Add context cache as a request level cache (#22294)

To avoid duplicated load of the same data in an HTTP request, we can set
a context cache to do that. i.e. Some pages may load a user from a
database with the same id in different areas on the same page. But the
code is hidden in two different deep logic. How should we share the
user? As a result of this PR, now if both entry functions accept
`context.Context` as the first parameter and we just need to refactor
`GetUserByID` to reuse the user from the context cache. Then it will not
be loaded twice on an HTTP request.

But of course, sometimes we would like to reload an object from the
database, that's why `RemoveContextData` is also exposed.

The core context cache is here. It defines a new context
```go
type cacheContext struct {
	ctx  context.Context
	data map[any]map[any]any
        lock sync.RWMutex
}

var cacheContextKey = struct{}{}

func WithCacheContext(ctx context.Context) context.Context {
	return context.WithValue(ctx, cacheContextKey, &cacheContext{
		ctx:  ctx,
		data: make(map[any]map[any]any),
	})
}
```

Then you can use the below 4 methods to read/write/del the data within
the same context.

```go
func GetContextData(ctx context.Context, tp, key any) any
func SetContextData(ctx context.Context, tp, key, value any)
func RemoveContextData(ctx context.Context, tp, key any)
func GetWithContextCache[T any](ctx context.Context, cacheGroupKey string, cacheTargetID any, f func() (T, error)) (T, error)
```

Then let's take a look at how `system.GetString` implement it.

```go
func GetSetting(ctx context.Context, key string) (string, error) {
	return cache.GetWithContextCache(ctx, contextCacheKey, key, func() (string, error) {
		return cache.GetString(genSettingCacheKey(key), func() (string, error) {
			res, err := GetSettingNoCache(ctx, key)
			if err != nil {
				return "", err
			}
			return res.SettingValue, nil
		})
	})
}
```

First, it will check if context data include the setting object with the
key. If not, it will query from the global cache which may be memory or
a Redis cache. If not, it will get the object from the database. In the
end, if the object gets from the global cache or database, it will be
set into the context cache.

An object stored in the context cache will only be destroyed after the
context disappeared.

cmd/admin_user_delete.go

@@ -57,7 +57,7 @@ func runDeleteUser(c *cli.Context) error {
 	var err error
 	var user *user_model.User
 	if c.IsSet("email") {
-		user, err = user_model.GetUserByEmail(c.String("email"))
+		user, err = user_model.GetUserByEmail(ctx, c.String("email"))
 	} else if c.IsSet("username") {
 		user, err = user_model.GetUserByName(ctx, c.String("username"))
 	} else {

models/activities/repo_activity.go

@@ -97,12 +97,12 @@ func GetActivityStatsTopAuthors(ctx context.Context, repo *repo_model.Repository
 	}
 	users := make(map[int64]*ActivityAuthorData)
 	var unknownUserID int64
-	unknownUserAvatarLink := user_model.NewGhostUser().AvatarLink()
+	unknownUserAvatarLink := user_model.NewGhostUser().AvatarLink(ctx)
 	for _, v := range code.Authors {
 		if len(v.Email) == 0 {
 			continue
 		}
-		u, err := user_model.GetUserByEmail(v.Email)
+		u, err := user_model.GetUserByEmail(ctx, v.Email)
 		if u == nil || user_model.IsErrUserNotExist(err) {
 			unknownUserID--
 			users[unknownUserID] = &ActivityAuthorData{
@@ -119,7 +119,7 @@ func GetActivityStatsTopAuthors(ctx context.Context, repo *repo_model.Repository
 			users[u.ID] = &ActivityAuthorData{
 				Name:       u.DisplayName(),
 				Login:      u.LowerName,
-				AvatarLink: u.AvatarLink(),
+				AvatarLink: u.AvatarLink(ctx),
 				HomeLink:   u.HomeLink(),
 				Commits:    v.Commits,
 			}

models/asymkey/gpg_key_commit_verification.go

@@ -4,6 +4,7 @@
 package asymkey
 
 import (
+	"context"
 	"fmt"
 	"hash"
 	"strings"
@@ -70,14 +71,14 @@ const (
 )
 
