remotecache

type Adapter interface {
	// CacheIdentity returns the engine cache's identity and generation.
	CacheIdentity() (cacheID string, generation uint64)
	// Export captures the requested roots and calls consume exactly once,
	// while the captured chains stay open. The export's Bundle is nil when no
	// root survived. The chains are released when consume returns.
	Export(ctx context.Context, req protocol.Export, consume func(context.Context, Export) error) error
	// Merge merges a bundle of the service's values into the cache.
	Merge(ctx context.Context, req protocol.Merge) (protocol.Merged, error)
	// OfferParts places offered parts on the cache's entries by number.
	OfferParts(ctx context.Context, req protocol.Offer) (protocol.Offered, error)
	// TakeRenewalRequest waits for the next read that needs fresh download
	// addresses; ReplyRenewal answers it.
	TakeRenewalRequest(ctx context.Context) (*dagql.RenewalRequest, error)
	ReplyRenewal(dagql.RenewalReply) dagql.RenewalReplyDisposition
}

type BlobSource interface {
	ReadBlob(ctx context.Context, dgst digest.Digest) (io.ReadCloser, int64, error)
}

type Config struct {
	// URL is the service's base URL; Run dials protocol.EnginePath under it.
	URL string
	// Token is the engine token, sent as the Basic username.
	Token string
	// EngineVersion and EngineName are sent in hello.
	EngineVersion string
	EngineName    string
	// Logger receives the connection's warnings and errors. Nil discards.
	Logger *slog.Logger
}

type Export struct {
	// Bundle is nil when no root survived.
	Bundle  *dagql.ValueBundle
	Skipped []protocol.SkippedRoot
	// Blobs reads the bundle's layer blobs for upload.
	Blobs BlobSource
}