From: Willy Tarreau <w@1wt.eu>
Date: Thu, 24 Sep 2020 05:27:06 +0000 (+0200)
Subject: MINOR: proxy: maintain per-state counters of listeners
X-Git-Tag: v2.3-dev6~55
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=efc0eec4c1c1a6f21efc4c0ead23761700c8acb6;p=thirdparty%2Fhaproxy.git

MINOR: proxy: maintain per-state counters of listeners

The proxy state tries to be synthetic but that doesn't work well with
many listeners, especially for transition phases or after a failed
pause/resume.

In order to address this, we'll instead rely on counters of listeners in
a given state for the 3 major states (ready, paused, listen) and a total
counter. We'll now be able to determine a proxy's state by comparing these
counters only.
---

diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index 2680fbffac..16fee4a2ea 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -395,6 +395,10 @@ struct proxy {
 	int uuid;				/* universally unique proxy ID, used for SNMP */
 	unsigned int backlog;			/* force the frontend's listen backlog */
 	unsigned long bind_proc;		/* bitmask of processes using this proxy */
+	unsigned int li_all;                    /* total number of listeners attached to this proxy */
+	unsigned int li_paused;                 /* total number of listeners paused (LI_PAUSED) */
+	unsigned int li_bound;                  /* total number of listeners ready (LI_LISTEN)  */
+	unsigned int li_ready;                  /* total number of listeners ready (>=LI_READY) */
 
 	/* warning: these structs are huge, keep them at the bottom */
 	struct sockaddr_storage dispatch_addr;	/* the default address to connect to */
diff --git a/src/listener.c b/src/listener.c
index 1ad017db8c..c4ee3c3190 100644
--- a/src/listener.c
+++ b/src/listener.c
@@ -218,9 +218,55 @@ REGISTER_CONFIG_POSTPARSER("multi-threaded accept queue", accept_queue_init);
 
 #endif // USE_THREAD
 
-/* adjust the listener's state */
+/* adjust the listener's state and its proxy's listener counters if needed.
+ * It must be called under the listener's lock, but uses atomic ops to change
+ * the proxy's counters so that the proxy lock is not needed.
+ */
 void listener_set_state(struct listener *l, enum li_state st)
 {
+	struct proxy *px = l->bind_conf->frontend;
+
+	if (px) {
+		/* from state */
+		switch (l->state) {
+		case LI_NEW: /* first call */
+			_HA_ATOMIC_ADD(&px->li_all, 1);
+			break;
+		case LI_INIT:
+		case LI_ASSIGNED:
+			break;
+		case LI_PAUSED:
+			_HA_ATOMIC_SUB(&px->li_paused, 1);
+			break;
+		case LI_LISTEN:
+			_HA_ATOMIC_SUB(&px->li_bound, 1);
+			break;
+		case LI_READY:
+		case LI_FULL:
+		case LI_LIMITED:
+			_HA_ATOMIC_SUB(&px->li_ready, 1);
+			break;
+		}
+
+		/* to state */
+		switch (st) {
+		case LI_NEW:
+		case LI_INIT:
+		case LI_ASSIGNED:
+			break;
+		case LI_PAUSED:
+			_HA_ATOMIC_ADD(&px->li_paused, 1);
+			break;
+		case LI_LISTEN:
+			_HA_ATOMIC_ADD(&px->li_bound, 1);
+			break;
+		case LI_READY:
+		case LI_FULL:
+		case LI_LIMITED:
+			_HA_ATOMIC_ADD(&px->li_ready, 1);
+			break;
+		}
+	}
 	l->state = st;
 }