Avoid re-issuing redundant cross-references. (#8734)

* Avoid re-issuing redundant cross-references.

* Remove unused func; fix lint

* Simplify code as suggested by @laftriks

* Update test

4 files changed, 56 insertions, 31 deletions

diff --git a/models/issue.go b/models/issue.go
index 0113f0a404..e28e7c01c3 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -722,11 +722,7 @@ func (issue *Issue) ChangeTitle(doer *User, oldTitle string) (err error) {
 		return fmt.Errorf("createComment: %v", err)
 	}
 
-	if err = issue.neuterCrossReferences(sess); err != nil {
-		return err
-	}
-
-	if err = issue.addCrossReferences(sess, doer); err != nil {
+	if err = issue.addCrossReferences(sess, doer, true); err != nil {
 		return err
 	}
 
@@ -790,10 +786,8 @@ func (issue *Issue) ChangeContent(doer *User, content string) (err error) {
 	if err = updateIssueCols(sess, issue, "content"); err != nil {
 		return fmt.Errorf("UpdateIssueCols: %v", err)
 	}
-	if err = issue.neuterCrossReferences(sess); err != nil {
-		return err
-	}
-	if err = issue.addCrossReferences(sess, doer); err != nil {
+
+	if err = issue.addCrossReferences(sess, doer, true); err != nil {
 		return err
 	}
 
@@ -944,7 +938,7 @@ func newIssue(e *xorm.Session, doer *User, opts NewIssueOptions) (err error) {
 	if err = opts.Issue.loadAttributes(e); err != nil {
 		return err
 	}
-	return opts.Issue.addCrossReferences(e, doer)
+	return opts.Issue.addCrossReferences(e, doer, false)
 }
 
 // NewIssue creates new issue with labels for repository.
@@ -1578,13 +1572,10 @@ func UpdateIssue(issue *Issue) error {
 	if err := updateIssue(sess, issue); err != nil {
 		return err
 	}
-	if err := issue.neuterCrossReferences(sess); err != nil {
-		return err
-	}
 	if err := issue.loadPoster(sess); err != nil {
 		return err
 	}
-	if err := issue.addCrossReferences(sess, issue.Poster); err != nil {
+	if err := issue.addCrossReferences(sess, issue.Poster, true); err != nil {
 		return err
 	}
 	return sess.Commit()
diff --git a/models/issue_comment.go b/models/issue_comment.go
index 7ac8c4df43..73fd9c8c83 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -545,7 +545,7 @@ func createComment(e *xorm.Session, opts *CreateCommentOptions) (_ *Comment, err
 		}
 	}
 
-	if err = comment.addCrossReferences(e, opts.Doer); err != nil {
+	if err = comment.addCrossReferences(e, opts.Doer, false); err != nil {
 		return nil, err
 	}
 
@@ -882,10 +882,7 @@ func UpdateComment(c *Comment, doer *User) error {
 	if err := c.loadIssue(sess); err != nil {
 		return err
 	}
-	if err := c.neuterCrossReferences(sess); err != nil {
-		return err
-	}
-	if err := c.addCrossReferences(sess, doer); err != nil {
+	if err := c.addCrossReferences(sess, doer, true); err != nil {
 		return err
 	}
 	if err := sess.Commit(); err != nil {
diff --git a/models/issue_xref.go b/models/issue_xref.go
index f41c154753..9f30aba259 100644
--- a/models/issue_xref.go
+++ b/models/issue_xref.go
@@ -25,20 +25,30 @@ type crossReferencesContext struct {
 	Doer        *User
 	OrigIssue   *Issue
 	OrigComment *Comment
+	RemoveOld   bool
 }
 
-func neuterCrossReferences(e Engine, issueID int64, commentID int64) error {
+func findOldCrossReferences(e Engine, issueID int64, commentID int64) ([]*Comment, error) {
 	active := make([]*Comment, 0, 10)
-	sess := e.Where("`ref_action` IN (?, ?, ?)", references.XRefActionNone, references.XRefActionCloses, references.XRefActionReopens).
+	return active, e.Where("`ref_action` IN (?, ?, ?)", references.XRefActionNone, references.XRefActionCloses, references.XRefActionReopens).
 		And("`ref_issue_id` = ?", issueID).
-		And("`ref_comment_id` = ?", commentID)
-	if err := sess.Find(&active); err != nil || len(active) == 0 {
+		And("`ref_comment_id` = ?", commentID).
+		Find(&active)
+}
+
+func neuterCrossReferences(e Engine, issueID int64, commentID int64) error {
+	active, err := findOldCrossReferences(e, issueID, commentID)
+	if err != nil {
 		return err
 	}
 	ids := make([]int64, len(active))
 	for i, c := range active {
 		ids[i] = c.ID
 	}
+	return neuterCrossReferencesIds(e, ids)
+}
+
+func neuterCrossReferencesIds(e Engine, ids []int64) error {
 	_, err := e.In("id", ids).Cols("`ref_action`").Update(&Comment{RefAction: references.XRefActionNeutered})
 	return err
 }
@@ -51,7 +61,7 @@ func neuterCrossReferences(e Engine, issueID int64, commentID int64) error {
 //          \/     \/            \/
 //
 
