MEDIUM: connection: protect idle conn lists with locks
This is a preparation work for connection reuse with sni/proxy
protocol/specific src-dst addresses.
Protect every access to idle conn lists with a lock. This is currently
strictly not needed because the access to the list are made with atomic
operations. However, to be able to reuse connection with specific
parameters, the list storage will be converted to eb-trees. As this
structure does not have atomic operation, it is mandatory to protect it
with a lock.
For this, the takeover lock is reused. Its role was to protect during
connection takeover. As it is now extended to general idle conns usage,
it is renamed to idle_conns_lock. A new lock section is also
instantiated named IDLE_CONNS_LOCK to isolate its impact on performance.
diff --git a/src/server.c b/src/server.c
index 453c598..2e49949 100644
--- a/src/server.c
+++ b/src/server.c
@@ -5277,6 +5277,8 @@
/* Move toremove_nb connections from idle_list to toremove_list, -1 means
* moving them all.
* Returns the number of connections moved.
+ *
+ * Must be called with idle_conns_lock held.
*/
static int srv_migrate_conns_to_remove(struct mt_list *idle_list, struct mt_list *toremove_list, int toremove_nb)
{
@@ -5308,10 +5310,12 @@
/* check all threads starting with ours */
for (i = tid;;) {
did_remove = 0;
+ HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[i].idle_conns_lock);
if (srv_migrate_conns_to_remove(&srv->idle_conns[i], &idle_conns[i].toremove_conns, -1) > 0)
did_remove = 1;
if (srv_migrate_conns_to_remove(&srv->safe_conns[i], &idle_conns[i].toremove_conns, -1) > 0)
did_remove = 1;
+ HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[i].idle_conns_lock);
if (did_remove)
task_wakeup(idle_conns[i].cleanup_task, TASK_WOKEN_OTHER);
@@ -5381,12 +5385,14 @@
max_conn = (exceed_conns * srv->curr_idle_thr[i]) /
curr_idle + 1;
+ HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[i].idle_conns_lock);
j = srv_migrate_conns_to_remove(&srv->idle_conns[i], &idle_conns[i].toremove_conns, max_conn);
if (j > 0)
did_remove = 1;
if (max_conn - j > 0 &&
srv_migrate_conns_to_remove(&srv->safe_conns[i], &idle_conns[i].toremove_conns, max_conn - j) > 0)
did_remove = 1;
+ HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[i].idle_conns_lock);
if (did_remove)
task_wakeup(idle_conns[i].cleanup_task, TASK_WOKEN_OTHER);