Rewrite delivery of issue and comment mails (#9009)

* Mail issue subscribers, rework the function

* Simplify a little more

* Fix unused variable

* Refactor mail delivery to avoid heavy load on server

* Avoid splitting into too many goroutines

* Fix comments and optimize GetMaileableUsersByIDs()

* Fix return on errors

models/issue.go

@@ -1219,6 +1219,19 @@ func Issues(opts *IssuesOptions) ([]*Issue, error) {
 	return issues, nil
 }
 
+// GetParticipantsIDsByIssueID returns the IDs of all users who participated in comments of an issue,
+// but skips joining with `user` for performance reasons.
+// User permissions must be verified elsewhere if required.
+func GetParticipantsIDsByIssueID(issueID int64) ([]int64, error) {
+	userIDs := make([]int64, 0, 5)
+	return userIDs, x.Table("comment").
+		Cols("poster_id").
+		Where("issue_id = ?", issueID).
+		And("type in (?,?,?)", CommentTypeComment, CommentTypeCode, CommentTypeReview).
+		Distinct("poster_id").
+		Find(&userIDs)
+}
+
 // GetParticipantsByIssueID returns all users who are participated in comments of an issue.
 func GetParticipantsByIssueID(issueID int64) ([]*User, error) {
 	return getParticipantsByIssueID(x, issueID)

models/issue_assignees.go

@@ -41,6 +41,18 @@ func (issue *Issue) loadAssignees(e Engine) (err error) {
 	return
 }
 
+// GetAssigneeIDsByIssue returns the IDs of users assigned to an issue
+// but skips joining with `user` for performance reasons.
+// User permissions must be verified elsewhere if required.
+func GetAssigneeIDsByIssue(issueID int64) ([]int64, error) {
+	userIDs := make([]int64, 0, 5)
+	return userIDs, x.Table("issue_assignees").
+		Cols("assignee_id").
+		Where("issue_id = ?", issueID).
+		Distinct("assignee_id").
+		Find(&userIDs)
+}
+
 // GetAssigneesByIssue returns everyone assigned to that issue
 func GetAssigneesByIssue(issue *Issue) (assignees []*User, err error) {
 	return getAssigneesByIssue(x, issue)

models/issue_watch.go

@@ -60,6 +60,18 @@ func getIssueWatch(e Engine, userID, issueID int64) (iw *IssueWatch, exists bool
 	return
 }
 
+// GetIssueWatchersIDs returns IDs of subscribers to a given issue id
+// but avoids joining with `user` for performance reasons
+// User permissions must be verified elsewhere if required
+func GetIssueWatchersIDs(issueID int64) ([]int64, error) {
+	ids := make([]int64, 0, 64)
+	return ids, x.Table("issue_watch").
+		Where("issue_id=?", issueID).
+		And("is_watching = ?", true).
+		Select("user_id").
+		Find(&ids)
+}
+
 // GetIssueWatchers returns watchers/unwatchers of a given issue
 func GetIssueWatchers(issueID int64) (IssueWatchList, error) {
 	return getIssueWatchers(x, issueID)

models/repo_watch.go

@@ -140,6 +140,18 @@ func GetWatchers(repoID int64) ([]*Watch, error) {
 	return getWatchers(x, repoID)
 }
 
+// GetRepoWatchersIDs returns IDs of watchers for a given repo ID
+// but avoids joining with `user` for performance reasons
+// User permissions must be verified elsewhere if required
+func GetRepoWatchersIDs(repoID int64) ([]int64, error) {
+	ids := make([]int64, 0, 64)
+	return ids, x.Table("watch").
+		Where("watch.repo_id=?", repoID).
+		And("watch.mode<>?", RepoWatchModeDont).
+		Select("user_id").
+		Find(&ids)
+}
+
 // GetWatchers returns range of users watching given repository.
 func (repo *Repository) GetWatchers(page int) ([]*User, error) {
 	users := make([]*User, 0, ItemsPerPage)

models/user.go

@@ -1307,6 +1307,20 @@ func getUserEmailsByNames(e Engine, names []string) []string {
 	return mails
 }
 
