commit 987a7f667698576d745674965973871363ffd719 Author: Nick Mathewson nickm@torproject.org Date: Fri Apr 27 10:30:30 2018 -0400

Move responsibility for or_state_save() to a scheduled callback

Closes ticket 25948. --- changes/ticket25948 | 9 +++++++++ src/or/main.c | 44 ++++++++++++++++++++++++++++++++++++++------ src/or/main.h | 1 + src/or/statefile.c | 7 +++++-- 4 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/changes/ticket25948 b/changes/ticket25948 new file mode 100644 index 000000000..7851d0b65 --- /dev/null +++ b/changes/ticket25948 @@ -0,0 +1,9 @@ + o Minor features (mainloop): + - Move responsibility for + saving the state file to disk + from a once-per-second callback to a callback that is only scheduled as + needed. Once enough items are removed from our once-per-second + callback, we can eliminate it entirely to conserve CPU when idle. + Closes ticket + 25948. + diff --git a/src/or/main.c b/src/or/main.c index c1103edb3..6b166d096 100644 --- a/src/or/main.c +++ b/src/or/main.c @@ -1355,6 +1355,7 @@ CALLBACK(retry_listeners); CALLBACK(rotate_onion_key); CALLBACK(rotate_x509_certificate); CALLBACK(save_stability); +CALLBACK(save_state); CALLBACK(write_bridge_ns); CALLBACK(write_stats_file);

@@ -1376,6 +1377,7 @@ STATIC periodic_event_item_t periodic_events[] = { CALLBACK(reset_padding_counts, PERIODIC_EVENT_ROLE_ALL, 0), CALLBACK(retry_listeners, PERIODIC_EVENT_ROLE_ALL, PERIODIC_EVENT_FLAG_NEED_NET), + CALLBACK(save_state, PERIODIC_EVENT_ROLE_ALL, 0), CALLBACK(rotate_x509_certificate, PERIODIC_EVENT_ROLE_ALL, 0), CALLBACK(write_stats_file, PERIODIC_EVENT_ROLE_ALL, 0),

@@ -1432,6 +1434,7 @@ static periodic_event_item_t *check_descriptor_event=NULL; static periodic_event_item_t *fetch_networkstatus_event=NULL; static periodic_event_item_t *launch_descriptor_fetches_event=NULL; static periodic_event_item_t *check_dns_honesty_event=NULL; +static periodic_event_item_t *save_state_event=NULL;

/** Reset all the periodic events so we'll do all our actions again as if we * just started up. @@ -1528,6 +1531,7 @@ initialize_periodic_events(void) NAMED_CALLBACK(fetch_networkstatus); NAMED_CALLBACK(launch_descriptor_fetches); NAMED_CALLBACK(check_dns_honesty); + NAMED_CALLBACK(save_state);

struct timeval one_second = { 1, 0 }; initialize_periodic_events_event = tor_evtimer_new( @@ -1598,8 +1602,9 @@ periodic_events_on_new_options(const or_options_t *options) void reschedule_descriptor_update_check(void) { - tor_assert(check_descriptor_event); - periodic_event_reschedule(check_descriptor_event); + if (check_descriptor_event) { + periodic_event_reschedule(check_descriptor_event); + } }

/** @@ -1745,10 +1750,6 @@ run_scheduled_events(time_t now) run_connection_housekeeping(i, now); }

- /* 8b. And if anything in our state is ready to get flushed to disk, we - * flush it. */ - or_state_save(now); - /* 11b. check pending unconfigured managed proxies */ if (!net_is_disabled() && pt_proxies_configuration_pending()) pt_configure_remaining_proxies(); @@ -1983,6 +1984,37 @@ check_expired_networkstatus_callback(time_t now, const or_options_t *options) }

/** + * Scheduled callback: Save the state file to disk if appropriate. + */ +static int +save_state_callback(time_t now, const or_options_t *options) +{ + (void) options; + (void) or_state_save(now); // only saves if appropriate + const time_t next_write = get_or_state()->next_write; + if (next_write == TIME_MAX) { + return 86400; + } else if (BUG(next_write <= now)) { + /* This can't happen due to clock jumps, since the value of next_write + * is based on the same "now" that we passed to or_state_save(). + */ + return PERIODIC_EVENT_NO_UPDATE; + } else { + return next_write - now; + } +} + +/** Reschedule the event for saving the state file. + * + * Run this when the state becomes dirty. */ +void +reschedule_or_state_save(void) +{ + tor_assert(save_state_event); + periodic_event_reschedule(save_state_event); +} + +/** * Periodic callback: Write statistics to disk if appropriate. */ static int diff --git a/src/or/main.h b/src/or/main.h index 2447339fb..836dbf1ca 100644 --- a/src/or/main.h +++ b/src/or/main.h @@ -61,6 +61,7 @@ void dns_servers_relaunch_checks(void); void reset_all_main_loop_timers(void); void reschedule_descriptor_update_check(void); void reschedule_directory_downloads(void); +void reschedule_or_state_save(void); void mainloop_schedule_postloop_cleanup(void); void rescan_periodic_events(const or_options_t *options);

diff --git a/src/or/statefile.c b/src/or/statefile.c index 26a631ced..c81ea44e0 100644 --- a/src/or/statefile.c +++ b/src/or/statefile.c @@ -37,6 +37,7 @@ #include "control.h" #include "entrynodes.h" #include "hibernate.h" +#include "main.h" #include "rephist.h" #include "router.h" #include "sandbox.h" @@ -472,7 +473,7 @@ or_state_save(time_t now)

tor_assert(global_state);

- if (global_state->next_write >= now) + if (global_state->next_write > now) return 0;

/* Call everything else that might dirty the state even more, in order @@ -686,8 +687,10 @@ save_transport_to_state(const char *transport, void or_state_mark_dirty(or_state_t *state, time_t when) { - if (state->next_write > when) + if (state->next_write > when) { state->next_write = when; + reschedule_or_state_save(); + } }

STATIC void