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Refactor responsibility for checking global write bucket emptiness

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We used to do this 10x per second in connection_buckets_refill();
instead, we now do it when the bucket becomes empty. This change is
part of the work of making connection_buckets_refill() obsolete.

Closes ticket 25828; bugfix on 0.2.3.5-alpha.
This commit is contained in:
Nick Mathewson 2018-04-17 12:05:39 -04:00
parent b36c450b57
commit 9af4cd6f31
2 changed files with 23 additions and 12 deletions
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7
changes/bug25828 Normal file
View File

@ -0,0 +1,7 @@
o Minor bugfixes (bandwidth management):
- Consider ourselves "low on write bandwidth" if we have exhausted our
write bandwidth some time in the last second. This was the
documented behavior before, but the actual behavior was to change
this value every TokenBucketRefillInterval. Fixes bug 25828; bugfix on
0.2.3.5-alpha.

26
src/or/connection.c
View File

@ -2814,10 +2814,10 @@ connection_is_rate_limited(connection_t *conn)
return 1; return 1;
} }
/** Did either global write bucket run dry last second? If so, /** When was either global write bucket last empty? If this was recent, then
* we are likely to run dry again this second, so be stingy with the * we're probably low on bandwidth, and we should be stingy with our bandwidth
* tokens we just put in. */ * usage. */
static int write_buckets_empty_last_second = 0; static time_t write_buckets_last_empty_at = -100;
/** How many seconds of no active local circuits will make the /** How many seconds of no active local circuits will make the
* connection revert to the "relayed" bandwidth class? */ * connection revert to the "relayed" bandwidth class? */
@ -2969,8 +2969,11 @@ global_write_bucket_low(connection_t *conn, size_t attempt, int priority)
if (smaller_bucket < attempt) if (smaller_bucket < attempt)
return 1; /* not enough space no matter the priority */ return 1; /* not enough space no matter the priority */
if (write_buckets_empty_last_second) {
const time_t diff = approx_time() - write_buckets_last_empty_at;
if (diff <= 1)
return 1; /* we're already hitting our limits, no more please */ return 1; /* we're already hitting our limits, no more please */
}
if (priority == 1) { /* old-style v1 query */ if (priority == 1) { /* old-style v1 query */
/* Could we handle *two* of these requests within the next two seconds? */ /* Could we handle *two* of these requests within the next two seconds? */
@ -3042,10 +3045,15 @@ connection_buckets_decrement(connection_t *conn, time_t now,
if (!connection_is_rate_limited(conn)) if (!connection_is_rate_limited(conn))
return; /* local IPs are free */ return; /* local IPs are free */
unsigned flags = 0;
if (connection_counts_as_relayed_traffic(conn, now)) { if (connection_counts_as_relayed_traffic(conn, now)) {
token_bucket_rw_dec(&global_relayed_bucket, num_read, num_written); flags = token_bucket_rw_dec(&global_relayed_bucket, num_read, num_written);
}
flags |= token_bucket_rw_dec(&global_bucket, num_read, num_written);
if (flags & TB_WRITE) {
write_buckets_last_empty_at = now;
} }
token_bucket_rw_dec(&global_bucket, num_read, num_written);
if (connection_speaks_cells(conn) && conn->state == OR_CONN_STATE_OPEN) { if (connection_speaks_cells(conn) && conn->state == OR_CONN_STATE_OPEN) {
or_connection_t *or_conn = TO_OR_CONN(conn); or_connection_t *or_conn = TO_OR_CONN(conn);
token_bucket_rw_dec(&or_conn->bucket, num_read, num_written); token_bucket_rw_dec(&or_conn->bucket, num_read, num_written);
@ -3185,10 +3193,6 @@ connection_bucket_refill_all(time_t now, uint32_t now_ts)
{ {
smartlist_t *conns = get_connection_array(); smartlist_t *conns = get_connection_array();
write_buckets_empty_last_second =
token_bucket_rw_get_write(&global_bucket) <= 0 ||
token_bucket_rw_get_write(&global_relayed_bucket) <= 0;
/* refill the global buckets */ /* refill the global buckets */
token_bucket_rw_refill(&global_bucket, now_ts); token_bucket_rw_refill(&global_bucket, now_ts);
token_bucket_rw_refill(&global_relayed_bucket, now_ts); token_bucket_rw_refill(&global_relayed_bucket, now_ts);