+// GetMaileableUsersByIDs gets users from ids, but only if they can receive mails
+func GetMaileableUsersByIDs(ids []int64) ([]*User, error) {
+	if len(ids) == 0 {
+		return nil, nil
+	}
+	ous := make([]*User, 0, len(ids))
+	return ous, x.In("id", ids).
+		Where("`type` = ?", UserTypeIndividual).
+		And("`prohibit_login` = ?", false).
+		And("`is_active` = ?", true).
+		And("`email_notifications_preference` = ?", EmailNotificationsEnabled).
+		Find(&ous)
+}
+
 // GetUsersByIDs returns all resolved users from a list of Ids.
 func GetUsersByIDs(ids []int64) ([]*User, error) {
 	ous := make([]*User, 0, len(ids))

services/mailer/mail.go

@@ -164,13 +164,7 @@ func SendCollaboratorMail(u, doer *models.User, repo *models.Repository) {
 	SendAsync(msg)
 }
 
-func composeIssueCommentMessage(issue *models.Issue, doer *models.User, actionType models.ActionType, fromMention bool,
-	content string, comment *models.Comment, tos []string, info string) *Message {
-
-	if err := issue.LoadPullRequest(); err != nil {
-		log.Error("LoadPullRequest: %v", err)
-		return nil
-	}
+func composeIssueCommentMessages(ctx *mailCommentContext, tos []string, fromMention bool, info string) []*Message {
 
 	var (
 		subject string
@@ -182,29 +176,29 @@ func composeIssueCommentMessage(issue *models.Issue, doer *models.User, actionTy
 	)
 
 	commentType := models.CommentTypeComment
-	if comment != nil {
+	if ctx.Comment != nil {
 		prefix = "Re: "
-		commentType = comment.Type
-		link = issue.HTMLURL() + "#" + comment.HashTag()
+		commentType = ctx.Comment.Type
+		link = ctx.Issue.HTMLURL() + "#" + ctx.Comment.HashTag()
 	} else {
-		link = issue.HTMLURL()
+		link = ctx.Issue.HTMLURL()
 	}
 
 	reviewType := models.ReviewTypeComment
-	if comment != nil && comment.Review != nil {
-		reviewType = comment.Review.Type
+	if ctx.Comment != nil && ctx.Comment.Review != nil {
+		reviewType = ctx.Comment.Review.Type
 	}
 
-	fallback = prefix + fallbackMailSubject(issue)
+	fallback = prefix + fallbackMailSubject(ctx.Issue)
 
 	// This is the body of the new issue or comment, not the mail body
-	body := string(markup.RenderByType(markdown.MarkupName, []byte(content), issue.Repo.HTMLURL(), issue.Repo.ComposeMetas()))
+	body := string(markup.RenderByType(markdown.MarkupName, []byte(ctx.Content), ctx.Issue.Repo.HTMLURL(), ctx.Issue.Repo.ComposeMetas()))
 
-	actType, actName, tplName := actionToTemplate(issue, actionType, commentType, reviewType)
+	actType, actName, tplName := actionToTemplate(ctx.Issue, ctx.ActionType, commentType, reviewType)
 
-	if comment != nil && comment.Review != nil {
+	if ctx.Comment != nil && ctx.Comment.Review != nil {
 		reviewComments = make([]*models.Comment, 0, 10)
-		for _, lines := range comment.Review.CodeComments {
+		for _, lines := range ctx.Comment.Review.CodeComments {
 			for _, comments := range lines {
 				reviewComments = append(reviewComments, comments...)
 			}
@@ -215,12 +209,12 @@ func composeIssueCommentMessage(issue *models.Issue, doer *models.User, actionTy
 		"FallbackSubject": fallback,
 		"Body":            body,
 		"Link":            link,
-		"Issue":           issue,
-		"Comment":         comment,
-		"IsPull":          issue.IsPull,
-		"User":            issue.Repo.MustOwner(),
-		"Repo":            issue.Repo.FullName(),
-		"Doer":            doer,
+		"Issue":           ctx.Issue,
+		"Comment":         ctx.Comment,
+		"IsPull":          ctx.Issue.IsPull,
+		"User":            ctx.Issue.Repo.MustOwner(),
+		"Repo":            ctx.Issue.Repo.FullName(),
+		"Doer":            ctx.Doer,
 		"IsMention":       fromMention,
 		"SubjectPrefix":   prefix,
 		"ActionType":      actType,
@@ -246,18 +240,23 @@ func composeIssueCommentMessage(issue *models.Issue, doer *models.User, actionTy
 		log.Error("ExecuteTemplate [%s]: %v", string(tplName)+"/body", err)
 	}
 
