From a9d3c1e6a31b0e6b847409fe82241789221dc101 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Fri, 30 Nov 2007 20:48:53 +0100
Subject: [PATCH] [MEDIUM] add the "nbsrv" ACL verb

The new "nbsrv" ACL verb matches the number of active servers in a backend.
By default, it applies to the backend where it is declared, but optionally
it can receive the name of another backend as an argument in parenthesis.

It counts the number of enabled active servers first, then the number of
enabled backup servers.
---
 src/backend.c |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/src/backend.c b/src/backend.c
index 1c54474..4dc2b9c 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -22,6 +22,7 @@
 #include <common/eb32tree.h>
 #include <common/time.h>
 
+#include <types/acl.h>
 #include <types/buffers.h>
 #include <types/global.h>
 #include <types/polling.h>
@@ -29,6 +30,7 @@
 #include <types/server.h>
 #include <types/session.h>
 
+#include <proto/acl.h>
 #include <proto/backend.h>
 #include <proto/client.h>
 #include <proto/fd.h>
@@ -1541,6 +1543,51 @@ int backend_parse_balance(const char **args, char *err, int errlen, struct proxy
 	return 0;
 }
 
+
+/************************************************************************/
+/*             All supported keywords must be declared here.            */
+/************************************************************************/
+
+/* set test->i to the number of enabled servers on the proxy */
+static int
+acl_fetch_nbsrv(struct proxy *px, struct session *l4, void *l7, int dir,
+                struct acl_expr *expr, struct acl_test *test)
+{
+	test->flags = ACL_TEST_F_VOL_TEST;
+	if (expr->arg_len) {
+		/* another proxy was designated, we must look for it */
+		for (px = proxy; px; px = px->next)
+			if ((px->cap & PR_CAP_BE) && !strcmp(px->id, expr->arg.str))
+				break;
+	}
+	if (!px)
+		return 0;
+
+	if (px->srv_act)
+		test->i = px->srv_act;
+	else if (px->lbprm.fbck)
+		test->i = 1;
+	else
+		test->i = px->srv_bck;
+
+	return 1;
+}
+
+
+/* Note: must not be declared <const> as its list will be overwritten */
+static struct acl_kw_list acl_kws = {{ },{
+	{ "nbsrv",   acl_parse_int,   acl_fetch_nbsrv,    acl_match_int },
+	{ NULL, NULL, NULL, NULL },
+}};
+
+
+__attribute__((constructor))
+static void __backend_init(void)
+{
+	acl_register_keywords(&acl_kws);
+}
+
+
 /*
  * Local variables:
  *  c-indent-level: 8
-- 
1.7.10.4