cache

type Cache interface {
	Bytes(context.Context, schema.Digest) ([]byte, error)
	Blob(schema.Digest) (io.ReadCloser, error) // XXX No context is required here to make it simpler for Compressed() to call Blob().

	WriteBlob(context.Context, schema.Digest, io.ReadCloser) error
	WriteBytes(context.Context, schema.Digest, []byte) error

	LoadEntry(context.Context, schema.Digest) (CachedOutput, bool, error)
	StoreEntry(context.Context, []schema.Digest, CachedOutput) error
}

type CachedOutput struct {
	Digest       schema.Digest
	Timestamp    time.Time
	CacheVersion int
	InputDigests map[string]string

	Debug struct {
		Serial                int64
		PackagePath, Typename string
	}
}