cache

type Entry struct {
	// StatusCode is the HTTP status code of the cached response.
	StatusCode int
	// Payload is the serialised response body.
	Payload []byte
	// Header contains the response headers as stored at cache time.
	Header http.Header
	// CreatedAt is the wall-clock time at which this entry was stored.
	CreatedAt time.Time
	// TTL is the freshness lifetime of the entry.
	TTL time.Duration
	// StaleWhileRevalidate is the window after TTL expiry during which a stale
	// response may be served while a background revalidation is in flight.
	StaleWhileRevalidate time.Duration
	// ETag is the entity tag from the upstream response, used for conditional
	// revalidation (If-None-Match).
	ETag string
	// LastModified is the Last-Modified value from the upstream response, used
	// for conditional revalidation (If-Modified-Since).
	LastModified string
	// VaryHeaders lists the request header names captured from the original
	// request that were used to derive the cache key, matching the upstream
	// Vary response header.
	VaryHeaders []string
	// CorrectedInitialAge is the age correction term defined in RFC 9111 §4.2.3.
	// When zero, setAgeHeader falls back to the legacy elapsed-time formula.
	CorrectedInitialAge time.Duration
	// ResponseTime is the local time at which the upstream response was received,
	// used together with CorrectedInitialAge for RFC 9111 §4.2.3 age calculation.
	ResponseTime time.Time
	// StaleIfError extends the hard-expiry retention window so the entry remains
	// retrievable during upstream error periods (RFC 5861 stale-if-error).
	StaleIfError time.Duration
}

type L2Client interface {
	Get(ctx context.Context, key string) (string, error)
	SetWithExpire(ctx context.Context, key string, value string, expire time.Duration) error
	Expire(ctx context.Context, key string, d time.Duration) (int64, error)
	Del(ctx context.Context, key string) (int64, error)
}

type L2Storage struct {
	// contains filtered or unexported fields
}

type LRUStorage struct {
	// contains filtered or unexported fields
}

type Options struct {
	MaxBytes   int64            // maximum number of bytes the in-process LRU (L1) is allowed to hold across all cached entries
	ListenAddr string           // Skipper's own address; revalidation requests loop back through it so the full filter chain runs
	NetOpts    skpnet.Options   // HTTP client options for background worker that re-fetches stale entries from origin
	L2Client   L2Client         // optional L2 cache; nil = in-process LRU only
	IsNoL2Err  func(error) bool // returns true if no L2Client error
	L1TTL      time.Duration    // max TTL for write-through L1 warming; 0 = write-around
	Metrics    metrics.Metrics  // nil defaults to metrics.Default
}

type ShardedByteLRU struct {
	// contains filtered or unexported fields
}

type Storage interface {
	// Get returns the entry for key, or (nil, nil) if the key is not found.
	Get(ctx context.Context, key string) (*Entry, error)

	// Set stores or overwrites the entry for key.
	Set(ctx context.Context, key string, entry *Entry) error

	// Delete removes the entry for key. It is not an error if the key does not exist.
	Delete(ctx context.Context, key string) error
}