-	msg := NewMessageFrom(tos, doer.DisplayName(), setting.MailService.FromEmail, subject, mailBody.String())
+	// Make sure to compose independent messages to avoid leaking user emails
+	msgs := make([]*Message, 0, len(tos))
+	for _, to := range tos {
+		msg := NewMessageFrom([]string{to}, ctx.Doer.DisplayName(), setting.MailService.FromEmail, subject, mailBody.String())
 		msg.Info = fmt.Sprintf("Subject: %s, %s", subject, info)
 
 		// Set Message-ID on first message so replies know what to reference
-	if comment == nil {
-		msg.SetHeader("Message-ID", "<"+issue.ReplyReference()+">")
+		if ctx.Comment == nil {
+			msg.SetHeader("Message-ID", "<"+ctx.Issue.ReplyReference()+">")
 		} else {
-		msg.SetHeader("In-Reply-To", "<"+issue.ReplyReference()+">")
-		msg.SetHeader("References", "<"+issue.ReplyReference()+">")
+			msg.SetHeader("In-Reply-To", "<"+ctx.Issue.ReplyReference()+">")
+			msg.SetHeader("References", "<"+ctx.Issue.ReplyReference()+">")
+		}
+		msgs = append(msgs, msg)
 	}
 
-	return msg
+	return msgs
 }
 
 func sanitizeSubject(subject string) string {
@@ -269,21 +268,15 @@ func sanitizeSubject(subject string) string {
 	return mime.QEncoding.Encode("utf-8", string(runes))
 }
 
-// SendIssueCommentMail composes and sends issue comment emails to target receivers.
-func SendIssueCommentMail(issue *models.Issue, doer *models.User, actionType models.ActionType, content string, comment *models.Comment, tos []string) {
-	if len(tos) == 0 {
-		return
-	}
-
-	SendAsync(composeIssueCommentMessage(issue, doer, actionType, false, content, comment, tos, "issue comment"))
-}
-
-// SendIssueMentionMail composes and sends issue mention emails to target receivers.
-func SendIssueMentionMail(issue *models.Issue, doer *models.User, actionType models.ActionType, content string, comment *models.Comment, tos []string) {
-	if len(tos) == 0 {
-		return
-	}
-	SendAsync(composeIssueCommentMessage(issue, doer, actionType, true, content, comment, tos, "issue mention"))
+// SendIssueAssignedMail composes and sends issue assigned email
+func SendIssueAssignedMail(issue *models.Issue, doer *models.User, content string, comment *models.Comment, tos []string) {
+	SendAsyncs(composeIssueCommentMessages(&mailCommentContext{
+		Issue:      issue,
+		Doer:       doer,
+		ActionType: models.ActionType(0),
+		Content:    content,
+		Comment:    comment,
+	}, tos, false, "issue assigned"))
 }
 
 // actionToTemplate returns the type and name of the action facing the user
@@ -341,8 +334,3 @@ func actionToTemplate(issue *models.Issue, actionType models.ActionType,
 	}
 	return
 }
-
-// SendIssueAssignedMail composes and sends issue assigned email
-func SendIssueAssignedMail(issue *models.Issue, doer *models.User, content string, comment *models.Comment, tos []string) {
-	SendAsync(composeIssueCommentMessage(issue, doer, models.ActionType(0), false, content, comment, tos, "issue assigned"))
-}

