stored_requests

type Cache interface {
	// Get works much like Fetcher.FetchRequests, with a few exceptions:
	//
	// 1. Any (actionable) errors should be logged by the implementation, rather than returned.
	// 2. The returned maps _may_ be written to.
	// 3. The returned maps must _not_ contain keys unless they were present in the argument ID list.
	// 4. Callers _should not_ assume that the returned maps contain key for every argument id.
	//    The returned map will miss entries for keys which don't exist in the cache.
	//
	// Nil slices and empty strings are treated as "no ops". That is, a nil requestID will always produce a nil
	// "stored request data" in the response.
	Get(ctx context.Context, requestIDs []string, impIDs []string) (requestData map[string]json.RawMessage, impData map[string]json.RawMessage)

	// Invalidate will ensure that all values associated with the given IDs
	// are no longer returned by the cache until new values are saved via Update
	Invalidate(ctx context.Context, requestIDs []string, impIDs []string)

	// Save will add or overwrite the data in the cache at the given keys
	Save(ctx context.Context, requestData map[string]json.RawMessage, impData map[string]json.RawMessage)
}

type ComposedCache []Cache

type Fetcher interface {
	// FetchRequests fetches the stored requests for the given IDs.
	//
	// The first return value will be the Stored Request data, or nil if it doesn't exist.
	// If requestID is an empty string, then this value will always be nil.
	//
	// The second return value will be a map from Stored Imp data. It will have a key for every ID
	// in the impIDs list, unless errors exist.
	//
	// The returned objects can only be read from. They may not be written to.
	FetchRequests(ctx context.Context, requestIDs []string, impIDs []string) (requestData map[string]json.RawMessage, impData map[string]json.RawMessage, errs []error)
}

type MultiFetcher []Fetcher

type NotFoundError struct {
	ID       string
	DataType string
}