Hands-On Software Engineering with Golang

Iterating links/edges

To obtain an iterator for the graph links or edges, users need to invoke the Links or Edges methods. Let's take a look at how the Links method is implemented:

func (s *InMemoryGraph) Links(fromID, toID uuid.UUID, retrievedBefore time.Time) (graph.LinkIterator, error) {
    from, to := fromID.String(), toID.String()

    s.mu.RLock()
    var list []*graph.Link
    for linkID, link := range s.links {
        if id := linkID.String(); id >= from && id < to && link.RetrievedAt.Before(retrievedBefore) {
            list = append(list, link)
        }
    }
    s.mu.RUnlock()

    return &linkIterator{s: s, links: list}, nil
}

In the preceding implementation, we obtain a read lock and then proceed to iterate all the links in the graph, searching for the ones that belong to the