(db.GetEngine(db.DefaultContext))
 }
 
 // GetIssueByID returns an issue by given ID.
 func GetIssueByID(id int64) (*Issue, error) {
-	return getIssueByID(db.DefaultContext().Engine(), id)
+	return getIssueByID(db.GetEngine(db.DefaultContext), id)
 }
 
 func getIssuesByIDs(e db.Engine, issueIDs []int64) ([]*Issue, error) {
@@ -1111,12 +1112,12 @@ func getIssueIDsByRepoID(e db.Engine, repoID int64) ([]int64, error) {
 
 // GetIssueIDsByRepoID returns all issue ids by repo id
 func GetIssueIDsByRepoID(repoID int64) ([]int64, error) {
-	return getIssueIDsByRepoID(db.DefaultContext().Engine(), repoID)
+	return getIssueIDsByRepoID(db.GetEngine(db.DefaultContext), repoID)
 }
 
 // GetIssuesByIDs return issues with the given IDs.
 func GetIssuesByIDs(issueIDs []int64) ([]*Issue, error) {
-	return getIssuesByIDs(db.DefaultContext().Engine(), issueIDs)
+	return getIssuesByIDs(db.GetEngine(db.DefaultContext), issueIDs)
 }
 
 // IssuesOptions represents options of an issue.
@@ -1316,7 +1317,7 @@ func applyReviewRequestedCondition(sess *xorm.Session, reviewRequestedID int64)
 
 // CountIssuesByRepo map from repoID to number of issues matching the options
 func CountIssuesByRepo(opts *IssuesOptions) (map[int64]int64, error) {
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 
 	sess.Join("INNER", "repository", "`issue`.repo_id = `repository`.id")
@@ -1344,7 +1345,7 @@ func CountIssuesByRepo(opts *IssuesOptions) (map[int64]int64, error) {
 // GetRepoIDsForIssuesOptions find all repo ids for the given options
 func GetRepoIDsForIssuesOptions(opts *IssuesOptions, user *User) ([]int64, error) {
 	repoIDs := make([]int64, 0, 5)
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 
 	sess.Join("INNER", "repository", "`issue`.repo_id = `repository`.id")
@@ -1364,7 +1365,7 @@ func GetRepoIDsForIssuesOptions(opts *IssuesOptions, user *User) ([]int64, error
 
 // Issues returns a list of issues by given conditions.
 func Issues(opts *IssuesOptions) ([]*Issue, error) {
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 
 	sess.Join("INNER", "repository", "`issue`.repo_id = `repository`.id")
@@ -1386,7 +1387,7 @@ func Issues(opts *IssuesOptions) ([]*Issue, error) {
 
 // CountIssues number return of issues by given conditions.
 func CountIssues(opts *IssuesOptions) (int64, error) {
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 
 	countsSlice := make([]*struct {
@@ -1411,7 +1412,7 @@ func CountIssues(opts *IssuesOptions) (int64, error) {
 // User permissions must be verified elsewhere if required.
 func GetParticipantsIDsByIssueID(issueID int64) ([]int64, error) {
 	userIDs := make([]int64, 0, 5)
-	return userIDs, db.DefaultContext().Engine().Table("comment").
+	return userIDs, db.GetEngine(db.DefaultContext).Table("comment").
 		Cols("poster_id").
 		Where("issue_id = ?", issueID).
 		And("type in (?,?,?)", CommentTypeComment, CommentTypeCode, CommentTypeReview).
@@ -1421,7 +1422,7 @@ func GetParticipantsIDsByIssueID(issueID int64) ([]int64, error) {
 
 // IsUserParticipantsOfIssue return true if user is participants of an issue
 func IsUserParticipantsOfIssue(user *User, issue *Issue) bool {
-	userIDs, err := issue.getParticipantIDsByIssue(db.DefaultContext().Engine())
+	userIDs, err := issue.getParticipantIDsByIssue(db.GetEngine(db.DefaultContext))
 	if err != nil {
 		log.Error(err.Error())
 		return false
@@ -1430,7 +1431,7 @@ func IsUserParticipantsOfIssue(user *User, issue *Issue) bool {
 }
 
