ratelimit: proper expire for replicated pipes

Instead of updating the last_used on every received pipe, we shall only
consider the last locally used value when we want to expire. This way,
we only replicate pipes that have been locally used recently, if the
ones that are not, will not be replicated, thus will eventually be
deleted by the backup nodes.

Thanks go to Ken Rice (SIPNav) for reporting this and troubleshooting
the problem.

(cherry picked from commit d430c1a)

modules/ratelimit/ratelimit.h

@@ -73,7 +73,8 @@ typedef struct rl_pipe {
 	int last_counter;			/* last counter */
 	int load;					/* countes the accesses */
 	rl_algo_t algo;				/* the algorithm used */
-	unsigned long last_used;	/* timestamp when the pipe was last accessed */
+	time_t last_used;			/* timestamp when the pipe was last accessed */
+	time_t last_local_used;		/* timestamp when the pipe was last locally accessed */
 	rl_repl_counter_t *dsts;	/* counters per destination */
 	rl_window_t rwin;			/* window of requests */
 } rl_pipe_t;

modules/ratelimit/ratelimit_helper.c

@@ -389,6 +389,7 @@ int w_rl_check(struct sip_msg *_m, str *name, int *limit, str *algorithm)
 				name->len, name->s, *pipe);
 		if ((*pipe)->algo == PIPE_ALGO_NETWORK)
 			should_update = 1;
+		(*pipe)->last_local_used = time(0);
 	} else {
 		LM_DBG("Pipe %.*s found: %p - last used %lu\n",
 			name->len, name->s, *pipe, (*pipe)->last_used);
@@ -476,7 +477,8 @@ void rl_timer(unsigned int ticks, void *param)
 				goto next_pipe;
 			}
 			/* check to see if it is expired */
-			if ((*pipe)->last_used + rl_expire_time < now) {
+			if (((*pipe)->last_local_used + rl_expire_time < now) &&
+				((*pipe)->last_used + rl_expire_time + rl_timer_interval < now)) {
 				/* this pipe is engaged in a transaction */
 				del = it;
 				if (iterator_next(&it) < 0)
@@ -904,6 +906,7 @@ void rl_timer_repl(utime_t ticks, void *param)
 	int nr = 0;
 	int ret = 0;
 	bin_packet_t packet;
+	time_t now = time(0);
 
 	if (bin_init(&packet, &pipe_repl_cap, RL_PIPE_COUNTER, BIN_VERSION, 0) < 0) {
 		LM_ERR("cannot initiate bin buffer\n");
@@ -928,6 +931,10 @@ void rl_timer_repl(utime_t ticks, void *param)
 			if (RL_USE_CDB(*pipe))
 				goto next_pipe;
 
+			/* do not replicate if about to expire */
+			if ((*pipe)->last_local_used + rl_expire_time < now)
+				goto next_pipe;
+
 			key = iterator_key(&it);
 			if (!key) {
 				LM_ERR("cannot retrieve pipe key\n");