type BlobCache interface {
	// Add returns a writer to add contents to cache
	Add(key string, opts ...Option) (Writer, error)

	// Get returns a reader to read the specified contents
	// from cache
	Get(key string, opts ...Option) (Reader, error)

	// Close closes the cache
	Close() error
}

type DirectoryCacheConfig struct {

	// Number of entries of LRU cache (default: 10).
	// This won't be used when DataCache is specified.
	MaxLRUCacheEntry int

	// Number of file descriptors to cache (default: 10).
	// This won't be used when FdCache is specified.
	MaxCacheFds int

	// On Add, wait until the data is fully written to the cache directory.
	SyncAdd bool

	// DataCache is an on-memory cache of the data.
	// OnEvicted will be overridden and replaced for internal use.
	DataCache *cacheutil.LRUCache

	// FdCache is a cache for opened file descriptors.
	// OnEvicted will be overridden and replaced for internal use.
	FdCache *cacheutil.LRUCache

	// BufPool will be used for pooling bytes.Buffer.
	BufPool *sync.Pool

	// Direct forcefully enables direct mode for all operation in cache.
	// Thus operation won't use on-memory caches.
	Direct bool
}

type MemoryCache struct {
	Membuf map[string]*bytes.Buffer
	// contains filtered or unexported fields
}

type Option func(o *cacheOpt) *cacheOpt

type Reader interface {
	io.ReaderAt
	Close() error
}

type Writer interface {
	io.WriteCloser
	Commit() error
	Abort() error
}