commit 6a2002fc091506f576934bbf50e7b8644b43bf4c Author: Nick Mathewson nickm@torproject.org Date: Fri Jul 8 14:38:02 2016 -0400
convert timers.c to use real monotonic time. --- src/common/timers.c | 50 +++++++++++++++++++++++++------------------------- src/common/timers.h | 3 ++- src/test/test-timers.c | 20 +++++++++++++++++--- 3 files changed, 44 insertions(+), 29 deletions(-)
diff --git a/src/common/timers.c b/src/common/timers.c index 2eb75a1..41b2008 100644 --- a/src/common/timers.c +++ b/src/common/timers.c @@ -19,9 +19,6 @@
/* Notes: * - * The use of tor_gettimeofday_cached_monotonic() is kind of ugly. It would - * be neat to fix it. - * * Having a way to free all timers on shutdown would free people from the * need to track them. Not sure if that's clever though. * @@ -72,6 +69,8 @@ struct timeout_cb { static struct timeouts *global_timeouts = NULL; static struct event *global_timer_event = NULL;
+static monotime_t start_of_time; + /** We need to choose this value carefully. Because we're using timer wheels, * it actually costs us to have extra resolution we don't use. So for now, * I'm going to define our resolution as .1 msec, and hope that's good enough. @@ -95,9 +94,8 @@ static struct event *global_timer_event = NULL; /** * Convert the timeval in <b>tv</b> to a timeout_t, and return it. * - * The output resolution is set by USEC_PER_TICK, and the time corresponding - * to 0 is the same as the time corresponding to 0 from - * tor_gettimeofday_cached_monotonic(). + * The output resolution is set by USEC_PER_TICK. Only use this to convert + * delays to number of ticks; the time represented by 0 is undefined. */ static timeout_t tv_to_timeout(const struct timeval *tv) @@ -108,7 +106,8 @@ tv_to_timeout(const struct timeval *tv) }
/** - * Convert the timeout in <b>t</b> to a timeval in <b>tv_out</b> + * Convert the timeout in <b>t</b> to a timeval in <b>tv_out</b>. Only + * use this for delays, not absolute times. */ static void timeout_to_tv(timeout_t t, struct timeval *tv_out) @@ -122,12 +121,10 @@ timeout_to_tv(timeout_t t, struct timeval *tv_out) * Update the timer <b>tv</b> to the current time in <b>tv</b>. */ static void -timer_advance_to_cur_time(const struct timeval *tv) +timer_advance_to_cur_time(const monotime_t *now) { - timeout_t cur_tick = tv_to_timeout(tv); - if (BUG(cur_tick < timeouts_get_curtime(global_timeouts))) { - cur_tick = timeouts_get_curtime(global_timeouts); // LCOV_EXCL_LINE - } + timeout_t cur_tick = CEIL_DIV(monotime_diff_usec(&start_of_time, now), + USEC_PER_TICK); timeouts_update(global_timeouts, cur_tick); }
@@ -138,11 +135,12 @@ timer_advance_to_cur_time(const struct timeval *tv) static void libevent_timer_reschedule(void) { - struct timeval now; - tor_gettimeofday_cached_monotonic(&now); + monotime_t now; + monotime_get(&now); timer_advance_to_cur_time(&now);
timeout_t delay = timeouts_timeout(global_timeouts); + struct timeval d; if (delay > MIN_CHECK_TICKS) delay = MIN_CHECK_TICKS; @@ -161,9 +159,8 @@ libevent_timer_callback(evutil_socket_t fd, short what, void *arg) (void)what; (void)arg;
- struct timeval now; - tor_gettimeofday_cache_clear(); - tor_gettimeofday_cached_monotonic(&now); + monotime_t now; + monotime_get(&now); timer_advance_to_cur_time(&now);
tor_timer_t *t; @@ -171,7 +168,6 @@ libevent_timer_callback(evutil_socket_t fd, short what, void *arg) t->callback.cb(t, t->callback.arg, &now); }
- tor_gettimeofday_cache_clear(); libevent_timer_reschedule(); }
@@ -194,6 +190,9 @@ timers_initialize(void) // LCOV_EXCL_STOP }