services/mailer/mail_comment.go

@@ -27,11 +27,18 @@ func mailParticipantsComment(ctx models.DBContext, c *models.Comment, opType mod
 	if err = models.UpdateIssueMentions(ctx, c.IssueID, userMentions); err != nil {
 		return fmt.Errorf("UpdateIssueMentions [%d]: %v", c.IssueID, err)
 	}
-	mentions := make([]string, len(userMentions))
+	mentions := make([]int64, len(userMentions))
 	for i, u := range userMentions {
-		mentions[i] = u.LowerName
+		mentions[i] = u.ID
 	}
-	if err = mailIssueCommentToParticipants(issue, c.Poster, opType, c.Content, c, mentions); err != nil {
+	if err = mailIssueCommentToParticipants(
+		&mailCommentContext{
+			Issue:      issue,
+			Doer:       c.Poster,
+			ActionType: opType,
+			Content:    c.Content,
+			Comment:    c,
+		}, mentions); err != nil {
 		log.Error("mailIssueCommentToParticipants: %v", err)
 	}
 	return nil

services/mailer/mail_issue.go

@@ -10,105 +10,118 @@ import (
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/references"
-
-	"github.com/unknwon/com"
 )
 
 func fallbackMailSubject(issue *models.Issue) string {
 	return fmt.Sprintf("[%s] %s (#%d)", issue.Repo.FullName(), issue.Title, issue.Index)
 }
 
+type mailCommentContext struct {
+	Issue      *models.Issue
+	Doer       *models.User
+	ActionType models.ActionType
+	Content    string
+	Comment    *models.Comment
+}
+
 // mailIssueCommentToParticipants can be used for both new issue creation and comment.
 // This function sends two list of emails:
 // 1. Repository watchers and users who are participated in comments.
 // 2. Users who are not in 1. but get mentioned in current issue/comment.
-func mailIssueCommentToParticipants(issue *models.Issue, doer *models.User, actionType models.ActionType, content string, comment *models.Comment, mentions []string) error {
+func mailIssueCommentToParticipants(ctx *mailCommentContext, mentions []int64) error {
 
-	watchers, err := models.GetWatchers(issue.RepoID)
-	if err != nil {
-		return fmt.Errorf("getWatchers [repo_id: %d]: %v", issue.RepoID, err)
+	// Required by the mail composer; make sure to load these before calling the async function
+	if err := ctx.Issue.LoadRepo(); err != nil {
+		return fmt.Errorf("LoadRepo(): %v", err)
 	}
-	participants, err := models.GetParticipantsByIssueID(issue.ID)
-	if err != nil {
-		return fmt.Errorf("getParticipantsByIssueID [issue_id: %d]: %v", issue.ID, err)
+	if err := ctx.Issue.LoadPoster(); err != nil {
+		return fmt.Errorf("LoadPoster(): %v", err)
+	}
+	if err := ctx.Issue.LoadPullRequest(); err != nil {
+		return fmt.Errorf("LoadPullRequest(): %v", err)
 	}
 
-	// In case the issue poster is not watching the repository and is active,
-	// even if we have duplicated in watchers, can be safely filtered out.
-	err = issue.LoadPoster()
+	// Enough room to avoid reallocations
+	unfiltered := make([]int64, 1, 64)
+
+	// =========== Original poster ===========
+	unfiltered[0] = ctx.Issue.PosterID
+
+	// =========== Assignees ===========
+	ids, err := models.GetAssigneeIDsByIssue(ctx.Issue.ID)
 	if err != nil {
-		return fmt.Errorf("GetUserByID [%d]: %v", issue.PosterID, err)
+		return fmt.Errorf("GetAssigneeIDsByIssue(%d): %v", ctx.Issue.ID, err)
 	}
-	if issue.PosterID != doer.ID && issue.Poster.IsActive && !issue.Poster.ProhibitLogin {
-		participants = append(participants, issue.Poster)
+	unfiltered = append(unfiltered, ids...)
+
+	// =========== Participants (i.e. commenters, reviewers) ===========
+	ids, err = models.GetParticipantsIDsByIssueID(ctx.Issue.ID)
+	if err != nil {
+		return fmt.Errorf("GetParticipantsIDsByIssueID(%d): %v", ctx.Issue.ID, err)
+	}
+	unfiltered = append(unfiltered, ids...)
+
+	// =========== Issue watchers ===========
+	ids, err = models.GetIssueWatchersIDs(ctx.Issue.ID)
+	if err != nil {
+		return fmt.Errorf("GetIssueWatchersIDs(%d): %v", ctx.Issue.ID, err)
+	}
+	unfiltered = append(unfiltered, ids...)
+
+	// =========== Repo watchers ===========
+	// Make repo watchers last, since it's likely the list with the most users
+	ids, err = models.GetRepoWatchersIDs(ctx.Issue.RepoID)
+	if err != nil {
+		return fmt.Errorf("GetRepoWatchersIDs(%d): %v", ctx.Issue.RepoID, err)
+	}
+	unfiltered = append(ids, unfiltered...)
+
+	visited := make(map[int64]bool, len(unfiltered)+len(mentions)+1)
+
+	// Avoid mailing the doer
+	visited[ctx.Doer.ID] = true
+
+	if err = mailIssueCommentBatch(ctx, unfiltered, visited, false); err != nil {
+		return fmt.Errorf("mailIssueCommentBatch(): %v", err)
 	}
 
