/**
* Generate a synthetic time using our distribution parameters.
*
* The return value will be within the [q_lo, q_hi) quantile points
* on the CDF.
*/
build_time_t
circuit_build_times_generate_sample(circuit_build_times_t *cbt,
double q_lo, double q_hi)
{
double randval = crypto_rand_double();
build_time_t ret;
double u;
/* Generate between [q_lo, q_hi) */
/*XXXX This is what nextafter is supposed to be for; we should use it on the
* platforms that support it. */
q_hi -= 1.0/(INT32_MAX);
tor_assert(q_lo >= 0);
tor_assert(q_hi < 1);
tor_assert(q_lo < q_hi);
u = q_lo + (q_hi-q_lo)*randval;
tor_assert(0 <= u && u < 1.0);
/* circuit_build_times_calculate_timeout returns <= INT32_MAX */
ret = (build_time_t)
tor_lround(circuit_build_times_calculate_timeout(cbt, u));
tor_assert(ret > 0);
return ret;
}
/**
* Estimate a new timeout based on history and set our timeout
* variable accordingly.
*/
static int
circuit_build_times_set_timeout_worker(circuit_build_times_t *cbt)
{
build_time_t max_time;
if (!circuit_build_times_enough_to_compute(cbt))
return 0;
if (!circuit_build_times_update_alpha(cbt))
return 0;
cbt->timeout_ms = circuit_build_times_calculate_timeout(cbt,
circuit_build_times_quantile_cutoff());
cbt->close_ms = circuit_build_times_calculate_timeout(cbt,
circuit_build_times_close_quantile());
max_time = circuit_build_times_max(cbt);
if (cbt->timeout_ms > max_time) {
log_info(LD_CIRC,
"Circuit build timeout of %dms is beyond the maximum build "
"time we have ever observed. Capping it to %dms.",
(int)cbt->timeout_ms, max_time);
cbt->timeout_ms = max_time;
}
if (max_time < INT32_MAX/2 && cbt->close_ms > 2*max_time) {
log_info(LD_CIRC,
"Circuit build measurement period of %dms is more than twice "
"the maximum build time we have ever observed. Capping it to "
"%dms.", (int)cbt->close_ms, 2*max_time);
cbt->close_ms = 2*max_time;
}
/* Sometimes really fast guard nodes give us such a steep curve
* that this ends up being not that much greater than timeout_ms.
* Make it be at least 1 min to handle this case. */
cbt->close_ms = MAX(cbt->close_ms, circuit_build_times_initial_timeout());
cbt->have_computed_timeout = 1;
return 1;
}
static void
test_circuit_timeout(void *arg)
{
/* Plan:
* 1. Generate 1000 samples
* 2. Estimate parameters
* 3. If difference, repeat
* 4. Save state
* 5. load state
* 6. Estimate parameters
* 7. compare differences
*/
circuit_build_times_t initial;
circuit_build_times_t estimate;
circuit_build_times_t final;
double timeout1, timeout2;
or_state_t *state=NULL;
int i, runs;
double close_ms;
(void)arg;
initialize_periodic_events();
circuit_build_times_init(&initial);
circuit_build_times_init(&estimate);
circuit_build_times_init(&final);
state = or_state_new();
circuitbuild_running_unit_tests();
#define timeout0 (build_time_t)(30*1000.0)
initial.Xm = 3000;
circuit_build_times_initial_alpha(&initial,
CBT_DEFAULT_QUANTILE_CUTOFF/100.0,
timeout0);
close_ms = MAX(circuit_build_times_calculate_timeout(&initial,
CBT_DEFAULT_CLOSE_QUANTILE/100.0),
CBT_DEFAULT_TIMEOUT_INITIAL_VALUE);
do {
for (i=0; i < CBT_DEFAULT_MIN_CIRCUITS_TO_OBSERVE; i++) {
build_time_t sample = circuit_build_times_generate_sample(&initial,0,1);
if (sample > close_ms) {
circuit_build_times_add_time(&estimate, CBT_BUILD_ABANDONED);
} else {
circuit_build_times_add_time(&estimate, sample);
}
}
circuit_build_times_update_alpha(&estimate);
timeout1 = circuit_build_times_calculate_timeout(&estimate,
CBT_DEFAULT_QUANTILE_CUTOFF/100.0);
circuit_build_times_set_timeout(&estimate);
log_notice(LD_CIRC, "Timeout1 is %f, Xm is %d", timeout1, estimate.Xm);
/* 2% error */
} while (fabs(circuit_build_times_cdf(&initial, timeout0) -
circuit_build_times_cdf(&initial, timeout1)) > 0.02);
tt_int_op(estimate.total_build_times, OP_LE, CBT_NCIRCUITS_TO_OBSERVE);
circuit_build_times_update_state(&estimate, state);
circuit_build_times_free_timeouts(&final);
tt_int_op(circuit_build_times_parse_state(&final, state), OP_EQ, 0);
circuit_build_times_update_alpha(&final);
timeout2 = circuit_build_times_calculate_timeout(&final,
CBT_DEFAULT_QUANTILE_CUTOFF/100.0);
circuit_build_times_set_timeout(&final);
log_notice(LD_CIRC, "Timeout2 is %f, Xm is %d", timeout2, final.Xm);
/* 5% here because some accuracy is lost due to histogram conversion */
tt_assert(fabs(circuit_build_times_cdf(&initial, timeout0) -
circuit_build_times_cdf(&initial, timeout2)) < 0.05);
for (runs = 0; runs < 50; runs++) {
int build_times_idx = 0;
int total_build_times = 0;
final.close_ms = final.timeout_ms = CBT_DEFAULT_TIMEOUT_INITIAL_VALUE;
estimate.close_ms = estimate.timeout_ms
= CBT_DEFAULT_TIMEOUT_INITIAL_VALUE;
for (i = 0; i < CBT_DEFAULT_RECENT_CIRCUITS*2; i++) {
circuit_build_times_network_circ_success(&estimate);
circuit_build_times_add_time(&estimate,
circuit_build_times_generate_sample(&estimate, 0,
CBT_DEFAULT_QUANTILE_CUTOFF/100.0));
circuit_build_times_network_circ_success(&estimate);
circuit_build_times_add_time(&final,
circuit_build_times_generate_sample(&final, 0,
CBT_DEFAULT_QUANTILE_CUTOFF/100.0));
}
tt_assert(!circuit_build_times_network_check_changed(&estimate));
tt_assert(!circuit_build_times_network_check_changed(&final));
/* Reset liveness to be non-live */
final.liveness.network_last_live = 0;
