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@@ -1653,15 +1653,41 @@ router_get_advertised_bandwidth_capped(const routerinfo_t *router)
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return result;
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}
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+/** Given an array of double/uint64_t unions that are currently being used as
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+ * doubles, convert them to uint64_t, and try to scale them linearly so as to
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+ * much of the range of uint64_t. If <b>total_out</b> is provided, set it to
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+ * the sum of all elements in the array _before_ scaling. */
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+/* private */ void
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+scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
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+ uint64_t *total_out)
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+{
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+ double total = 0.0;
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+ double scale_factor;
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+ int i;
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+ /* big, but far away from overflowing an int64_t */
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+#define SCALE_TO_U64_MAX (INT64_MAX / 4)
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+
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+ for (i = 0; i < n_entries; ++i)
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+ total += entries[i].dbl;
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+
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+ scale_factor = SCALE_TO_U64_MAX / total;
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+
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+ for (i = 0; i < n_entries; ++i)
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+ entries[i].u64 = tor_llround(entries[i].dbl * scale_factor);
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+
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+ if (total_out)
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+ *total_out = (uint64_t) total;
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+
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+#undef SCALE_TO_U64_MAX
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+}
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+
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/** Pick a random element of <b>n_entries</b>-element array <b>entries</b>,
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- * choosing each element with a probability proportional to its value, and
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- * return the index of that element. If all elements are 0, choose an index
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- * at random. If <b>total_out</b> is provided, set it to the sum of all
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- * elements in the array. Return -1 on error.
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+ * choosing each element with a probability proportional to its (uint64_t)
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+ * value, and return the index of that element. If all elements are 0, choose
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+ * an index at random. Return -1 on error.
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*/
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/* private */ int
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-choose_array_element_by_weight(const uint64_t *entries, int n_entries,
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- uint64_t *total_out)
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+choose_array_element_by_weight(const u64_dbl_t *entries, int n_entries)
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{
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int i, i_chosen=-1, n_chosen=0;
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uint64_t total_so_far = 0;
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@@ -1669,10 +1695,7 @@ choose_array_element_by_weight(const uint64_t *entries, int n_entries,
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uint64_t total = 0;
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for (i = 0; i < n_entries; ++i)
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- total += entries[i];
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-
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- if (total_out)
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- *total_out = total;
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+ total += entries[i].u64;
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if (n_entries < 1)
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return -1;
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@@ -1683,7 +1706,7 @@ choose_array_element_by_weight(const uint64_t *entries, int n_entries,
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rand_val = crypto_rand_uint64(total);
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for (i = 0; i < n_entries; ++i) {
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- total_so_far += entries[i];
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+ total_so_far += entries[i].u64;
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if (total_so_far > rand_val) {
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i_chosen = i;
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n_chosen++;
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@@ -1753,7 +1776,7 @@ smartlist_choose_node_by_bandwidth_weights(smartlist_t *sl,
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double Wg = -1, Wm = -1, We = -1, Wd = -1;
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double Wgb = -1, Wmb = -1, Web = -1, Wdb = -1;
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uint64_t weighted_bw = 0;
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- uint64_t *bandwidths;
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+ u64_dbl_t *bandwidths;
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/* Can't choose exit and guard at same time */
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tor_assert(rule == NO_WEIGHTING ||
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@@ -1834,7 +1857,7 @@ smartlist_choose_node_by_bandwidth_weights(smartlist_t *sl,
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Web /= weight_scale;
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Wdb /= weight_scale;
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- bandwidths = tor_malloc_zero(sizeof(uint64_t)*smartlist_len(sl));
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+ bandwidths = tor_malloc_zero(sizeof(u64_dbl_t)*smartlist_len(sl));
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// Cycle through smartlist and total the bandwidth.
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SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {
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@@ -1879,9 +1902,9 @@ smartlist_choose_node_by_bandwidth_weights(smartlist_t *sl,
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if (weight < 0.0)
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weight = 0.0;
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- bandwidths[node_sl_idx] = tor_llround(weight*this_bw + 0.5);
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+ bandwidths[node_sl_idx].dbl = weight*this_bw + 0.5;
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if (is_me)
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- sl_last_weighted_bw_of_me = bandwidths[node_sl_idx];
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+ sl_last_weighted_bw_of_me = (uint64_t) bandwidths[node_sl_idx].dbl;
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} SMARTLIST_FOREACH_END(node);
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log_debug(LD_CIRC, "Choosing node for rule %s based on weights "
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@@ -1889,10 +1912,12 @@ smartlist_choose_node_by_bandwidth_weights(smartlist_t *sl,
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bandwidth_weight_rule_to_string(rule),
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Wg, Wm, We, Wd, U64_PRINTF_ARG(weighted_bw));
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+ scale_array_elements_to_u64(bandwidths, smartlist_len(sl),
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+ &sl_last_total_weighted_bw);
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+
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{
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int idx = choose_array_element_by_weight(bandwidths,
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- smartlist_len(sl),
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- &sl_last_total_weighted_bw);
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+ smartlist_len(sl));
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tor_free(bandwidths);
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return idx < 0 ? NULL : smartlist_get(sl, idx);
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}
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@@ -1916,12 +1941,12 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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bandwidth_weight_rule_t rule)
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{
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unsigned int i;
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- uint64_t *bandwidths;
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+ u64_dbl_t *bandwidths;
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int is_exit;
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int is_guard;
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int is_fast;
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- uint64_t total_nonexit_bw = 0, total_exit_bw = 0;
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- uint64_t total_nonguard_bw = 0, total_guard_bw = 0;
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+ double total_nonexit_bw = 0, total_exit_bw = 0;