 // ParseCommitsWithSignature checks if signaute of commits are corresponding to users gpg keys.
-func ParseCommitsWithSignature(oldCommits []*user_model.UserCommit, repoTrustModel repo_model.TrustModelType, isOwnerMemberCollaborator func(*user_model.User) (bool, error)) []*SignCommit {
+func ParseCommitsWithSignature(ctx context.Context, oldCommits []*user_model.UserCommit, repoTrustModel repo_model.TrustModelType, isOwnerMemberCollaborator func(*user_model.User) (bool, error)) []*SignCommit {
 	newCommits := make([]*SignCommit, 0, len(oldCommits))
 	keyMap := map[string]bool{}
 
 	for _, c := range oldCommits {
 		signCommit := &SignCommit{
 			UserCommit:   c,
-			Verification: ParseCommitWithSignature(c.Commit),
+			Verification: ParseCommitWithSignature(ctx, c.Commit),
 		}
 
 		_ = CalculateTrustStatus(signCommit.Verification, repoTrustModel, isOwnerMemberCollaborator, &keyMap)
@@ -88,13 +89,13 @@ func ParseCommitsWithSignature(oldCommits []*user_model.UserCommit, repoTrustMod
 }
 
 // ParseCommitWithSignature check if signature is good against keystore.
-func ParseCommitWithSignature(c *git.Commit) *CommitVerification {
+func ParseCommitWithSignature(ctx context.Context, c *git.Commit) *CommitVerification {
 	var committer *user_model.User
 	if c.Committer != nil {
 		var err error
 		// Find Committer account
-		committer, err = user_model.GetUserByEmail(c.Committer.Email) // This finds the user by primary email or activated email so commit will not be valid if email is not
-		if err != nil {                                               // Skipping not user for committer
+		committer, err = user_model.GetUserByEmail(ctx, c.Committer.Email) // This finds the user by primary email or activated email so commit will not be valid if email is not
+		if err != nil {                                                    // Skipping not user for committer
 			committer = &user_model.User{
 				Name:  c.Committer.Name,
 				Email: c.Committer.Email,

models/avatars/avatar.go

@@ -147,13 +147,13 @@ func generateRecognizedAvatarURL(u url.URL, size int) string {
 // generateEmailAvatarLink returns a email avatar link.
 // if final is true, it may use a slow path (eg: query DNS).
 // if final is false, it always uses a fast path.
-func generateEmailAvatarLink(email string, size int, final bool) string {
+func generateEmailAvatarLink(ctx context.Context, email string, size int, final bool) string {
 	email = strings.TrimSpace(email)
 	if email == "" {
 		return DefaultAvatarLink()
 	}
 
-	enableFederatedAvatar := system_model.GetSettingBool(system_model.KeyPictureEnableFederatedAvatar)
+	enableFederatedAvatar := system_model.GetSettingBool(ctx, system_model.KeyPictureEnableFederatedAvatar)
 
 	var err error
 	if enableFederatedAvatar && system_model.LibravatarService != nil {
@@ -174,7 +174,7 @@ func generateEmailAvatarLink(email string, size int, final bool) string {
 		return urlStr
 	}
 
-	disableGravatar := system_model.GetSettingBool(system_model.KeyPictureDisableGravatar)
+	disableGravatar := system_model.GetSettingBool(ctx, system_model.KeyPictureDisableGravatar)
 	if !disableGravatar {
 		// copy GravatarSourceURL, because we will modify its Path.
 		avatarURLCopy := *system_model.GravatarSourceURL
@@ -186,11 +186,11 @@ func generateEmailAvatarLink(email string, size int, final bool) string {
 }
 
 // GenerateEmailAvatarFastLink returns a avatar link (fast, the link may be a delegated one: "/avatar/${hash}")
-func GenerateEmailAvatarFastLink(email string, size int) string {
-	return generateEmailAvatarLink(email, size, false)
+func GenerateEmailAvatarFastLink(ctx context.Context, email string, size int) string {
+	return generateEmailAvatarLink(ctx, email, size, false)
 }
 
 // GenerateEmailAvatarFinalLink returns a avatar final link (maybe slow)
-func GenerateEmailAvatarFinalLink(email string, size int) string {
-	return generateEmailAvatarLink(email, size, true)
+func GenerateEmailAvatarFinalLink(ctx context.Context, email string, size int) string {
+	return generateEmailAvatarLink(ctx, email, size, true)
 }

models/avatars/avatar_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	avatars_model "code.gitea.io/gitea/models/avatars"
+	"code.gitea.io/gitea/models/db"
 	system_model "code.gitea.io/gitea/models/system"
 	"code.gitea.io/gitea/modules/setting"
 
