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More ratelimit optimizations

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This commit is contained in:
Nils O. Selåsdal
2013-10-15 21:35:10 +02:00
parent c1ef4af4ad
commit 0a36c669c6
2 changed files with 10 additions and 9 deletions
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include/ucore/rate_limit.h
+2 -2
View File
@@ -34,7 +34,7 @@
*
* uc_ratelimit_init(&r,20, 1, time(NULL));
*
* NOTE. 2 * (period + 1) * tickets * tickets must not exceed the range of the RateLimit.funds
* NOTE. (period + 1) * tickets must not exceed the range of the RateLimit.funds
*
* for (;;) {
* int fd = accept(..);
@@ -67,7 +67,7 @@ struct RateLimit {
* Initialize a struct RateLimit, which can hand out @tickets per @period
* the perioid must be in the same units as the current_ts
*
* NOTE. 2 * (period + 1) * tickets * tickets must not exceed the range of the RateLimit.funds
* NOTE. 2 * (period + 1) * tickets must not exceed the range of the RateLimit.funds
*
* @param r RateLimit to initialize
* @param tickets number of tickets (bucket depth)
src/rate_limit.c
+7 -6
View File
@@ -5,11 +5,7 @@ void uc_ratelimit_init(struct RateLimit *r, long tickets, long period, long curr
{
r->tickets = tickets;
if (tickets > period) {
r->ticket_cost = tickets * period;
} else {
r->ticket_cost = period;
}
r->period = period;
r->funds = r->ticket_cost * tickets;
@@ -48,8 +44,13 @@ int uc_ratelimit_allow(struct RateLimit *r, long current_ts)
//Calculate the cost of tickets that became available since
//the last time.
r->funds += diff_period *
((r->tickets * r->ticket_cost) / r->period);
r->funds += diff_period * r->tickets;
//the below is the real algorithm, with ticket_cost =
//tickets * period.
//we have optimized this to the expression used above
//r->funds += diff_period *
// ((r->tickets * r->ticket_cost) / r->period);
//throttle handing out tickets
if (r->funds > r->ticket_cost * r->tickets) {