-	// Assignees must receive any communications
-	assignees, err := models.GetAssigneesByIssue(issue)
+	// =========== Mentions ===========
+	if err = mailIssueCommentBatch(ctx, mentions, visited, true); err != nil {
+		return fmt.Errorf("mailIssueCommentBatch() mentions: %v", err)
+	}
+
+	return nil
+}
+
+func mailIssueCommentBatch(ctx *mailCommentContext, ids []int64, visited map[int64]bool, fromMention bool) error {
+	const batchSize = 100
+	for i := 0; i < len(ids); i += batchSize {
+		var last int
+		if i+batchSize < len(ids) {
+			last = i + batchSize
+		} else {
+			last = len(ids)
+		}
+		unique := make([]int64, 0, last-i)
+		for j := i; j < last; j++ {
+			id := ids[j]
+			if _, ok := visited[id]; !ok {
+				unique = append(unique, id)
+				visited[id] = true
+			}
+		}
+		recipients, err := models.GetMaileableUsersByIDs(unique)
 		if err != nil {
 			return err
 		}
-
-	for _, assignee := range assignees {
-		if assignee.ID != doer.ID {
-			participants = append(participants, assignee)
+		// TODO: Check issue visibility for each user
+		// TODO: Separate recipients by language for i18n mail templates
+		tos := make([]string, len(recipients))
+		for i := range recipients {
+			tos[i] = recipients[i].Email
 		}
+		SendAsyncs(composeIssueCommentMessages(ctx, tos, fromMention, "issue comments"))
 	}
-
-	tos := make([]string, 0, len(watchers)) // List of email addresses.
-	names := make([]string, 0, len(watchers))
-	for i := range watchers {
-		if watchers[i].UserID == doer.ID {
-			continue
-		}
-
-		to, err := models.GetUserByID(watchers[i].UserID)
-		if err != nil {
-			return fmt.Errorf("GetUserByID [%d]: %v", watchers[i].UserID, err)
-		}
-		if to.IsOrganization() || to.EmailNotifications() != models.EmailNotificationsEnabled {
-			continue
-		}
-
-		tos = append(tos, to.Email)
-		names = append(names, to.Name)
-	}
-	for i := range participants {
-		if participants[i].ID == doer.ID ||
-			com.IsSliceContainsStr(names, participants[i].Name) ||
-			participants[i].EmailNotifications() != models.EmailNotificationsEnabled {
-			continue
-		}
-
-		tos = append(tos, participants[i].Email)
-		names = append(names, participants[i].Name)
-	}
-
-	if err := issue.LoadRepo(); err != nil {
-		return err
-	}
-
-	for _, to := range tos {
-		SendIssueCommentMail(issue, doer, actionType, content, comment, []string{to})
-	}
-
-	// Mail mentioned people and exclude watchers.
-	names = append(names, doer.Name)
-	tos = make([]string, 0, len(mentions)) // list of user names.
-	for i := range mentions {
-		if com.IsSliceContainsStr(names, mentions[i]) {
-			continue
-		}
-
-		tos = append(tos, mentions[i])
-	}
-
-	emails := models.GetUserEmailsByNames(tos)
-
-	for _, to := range emails {
-		SendIssueMentionMail(issue, doer, actionType, content, comment, []string{to})
-	}
-
 	return nil
 }
 
