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Refactor out u64_dbl_t

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This type saved a tiny amount of allocation, but not enough to be
worth keeping.

(This is in preparation for moving choose_array_element_by_weight)
This commit is contained in:
Nick Mathewson 2016-04-27 10:16:43 -04:00
parent ce854a8d22
commit 20432fc541
3 changed files with 59 additions and 57 deletions
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58
src/or/routerlist.c
View File

@ -67,7 +67,7 @@ typedef struct cert_list_t cert_list_t;
/* static function prototypes */
static int compute_weighted_bandwidths(const smartlist_t *sl,
bandwidth_weight_rule_t rule,
u64_dbl_t **bandwidths_out);
double **bandwidths_out);
static const routerstatus_t *router_pick_trusteddirserver_impl(
const smartlist_t *sourcelist, dirinfo_type_t auth,
int flags, int *n_busy_out);
@ -1799,20 +1799,23 @@ dirserver_choose_by_weight(const smartlist_t *servers, double authority_weight)
{
int n = smartlist_len(servers);
int i;
u64_dbl_t *weights;
double *weights_dbl;
uint64_t *weights_u64;
const dir_server_t *ds;
weights = tor_calloc(n, sizeof(u64_dbl_t));
weights_dbl = tor_calloc(n, sizeof(double));
weights_u64 = tor_calloc(n, sizeof(uint64_t));
for (i = 0; i < n; ++i) {
ds = smartlist_get(servers, i);
weights[i].dbl = ds->weight;
weights_dbl[i] = ds->weight;
if (ds->is_authority)
weights[i].dbl *= authority_weight;
weights_dbl[i] *= authority_weight;
}
scale_array_elements_to_u64(weights, n, NULL);
i = choose_array_element_by_weight(weights, n);
tor_free(weights);
scale_array_elements_to_u64(weights_u64, weights_dbl, n, NULL);
i = choose_array_element_by_weight(weights_u64, n);
tor_free(weights_dbl);
tor_free(weights_u64);
return (i < 0) ? NULL : smartlist_get(servers, i);
}
@ -2075,7 +2078,8 @@ router_get_advertised_bandwidth_capped(const routerinfo_t *router)
* much of the range of uint64_t. If <b>total_out</b> is provided, set it to
* the sum of all elements in the array _before_ scaling. */
STATIC void
scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
scale_array_elements_to_u64(uint64_t *entries_out, const double *entries_in,
int n_entries,
uint64_t *total_out)
{
double total = 0.0;
@ -2085,13 +2089,13 @@ scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
#define SCALE_TO_U64_MAX ((int64_t) (INT64_MAX / 4))
for (i = 0; i < n_entries; ++i)
total += entries[i].dbl;
total += entries_in[i];
if (total > 0.0)
scale_factor = SCALE_TO_U64_MAX / total;
for (i = 0; i < n_entries; ++i)
entries[i].u64 = tor_llround(entries[i].dbl * scale_factor);
entries_out[i] = tor_llround(entries_in[i] * scale_factor);
if (total_out)
*total_out = (uint64_t) total;
@ -2119,7 +2123,7 @@ gt_i64_timei(uint64_t a, uint64_t b)
* an index at random. Return -1 on error.
*/
STATIC int
choose_array_element_by_weight(const u64_dbl_t *entries, int n_entries)
choose_array_element_by_weight(const uint64_t *entries, int n_entries)
{