-func (issue *Issue) addCrossReferences(e *xorm.Session, doer *User) error {
+func (issue *Issue) addCrossReferences(e *xorm.Session, doer *User, removeOld bool) error {
 	var commentType CommentType
 	if issue.IsPull {
 		commentType = CommentTypePullRef
@@ -62,6 +72,7 @@ func (issue *Issue) addCrossReferences(e *xorm.Session, doer *User) error {
 		Type:      commentType,
 		Doer:      doer,
 		OrigIssue: issue,
+		RemoveOld: removeOld,
 	}
 	return issue.createCrossReferences(e, ctx, issue.Title, issue.Content)
 }
@@ -71,6 +82,35 @@ func (issue *Issue) createCrossReferences(e *xorm.Session, ctx *crossReferencesC
 	if err != nil {
 		return err
 	}
+	if ctx.RemoveOld {
+		var commentID int64
+		if ctx.OrigComment != nil {
+			commentID = ctx.OrigComment.ID
+		}
+		active, err := findOldCrossReferences(e, ctx.OrigIssue.ID, commentID)
+		if err != nil {
+			return err
+		}
+		ids := make([]int64, 0, len(active))
+		for _, c := range active {
+			found := false
+			for i, x := range xreflist {
+				if x.Issue.ID == c.IssueID && x.Action == c.RefAction {
+					found = true
+					xreflist = append(xreflist[:i], xreflist[i+1:]...)
+					break
+				}
+			}
+			if !found {
+				ids = append(ids, c.ID)
+			}
+		}
+		if len(ids) > 0 {
+			if err = neuterCrossReferencesIds(e, ids); err != nil {
+				return err
+			}
+		}
+	}
 	for _, xref := range xreflist {
 		var refCommentID int64
 		if ctx.OrigComment != nil {
@@ -193,10 +233,6 @@ func (issue *Issue) verifyReferencedIssue(e Engine, ctx *crossReferencesContext,
 	return refIssue, refAction, nil
 }
 
-func (issue *Issue) neuterCrossReferences(e Engine) error {
-	return neuterCrossReferences(e, issue.ID, 0)
-}
-
 // _________                                       __
 // \_   ___ \  ____   _____   _____   ____   _____/  |_
 // /    \  \/ /  _ \ /     \ /     \_/ __ \ /    \   __\
@@ -205,7 +241,7 @@ func (issue *Issue) neuterCrossReferences(e Engine) error {
 //         \/             \/      \/     \/     \/
 //
 
-func (comment *Comment) addCrossReferences(e *xorm.Session, doer *User) error {
+func (comment *Comment) addCrossReferences(e *xorm.Session, doer *User, removeOld bool) error {
 	if comment.Type != CommentTypeCode && comment.Type != CommentTypeComment {
 		return nil
 	}
@@ -217,6 +253,7 @@ func (comment *Comment) addCrossReferences(e *xorm.Session, doer *User) error {
 		Doer:        doer,
 		OrigIssue:   comment.Issue,
 		OrigComment: comment,
+		RemoveOld:   removeOld,
 	}
 	return comment.Issue.createCrossReferences(e, ctx, "", comment.Content)
 }
diff --git a/models/issue_xref_test.go b/models/issue_xref_test.go
index 4fc6011d78..c13577e905 100644
--- a/models/issue_xref_test.go
+++ b/models/issue_xref_test.go
@@ -133,7 +133,7 @@ func testCreateIssue(t *testing.T, repo, doer int64, title, content string, ispu
 	assert.NoError(t, err)
 	i, err = getIssueByID(sess, i.ID)
 	assert.NoError(t, err)
-	assert.NoError(t, i.addCrossReferences(sess, d))
+	assert.NoError(t, i.addCrossReferences(sess, d, false))
 	assert.NoError(t, sess.Commit())
 	return i
 }
@@ -158,7 +158,7 @@ func testCreateComment(t *testing.T, repo, doer, issue int64, content string) *C
 	assert.NoError(t, sess.Begin())
 	_, err := sess.Insert(c)
 	assert.NoError(t, err)
-	assert.NoError(t, c.addCrossReferences(sess, d))
+	assert.NoError(t, c.addCrossReferences(sess, d, false))
 	assert.NoError(t, sess.Commit())
 	return c
 }