diff options
Diffstat (limited to 'modules/cache/context.go')
| -rw-r--r-- | modules/cache/context.go | 179 |
1 files changed, 21 insertions, 158 deletions
diff --git a/modules/cache/context.go b/modules/cache/context.go index 484cee659a..23f7c23a52 100644 --- a/modules/cache/context.go +++ b/modules/cache/context.go @@ -5,176 +5,39 @@ package cache import ( "context" - "sync" "time" - - "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 { - data map[any]map[any]any - lock sync.RWMutex - created time.Time - discard bool -} - -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() - - if cc.discard { - return - } - - d := cc.data[tp] - if d == nil { - d = make(map[any]any) - cc.data[tp] = d - } - d[key] = value -} - -func (cc *cacheContext) Delete(tp, key any) { - cc.lock.Lock() - defer cc.lock.Unlock() - delete(cc.data[tp], key) -} - -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, 5 minutes is enough. -// If a cacheContext is used more than 5 minutes, it's probably misuse. -const cacheContextLifetime = 5 * time.Minute - -var timeNow = time.Now +type cacheContextKeyType struct{} -func (cc *cacheContext) Expired() bool { - return timeNow().Sub(cc.created) > cacheContextLifetime -} - -var cacheContextKey = struct{}{} - -/* -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. +var cacheContextKey = cacheContextKeyType{} -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. -*/ +// contextCacheLifetime is the max lifetime of context cache. +// Since context cache is used to cache data in a request level context, 5 minutes is enough. +// If a context cache is used more than 5 minutes, it's probably abused. +const contextCacheLifetime = 5 * time.Minute func WithCacheContext(ctx context.Context) context.Context { - if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok { - if !c.isDiscard() { - // reuse parent context - return ctx - } - } - // FIXME: review the use of this nolint directive - return context.WithValue(ctx, cacheContextKey, &cacheContext{ //nolint:staticcheck - data: make(map[any]map[any]any), - created: timeNow(), - }) -} - -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() + if c := GetContextCache(ctx); c != nil { return ctx } - - return ctx -} - -func GetContextData(ctx context.Context, tp, key any) any { - if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok { - 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, is highly likely to be misused for long-life tasks: %v", c) - return nil - } - return c.Get(tp, key) - } - return nil + return context.WithValue(ctx, cacheContextKey, NewEphemeralCache(contextCacheLifetime)) } -func SetContextData(ctx context.Context, tp, key, value any) { - if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok { - 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, is highly likely to be misused for long-life tasks: %v", c) - return - } - c.Put(tp, key, value) - return - } -} - -func RemoveContextData(ctx context.Context, tp, key any) { - if c, ok := ctx.Value(cacheContextKey).(*cacheContext); ok { - 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, is highly likely to be misused for long-life tasks: %v", c) - return - } - c.Delete(tp, key) - } +func GetContextCache(ctx context.Context) *EphemeralCache { + c, _ := ctx.Value(cacheContextKey).(*EphemeralCache) + return c } // 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 +// FIXME: in some cases, the "context cache" should not be used, because it has uncontrollable behaviors +// For example, these calls: +// * GetWithContextCache(TargetID) -> OtherCodeCreateModel(TargetID) -> GetWithContextCache(TargetID) +// Will cause the second call is not able to get the correct created target. +// UNLESS it is certain that the target won't be changed during the request, DO NOT use it. +func GetWithContextCache[T, K any](ctx context.Context, groupKey string, targetKey K, f func(context.Context, K) (T, error)) (T, error) { + if c := GetContextCache(ctx); c != nil { + return GetWithEphemeralCache(ctx, c, groupKey, targetKey, f) + } + return f(ctx, targetKey) } |