@@ -16,15 +17,15 @@ import (
 const gravatarSource = "https://secure.gravatar.com/avatar/"
 
 func disableGravatar(t *testing.T) {
-	err := system_model.SetSettingNoVersion(system_model.KeyPictureEnableFederatedAvatar, "false")
+	err := system_model.SetSettingNoVersion(db.DefaultContext, system_model.KeyPictureEnableFederatedAvatar, "false")
 	assert.NoError(t, err)
-	err = system_model.SetSettingNoVersion(system_model.KeyPictureDisableGravatar, "true")
+	err = system_model.SetSettingNoVersion(db.DefaultContext, system_model.KeyPictureDisableGravatar, "true")
 	assert.NoError(t, err)
 	system_model.LibravatarService = nil
 }
 
 func enableGravatar(t *testing.T) {
-	err := system_model.SetSettingNoVersion(system_model.KeyPictureDisableGravatar, "false")
+	err := system_model.SetSettingNoVersion(db.DefaultContext, system_model.KeyPictureDisableGravatar, "false")
 	assert.NoError(t, err)
 	setting.GravatarSource = gravatarSource
 	err = system_model.Init()
@@ -47,11 +48,11 @@ func TestSizedAvatarLink(t *testing.T) {
 
 	disableGravatar(t)
 	assert.Equal(t, "/testsuburl/assets/img/avatar_default.png",
-		avatars_model.GenerateEmailAvatarFastLink("[email protected]", 100))
+		avatars_model.GenerateEmailAvatarFastLink(db.DefaultContext, "[email protected]", 100))
 
 	enableGravatar(t)
 	assert.Equal(t,
 		"https://secure.gravatar.com/avatar/353cbad9b58e69c96154ad99f92bedc7?d=identicon&s=100",
-		avatars_model.GenerateEmailAvatarFastLink("[email protected]", 100),
+		avatars_model.GenerateEmailAvatarFastLink(db.DefaultContext, "[email protected]", 100),
 	)
 }

models/git/commit_status.go

@@ -351,7 +351,8 @@ func hashCommitStatusContext(context string) string {
 func ConvertFromGitCommit(ctx context.Context, commits []*git.Commit, repo *repo_model.Repository) []*SignCommitWithStatuses {
 	return ParseCommitsWithStatus(ctx,
 		asymkey_model.ParseCommitsWithSignature(
-			user_model.ValidateCommitsWithEmails(commits),
+			ctx,
+			user_model.ValidateCommitsWithEmails(ctx, commits),
 			repo.GetTrustModel(),
 			func(user *user_model.User) (bool, error) {
 				return repo_model.IsOwnerMemberCollaborator(repo, user.ID)

models/organization/org.go

@@ -156,8 +156,8 @@ func (org *Organization) hasMemberWithUserID(ctx context.Context, userID int64)
 }
 
 // AvatarLink returns the full avatar link with http host
-func (org *Organization) AvatarLink() string {
-	return org.AsUser().AvatarLink()
+func (org *Organization) AvatarLink(ctx context.Context) string {
+	return org.AsUser().AvatarLink(ctx)
 }
 
 // HTMLURL returns the organization's full link.

models/repo/avatar.go

@@ -85,12 +85,7 @@ func (repo *Repository) relAvatarLink(ctx context.Context) string {
 }
 
 // AvatarLink returns a link to the repository's avatar.
-func (repo *Repository) AvatarLink() string {
-	return repo.avatarLink(db.DefaultContext)
-}
-
-// avatarLink returns user avatar absolute link.
-func (repo *Repository) avatarLink(ctx context.Context) string {
+func (repo *Repository) AvatarLink(ctx context.Context) string {
 	link := repo.relAvatarLink(ctx)
 	// we only prepend our AppURL to our known (relative, internal) avatar link to get an absolute URL
 	if strings.HasPrefix(link, "/") && !strings.HasPrefix(link, "//") {

models/system/setting.go

@@ -80,8 +80,8 @@ func IsErrDataExpired(err error) bool {
 }
 
 // GetSettingNoCache returns specific setting without using the cache
-func GetSettingNoCache(key string) (*Setting, error) {
-	v, err := GetSettings([]string{key})
+func GetSettingNoCache(ctx context.Context, key string) (*Setting, error) {
+	v, err := GetSettings(ctx, []string{key})
 	if err != nil {
 		return nil, err
 	}
@@ -91,27 +91,31 @@ func GetSettingNoCache(key string) (*Setting, error) {
 	return v[strings.ToLower(key)], nil
 }
 
