From 6d5440e80e7ecd95c52b3f3d5217e1693294404e Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Thu, 11 Aug 2011 15:15:17 -0400 Subject: Fix handling of group rate limits under 64 bytes of burst The "min_share" logic, which was designed to prevent piles of extremely small writes when running up against a group rate limit, could lead to confusing behavior if you ever set a min_share less than your burst rate. If that happened, then as soon as your group rate limit was exhausted, you'd stop reading/writing, and never start again, since the amount readable/writeable would never actually hit min_share. We now cap min_share at the rate per tick. Found by George Kadianakis --- bufferevent_ratelim.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'bufferevent_ratelim.c') diff --git a/bufferevent_ratelim.c b/bufferevent_ratelim.c index 85904e82..827b346c 100644 --- a/bufferevent_ratelim.c +++ b/bufferevent_ratelim.c @@ -636,13 +636,15 @@ bufferevent_rate_limit_group_new(struct event_base *base, ev_token_bucket_init(&g->rate_limit, cfg, tick, 0); - g->min_share = 64; event_assign(&g->master_refill_event, base, -1, EV_PERSIST, _bev_group_refill_callback, g); /*XXXX handle event_add failure */ event_add(&g->master_refill_event, &cfg->tick_timeout); EVTHREAD_ALLOC_LOCK(g->lock, EVTHREAD_LOCKTYPE_RECURSIVE); + + bufferevent_rate_limit_group_set_min_share(g, 64); + return g; } @@ -670,6 +672,9 @@ bufferevent_rate_limit_group_set_cfg( event_add(&g->master_refill_event, &cfg->tick_timeout); } + /* The new limits might force us to adjust min_share differently. */ + bufferevent_rate_limit_group_set_min_share(g, g->configured_min_share); + UNLOCK_GROUP(g); return 0; } @@ -682,6 +687,15 @@ bufferevent_rate_limit_group_set_min_share( if (share > EV_SSIZE_MAX) return -1; + g->configured_min_share = share; + + /* Can't set share to less than the one-tick maximum. IOW, at steady + * state, at least one connection can go per tick. */ + if (share > g->rate_limit_cfg.read_rate) + share = g->rate_limit_cfg.read_rate; + if (share > g->rate_limit_cfg.write_rate) + share = g->rate_limit_cfg.write_rate; + g->min_share = share; return 0; } -- cgit v1.2.1