commit ad8977e39461807dd04e34dc7fa3c12ccef0b62d Author: Nick Mathewson nickm@torproject.org Date: Sun Jun 1 16:48:43 2014 -0400

Avoid needless router_dir_info_has_changed from router_set_status

On some profiles of Andrea's from #11332, I found that a great deal of time can still be attributed to functions called from update_router_have_minimum_dir_info(). This is making our digestmap, tor_memeq, and siphash functions take a much bigger portion of runtime than they really should.

If we're calling update_router_have_minimum_dir_info() too often, that's because we're calling router_dir_info_changed() too often. And it looks like most of the callers of router_dir_info_changed() are coming as tail-calls from router_set_status() as invoked by channel_do_open_actions().

But we don't need to call router_dir_info_changed() so much! (I'm not quite sure we need to call it from here at all, but...) Surely we don't need to call it from router_set_status when the router's status has not actually changed.

This patch makes us call router_dir_info_changed() from router_set_status only when we are changing the router's status.

Fix for bug 12170. This is leftover from our fix back in 273ee3e81 in 0.1.2.1-alpha, where we started caching the value of update_router_have_minimum_dir_info(). --- changes/bug12170 | 11 +++++++++++ src/or/nodelist.c | 6 ++++-- 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/changes/bug12170 b/changes/bug12170 new file mode 100644 index 0000000..e462e4f --- /dev/null +++ b/changes/bug12170 @@ -0,0 +1,11 @@ + o Major bugfixes (performance): + - Do not recompute whether we have sufficient information to build + circuits every time we make a successful connection. Previously, + we would forget our cached value for this flag every time we + successfully opened a channel (or marked a router as running or not + running for any + other reason), regardless of whether we had + previously believed the router to be running. This forced us to + run a fairly expensive update operation with relatively + high frequency. + Fixes bug 12170; bugfix on 0.1.2.1-alpha. diff --git a/src/or/nodelist.c b/src/or/nodelist.c index 178f084..3ac700c 100644 --- a/src/or/nodelist.c +++ b/src/or/nodelist.c @@ -1216,10 +1216,12 @@ router_set_status(const char *digest, int up) if (!up && node_is_me(node) && !net_is_disabled()) log_warn(LD_NET, "We just marked ourself as down. Are your external " "addresses reachable?"); + + if (bool_neq(node->is_running, up)) + router_dir_info_changed(); + node->is_running = up; } - - router_dir_info_changed(); }

/** True iff, the last time we checked whether we had enough directory info