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Calculate relay weighted bandwidth using guardfraction bandwidths.

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Now use the guardfraction function to calculate individual relay
bandwidth weights.
This commit is contained in:
George Kadianakis
2015-01-29 15:07:35 +00:00
committed by Nick Mathewson
parent f7a8b19184
commit b941f109ac
1 changed files with 41 additions and 1 deletions
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src/or/routerlist.c
+41 -1
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@@ -2003,6 +2003,7 @@ compute_weighted_bandwidths(const smartlist_t *sl,
double Wg = -1, Wm = -1, We = -1, Wd = -1;
double Wgb = -1, Wmb = -1, Web = -1, Wdb = -1;
uint64_t weighted_bw = 0;
guardfraction_bandwidth_t guardfraction_bw;
u64_dbl_t *bandwidths;
/* Can't choose exit and guard at same time */
@@ -2092,6 +2093,8 @@ compute_weighted_bandwidths(const smartlist_t *sl,
SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {
int is_exit = 0, is_guard = 0, is_dir = 0, this_bw = 0;
double weight = 1;
double weight_without_guard_flag = 0; /* Used for guardfraction */
double final_weight = 0;
is_exit = node->is_exit && ! node->is_bad_exit;
is_guard = node->is_possible_guard;
is_dir = node_is_dir(node);
@@ -2119,8 +2122,10 @@ compute_weighted_bandwidths(const smartlist_t *sl,
if (is_guard && is_exit) {
weight = (is_dir ? Wdb*Wd : Wd);
weight_without_guard_flag = (is_dir ? Web*We : We);
} else if (is_guard) {
weight = (is_dir ? Wgb*Wg : Wg);
weight_without_guard_flag = (is_dir ? Wmb*Wm : Wm);
} else if (is_exit) {
weight = (is_dir ? Web*We : We);
} else { // middle
@@ -2132,8 +2137,43 @@ compute_weighted_bandwidths(const smartlist_t *sl,
this_bw = 0;
if (weight < 0.0)
weight = 0.0;
if (weight_without_guard_flag < 0.0)
weight_without_guard_flag = 0.0;
bandwidths[node_sl_idx].dbl = weight*this_bw + 0.5;
/* If guardfraction information is available in the consensus, we
* want to calculate this router's bandwidth according to its
* guardfraction. Quoting from proposal236:
*
* Let Wpf denote the weight from the 'bandwidth-weights' line a
* client would apply to N for position p if it had the guard
* flag, Wpn the weight if it did not have the guard flag, and B the
* measured bandwidth of N in the consensus. Then instead of choosing
* N for position p proportionally to Wpf*B or Wpn*B, clients should
* choose N proportionally to F*Wpf*B + (1-F)*Wpn*B.
*/
if (node->rs && node->rs->has_guardfraction && rule != WEIGHT_FOR_GUARD) {
/* XXX The assert should actually check for is_guard. However,
* that crashes dirauths because of #13297. This should be
* equivalent: */
tor_assert(node->rs->is_possible_guard);
guard_get_guardfraction_bandwidth(&guardfraction_bw,
this_bw,
node->rs->guardfraction_percentage);
/* Calculate final_weight = F*Wpf*B + (1-F)*Wpn*B */
final_weight =
guardfraction_bw.guard_bw * weight +
guardfraction_bw.non_guard_bw * weight_without_guard_flag;
log_warn(LD_GENERAL, "%s: Guardfraction weight %f instead of %f (%s)",
node->rs->nickname, final_weight, weight*this_bw,
bandwidth_weight_rule_to_string(rule));
} else { /* no guardfraction information. calculate the weight normally. */
final_weight = weight*this_bw;
}
bandwidths[node_sl_idx].dbl = final_weight + 0.5;
} SMARTLIST_FOREACH_END(node);
log_debug(LD_CIRC, "Generated weighted bandwidths for rule %s based "