+const contextCacheKey = "system_setting"
+
 // GetSetting returns the setting value via the key
-func GetSetting(key string) (string, error) {
-	return cache.GetString(genSettingCacheKey(key), func() (string, error) {
-		res, err := GetSettingNoCache(key)
-		if err != nil {
-			return "", err
-		}
-		return res.SettingValue, nil
+func GetSetting(ctx context.Context, key string) (string, error) {
+	return cache.GetWithContextCache(ctx, contextCacheKey, key, func() (string, error) {
+		return cache.GetString(genSettingCacheKey(key), func() (string, error) {
+			res, err := GetSettingNoCache(ctx, key)
+			if err != nil {
+				return "", err
+			}
+			return res.SettingValue, nil
+		})
 	})
 }
 
 // GetSettingBool return bool value of setting,
 // none existing keys and errors are ignored and result in false
-func GetSettingBool(key string) bool {
-	s, _ := GetSetting(key)
+func GetSettingBool(ctx context.Context, key string) bool {
+	s, _ := GetSetting(ctx, key)
 	v, _ := strconv.ParseBool(s)
 	return v
 }
 
 // GetSettings returns specific settings
-func GetSettings(keys []string) (map[string]*Setting, error) {
+func GetSettings(ctx context.Context, keys []string) (map[string]*Setting, error) {
 	for i := 0; i < len(keys); i++ {
 		keys[i] = strings.ToLower(keys[i])
 	}
@@ -161,16 +165,17 @@ func GetAllSettings() (AllSettings, error) {
 }
 
 // DeleteSetting deletes a specific setting for a user
-func DeleteSetting(setting *Setting) error {
+func DeleteSetting(ctx context.Context, setting *Setting) error {
+	cache.RemoveContextData(ctx, contextCacheKey, setting.SettingKey)
 	cache.Remove(genSettingCacheKey(setting.SettingKey))
 	_, err := db.GetEngine(db.DefaultContext).Delete(setting)
 	return err
 }
 
-func SetSettingNoVersion(key, value string) error {
-	s, err := GetSettingNoCache(key)
+func SetSettingNoVersion(ctx context.Context, key, value string) error {
+	s, err := GetSettingNoCache(ctx, key)
 	if IsErrSettingIsNotExist(err) {
-		return SetSetting(&Setting{
+		return SetSetting(ctx, &Setting{
 			SettingKey:   key,
 			SettingValue: value,
 		})
@@ -179,11 +184,11 @@ func SetSettingNoVersion(key, value string) error {
 		return err
 	}
 	s.SettingValue = value
-	return SetSetting(s)
+	return SetSetting(ctx, s)
 }
 
 // SetSetting updates a users' setting for a specific key
-func SetSetting(setting *Setting) error {
+func SetSetting(ctx context.Context, setting *Setting) error {
 	if err := upsertSettingValue(strings.ToLower(setting.SettingKey), setting.SettingValue, setting.Version); err != nil {
 		return err
 	}
@@ -192,9 +197,11 @@ func SetSetting(setting *Setting) error {
 
 	cc := cache.GetCache()
 	if cc != nil {
-		return cc.Put(genSettingCacheKey(setting.SettingKey), setting.SettingValue, setting_module.CacheService.TTLSeconds())
+		if err := cc.Put(genSettingCacheKey(setting.SettingKey), setting.SettingValue, setting_module.CacheService.TTLSeconds()); err != nil {
+			return err
+		}
 	}
-
+	cache.SetContextData(ctx, contextCacheKey, setting.SettingKey, setting.SettingValue)
 	return nil
 }
 