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+ double total_nonguard_bw = 0, total_guard_bw = 0;
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double exit_weight;
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double guard_weight;
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int n_unknown = 0;
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@@ -1950,7 +1975,7 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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/* First count the total bandwidth weight, and make a list
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* of each value. We use UINT64_MAX to indicate "unknown". */
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- bandwidths = tor_malloc_zero(sizeof(uint64_t)*smartlist_len(sl));
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+ bandwidths = tor_malloc_zero(sizeof(u64_dbl_t)*smartlist_len(sl));
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fast_bits = bitarray_init_zero(smartlist_len(sl));
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exit_bits = bitarray_init_zero(smartlist_len(sl));
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guard_bits = bitarray_init_zero(smartlist_len(sl));
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@@ -1986,7 +2011,7 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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bitarray_set(fast_bits, i);
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if (is_known) {
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- bandwidths[i] = this_bw;
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+ bandwidths[i].dbl = this_bw;
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if (is_guard)
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total_guard_bw += this_bw;
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else
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@@ -1997,14 +2022,16 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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total_nonexit_bw += this_bw;
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} else {
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++n_unknown;
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- bandwidths[i] = UINT64_MAX;
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+ bandwidths[i].dbl = -1.0;
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}
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} SMARTLIST_FOREACH_END(node);
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+#define EPSILON .1
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+
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/* Now, fill in the unknown values. */
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if (n_unknown) {
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int32_t avg_fast, avg_slow;
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- if (total_exit_bw+total_nonexit_bw) {
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+ if (total_exit_bw+total_nonexit_bw < EPSILON) {
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/* if there's some bandwidth, there's at least one known router,
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* so no worries about div by 0 here */
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int n_known = smartlist_len(sl)-n_unknown;
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@@ -2015,25 +2042,25 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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avg_slow = 20000;
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}
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for (i=0; i<(unsigned)smartlist_len(sl); ++i) {
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- if (bandwidths[i] != UINT64_MAX)
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+ if (bandwidths[i].dbl >= 0.0)
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continue;
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is_fast = bitarray_is_set(fast_bits, i);
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is_exit = bitarray_is_set(exit_bits, i);
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is_guard = bitarray_is_set(guard_bits, i);
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- bandwidths[i] = is_fast ? avg_fast : avg_slow;
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+ bandwidths[i].dbl = is_fast ? avg_fast : avg_slow;
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if (is_exit)
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- total_exit_bw += bandwidths[i];
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+ total_exit_bw += bandwidths[i].dbl;
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else
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- total_nonexit_bw += bandwidths[i];
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+ total_nonexit_bw += bandwidths[i].dbl;
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if (is_guard)
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- total_guard_bw += bandwidths[i];
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+ total_guard_bw += bandwidths[i].dbl;
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else
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- total_nonguard_bw += bandwidths[i];
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+ total_nonguard_bw += bandwidths[i].dbl;
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}
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}
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/* If there's no bandwidth at all, pick at random. */
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- if (!(total_exit_bw+total_nonexit_bw)) {
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+ if (total_exit_bw+total_nonexit_bw < EPSILON) {
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tor_free(bandwidths);
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tor_free(fast_bits);
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tor_free(exit_bits);
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@@ -2050,12 +2077,12 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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* For detailed derivation of this formula, see
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* http://archives.seul.org/or/dev/Jul-2007/msg00056.html
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*/
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- if (rule == WEIGHT_FOR_EXIT || !total_exit_bw)
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+ if (rule == WEIGHT_FOR_EXIT || total_exit_bw<EPSILON)
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exit_weight = 1.0;
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else
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exit_weight = 1.0 - all_bw/(3.0*exit_bw);
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- if (rule == WEIGHT_FOR_GUARD || !total_guard_bw)
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+ if (rule == WEIGHT_FOR_GUARD || total_guard_bw<EPSILON)
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guard_weight = 1.0;
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else
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guard_weight = 1.0 - all_bw/(3.0*guard_bw);
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@@ -2068,19 +2095,19 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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sl_last_weighted_bw_of_me = 0;
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for (i=0; i < (unsigned)smartlist_len(sl); i++) {
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- tor_assert(bandwidths[i] < UINT64_MAX);
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+ tor_assert(bandwidths[i].dbl >= 0.0);
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is_exit = bitarray_is_set(exit_bits, i);
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is_guard = bitarray_is_set(guard_bits, i);
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if (is_exit && is_guard)
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- bandwidths[i] = tor_llround(bandwidths[i] * exit_weight * guard_weight);
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+ bandwidths[i].dbl *= exit_weight * guard_weight;
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else if (is_guard)
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- bandwidths[i] = tor_llround(bandwidths[i] * guard_weight);
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+ bandwidths[i].dbl *= guard_weight;
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else if (is_exit)
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- bandwidths[i] = tor_llround(bandwidths[i] * exit_weight);
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+ bandwidths[i].dbl *= exit_weight;
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if (i == (unsigned) me_idx)
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- sl_last_weighted_bw_of_me = bandwidths[i];
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+ sl_last_weighted_bw_of_me = (uint64_t) bandwidths[i].dbl;
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}
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}
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@@ -2099,10 +2126,12 @@ smartlist_choose_node_by_bandwidth(smartlist_t *sl,
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guard_weight, (int)(rule == WEIGHT_FOR_GUARD));
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#endif
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+ scale_array_elements_to_u64(bandwidths, smartlist_len(sl),
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+ &sl_last_total_weighted_bw);
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+
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{
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int idx = choose_array_element_by_weight(bandwidths,
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- smartlist_len(sl),
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- &sl_last_total_weighted_bw);
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+ smartlist_len(sl));
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tor_free(bandwidths);
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tor_free(fast_bits);
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tor_free(exit_bits);
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