 // UpdateIssueMentions updates issue-user relations for mentioned users.
-func UpdateIssueMentions(ctx *db.Context, issueID int64, mentions []*User) error {
+func UpdateIssueMentions(ctx context.Context, issueID int64, mentions []*User) error {
 	if len(mentions) == 0 {
 		return nil
 	}
@@ -1529,7 +1530,7 @@ func getIssueStatsChunk(opts *IssueStatsOptions, issueIDs []int64) (*IssueStats,
 	stats := &IssueStats{}
 
 	countSession := func(opts *IssueStatsOptions) *xorm.Session {
-		sess := db.DefaultContext().Engine().
+		sess := db.GetEngine(db.DefaultContext).
 			Where("issue.repo_id = ?", opts.RepoID)
 
 		if len(opts.IssueIDs) > 0 {
@@ -1623,7 +1624,7 @@ func GetUserIssueStats(opts UserIssueStatsOptions) (*IssueStats, error) {
 	}
 
 	sess := func(cond builder.Cond) *xorm.Session {
-		s := db.DefaultContext().Engine().Where(cond)
+		s := db.GetEngine(db.DefaultContext).Where(cond)
 		if len(opts.LabelIDs) > 0 {
 			s.Join("INNER", "issue_label", "issue_label.issue_id = issue.id").
 				In("issue_label.label_id", opts.LabelIDs)
@@ -1735,7 +1736,7 @@ func GetUserIssueStats(opts UserIssueStatsOptions) (*IssueStats, error) {
 // GetRepoIssueStats returns number of open and closed repository issues by given filter mode.
 func GetRepoIssueStats(repoID, uid int64, filterMode int, isPull bool) (numOpen, numClosed int64) {
 	countSession := func(isClosed, isPull bool, repoID int64) *xorm.Session {
-		sess := db.DefaultContext().Engine().
+		sess := db.GetEngine(db.DefaultContext).
 			Where("is_closed = ?", isClosed).
 			And("is_pull = ?", isPull).
 			And("repo_id = ?", repoID)
@@ -1787,7 +1788,7 @@ func SearchIssueIDsByKeyword(kw string, repoIDs []int64, limit, start int) (int6
 		ID          int64
 		UpdatedUnix int64
 	}, 0, limit)
-	err := db.DefaultContext().Engine().Distinct("id", "updated_unix").Table("issue").Where(cond).
+	err := db.GetEngine(db.DefaultContext).Distinct("id", "updated_unix").Table("issue").Where(cond).
 		OrderBy("`updated_unix` DESC").Limit(limit, start).
 		Find(&res)
 	if err != nil {
@@ -1797,7 +1798,7 @@ func SearchIssueIDsByKeyword(kw string, repoIDs []int64, limit, start int) (int6
 		ids = append(ids, r.ID)
 	}
 
-	total, err := db.DefaultContext().Engine().Distinct("id").Table("issue").Where(cond).Count()
+	total, err := db.GetEngine(db.DefaultContext).Distinct("id").Table("issue").Where(cond).Count()
 	if err != nil {
 		return 0, nil, err
 	}
@@ -1809,7 +1810,7 @@ func SearchIssueIDsByKeyword(kw string, repoIDs []int64, limit, start int) (int6
 // If the issue status is changed a statusChangeComment is returned
 // similarly if the title is changed the titleChanged bool is set to true
 func UpdateIssueByAPI(issue *Issue, doer *User) (statusChangeComment *Comment, titleChanged bool, err error) {
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 	if err := sess.Begin(); err != nil {
 		return nil, false, err
@@ -1868,7 +1869,7 @@ func UpdateIssueDeadline(issue *Issue, deadlineUnix timeutil.TimeStamp, doer *Us
 		return nil
 	}
 
-	sess := db.DefaultContext().NewSession()
+	sess := db.NewSession(db.DefaultContext)
 	defer sess.Close()
 	if err := sess.Begin(); err != nil {
 		return err
@@ -1941,12 +1942,12 @@ func (issue *Issue) getBlockingDependencies(e db.Engine) (issueDeps []*Dependenc
 
 // BlockedByDependencies finds all Dependencies an issue is blocked by
 func (issue *Issue) BlockedByDependencies() ([]*DependencyInfo, error) {
-	return issue.getBlockedByDependencies(db.DefaultContext().Engine())
+	return issue.getBlockedByDependencies(db.GetEngine(db.DefaultContext))
 }
 
 // BlockingDependencies returns all blocking dependencies, aka all other issues a given issue blocks
 func (issue *Issue) BlockingDependencies() ([]*DependencyInfo, error) {
-	return issue.getBlockingDependencies(db.DefaultContext().Engine())
+	return issue.getBlockingDependencies(db.GetEngine(db.DefaultContext))
 }
 
 func (issue *Issue) updateClosedNum(e db.Engine) (err error) {
@@ -1969,7 +1970,7 @@ func (issue *Issue) updateClosedNum(e db.Engine) (err error) {
 }
 
 // FindAndUpdateIssueMentions finds users mentioned in the given content string, and saves them in the database.
-func (issue *Issue) FindAndUpdateIssueMentions(ctx *db.Context, doer *User, content string) (mentions []*User, err error) {
+func (issue *Issue) FindAndUpdateIssueMentions(ctx context.Context, doer *User, content string) (mentions []*User, err error) {
 	rawMentions := references.FindAllMentionsMarkdown(content)
 	mentions, err = issue.ResolveMentionsByVisibility(ctx, doer, rawMentions)
 	if err != nil {
@@ -1983,18 +1984,18 @@ func (issue *Issue) FindAndUpdateIssueMentions(ctx *db.Context, doer *User, cont
 
