forgejo/modules/cache/context.go

180 lines
5 KiB
Go
Raw Permalink Normal View History

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 13:37:34 +00:00
// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package cache
import (
"context"
"sync"
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
"time"
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 13:37:34 +00:00
"code.gitea.io/gitea/modules/log"
)
// cacheContext is a context that can be used to cache data in a request level context
// This is useful for caching data that is expensive to calculate and is likely to be
// used multiple times in a request.
type cacheContext struct {
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
data map[any]map[any]any
lock sync.RWMutex
created time.Time
discard bool
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 13:37:34 +00:00
}
func (cc *cacheContext) Get(tp, key any) any {
cc.lock.RLock()
defer cc.lock.RUnlock()
return cc.data[tp][key]
}
func (cc *cacheContext) Put(tp, key, value any) {
cc.lock.Lock()
defer cc.lock.Unlock()
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
if cc.discard {
return
}
d := cc.data[tp]
if d == nil {
d = make(map[any]any)
cc.data[tp] = d
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 13:37:34 +00:00
}
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
d[key] = value
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 13:37:34 +00:00
}
func (cc *cacheContext) Delete(tp, key any) {
cc.lock.Lock()
defer cc.lock.Unlock()
delete(cc.data[tp], key)
}
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
func (cc *cacheContext) Discard() {
cc.lock.Lock()
defer cc.lock.Unlock()
cc.data = nil
cc.discard = true
}
func (cc *cacheContext) isDiscard() bool {
cc.lock.RLock()
defer cc.lock.RUnlock()
return cc.discard
}
// cacheContextLifetime is the max lifetime of cacheContext.
// Since cacheContext is used to cache data in a request level context, 10s is enough.
// If a cacheContext is used more than 10s, it's probably misuse.
const cacheContextLifetime = 10 * time.Second
var timeNow = time.Now
func (cc *cacheContext) Expired() bool {
return timeNow().Sub(cc.created) > cacheContextLifetime
}
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 13:37:34 +00:00
var cacheContextKey = struct{}{}
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
/*
Since there are both WithCacheContext and WithNoCacheContext,
it may be confusing when there is nesting.
Some cases to explain the design:
When:
- A, B or C means a cache context.
- A', B' or C' means a discard cache context.
- ctx means context.Backgrand().
- A(ctx) means a cache context with ctx as the parent context.
- B(A(ctx)) means a cache context with A(ctx) as the parent context.
- With is alias of WithCacheContext.
- WithNo is alias of WithNoCacheContext.
So:
- With(ctx) -> A(ctx)
- With(With(ctx)) -> A(ctx), not B(A(ctx)), always reuse parent cache context if possible.
- With(With(With(ctx))) -> A(ctx), not C(B(A(ctx))), ditto.
- WithNo(ctx) -> ctx, not A'(ctx), don't create new cache context if we don't have to.
- WithNo(With(ctx)) -> A'(ctx)
- WithNo(WithNo(With(ctx))) -> A'(ctx), not B'(A'(ctx)), don't create new cache context if we don't have to.
- With(WithNo(With(ctx))) -> B(A'(ctx)), not A(ctx), never reuse a discard cache context.
- WithNo(With(WithNo(With(ctx)))) -> B'(A'(ctx))
- With(WithNo(With(WithNo(With(ctx))))) -> C(B'(A'(ctx))), so there's always only one not-discard cache context.
*/
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 13:37:34 +00:00
func WithCacheContext(ctx context.Context) context.Context {
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok {
if !c.isDiscard() {
// reuse parent context
return ctx
}
}
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 13:37:34 +00:00
return context.WithValue(ctx, cacheContextKey, &cacheContext{
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
data: make(map[any]map[any]any),
created: timeNow(),
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 13:37:34 +00:00
})
}
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
func WithNoCacheContext(ctx context.Context) context.Context {
if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok {
// The caller want to run long-life tasks, but the parent context is a cache context.
// So we should disable and clean the cache data, or it will be kept in memory for a long time.
c.Discard()
return ctx
}
return ctx
}
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 13:37:34 +00:00
func GetContextData(ctx context.Context, tp, key any) any {
if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok {
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
if c.Expired() {
// The warning means that the cache context is misused for long-life task,
// it can be resolved with WithNoCacheContext(ctx).
log.Warn("cache context is expired, may be misused for long-life tasks: %v", c)
return nil
}
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 13:37:34 +00:00
return c.Get(tp, key)
}
return nil
}
func SetContextData(ctx context.Context, tp, key, value any) {
if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok {
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
if c.Expired() {
// The warning means that the cache context is misused for long-life task,
// it can be resolved with WithNoCacheContext(ctx).
log.Warn("cache context is expired, may be misused for long-life tasks: %v", c)
return
}
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 13:37:34 +00:00
c.Put(tp, key, value)
return
}
}
func RemoveContextData(ctx context.Context, tp, key any) {
if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok {
Improve cache context (#23330) Related to: #22294 #23186 #23054 Replace: #23218 Some discussion is in the comments of #23218. Highlights: - Add Expiration for cache context. If a cache context has been used for more than 10s, the cache data will be ignored, and warning logs will be printed. - Add `discard` field to `cacheContext`, a `cacheContext` with `discard` true will drop all cached data and won't store any new one. - Introduce `WithNoCacheContext`, if one wants to run long-life tasks, but the parent context is a cache context, `WithNoCacheContext(perentCtx)` will discard the cache data, so it will be safe to keep the context for a long time. - It will be fine to treat an original context as a cache context, like `GetContextData(context.Backgraud())`, no warning logs will be printed. Some cases about nesting: When: - *A*, *B* or *C* means a cache context. - ~*A*~, ~*B*~ or ~*C*~ means a discard cache context. - `ctx` means `context.Backgrand()` - *A(ctx)* means a cache context with `ctx` as the parent context. - *B(A(ctx))* means a cache context with `A(ctx)` as the parent context. - `With` means `WithCacheContext` - `WithNo` means `WithNoCacheContext` So: - `With(ctx)` -> *A(ctx)* - `With(With(ctx))` -> *A(ctx)*, not *B(A(ctx))* - `With(With(With(ctx)))` -> *A(ctx)*, not *C(B(A(ctx)))* - `WithNo(ctx)` -> *ctx*, not *~A~(ctx)* - `WithNo(With(ctx))` -> *~A~(ctx)* - `WithNo(WithNo(With(ctx)))` -> *~A~(ctx)*, not *~B~(~A~(ctx))* - `With(WithNo(With(ctx)))` -> *B(~A~(ctx))* - `WithNo(With(WithNo(With(ctx))))` -> *~B~(~A~(ctx))* - `With(WithNo(With(WithNo(With(ctx)))))` -> *C(~B~(~A~(ctx)))*
2023-03-08 17:57:05 +00:00
if c.Expired() {
// The warning means that the cache context is misused for long-life task,
// it can be resolved with WithNoCacheContext(ctx).
log.Warn("cache context is expired, may be misused for long-life tasks: %v", c)
return
}
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 13:37:34 +00:00
c.Delete(tp, key)
}
}
// GetWithContextCache returns the cache value of the given key in the given context.
func GetWithContextCache[T any](ctx context.Context, cacheGroupKey string, cacheTargetID any, f func() (T, error)) (T, error) {
v := GetContextData(ctx, cacheGroupKey, cacheTargetID)
if vv, ok := v.(T); ok {
return vv, nil
}
t, err := f()
if err != nil {
return t, err
}
SetContextData(ctx, cacheGroupKey, cacheTargetID, t)
return t, nil
}