+ monotime_init(); + monotime_get(&start_of_time); + struct event *timer_event; timer_event = tor_event_new(tor_libevent_get_base(), -1, 0, libevent_timer_callback, NULL); @@ -256,24 +255,25 @@ timer_set_cb(tor_timer_t *t, timer_cb_fn_t cb, void *arg) }
/** - * Schedule the timer t to fire at the current time plus a delay of <b>tv</b>. - * All times are relative to tor_gettimeofday_cached_monotonic. + * Schedule the timer t to fire at the current time plus a delay of + * <b>delay</b> microseconds. All times are relative to monotime_get(). */ void timer_schedule(tor_timer_t *t, const struct timeval *tv) { - const timeout_t when = tv_to_timeout(tv); - struct timeval now; - tor_gettimeofday_cached_monotonic(&now); + const timeout_t delay = tv_to_timeout(tv); + + monotime_t now; + monotime_get(&now); timer_advance_to_cur_time(&now);
/* Take the old timeout value. */ timeout_t to = timeouts_timeout(global_timeouts);
- timeouts_add(global_timeouts, t, when); + timeouts_add(global_timeouts, t, delay);
/* Should we update the libevent timer? */ - if (to <= when) { + if (to <= delay) { return; /* we're already going to fire before this timer would trigger. */ } libevent_timer_reschedule(); diff --git a/src/common/timers.h b/src/common/timers.h index 594cf38..2c36af1 100644 --- a/src/common/timers.h +++ b/src/common/timers.h @@ -7,8 +7,9 @@ #include "orconfig.h" #include "testsupport.h"
+struct monotime_t; typedef struct timeout tor_timer_t; -typedef void (*timer_cb_fn_t)(tor_timer_t *, void *, const struct timeval *); +typedef void (*timer_cb_fn_t)(tor_timer_t *, void *, const struct monotime_t *); tor_timer_t *timer_new(timer_cb_fn_t cb, void *arg); void timer_set_cb(tor_timer_t *t, timer_cb_fn_t cb, void *arg); void timer_schedule(tor_timer_t *t, const struct timeval *delay); diff --git a/src/test/test-timers.c b/src/test/test-timers.c index 1189fd8..b5fcade 100644 --- a/src/test/test-timers.c +++ b/src/test/test-timers.c @@ -28,15 +28,26 @@ static tor_timer_t *timers[N_TIMERS] = {NULL}; static int n_active_timers = 0; static int n_fired = 0;
+static monotime_t started_at; +static int64_t delay_usec[N_TIMERS]; +static int64_t diffs_mono_usec[N_TIMERS]; + static void -timer_cb(tor_timer_t *t, void *arg, const struct timeval *now) +timer_cb(tor_timer_t *t, void *arg, const monotime_t *now_mono) { + struct timeval now; + + tor_gettimeofday(&now); tor_timer_t **t_ptr = arg; tor_assert(*t_ptr == t); int idx = (int) (t_ptr - timers); ++fired[idx]; - timersub(now, &fire_at[idx], &difference[idx]); + timersub(&now, &fire_at[idx], &difference[idx]); + diffs_mono_usec[idx] = + monotime_diff_usec(&started_at, now_mono) - + delay_usec[idx]; ++n_fired; + // printf("%d / %d\n",n_fired, N_TIMERS); if (n_fired == n_active_timers) { event_base_loopbreak(tor_libevent_get_base()); @@ -57,10 +68,12 @@ main(int argc, char **argv) int ret; struct timeval now; tor_gettimeofday(&now); + monotime_get(&started_at); for (i = 0; i < N_TIMERS; ++i) { struct timeval delay; delay.tv_sec = crypto_rand_int_range(0,MAX_DURATION); delay.tv_usec = crypto_rand_int_range(0,1000000); + delay_usec[i] = delay.tv_sec * 1000000 + delay.tv_usec; timeradd(&now, &delay, &fire_at[i]); timers[i] = timer_new(timer_cb, &timers[i]); timer_schedule(timers[i], &delay); @@ -88,7 +101,8 @@ main(int argc, char **argv) continue; } tor_assert(fired[i] == 1); - int64_t diff = difference[i].tv_usec + difference[i].tv_sec * 1000000; + //int64_t diff = difference[i].tv_usec + difference[i].tv_sec * 1000000; + int64_t diff = diffs_mono_usec[i]; total_difference += diff; total_square_difference += diff*diff; }