[MEDIUM] session: add concurrent connections counter

The new "conn_cur" session counter has been added. It is automatically
updated upon "track XXX" directives, and the entry is touched at the
moment we increment the value so that we don't consider further counter
updates as real updates, otherwise we would end up updating upon completion,
which may not be desired. Probably that some other event counters (eg: HTTP
requests) will have to be updated upon each event though.

This counter can be matched against current session's source address using
the "src_conn_cur" ACL.

include/proto/session.h

@@ -52,6 +52,11 @@ int parse_track_counters(char **args, int *arg,
  */
 static inline void session_store_counters(struct session *s)
 {
+	if (s->tracked_counters) {
+		void *ptr = stktable_data_ptr(s->tracked_table, s->tracked_counters, STKTABLE_DT_CONN_CUR);
+		if (ptr)
+			stktable_data_cast(ptr, conn_cur)--;
+	}
 	s->tracked_counters->ref_cnt--;
 	s->tracked_counters = NULL;
 }
@@ -65,6 +70,13 @@ static inline void session_track_counters(struct session *s, struct stktable *t,
 	ts->ref_cnt++;
 	s->tracked_table = t;
 	s->tracked_counters = ts;
+	if (ts) {
+		void *ptr = stktable_data_ptr(t, ts, STKTABLE_DT_CONN_CUR);
+		if (ptr)
+			stktable_data_cast(ptr, conn_cur)++;
+		if (tick_isset(t->expire))
+			ts->expire = tick_add(now_ms, MS_TO_TICKS(t->expire));
+	}
 }
 
 static void inline trace_term(struct session *s, unsigned int code)

include/types/stick_table.h

@@ -43,13 +43,15 @@ enum {
 enum {
 	STKTABLE_DT_SERVER_ID,    /* the server ID to use with this session if > 0 */
 	STKTABLE_DT_CONN_CNT,     /* cumulated number of connections */
+	STKTABLE_DT_CONN_CUR,     /* concurrent number of connections */
 	STKTABLE_DATA_TYPES       /* Number of data types, must always be last */
 };
 
 /* stick_table extra data. This is mainly used for casting or size computation */
 union stktable_data {
-	unsigned int conn_cnt;
 	int server_id;
+	unsigned int conn_cnt;
+	unsigned int conn_cur;
 };
 
 /* known data types */

src/session.c

@@ -2127,11 +2127,45 @@ acl_fetch_src_updt_conn_cnt(struct proxy *px, struct session *l4, void *l7, int
 	return 1;
 }
 
+/* set test->i to the number of concurrent connections from the session's source
+ * address in the table pointed to by expr.
+ */
+static int
+acl_fetch_src_conn_cur(struct proxy *px, struct session *l4, void *l7, int dir,
+                       struct acl_expr *expr, struct acl_test *test)
+{
+	struct stksess *ts;
+	struct stktable_key *key;
+
+	key = tcpv4_src_to_stktable_key(l4);
+	if (!key)
+		return 0; /* only TCPv4 is supported right now */
+
+	if (expr->arg_len)
+		px = find_stktable(expr->arg.str);
+
+	if (!px)
+		return 0; /* table not found */
+
+	test->flags = ACL_TEST_F_VOL_TEST;
+	test->i = 0;
+
+	if ((ts = stktable_lookup_key(&px->table, key)) != NULL) {
+		void *ptr = stktable_data_ptr(&px->table, ts, STKTABLE_DT_CONN_CUR);
+		if (!ptr)
+			return 0; /* parameter not stored */
+		test->i = stktable_data_cast(ptr, conn_cur);
+	}
+
+	return 1;
+}
+
 
 /* Note: must not be declared <const> as its list will be overwritten */
 static struct acl_kw_list acl_kws = {{ },{
 	{ "src_conn_cnt",       acl_parse_int,   acl_fetch_src_conn_cnt,      acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "src_updt_conn_cnt",  acl_parse_int,   acl_fetch_src_updt_conn_cnt, acl_match_int, ACL_USE_TCP4_VOLATILE },
+	{ "src_conn_cur",       acl_parse_int,   acl_fetch_src_conn_cur,      acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ NULL, NULL, NULL, NULL },
 }};
 

src/stick_table.c

@@ -525,8 +525,9 @@ int stktable_compatible_pattern(struct pattern_expr *expr, unsigned long table_t
 
 /* Extra data types processing */
 struct stktable_data_type stktable_data_types[STKTABLE_DATA_TYPES] = {
-	[STKTABLE_DT_CONN_CNT]  = { .name = "conn_cnt", .data_length = stktable_data_size(conn_cnt) },
 	[STKTABLE_DT_SERVER_ID] = { .name = "server_id", .data_length = stktable_data_size(server_id) },
+	[STKTABLE_DT_CONN_CNT]  = { .name = "conn_cnt",  .data_length = stktable_data_size(conn_cnt)  },
+	[STKTABLE_DT_CONN_CUR]  = { .name = "conn_cur",  .data_length = stktable_data_size(conn_cur)  },
 };
 
 /*