Fix context cache bug & enable context cache for dashabord commits' authors (#26991)

Unfortunately, when a system setting hasn't been stored in the database,
it cannot be cached.
Meanwhile, this PR also uses context cache for push email avatar display
which should avoid to read user table via email address again and again.

According to my local test, this should reduce dashboard elapsed time
from 150ms -> 80ms .

2 files changed, 21 insertions, 45 deletions

diff --git a/modules/repository/commits.go b/modules/repository/commits.go
index 96844d5b1d..ede60429a1 100644
--- a/modules/repository/commits.go
+++ b/modules/repository/commits.go
@@ -11,6 +11,7 @@ import (
 
 	"code.gitea.io/gitea/models/avatars"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
@@ -34,42 +35,36 @@ type PushCommits struct {
 	HeadCommit *PushCommit
 	CompareURL string
 	Len        int
-
-	avatars    map[string]string
-	emailUsers map[string]*user_model.User
 }
 
 // NewPushCommits creates a new PushCommits object.
 func NewPushCommits() *PushCommits {
-	return &PushCommits{
-		avatars:    make(map[string]string),
-		emailUsers: make(map[string]*user_model.User),
-	}
+	return &PushCommits{}
 }
 
 // toAPIPayloadCommit converts a single PushCommit to an api.PayloadCommit object.
-func (pc *PushCommits) toAPIPayloadCommit(ctx context.Context, repoPath, repoLink string, commit *PushCommit) (*api.PayloadCommit, error) {
+func (pc *PushCommits) toAPIPayloadCommit(ctx context.Context, emailUsers map[string]*user_model.User, repoPath, repoLink string, commit *PushCommit) (*api.PayloadCommit, error) {
 	var err error
 	authorUsername := ""
-	author, ok := pc.emailUsers[commit.AuthorEmail]
+	author, ok := emailUsers[commit.AuthorEmail]
 	if !ok {
 		author, err = user_model.GetUserByEmail(ctx, commit.AuthorEmail)
 		if err == nil {
 			authorUsername = author.Name
-			pc.emailUsers[commit.AuthorEmail] = author
+			emailUsers[commit.AuthorEmail] = author
 		}
 	} else {
 		authorUsername = author.Name
 	}
 
 	committerUsername := ""
-	committer, ok := pc.emailUsers[commit.CommitterEmail]
+	committer, ok := emailUsers[commit.CommitterEmail]
 	if !ok {
 		committer, err = user_model.GetUserByEmail(ctx, commit.CommitterEmail)
 		if err == nil {
 			// TODO: check errors other than email not found.
 			committerUsername = committer.Name
-			pc.emailUsers[commit.CommitterEmail] = committer
+			emailUsers[commit.CommitterEmail] = committer
 		}
 	} else {
 		committerUsername = committer.Name
@@ -107,11 +102,10 @@ func (pc *PushCommits) ToAPIPayloadCommits(ctx context.Context, repoPath, repoLi
 	commits := make([]*api.PayloadCommit, len(pc.Commits))
 	var headCommit *api.PayloadCommit
 
-	if pc.emailUsers == nil {
-		pc.emailUsers = make(map[string]*user_model.User)
-	}
+	emailUsers := make(map[string]*user_model.User)
+
 	for i, commit := range pc.Commits {
-		apiCommit, err := pc.toAPIPayloadCommit(ctx, repoPath, repoLink, commit)
+		apiCommit, err := pc.toAPIPayloadCommit(ctx, emailUsers, repoPath, repoLink, commit)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -123,7 +117,7 @@ func (pc *PushCommits) ToAPIPayloadCommits(ctx context.Context, repoPath, repoLi
 	}
 	if pc.HeadCommit != nil && headCommit == nil {
 		var err error
-		headCommit, err = pc.toAPIPayloadCommit(ctx, repoPath, repoLink, pc.HeadCommit)
+		headCommit, err = pc.toAPIPayloadCommit(ctx, emailUsers, repoPath, repoLink, pc.HeadCommit)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -134,35 +128,21 @@ func (pc *PushCommits) ToAPIPayloadCommits(ctx context.Context, repoPath, repoLi
 // AvatarLink tries to match user in database with e-mail
 // in order to show custom avatar, and falls back to general avatar link.
 func (pc *PushCommits) AvatarLink(ctx context.Context, email string) string {
-	if pc.avatars == nil {
-		pc.avatars = make(map[string]string)
-	}
-	avatar, ok := pc.avatars[email]
-	if ok {
-		return avatar
-	}
-
 	size := avatars.DefaultAvatarPixelSize * setting.Avatar.RenderedSizeFactor
 
-	u, ok := pc.emailUsers[email]
-	if !ok {
-		var err error
-		u, err = user_model.GetUserByEmail(ctx, email)
+	v, _ := cache.GetWithContextCache(ctx, "push_commits", email, func() (string, error) {
+		u, err := user_model.GetUserByEmail(ctx, email)
 		if err != nil {
-			pc.avatars[email] = avatars.GenerateEmailAvatarFastLink(ctx, email, size)
 			if !user_model.IsErrUserNotExist(err) {
 				log.Error("GetUserByEmail: %v", err)
-				return ""
+				return "", err
 			}
-		} else {
-			pc.emailUsers[email] = u
+			return avatars.GenerateEmailAvatarFastLink(ctx, email, size), nil
 		}
-	}
-	if u != nil {
-		pc.avatars[email] = u.AvatarLinkWithSize(ctx, size)
-	}
+		return u.AvatarLinkWithSize(ctx, size), nil
+	})
 
-	return pc.avatars[email]
+	return v
 }
 
 // CommitToPushCommit transforms a git.Commit to PushCommit type.
@@ -189,7 +169,5 @@ func GitToPushCommits(gitCommits []*git.Commit) *PushCommits {
 		HeadCommit: nil,
 		CompareURL: "",
 		Len:        len(commits),
-		avatars:    make(map[string]string),
-		emailUsers: make(map[string]*user_model.User),
 	}
 }
diff --git a/modules/repository/commits_test.go b/modules/repository/commits_test.go
index b6ad967d4c..0931092597 100644
--- a/modules/repository/commits_test.go
+++ b/modules/repository/commits_test.go
@@ -103,11 +103,9 @@ func TestPushCommits_ToAPIPayloadCommits(t *testing.T) {
 	assert.EqualValues(t, []string{"readme.md"}, headCommit.Modified)
 }
 
-func enableGravatar(t *testing.T) {
-	err := system_model.SetSettingNoVersion(db.DefaultContext, system_model.KeyPictureDisableGravatar, "false")
-	assert.NoError(t, err)
+func initGravatarSource(t *testing.T) {
 	setting.GravatarSource = "https://secure.gravatar.com/avatar"
-	err = system_model.Init(db.DefaultContext)
+	err := system_model.Init(db.DefaultContext)
 	assert.NoError(t, err)
 }
 
@@ -134,7 +132,7 @@ func TestPushCommits_AvatarLink(t *testing.T) {
 		},
 	}
 
-	enableGravatar(t)
+	initGravatarSource(t)
 
 	assert.Equal(t,
 		"https://secure.gravatar.com/avatar/ab53a2911ddf9b4817ac01ddcd3d975f?d=identicon&s="+strconv.Itoa(28*setting.Avatar.RenderedSizeFactor),