@@ -127,11 +140,18 @@ func mailParticipants(ctx models.DBContext, issue *models.Issue, doer *models.Us
 	if err = models.UpdateIssueMentions(ctx, issue.ID, userMentions); err != nil {
 		return fmt.Errorf("UpdateIssueMentions [%d]: %v", issue.ID, err)
 	}
-	mentions := make([]string, len(userMentions))
+	mentions := make([]int64, len(userMentions))
 	for i, u := range userMentions {
-		mentions[i] = u.LowerName
+		mentions[i] = u.ID
 	}
-	if err = mailIssueCommentToParticipants(issue, doer, opType, issue.Content, nil, mentions); err != nil {
+	if err = mailIssueCommentToParticipants(
+		&mailCommentContext{
+			Issue:      issue,
+			Doer:       doer,
+			ActionType: opType,
+			Content:    issue.Content,
+			Comment:    nil,
+		}, mentions); err != nil {
 		log.Error("mailIssueCommentToParticipants: %v", err)
 	}
 	return nil

services/mailer/mail_test.go

@@ -58,12 +58,16 @@ func TestComposeIssueCommentMessage(t *testing.T) {
 	InitMailRender(stpl, btpl)
 
 	tos := []string{"test@gitea.com", "test2@gitea.com"}
-	msg := composeIssueCommentMessage(issue, doer, models.ActionCommentIssue, false, "test body", comment, tos, "issue comment")
+	msgs := composeIssueCommentMessages(&mailCommentContext{Issue: issue, Doer: doer, ActionType: models.ActionCommentIssue,
+		Content: "test body", Comment: comment}, tos, false, "issue comment")
+	assert.Len(t, msgs, 2)
 
-	subject := msg.GetHeader("Subject")
-	inreplyTo := msg.GetHeader("In-Reply-To")
-	references := msg.GetHeader("References")
+	mailto := msgs[0].GetHeader("To")
+	subject := msgs[0].GetHeader("Subject")
+	inreplyTo := msgs[0].GetHeader("In-Reply-To")
+	references := msgs[0].GetHeader("References")
 
+	assert.Len(t, mailto, 1, "exactly one recipient is expected in the To field")
 	assert.Equal(t, "Re: ", subject[0][:4], "Comment reply subject should contain Re:")
 	assert.Equal(t, "Re: [user2/repo1] @user2 #1 - issue1", subject[0])
 	assert.Equal(t, inreplyTo[0], "<user2/repo1/issues/1@localhost>", "In-Reply-To header doesn't match")
@@ -88,14 +92,18 @@ func TestComposeIssueMessage(t *testing.T) {
 	InitMailRender(stpl, btpl)
 
 	tos := []string{"test@gitea.com", "test2@gitea.com"}
-	msg := composeIssueCommentMessage(issue, doer, models.ActionCreateIssue, false, "test body", nil, tos, "issue create")
+	msgs := composeIssueCommentMessages(&mailCommentContext{Issue: issue, Doer: doer, ActionType: models.ActionCreateIssue,
+		Content: "test body"}, tos, false, "issue create")
+	assert.Len(t, msgs, 2)
 
-	subject := msg.GetHeader("Subject")
-	messageID := msg.GetHeader("Message-ID")
+	mailto := msgs[0].GetHeader("To")
+	subject := msgs[0].GetHeader("Subject")
+	messageID := msgs[0].GetHeader("Message-ID")
 
+	assert.Len(t, mailto, 1, "exactly one recipient is expected in the To field")
 	assert.Equal(t, "[user2/repo1] @user2 #1 - issue1", subject[0])
-	assert.Nil(t, msg.GetHeader("In-Reply-To"))
-	assert.Nil(t, msg.GetHeader("References"))
+	assert.Nil(t, msgs[0].GetHeader("In-Reply-To"))
+	assert.Nil(t, msgs[0].GetHeader("References"))
 	assert.Equal(t, messageID[0], "<user2/repo1/issues/1@localhost>", "Message-ID header doesn't match")
 }
 
@@ -134,20 +142,24 @@ func TestTemplateSelection(t *testing.T) {
 		assert.Contains(t, wholemsg, expBody)
 	}
 
