MINOR: proxy: Be able to reference the defaults section used by a proxy

A proxy may now references the defaults section it is used. To do so, a
pointer on the default proxy was added in the proxy structure. And a
refcount must be used to track proxies using a default proxy. A default
proxy is destroyed iff its refcount is equal to zero and when it drops to
zero.

All this stuff must be performed during init/deinit staged for now. All
unreferenced default proxies are removed after the configuration parsing.

This patch is mandatory to support TCP/HTTP rules in defaults sections.

include/haproxy/proxy-t.h

@@ -275,6 +275,7 @@ struct proxy {
 		struct proxy *be;		/* default backend, or NULL if none set */
 		char *name;			/* default backend name during config parse */
 	} defbe;
+	struct proxy *defpx;                    /* default proxy used to init this one (may be NULL) */
 	struct list acl;                        /* ACL declared on this proxy */
 	struct list http_req_rules;		/* HTTP request rules: allow/deny/... */
 	struct list http_res_rules;		/* HTTP response rules: allow/deny/... */
@@ -421,6 +422,7 @@ struct proxy {
 		struct list listeners;		/* list of listeners belonging to this frontend */
 		struct list errors;             /* list of all custom error files */
 		struct arg_list args;           /* sample arg list that need to be resolved */
+		unsigned int refcount;          /* refcount on this proxy (only used for default proxy for now) */
 		struct ebpt_node by_name;       /* proxies are stored sorted by name here */
 		char *logformat_string;		/* log format string */
 		char *lfs_file;                 /* file name where the logformat string appears (strdup) */

include/haproxy/proxy.h

@@ -61,7 +61,9 @@ void init_new_proxy(struct proxy *p);
 void proxy_preset_defaults(struct proxy *defproxy);
 void proxy_free_defaults(struct proxy *defproxy);
 void proxy_destroy_defaults(struct proxy *px);
-void proxy_destroy_all_defaults(void);
+void proxy_destroy_all_unref_defaults(void);
+void proxy_ref_defaults(struct proxy *px, struct proxy *defpx);
+void proxy_unref_defaults(struct proxy *px);
 struct proxy *alloc_new_proxy(const char *name, unsigned int cap,
                               char **errmsg);
 struct proxy *parse_new_proxy(const char *name, unsigned int cap,

src/haproxy.c

@@ -1990,8 +1990,9 @@ static void init(int argc, char **argv)
 		ha_warning("a master CLI socket was defined, but master-worker mode (-W) is not enabled.\n");
 	}
 
-	/* defaults sections are not needed anymore */
-	proxy_destroy_all_defaults();
+	/* destroy unreferenced defaults proxies  */
+	proxy_destroy_all_unref_defaults();
+
 
 	err_code |= check_config_validity();
 	for (px = proxies_list; px; px = px->next) {
@@ -2483,6 +2484,9 @@ void deinit(void)
 		free_proxy(p0);
 	}/* end while(p) */
 
+	/* destroy all referenced defaults proxies  */
+	proxy_destroy_all_unref_defaults();
+
 	while (ua) {
 		struct stat_scope *scope, *scopep;
 

src/proxy.c

@@ -146,6 +146,7 @@ void free_proxy(struct proxy *p)
 	if (!p)
 		return;
 
+	proxy_unref_defaults(p);
 	free(p->conf.file);
 	free(p->id);
 	free(p->cookie_name);
@@ -1471,22 +1472,57 @@ void proxy_destroy_defaults(struct proxy *px)
 		return;
 	if (!(px->cap & PR_CAP_DEF))
 		return;
+	BUG_ON(px->conf.refcount != 0);
 	ebpt_delete(&px->conf.by_name);
 	proxy_free_defaults(px);
 	free(px);
 }
 
-void proxy_destroy_all_defaults()
+/* delete all unreferenced default proxies. A default proxy is unreferenced if
+ * its refcount is equal to zero.
+ */
+void proxy_destroy_all_unref_defaults()
 {
 	struct ebpt_node *n;
 
-	while ((n = ebpt_first(&defproxy_by_name))) {
+	n = ebpt_first(&defproxy_by_name);
+	while (n) {
 		struct proxy *px = container_of(n, struct proxy, conf.by_name);
 		BUG_ON(!(px->cap & PR_CAP_DEF));
-		proxy_destroy_defaults(px);
+		n = ebpt_next(n);
+		if (!px->conf.refcount)
+			proxy_destroy_defaults(px);
 	}
 }
 
+/* Add a reference on the default proxy <defpx> for the proxy <px> Nothing is
+ * done if <px> already references <defpx>. Otherwise, the default proxy
+ * refcount is incremented by one. For now, this operation is not thread safe
+ * and is perform during init stage only.
+ */
+void proxy_ref_defaults(struct proxy *px, struct proxy *defpx)
+{
+	if (px->defpx == defpx)
+		return;
+	BUG_ON(px->defpx != NULL);
+	px->defpx = defpx;
+	defpx->conf.refcount++;
+}
+
+/* proxy <px> removes its reference on its default proxy. The default proxy
+ * refcount is decremented by one. If it was the last reference, the
+ * corresponding default proxy is destroyed. For now this operation is not
+ * thread safe and is performed during deinit staged only.
+*/
+void proxy_unref_defaults(struct proxy *px)
+{
+	if (px->defpx == NULL)
+		return;
+	if (!--px->defpx->conf.refcount)
+		proxy_destroy_defaults(px->defpx);
+	px->defpx = NULL;
+}
+
 /* Allocates a new proxy <name> of type <cap>.
  * Returns the proxy instance on success. On error, NULL is returned.
  */