Documentation
¶
Overview ¶
Package cache is a key-value cache with a time to live: a Store (in memory by default), typed helpers, an HTTP response cache interceptor and Wrap to cache a function.
dygo.Module{Imports: []*dygo.Module{cache.Module(cache.Options{TTL: time.Minute})}}
u, err := cache.GetOrSet(ctx, c, "user:"+id, 0, func(ctx context.Context) (*User, error) {
return s.repo.Find(ctx, id)
})
r.Get("/products", dygo.Handle(c.List), cache.TTL(30*time.Second))
r = r.Use(dygo.Interceptors(dygo.Ref[*cache.Interceptor]()))
Values are stored as JSON, so every store (memory, Redis) behaves the same.
Index ¶
- func Get[T any](ctx context.Context, c *Cache, key string) (T, bool, error)
- func GetOrSet[T any](ctx context.Context, c *Cache, key string, ttl time.Duration, ...) (T, error)
- func Key(k string) dygo.RouteOption
- func Module(o Options) *dygo.Module
- func NoCache() dygo.RouteOption
- func Set(ctx context.Context, c *Cache, key string, v any, ttl time.Duration) error
- func TTL(d time.Duration) dygo.RouteOption
- func Wrap[K comparable, V any](c *Cache, prefix string, ttl time.Duration, ...) func(ctx context.Context, k K) (V, error)
- type Cache
- type Interceptor
- type Memory
- type Options
- type Store
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GetOrSet ¶
func GetOrSet[T any](ctx context.Context, c *Cache, key string, ttl time.Duration, fn func(ctx context.Context) (T, error)) (T, error)
GetOrSet returns the cached value of key, or calls fn, stores its result and returns it. Concurrent callers for the same missing key share one fn call. An error from fn is returned and not cached.
func Key ¶
func Key(k string) dygo.RouteOption
Key sets a fixed cache key for a route, like @CacheKey. By default the key is the request path with its query.
func Module ¶
Module provides *Cache and the HTTP *Interceptor. It is global; import it once in the root module.
func TTL ¶
func TTL(d time.Duration) dygo.RouteOption
TTL sets the time to live of a route's cached responses, like @CacheTTL.
func Wrap ¶
func Wrap[K comparable, V any](c *Cache, prefix string, ttl time.Duration, fn func(ctx context.Context, k K) (V, error)) func(ctx context.Context, k K) (V, error)
Wrap returns fn with its results cached under prefix + ":" + the argument (formatted with %v), for ttl (0 is the default TTL). Go cannot implement an interface at runtime, so caching a service means a small decorator that keeps the wrapped functions:
type cachedUsers struct {
Users
byID func(context.Context, string) (*User, error)
}
func (u cachedUsers) ByID(ctx context.Context, id string) (*User, error) { return u.byID(ctx, id) }
func NewCachedUsers(u *UserService, c *cache.Cache) Users {
return cachedUsers{Users: u, byID: cache.Wrap(c, "user", time.Minute, u.ByID)}
}
Types ¶
type Cache ¶
type Cache struct {
// contains filtered or unexported fields
}
Cache reads and writes JSON values in a Store.
type Interceptor ¶
type Interceptor struct {
// contains filtered or unexported fields
}
Interceptor caches the results of GET routes. It caches JSON results, strings and byte slices, not Responders (streams, files, SSE) or NoContent; headers set by the handler are not cached. Other methods and transports pass through. A JSON result is encoded once: the interceptor returns it as dygo.RawJSON, on a hit and on a miss, so interceptors outside it see the encoded bytes.
func NewInterceptor ¶
func NewInterceptor(c *Cache) *Interceptor
NewInterceptor returns the interceptor for c.
func (*Interceptor) Intercept ¶
func (i *Interceptor) Intercept(ec dygo.ExecutionContext, next dygo.CallHandler) (any, error)
Intercept implements dygo.Interceptor.
type Memory ¶
type Memory struct {
// contains filtered or unexported fields
}
Memory is an in-process Store that keeps at most a fixed number of entries and evicts the least recently used one when full. Expired entries are removed when read or evicted.
type Options ¶
type Store ¶
type Store interface {
Get(ctx context.Context, key string) (val []byte, ok bool, err error)
Set(ctx context.Context, key string, val []byte, ttl time.Duration) error
Delete(ctx context.Context, key string) error
}
Store keeps raw values. Implementations must be safe for concurrent use. Get returns ok false for a missing or expired key.
Source Files