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mirror of https://github.com/go-gitea/gitea synced 2025-07-22 18:28:37 +00:00

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.
This commit is contained in:
Lunny Xiao
2023-02-15 21:37:34 +08:00
committed by GitHub
parent 03638f9725
commit bd820aa9c5
150 changed files with 663 additions and 516 deletions

View File

@@ -4,6 +4,8 @@
package convert
import (
"context"
"code.gitea.io/gitea/models/perm"
user_model "code.gitea.io/gitea/models/user"
api "code.gitea.io/gitea/modules/structs"
@@ -11,7 +13,7 @@ import (
// ToUser convert user_model.User to api.User
// if doer is set, private information is added if the doer has the permission to see it
func ToUser(user, doer *user_model.User) *api.User {
func ToUser(ctx context.Context, user, doer *user_model.User) *api.User {
if user == nil {
return nil
}
@@ -21,36 +23,36 @@ func ToUser(user, doer *user_model.User) *api.User {
signed = true
authed = doer.ID == user.ID || doer.IsAdmin
}
return toUser(user, signed, authed)
return toUser(ctx, user, signed, authed)
}
// ToUsers convert list of user_model.User to list of api.User
func ToUsers(doer *user_model.User, users []*user_model.User) []*api.User {
func ToUsers(ctx context.Context, doer *user_model.User, users []*user_model.User) []*api.User {
result := make([]*api.User, len(users))
for i := range users {
result[i] = ToUser(users[i], doer)
result[i] = ToUser(ctx, users[i], doer)
}
return result
}
// ToUserWithAccessMode convert user_model.User to api.User
// AccessMode is not none show add some more information
func ToUserWithAccessMode(user *user_model.User, accessMode perm.AccessMode) *api.User {
func ToUserWithAccessMode(ctx context.Context, user *user_model.User, accessMode perm.AccessMode) *api.User {
if user == nil {
return nil
}
return toUser(user, accessMode != perm.AccessModeNone, false)
return toUser(ctx, user, accessMode != perm.AccessModeNone, false)
}
// toUser convert user_model.User to api.User
// signed shall only be set if requester is logged in. authed shall only be set if user is site admin or user himself
func toUser(user *user_model.User, signed, authed bool) *api.User {
func toUser(ctx context.Context, user *user_model.User, signed, authed bool) *api.User {
result := &api.User{
ID: user.ID,
UserName: user.Name,
FullName: user.FullName,
Email: user.GetEmail(),
AvatarURL: user.AvatarLink(),
AvatarURL: user.AvatarLink(ctx),
Created: user.CreatedUnix.AsTime(),
Restricted: user.IsRestricted,
Location: user.Location,
@@ -97,9 +99,9 @@ func User2UserSettings(user *user_model.User) api.UserSettings {
}
// ToUserAndPermission return User and its collaboration permission for a repository
func ToUserAndPermission(user, doer *user_model.User, accessMode perm.AccessMode) api.RepoCollaboratorPermission {
func ToUserAndPermission(ctx context.Context, user, doer *user_model.User, accessMode perm.AccessMode) api.RepoCollaboratorPermission {
return api.RepoCollaboratorPermission{
User: ToUser(user, doer),
User: ToUser(ctx, user, doer),
Permission: accessMode.String(),
RoleName: accessMode.String(),
}