@@ -244,7 +251,7 @@ var (
 
 func Init() error {
 	var disableGravatar bool
-	disableGravatarSetting, err := GetSettingNoCache(KeyPictureDisableGravatar)
+	disableGravatarSetting, err := GetSettingNoCache(db.DefaultContext, KeyPictureDisableGravatar)
 	if IsErrSettingIsNotExist(err) {
 		disableGravatar = setting_module.GetDefaultDisableGravatar()
 		disableGravatarSetting = &Setting{SettingValue: strconv.FormatBool(disableGravatar)}
@@ -255,7 +262,7 @@ func Init() error {
 	}
 
 	var enableFederatedAvatar bool
-	enableFederatedAvatarSetting, err := GetSettingNoCache(KeyPictureEnableFederatedAvatar)
+	enableFederatedAvatarSetting, err := GetSettingNoCache(db.DefaultContext, KeyPictureEnableFederatedAvatar)
 	if IsErrSettingIsNotExist(err) {
 		enableFederatedAvatar = setting_module.GetDefaultEnableFederatedAvatar(disableGravatar)
 		enableFederatedAvatarSetting = &Setting{SettingValue: strconv.FormatBool(enableFederatedAvatar)}
@@ -268,13 +275,13 @@ func Init() error {
 	if setting_module.OfflineMode {
 		disableGravatar = true
 		enableFederatedAvatar = false
-		if !GetSettingBool(KeyPictureDisableGravatar) {
-			if err := SetSettingNoVersion(KeyPictureDisableGravatar, "true"); err != nil {
+		if !GetSettingBool(db.DefaultContext, KeyPictureDisableGravatar) {
+			if err := SetSettingNoVersion(db.DefaultContext, KeyPictureDisableGravatar, "true"); err != nil {
 				return fmt.Errorf("Failed to set setting %q: %w", KeyPictureDisableGravatar, err)
 			}
 		}
-		if GetSettingBool(KeyPictureEnableFederatedAvatar) {
-			if err := SetSettingNoVersion(KeyPictureEnableFederatedAvatar, "false"); err != nil {
+		if GetSettingBool(db.DefaultContext, KeyPictureEnableFederatedAvatar) {
+			if err := SetSettingNoVersion(db.DefaultContext, KeyPictureEnableFederatedAvatar, "false"); err != nil {
 				return fmt.Errorf("Failed to set setting %q: %w", KeyPictureEnableFederatedAvatar, err)
 			}
 		}

models/system/setting_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"testing"
 
+	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/models/system"
 	"code.gitea.io/gitea/models/unittest"
 
@@ -20,24 +21,24 @@ func TestSettings(t *testing.T) {
 	newSetting := &system.Setting{SettingKey: keyName, SettingValue: "50"}
 
 	// create setting
-	err := system.SetSetting(newSetting)
+	err := system.SetSetting(db.DefaultContext, newSetting)
 	assert.NoError(t, err)
 	// test about saving unchanged values
-	err = system.SetSetting(newSetting)
+	err = system.SetSetting(db.DefaultContext, newSetting)
 	assert.NoError(t, err)
 
 	// get specific setting
-	settings, err := system.GetSettings([]string{keyName})
+	settings, err := system.GetSettings(db.DefaultContext, []string{keyName})
 	assert.NoError(t, err)
 	assert.Len(t, settings, 1)
 	assert.EqualValues(t, newSetting.SettingValue, settings[strings.ToLower(keyName)].SettingValue)
 
 	// updated setting
 	updatedSetting := &system.Setting{SettingKey: keyName, SettingValue: "100", Version: settings[strings.ToLower(keyName)].Version}
-	err = system.SetSetting(updatedSetting)
+	err = system.SetSetting(db.DefaultContext, updatedSetting)
 	assert.NoError(t, err)
 
-	value, err := system.GetSetting(keyName)
+	value, err := system.GetSetting(db.DefaultContext, keyName)
 	assert.NoError(t, err)
 	assert.EqualValues(t, updatedSetting.SettingValue, value)
 
@@ -48,7 +49,7 @@ func TestSettings(t *testing.T) {
 	assert.EqualValues(t, updatedSetting.SettingValue, settings[strings.ToLower(updatedSetting.SettingKey)].SettingValue)
 
 	// delete setting
-	err = system.DeleteSetting(&system.Setting{SettingKey: strings.ToLower(keyName)})
+	err = system.DeleteSetting(db.DefaultContext, &system.Setting{SettingKey: strings.ToLower(keyName)})
 	assert.NoError(t, err)
 	settings, err = system.GetAllSettings()
 	assert.NoError(t, err)