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authorNick Mathewson <nickm@torproject.org>2017-09-22 15:29:15 -0400
committerNick Mathewson <nickm@torproject.org>2017-11-08 10:45:18 -0500
commit3c03e237ab372f495fa2498e925813931ba381da (patch)
tree01dcb809cff24a7bf4e3ced8fd5862d4707ea5d5
parent04d4786cc40b2d80b4cd34e7d5339b0100861c8f (diff)
downloadtor-3c03e237ab372f495fa2498e925813931ba381da.tar.gz
tor-3c03e237ab372f495fa2498e925813931ba381da.zip
Remove an erroneous 0.5 in compute_weighted_bandwidths()
Back in 0.2.4.3-alpha (e106812a778f537), when we switched from using double to using uint64 for selecting by bandwidth, I got the math wrong: I should have used llround(x), or (uint64_t)(x+0.5), but instead I wrote llround(x+0.5). That means we would always round up, rather than rounding to the closest integer Fixes bug 23318; bugfix on 0.2.4.3-alpha.
-rw-r--r--changes/bug233187
-rw-r--r--src/or/routerlist.c2
2 files changed, 8 insertions, 1 deletions
diff --git a/changes/bug23318 b/changes/bug23318
new file mode 100644
index 0000000000..32c85eb194
--- /dev/null
+++ b/changes/bug23318
@@ -0,0 +1,7 @@
+ o Minor bugfixes (path selection):
+ - When selecting relays by bandwidth, avoid a rounding error that
+ could sometimes cause load to be imbalanced incorrectly. Previously,
+ we would always round upwards; now, we round towards the nearest
+ integer. This had the biggest effect when a relay's weight adjustments
+ should have given it weight 0, but it got weight 1 instead.
+ Fixes bug 23318; bugfix on 0.2.4.3-alpha.
diff --git a/src/or/routerlist.c b/src/or/routerlist.c
index 2365f28fd2..faf2eeda5d 100644
--- a/src/or/routerlist.c
+++ b/src/or/routerlist.c
@@ -2713,7 +2713,7 @@ compute_weighted_bandwidths(const smartlist_t *sl,
final_weight = weight*this_bw;
}
- bandwidths[node_sl_idx] = final_weight + 0.5;
+ bandwidths[node_sl_idx] = final_weight;
} SMARTLIST_FOREACH_END(node);
log_debug(LD_CIRC, "Generated weighted bandwidths for rule %s based "