Improved circuit queue out-of-memory handler

Previously, when we ran low on memory, we'd close whichever circuits
had the most queued cells. Now, we close those that have the
*oldest* queued cells, on the theory that those are most responsible
for us running low on memory, and that those are the least likely to
actually drain on their own if we wait a little longer.

Based on analysis from a forthcoming paper by Jansen, Tschorsch,
Johnson, and Scheuermann. Fixes bug 9093.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/or/relay.c b/src/or/relay.c
index fda9e89ca4..a193ad8431 100644
--- a/src/or/relay.c
+++ b/src/or/relay.c
@@ -1904,15 +1904,19 @@ cell_queue_append(cell_queue_t *queue, packed_cell_t *cell)
 void
 cell_queue_append_packed_copy(cell_queue_t *queue, const cell_t *cell)
 {
+  struct timeval now;
   packed_cell_t *copy = packed_cell_copy(cell);
+  tor_gettimeofday_cached(&now);
+  copy->inserted_time = (uint32_t)tv_to_msec(&now);
+
   /* Remember the time when this cell was put in the queue. */
+  /*XXXX This may be obsoleted by inserted_time */
   if (get_options()->CellStatistics) {
-    struct timeval now;
     uint32_t added;
     insertion_time_queue_t *it_queue = queue->insertion_times;
     if (!it_pool)
       it_pool = mp_pool_new(sizeof(insertion_time_elem_t), 1024);
-    tor_gettimeofday_cached(&now);
+
 #define SECONDS_IN_A_DAY 86400L
     added = (uint32_t)(((now.tv_sec % SECONDS_IN_A_DAY) * 100L)
             + ((uint32_t)now.tv_usec / (uint32_t)10000L));