int i, i_chosen=-1, n_chosen=0;
uint64_t total_so_far = 0;
@ -2127,7 +2131,7 @@ choose_array_element_by_weight(const u64_dbl_t *entries, int n_entries)
uint64_t total = 0;
for (i = 0; i < n_entries; ++i)
total += entries[i].u64;
total += entries[i];
if (n_entries < 1)
return -1;
@ -2140,7 +2144,7 @@ choose_array_element_by_weight(const u64_dbl_t *entries, int n_entries)
rand_val = crypto_rand_uint64(total);
for (i = 0; i < n_entries; ++i) {
total_so_far += entries[i].u64;
total_so_far += entries[i];
if (gt_i64_timei(total_so_far, rand_val)) {
i_chosen = i;
n_chosen++;
@ -2206,17 +2210,21 @@ static const node_t *
smartlist_choose_node_by_bandwidth_weights(const smartlist_t *sl,
bandwidth_weight_rule_t rule)
{
u64_dbl_t *bandwidths=NULL;
double *bandwidths_dbl=NULL;
uint64_t *bandwidths_u64=NULL;
if (compute_weighted_bandwidths(sl, rule, &bandwidths) < 0)
if (compute_weighted_bandwidths(sl, rule, &bandwidths_dbl) < 0)
return NULL;
scale_array_elements_to_u64(bandwidths, smartlist_len(sl), NULL);
bandwidths_u64 = tor_calloc(smartlist_len(sl), sizeof(uint64_t));
scale_array_elements_to_u64(bandwidths_u64, bandwidths_dbl,
smartlist_len(sl), NULL);
{
int idx = choose_array_element_by_weight(bandwidths,
int idx = choose_array_element_by_weight(bandwidths_u64,
smartlist_len(sl));
tor_free(bandwidths);
tor_free(bandwidths_dbl);
tor_free(bandwidths_u64);
return idx < 0 ? NULL : smartlist_get(sl, idx);
}
}
@ -2229,14 +2237,14 @@ smartlist_choose_node_by_bandwidth_weights(const smartlist_t *sl,
static int
compute_weighted_bandwidths(const smartlist_t *sl,
bandwidth_weight_rule_t rule,
u64_dbl_t **bandwidths_out)
double **bandwidths_out)
{
int64_t weight_scale;
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;
double *bandwidths;
/* Can't choose exit and guard at same time */
tor_assert(rule == NO_WEIGHTING ||
@ -2318,7 +2326,7 @@ compute_weighted_bandwidths(const smartlist_t *sl,
Web /= weight_scale;
Wdb /= weight_scale;
bandwidths = tor_calloc(smartlist_len(sl), sizeof(u64_dbl_t));
bandwidths = tor_calloc(smartlist_len(sl), sizeof(double));
// Cycle through smartlist and total the bandwidth.
static int warned_missing_bw = 0;
@ -2405,7 +2413,7 @@ compute_weighted_bandwidths(const smartlist_t *sl,
final_weight = weight*this_bw;
}
bandwidths[node_sl_idx].dbl = final_weight + 0.5;
bandwidths[node_sl_idx] = final_weight + 0.5;
} SMARTLIST_FOREACH_END(node);
log_debug(LD_CIRC, "Generated weighted bandwidths for rule %s based "
@ -2426,7 +2434,7 @@ double
frac_nodes_with_descriptors(const smartlist_t *sl,
bandwidth_weight_rule_t rule)
{
u64_dbl_t *bandwidths = NULL;
double *bandwidths = NULL;
double total, present;
if (smartlist_len(sl) == 0)
@ -2443,7 +2451,7 @@ frac_nodes_with_descriptors(const smartlist_t *sl,
total = present = 0.0;
SMARTLIST_FOREACH_BEGIN(sl, const node_t *, node) {
const double bw = bandwidths[node_sl_idx].dbl;
const double bw = bandwidths[node_sl_idx];
total += bw;
if (node_has_descriptor(node))
present += bw;