 // ResolveMentionsByVisibility returns the users mentioned in an issue, removing those that
 // don't have access to reading it. Teams are expanded into their users, but organizations are ignored.
-func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, mentions []string) (users []*User, err error) {
+func (issue *Issue) ResolveMentionsByVisibility(ctx context.Context, doer *User, mentions []string) (users []*User, err error) {
 	if len(mentions) == 0 {
 		return
 	}
-	if err = issue.loadRepo(ctx.Engine()); err != nil {
+	if err = issue.loadRepo(db.GetEngine(ctx)); err != nil {
 		return
 	}
 
 	resolved := make(map[string]bool, 10)
 	var mentionTeams []string
 
-	if err := issue.Repo.getOwner(ctx.Engine()); err != nil {
+	if err := issue.Repo.getOwner(db.GetEngine(ctx)); err != nil {
 		return nil, err
 	}
 
@@ -2023,7 +2024,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 
 	if issue.Repo.Owner.IsOrganization() && len(mentionTeams) > 0 {
 		teams := make([]*Team, 0, len(mentionTeams))
-		if err := ctx.Engine().
+		if err := db.GetEngine(ctx).
 			Join("INNER", "team_repo", "team_repo.team_id = team.id").
 			Where("team_repo.repo_id=?", issue.Repo.ID).
 			In("team.lower_name", mentionTeams).
@@ -2042,7 +2043,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 					resolved[issue.Repo.Owner.LowerName+"/"+team.LowerName] = true
 					continue
 				}
-				has, err := ctx.Engine().Get(&TeamUnit{OrgID: issue.Repo.Owner.ID, TeamID: team.ID, Type: unittype})
+				has, err := db.GetEngine(ctx).Get(&TeamUnit{OrgID: issue.Repo.Owner.ID, TeamID: team.ID, Type: unittype})
 				if err != nil {
 					return nil, fmt.Errorf("get team units (%d): %v", team.ID, err)
 				}
@@ -2053,7 +2054,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 			}
 			if len(checked) != 0 {
 				teamusers := make([]*User, 0, 20)
-				if err := ctx.Engine().
+				if err := db.GetEngine(ctx).
 					Join("INNER", "team_user", "team_user.uid = `user`.id").
 					In("`team_user`.team_id", checked).
 					And("`user`.is_active = ?", true).
@@ -2090,7 +2091,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 	}
 
 	unchecked := make([]*User, 0, len(mentionUsers))
-	if err := ctx.Engine().
+	if err := db.GetEngine(ctx).
 		Where("`user`.is_active = ?", true).
 		And("`user`.prohibit_login = ?", false).
 		In("`user`.lower_name", mentionUsers).
@@ -2102,7 +2103,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 			continue
 		}
 		// Normal users must have read access to the referencing issue
-		perm, err := getUserRepoPermission(ctx.Engine(), issue.Repo, user)
+		perm, err := getUserRepoPermission(db.GetEngine(ctx), issue.Repo, user)
 		if err != nil {
 			return nil, fmt.Errorf("getUserRepoPermission [%d]: %v", user.ID, err)
 		}
@@ -2117,7 +2118,7 @@ func (issue *Issue) ResolveMentionsByVisibility(ctx *db.Context, doer *User, men
 
 // UpdateIssuesMigrationsByType updates all migrated repositories' issues from gitServiceType to replace originalAuthorID to posterID
 func UpdateIssuesMigrationsByType(gitServiceType structs.GitServiceType, originalAuthorID string, posterID int64) error {
-	_, err := db.DefaultContext().Engine().Table("issue").
+	_, err := db.GetEngine(db.DefaultContext).Table("issue").
 		Where("repo_id IN (SELECT id FROM repository WHERE original_service_type = ?)", gitServiceType).
 		And("original_author_id = ?", originalAuthorID).
 		Update(map[string]interface{}{
@@ -2130,7 +2131,7 @@ func UpdateIssuesMigrationsByType(gitServiceType structs.GitServiceType, origina
 
 // UpdateReactionsMigrationsByType updates all migrated repositories' reactions from gitServiceType to replace originalAuthorID to posterID
 func UpdateReactionsMigrationsByType(gitServiceType structs.GitServiceType, originalAuthorID string, userID int64) error {
-	_, err := db.DefaultContext().Engine().Table("reaction").
+	_, err := db.GetEngine(db.DefaultContext).Table("reaction").
 		Where("original_author_id = ?", originalAuthorID).
 		And(migratedIssueCond(gitServiceType)).
 		Update(map[string]interface{}{