-	msg := composeIssueCommentMessage(issue, doer, models.ActionCreateIssue, false, "test body", nil, tos, "TestTemplateSelection")
+	msg := testComposeIssueCommentMessage(t, &mailCommentContext{Issue: issue, Doer: doer, ActionType: models.ActionCreateIssue,
+		Content: "test body"}, tos, false, "TestTemplateSelection")
 	expect(t, msg, "issue/new/subject", "issue/new/body")
 
 	comment := models.AssertExistsAndLoadBean(t, &models.Comment{ID: 2, Issue: issue}).(*models.Comment)
-	msg = composeIssueCommentMessage(issue, doer, models.ActionCommentIssue, false, "test body", comment, tos, "TestTemplateSelection")
+	msg = testComposeIssueCommentMessage(t, &mailCommentContext{Issue: issue, Doer: doer, ActionType: models.ActionCommentIssue,
+		Content: "test body", Comment: comment}, tos, false, "TestTemplateSelection")
 	expect(t, msg, "issue/default/subject", "issue/default/body")
 
 	pull := models.AssertExistsAndLoadBean(t, &models.Issue{ID: 2, Repo: repo, Poster: doer}).(*models.Issue)
 	comment = models.AssertExistsAndLoadBean(t, &models.Comment{ID: 4, Issue: pull}).(*models.Comment)
-	msg = composeIssueCommentMessage(pull, doer, models.ActionCommentIssue, false, "test body", comment, tos, "TestTemplateSelection")
+	msg = testComposeIssueCommentMessage(t, &mailCommentContext{Issue: pull, Doer: doer, ActionType: models.ActionCommentIssue,
+		Content: "test body", Comment: comment}, tos, false, "TestTemplateSelection")
 	expect(t, msg, "pull/comment/subject", "pull/comment/body")
 
-	msg = composeIssueCommentMessage(issue, doer, models.ActionCloseIssue, false, "test body", nil, tos, "TestTemplateSelection")
-	expect(t, msg, "[user2/repo1] issue1 (#1)", "issue/close/body")
+	msg = testComposeIssueCommentMessage(t, &mailCommentContext{Issue: issue, Doer: doer, ActionType: models.ActionCloseIssue,
+		Content: "test body", Comment: comment}, tos, false, "TestTemplateSelection")
+	expect(t, msg, "Re: [user2/repo1] issue1 (#1)", "issue/close/body")
 }
 
 func TestTemplateServices(t *testing.T) {
@@ -173,7 +185,8 @@ func TestTemplateServices(t *testing.T) {
 		InitMailRender(stpl, btpl)
 
 		tos := []string{"test@gitea.com"}
-		msg := composeIssueCommentMessage(issue, doer, actionType, fromMention, "test body", comment, tos, "TestTemplateServices")
+		msg := testComposeIssueCommentMessage(t, &mailCommentContext{Issue: issue, Doer: doer, ActionType: actionType,
+			Content: "test body", Comment: comment}, tos, fromMention, "TestTemplateServices")
 
 		subject := msg.GetHeader("Subject")
 		msgbuf := new(bytes.Buffer)
@@ -202,3 +215,9 @@ func TestTemplateServices(t *testing.T) {
 		"Re: [user2/repo1] issue1 (#1)",
 		"//Re: //")
 }
+
+func testComposeIssueCommentMessage(t *testing.T, ctx *mailCommentContext, tos []string, fromMention bool, info string) *Message {
+	msgs := composeIssueCommentMessages(ctx, tos, fromMention, info)
+	assert.Len(t, msgs, 1)
+	return msgs[0]
+}

services/mailer/mailer.go

@@ -295,9 +295,18 @@ func NewContext() {
 	go processMailQueue()
 }
 
-// SendAsync send mail asynchronous
+// SendAsync send mail asynchronously
 func SendAsync(msg *Message) {
 	go func() {
 		mailQueue <- msg
 	}()
 }
+
+// SendAsyncs send mails asynchronously
+func SendAsyncs(msgs []*Message) {
+	go func() {
+		for _, msg := range msgs {
+			mailQueue <- msg
+		}
+	}()
+}