[dpdk-dev] [PATCH v4 05/29] graph: implement internal graph operation helpers

[Jerin Jacob]

On Tue, Apr 7, 2020 at 5:46 PM Andrzej Ostruszka <amo at semihalf.com> wrote:

> > +int
> > +graph_bfs(struct graph *graph, struct graph_node *start)
> > +{
> > +     struct graph_node **queue, *v, *tmp;
> > +     uint16_t head = 0, tail = 0;
> > +     rte_edge_t i;
> > +     size_t sz;
> > +
> > +     sz = sizeof(struct graph_node *) * graph_nodes_count(graph);
> > +     queue = malloc(sz);
> > +     if (queue == NULL)
> > +             SET_ERR_JMP(ENOMEM, fail, "Failed to alloc BFS queue of %zu",
> > +                         sz);
> > +
> > +     /* BFS algorithm */
> > +     queue[tail++] = start;
> > +     start->visited = true;
> > +     while (head != tail) {
> > +             v = queue[head++];
> > +             for (i = 0; i < v->node->nb_edges; i++) {
> > +                     tmp = v->adjacency_list[i];
> > +                     if (tmp->visited == false) {
> > +                             queue[tail++] = tmp;
> > +                             tmp->visited = true;
> > +                     }
> > +             }
> > +     }
> > +
> > +     free(queue);
> > +     return 0;
> > +
> > +fail:
> > +     return -rte_errno;
> > +}
>
> What is the purpose of this function?  It looks like just marking as
> visited.  Then maybe change the name to graph_mark_bfs() or something
> like that.

graph_ops.c has all generic graph-related functions.
BFS(Breadth-First Search) is a generic graph operation. The primitive
can be used for various other graph operations.
IMO, It is better to avoid connecting with a marking using case in the
function name.


>
> > +
> > +/* Check whether a node has connected path or parent node */
> > +int
> > +graph_has_isolated_node(struct graph *graph)
> > +{
> > +     struct graph_node *graph_node;
> > +
> > +     graph_mark_nodes_as_not_visited(graph);

See below,

> > +
> > +     STAILQ_FOREACH(graph_node, &graph->node_list, next) {
> > +             if (graph_node->node->flags & RTE_NODE_SOURCE_F) {
> > +                     if (graph_node->node->nb_edges == 0)
> > +                             SET_ERR_JMP(EINVAL, fail,
> > +                                         "%s node needs minimum one edge",
> > +                                         graph_node->node->name);
> > +                     if (graph_bfs(graph, graph_node))
> > +                             goto fail;
> > +             }
> > +     }
> > +
> > +     STAILQ_FOREACH(graph_node, &graph->node_list, next)
> > +             if (graph_node->visited == false)
> > +                     SET_ERR_JMP(EINVAL, fail, "Found isolated node %s",
> > +                                 graph_node->node->name);> +
> > +     return 0;
>
> You don't want to clear visited because it will not be used or cleared
> on next call?

See above graph_mark_nodes_as_not_visited() function.

>
> With regards
> Andrzej Ostruszka