commit 5a9903b9e09697ac131c841310dd82eebcca02e0 Author: Nick Mathewson nickm@torproject.org Date: Mon Nov 22 12:39:22 2010 -0500

Handle negative run lengths in wfu/mtbf calculations --- changes/bug1035 | 5 +++++ src/or/rephist.c | 22 +++++++++++++++------- 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/changes/bug1035 b/changes/bug1035 index 4b62b46..041e3b3 100644 --- a/changes/bug1035 +++ b/changes/bug1035 @@ -4,4 +4,9 @@ treat it as having any downtime for the purposes of stability calculation, whereas clients would experience downtime since the IP could take a while to propagate to them. Resolves issue 1035. + o Minor bugfixes (authorities) + - Try to be more robust to hops back in time when calculating + router stability. Previously, if a run of uptime or downtime + appeared to be negative, the calculation could give incorrect + results. Bugfix on 0.2.0.6-alpha.

diff --git a/src/or/rephist.c b/src/or/rephist.c index a0c9c9f..e59fcb5 100644 --- a/src/or/rephist.c +++ b/src/or/rephist.c @@ -380,12 +380,20 @@ rep_hist_note_router_unreachable(const char *id, time_t when) long run_length = when - hist->start_of_run; format_local_iso_time(tbuf, hist->start_of_run);

- hist->weighted_run_length += run_length; hist->total_run_weights += 1.0; hist->start_of_run = 0; - hist->weighted_uptime += run_length; - hist->total_weighted_time += run_length; + if (run_length < 0) { + unsigned long penalty = -run_length; +#define SUBTRACT_CLAMPED(var, penalty) \ + do { (var) = (var) < (penalty) ? 0 : (var) - (penalty); } while (0)

+ SUBTRACT_CLAMPED(hist->weighted_run_length, penalty); + SUBTRACT_CLAMPED(hist->weighted_uptime, penalty); + } else { + hist->weighted_run_length += run_length; + hist->weighted_uptime += run_length; + hist->total_weighted_time += run_length; + } was_running = 1; log_info(LD_HIST, "Router %s is now non-Running: it had previously been " "Running since %s. Its total weighted uptime is %lu/%lu.", @@ -458,7 +466,7 @@ rep_hist_downrate_old_runs(time_t now) static double get_stability(or_history_t *hist, time_t when) { - unsigned long total = hist->weighted_run_length; + long total = hist->weighted_run_length; double total_weights = hist->total_run_weights;

if (hist->start_of_run) { @@ -494,8 +502,8 @@ get_total_weighted_time(or_history_t *hist, time_t when) static double get_weighted_fractional_uptime(or_history_t *hist, time_t when) { - unsigned long total = hist->total_weighted_time; - unsigned long up = hist->weighted_uptime; + long total = hist->total_weighted_time; + long up = hist->weighted_uptime;

if (hist->start_of_run) { long run_length = (when - hist->start_of_run);