identity_export.go

type UserID int64

func export(customerID string) map[UserID]UserID {
    graph := fetchGraph(customerID)
    for src, _ := range graph {
        find(graph, src) // Since this function mutates the graph, we don't need to store the results separately
    }
    return graph
}

func fetchGraph(customerID string) map[UserID]UserID {
    graph := queryUsersDB("SELECT src, dest FROM edges WHERE customer_id = ?", customerID)
    ...
    return ...
}

// find returns the set identifier for a given source, mutating the graph with path compression
func find(graph map[UserID]UserID, source UserID) UserID {
    // Find the root, recording all elements in the path along the way
    path := make([]UserID)
    current := source
    for _, ok := graph[current]; ok {
        path = append(path, current)
        current = graph[current]
    }

    // Path compression - point all elements in path directly to the root
    if current != source {
        for _, elem := range path {
            graph[elem] = current
        }
    }

    // Return root
    return current
}