Commit fcf906ec authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Add a function to compute fraction of nodes (by weighted bw) with descriptors

parent 42c4418b

src/or/routerlist.c

+42 −4
Original line number Diff line number Diff line
@@ -1706,8 +1706,8 @@ smartlist_choose_node_by_bandwidth_weights(const smartlist_t *sl, 
/** Given a list of routers and a weighting rule as in

 * smartlist_choose_node_by_bandwidth_weights, compute weighted bandwidth

 * values for each node and store them in a freshly allocated

 * *<b>bandwidths_out</b> of the same length as <b>sl</b>. Return 0 on

 * success, -1 on failure. */

 * *<b>bandwidths_out</b> of the same length as <b>sl</b>, and holding results

 * as doubles. Return 0 on success, -1 on failure. */

static int

compute_weighted_bandwidths(const smartlist_t *sl,

                            bandwidth_weight_rule_t rule,
@@ -1859,6 +1859,44 @@ compute_weighted_bandwidths(const smartlist_t *sl, 
  return 0;

}



/** For all nodes in <b>sl</b>, return the fraction of those nodes, weighted

 * by their weighted bandwidths with rule <b>rule</b>, for which we have

 * descriptors. */

double

frac_nodes_with_descriptors(const smartlist_t *sl,

                            bandwidth_weight_rule_t rule)

{

  u64_dbl_t *bandwidths = NULL;

  double total, present;



  if (smartlist_len(sl) == 0)

    return 0.0;



  if (compute_weighted_bandwidths(sl, rule, &bandwidths) < 0) {

    int n_with_descs = 0;

    SMARTLIST_FOREACH(sl, const node_t *, node, {

      if (node_has_descriptor(node))

        n_with_descs++;

    });

    return ((double)n_with_descs) / (double)smartlist_len(sl);

  }



  total = present = 0.0;

  SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {

    const double bw = bandwidths[node_sl_idx].dbl;

    total += bw;

    if (node_has_descriptor(node))

      present += bw;

  } SMARTLIST_FOREACH_END(node);



  tor_free(bandwidths);



  if (total < 1.0)

    return 0;



  return present / total;

}



/** Helper function:

 * choose a random node_t element of smartlist <b>sl</b>, weighted by

 * the advertised bandwidth of each element.
@@ -1873,7 +1911,7 @@ compute_weighted_bandwidths(const smartlist_t *sl, 
 * guards proportionally less.

 */

static const node_t *

smartlist_choose_node_by_bandwidth(smartlist_t *sl,

smartlist_choose_node_by_bandwidth(const smartlist_t *sl,

                                   bandwidth_weight_rule_t rule)

{

  unsigned int i;
@@ -2079,7 +2117,7 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl, 
/** Choose a random element of status list <b>sl</b>, weighted by

 * the advertised bandwidth of each node */

const node_t *

node_sl_choose_by_bandwidth(smartlist_t *sl,

node_sl_choose_by_bandwidth(const smartlist_t *sl,

                            bandwidth_weight_rule_t rule)

{ /*XXXX MOVE */

  const node_t *ret;

src/or/routerlist.h

+3 −1
Original line number Diff line number Diff line
@@ -47,7 +47,9 @@ const routerinfo_t *routerlist_find_my_routerinfo(void); 
uint32_t router_get_advertised_bandwidth(const routerinfo_t *router);

uint32_t router_get_advertised_bandwidth_capped(const routerinfo_t *router);



const node_t *node_sl_choose_by_bandwidth(smartlist_t *sl,

const node_t *node_sl_choose_by_bandwidth(const smartlist_t *sl,

                                          bandwidth_weight_rule_t rule);

double frac_nodes_with_descriptors(const smartlist_t *sl,

                                   bandwidth_weight_rule_t rule);



const node_t *router_choose_random_node(smartlist_t *excludedsmartlist,