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forgejo/models/repo/avatar.go
Lunny Xiao bd820aa9c5
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.
2023-02-15 21:37:34 +08:00

96 lines
2.9 KiB
Go

// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package repo
import (
"context"
"fmt"
"image/png"
"io"
"net/url"
"strings"
"code.gitea.io/gitea/models/db"
"code.gitea.io/gitea/modules/avatar"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/storage"
)
// CustomAvatarRelativePath returns repository custom avatar file path.
func (repo *Repository) CustomAvatarRelativePath() string {
return repo.Avatar
}
// ExistsWithAvatarAtStoragePath returns true if there is a user with this Avatar
func ExistsWithAvatarAtStoragePath(ctx context.Context, storagePath string) (bool, error) {
// See func (repo *Repository) CustomAvatarRelativePath()
// repo.Avatar is used directly as the storage path - therefore we can check for existence directly using the path
return db.GetEngine(ctx).Where("`avatar`=?", storagePath).Exist(new(Repository))
}
// RelAvatarLink returns a relative link to the repository's avatar.
func (repo *Repository) RelAvatarLink() string {
return repo.relAvatarLink(db.DefaultContext)
}
// generateRandomAvatar generates a random avatar for repository.
func generateRandomAvatar(ctx context.Context, repo *Repository) error {
idToString := fmt.Sprintf("%d", repo.ID)
seed := idToString
img, err := avatar.RandomImage([]byte(seed))
if err != nil {
return fmt.Errorf("RandomImage: %w", err)
}
repo.Avatar = idToString
if err := storage.SaveFrom(storage.RepoAvatars, repo.CustomAvatarRelativePath(), func(w io.Writer) error {
if err := png.Encode(w, img); err != nil {
log.Error("Encode: %v", err)
}
return err
}); err != nil {
return fmt.Errorf("Failed to create dir %s: %w", repo.CustomAvatarRelativePath(), err)
}
log.Info("New random avatar created for repository: %d", repo.ID)
if _, err := db.GetEngine(ctx).ID(repo.ID).Cols("avatar").NoAutoTime().Update(repo); err != nil {
return err
}
return nil
}
func (repo *Repository) relAvatarLink(ctx context.Context) string {
// If no avatar - path is empty
avatarPath := repo.CustomAvatarRelativePath()
if len(avatarPath) == 0 {
switch mode := setting.RepoAvatar.Fallback; mode {
case "image":
return setting.RepoAvatar.FallbackImage
case "random":
if err := generateRandomAvatar(ctx, repo); err != nil {
log.Error("generateRandomAvatar: %v", err)
}
default:
// default behaviour: do not display avatar
return ""
}
}
return setting.AppSubURL + "/repo-avatars/" + url.PathEscape(repo.Avatar)
}
// AvatarLink returns a link to the repository's avatar.
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, "//") {
return setting.AppURL + strings.TrimPrefix(link, setting.AppSubURL)[1:]
}
// otherwise, return the link as it is
return link
}