Hands-On Software Engineering with Golang

Removing stale edges

The last bit of functionality that we need to explore is the RemoveStaleEdges method. The caller invokes it with the ID of a link (the origin) and an updatedBefore value:

func (s *InMemoryGraph) RemoveStaleEdges(fromID uuid.UUID, updatedBefore time.Time) error {
    s.mu.Lock()
    defer s.mu.Unlock()

    var newEdgeList edgeList
    for _, edgeID := range s.linkEdgeMap[fromID] {
        edge := s.edges[edgeID]
        if edge.UpdatedAt.Before(updatedBefore) {
            delete(s.edges, edgeID)
            continue
        }
        newEdgeList = append(newEdgeList, edgeID)
    }
    s.linkEdgeMap[fromID] = newEdgeList
    return nil
}

As with other operations that mutate the graph's contents, we need to acquire a write lock. Then, we iterate the list of edges that originate from the specified source ...