commit 8a81a70878bb0f77ebdf1e6fda436b4b6af14f9a Author: Nick Mathewson nickm@torproject.org Date: Thu Apr 26 12:20:01 2018 -0400

Move consdiffmgr_rescan() into a mainloop event.

The change here was very simple, since there is a flag set whenever we want to schedule this event.

Closes ticket 25391. m --- changes/ticket25931 | 9 +++++++++ src/or/consdiffmgr.c | 33 +++++++++++++++++++++++++++++++-- src/or/main.c | 6 ------ 3 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/changes/ticket25931 b/changes/ticket25931 new file mode 100644 index 000000000..20ce76188 --- /dev/null +++ b/changes/ticket25931 @@ -0,0 +1,9 @@ + o Minor features (mainloop): + - Move responsibility for + rescanning the consensus cache + 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: + 25931. + diff --git a/src/or/consdiffmgr.c b/src/or/consdiffmgr.c index 02b905a52..323f4f9ca 100644 --- a/src/or/consdiffmgr.c +++ b/src/or/consdiffmgr.c @@ -99,6 +99,14 @@ static const compress_method_t compress_diffs_with[] = { #endif };

+/** + * Event for rescanning the cache. + */ +static mainloop_event_t *consdiffmgr_rescan_ev = NULL; + +static void consdiffmgr_rescan_cb(mainloop_event_t *ev, void *arg); +static void mark_cdm_cache_dirty(void); + /** How many different methods will we try to use for diff compression? */ STATIC unsigned n_diff_compression_methods(void) @@ -372,7 +380,9 @@ cdm_cache_init(void) } else { consdiffmgr_set_cache_flags(); } - cdm_cache_dirty = 1; + consdiffmgr_rescan_ev = + mainloop_event_postloop_new(consdiffmgr_rescan_cb, NULL); + mark_cdm_cache_dirty(); cdm_cache_loaded = 0; }

@@ -1095,6 +1105,24 @@ consdiffmgr_rescan(void) cdm_cache_dirty = 0; }

+/** Callback wrapper for consdiffmgr_rescan */ +static void +consdiffmgr_rescan_cb(mainloop_event_t *ev, void *arg) +{ + (void)ev; + (void)arg; + consdiffmgr_rescan(); +} + +/** Mark the cache as dirty, and schedule a rescan event. */ +static void +mark_cdm_cache_dirty(void) +{ + cdm_cache_dirty = 1; + tor_assert(consdiffmgr_rescan_ev); + mainloop_event_activate(consdiffmgr_rescan_ev); +} + /** * Helper: compare two files by their from-valid-after and valid-after labels, * trying to sort in ascending order by from-valid-after (when present) and @@ -1219,6 +1247,7 @@ consdiffmgr_free_all(void) memset(latest_consensus, 0, sizeof(latest_consensus)); consensus_cache_free(cons_diff_cache); cons_diff_cache = NULL; + mainloop_event_free(consdiffmgr_rescan_ev); }

/* ===== @@ -1750,7 +1779,7 @@ consensus_compress_worker_replyfn(void *work_) compress_consensus_with, job->out, "consensus"); - cdm_cache_dirty = 1; + mark_cdm_cache_dirty();

unsigned u; consensus_flavor_t f = job->flavor; diff --git a/src/or/main.c b/src/or/main.c index ffe407329..7e489a999 100644 --- a/src/or/main.c +++ b/src/or/main.c @@ -1730,12 +1730,6 @@ run_scheduled_events(time_t now) /* 11b. check pending unconfigured managed proxies */ if (!net_is_disabled() && pt_proxies_configuration_pending()) pt_configure_remaining_proxies(); - - /* 12. launch diff computations. (This is free if there are none to - * launch.) */ - if (dir_server_mode(options)) { - consdiffmgr_rescan(); - } }

/* Periodic callback: rotate the onion keys after the period defined by the