13
src/or/routerlist.h
View File

@ -217,17 +217,10 @@ int hex_digest_nickname_matches(const char *hexdigest,
const char *nickname, int is_named);
#ifdef ROUTERLIST_PRIVATE
/** Helper type for choosing routers by bandwidth: contains a union of
* double and uint64_t. Before we call scale_array_elements_to_u64, it holds
* a double; after, it holds a uint64_t. */
typedef union u64_dbl_t {
uint64_t u64;
double dbl;
} u64_dbl_t;
STATIC int choose_array_element_by_weight(const u64_dbl_t *entries,
STATIC int choose_array_element_by_weight(const uint64_t *entries,
int n_entries);
STATIC void scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
STATIC void scale_array_elements_to_u64(uint64_t *entries_out,
const double *entries_in, int n_entries,
uint64_t *total_out);
STATIC const routerstatus_t *router_pick_directory_server_impl(
dirinfo_type_t auth, int flags,

45
src/test/test_dir.c
View File

@ -2149,56 +2149,57 @@ test_dir_scale_bw(void *testdata)
1.0/7,
12.0,
24.0 };
u64_dbl_t vals[8];
double vals_dbl[8];
uint64_t vals_u64[8];
uint64_t total;
int i;
(void) testdata;
for (i=0; i<8; ++i)
vals[i].dbl = v[i];
vals_dbl[i] = v[i];
scale_array_elements_to_u64(vals, 8, &total);
scale_array_elements_to_u64(vals_u64, vals_dbl, 8, &total);
tt_int_op((int)total, OP_EQ, 48);
total = 0;
for (i=0; i<8; ++i) {
total += vals[i].u64;
total += vals_u64[i];
}
tt_assert(total >= (U64_LITERAL(1)<<60));
tt_assert(total <= (U64_LITERAL(1)<<62));
for (i=0; i<8; ++i) {
/* vals[2].u64 is the scaled value of 1.0 */
double ratio = ((double)vals[i].u64) / vals[2].u64;
double ratio = ((double)vals_u64[i]) / vals_u64[2];
tt_double_op(fabs(ratio - v[i]), OP_LT, .00001);
}
/* test handling of no entries */
total = 1;
scale_array_elements_to_u64(vals, 0, &total);
scale_array_elements_to_u64(vals_u64, vals_dbl, 0, &total);
tt_assert(total == 0);
/* make sure we don't read the array when we have no entries
* may require compiler flags to catch NULL dereferences */
total = 1;
scale_array_elements_to_u64(NULL, 0, &total);
scale_array_elements_to_u64(NULL, NULL, 0, &total);
tt_assert(total == 0);
scale_array_elements_to_u64(NULL, 0, NULL);
scale_array_elements_to_u64(NULL, NULL, 0, NULL);
/* test handling of zero totals */
total = 1;
vals[0].dbl = 0.0;
scale_array_elements_to_u64(vals, 1, &total);
vals_dbl[0] = 0.0;
scale_array_elements_to_u64(vals_u64, vals_dbl, 1, &total);
tt_assert(total == 0);
tt_assert(vals[0].u64 == 0);
tt_assert(vals_u64[0] == 0);
vals[0].dbl = 0.0;
vals[1].dbl = 0.0;
scale_array_elements_to_u64(vals, 2, NULL);
tt_assert(vals[0].u64 == 0);
tt_assert(vals[1].u64 == 0);
vals_dbl[0] = 0.0;
vals_dbl[1] = 0.0;
scale_array_elements_to_u64(vals_u64, vals_dbl, 2, NULL);
tt_assert(vals_u64[0] == 0);
tt_assert(vals_u64[1] == 0);
done:
;
@ -2209,7 +2210,7 @@ test_dir_random_weighted(void *testdata)
{
int histogram[10];
uint64_t vals[10] = {3,1,2,4,6,0,7,5,8,9}, total=0;
u64_dbl_t inp[10];
uint64_t inp_u64[10];
int i, choice;
const int n = 50000;
double max_sq_error;
@ -2219,12 +2220,12 @@ test_dir_random_weighted(void *testdata)
* in a scrambled order to make sure we don't depend on order. */
memset(histogram,0,sizeof(histogram));
for (i=0; i<10; ++i) {
inp[i].u64 = vals[i];
inp_u64[i] = vals[i];
total += vals[i];
}
tt_u64_op(total, OP_EQ, 45);
for (i=0; i<n; ++i) {
choice = choose_array_element_by_weight(inp, 10);
choice = choose_array_element_by_weight(inp_u64, 10);
tt_int_op(choice, OP_GE, 0);
tt_int_op(choice, OP_LT, 10);
histogram[choice]++;
@ -2251,16 +2252,16 @@ test_dir_random_weighted(void *testdata)
/* Now try a singleton; do we choose it? */
for (i = 0; i < 100; ++i) {
choice = choose_array_element_by_weight(inp, 1);
choice = choose_array_element_by_weight(inp_u64, 1);
tt_int_op(choice, OP_EQ, 0);
}
/* Now try an array of zeros. We should choose randomly. */
memset(histogram,0,sizeof(histogram));
for (i = 0; i < 5; ++i)
inp[i].u64 = 0;
inp_u64[i] = 0;
for (i = 0; i < n; ++i) {
choice = choose_array_element_by_weight(inp, 5);
choice = choose_array_element_by_weight(inp_u64, 5);
tt_int_op(choice, OP_GE, 0);
tt_int_op(choice, OP_LT, 5);
histogram[choice]++;