MINOR: checks/event_hdl: SERVER_CHECK event

Adding a new event type: SERVER_CHECK.

This event is published when a server's check state ought to be reported.
(check status change or check result)

SERVER_CHECK event is provided as a server event with additional data
carrying relevant check's context such as check's result and health.

include/haproxy/event_hdl-t.h

@@ -272,6 +272,8 @@ struct event_hdl_sub {
 #define EVENT_HDL_SUB_SERVER_STATE                      EVENT_HDL_SUB_TYPE(1,5)
 /* server admin change */
 #define EVENT_HDL_SUB_SERVER_ADMIN                      EVENT_HDL_SUB_TYPE(1,6)
+/* server check-related (agent or health) event */
+#define EVENT_HDL_SUB_SERVER_CHECK                      EVENT_HDL_SUB_TYPE(1,7)
 
 /*	---------------------------------------        */
 

include/haproxy/server-t.h

@@ -443,6 +443,7 @@ struct event_hdl_cb_data_server {
 	 *   EVENT_HDL_SUB_SERVER_DOWN
 	 *   EVENT_HDL_SUB_SERVER_STATE
 	 *   EVENT_HDL_SUB_SERVER_ADMIN
+	 *   EVENT_HDL_SUB_SERVER_CHECK
 	 */
 	struct {
 		/* safe data can be safely used from both
@@ -543,6 +544,25 @@ struct event_hdl_cb_data_server_admin {
 	/* no unsafe data */
 };
 
+/* data provided to EVENT_HDL_SUB_SERVER_CHECK handlers through
+ * event_hdl facility
+ *
+ * Note that this may be casted to regular event_hdl_cb_data_server if
+ * you don't care about check related optional info
+ */
+struct event_hdl_cb_data_server_check {
+	/* provided by:
+	 *   EVENT_HDL_SUB_SERVER_CHECK
+	 */
+	struct event_hdl_cb_data_server server;                 /* must be at the beginning */
+	struct {
+		struct event_hdl_cb_data_server_checkres res;   /* check result snapshot */
+	} safe;
+	struct {
+		struct check *ptr;                              /* check ptr */
+	} unsafe;
+};
+
 /* Storage structure to load server-state lines from a flat file into
  * an ebtree, for faster processing
  */

include/haproxy/server.h

@@ -66,6 +66,7 @@ int srv_init_per_thr(struct server *srv);
 void srv_set_ssl(struct server *s, int use_ssl);
 const char *srv_adm_st_chg_cause(enum srv_adm_st_chg_cause cause);
 const char *srv_op_st_chg_cause(enum srv_op_st_chg_cause cause);
+void srv_event_hdl_publish_check(struct server *srv, struct check *check);
 
 /* functions related to server name resolution */
 int srv_prepare_for_resolution(struct server *srv, const char *hostname);

src/check.c

@@ -464,7 +464,7 @@ void set_server_check_status(struct check *check, short status, const char *desc
 {
 	struct server *s = check->server;
 	short prev_status = check->status;
-	int report = 0;
+	int report = (status != prev_status) ? 1 : 0;
 
 	TRACE_POINT(CHK_EV_HCHK_RUN, check);
 
@@ -505,8 +505,6 @@ void set_server_check_status(struct check *check, short status, const char *desc
 	 */
 	if (!s)
 	    return;
-	report = 0;
-
 
 	switch (check->result) {
 	case CHK_RES_FAILED:
@@ -543,8 +541,10 @@ void set_server_check_status(struct check *check, short status, const char *desc
 		break;
 	}
 
-	if (s->proxy->options2 & PR_O2_LOGHCHKS &&
-	    (status != prev_status || report)) {
+	if (report)
+		srv_event_hdl_publish_check(s, check);
+
+	if (s->proxy->options2 & PR_O2_LOGHCHKS && report) {
 		chunk_printf(&trash,
 		             "%s check for %sserver %s/%s %s%s",
 			     (check->state & CHK_ST_AGENT) ? "Agent" : "Health",

src/event_hdl.c

@@ -31,6 +31,7 @@ static struct event_hdl_sub_type_map event_hdl_sub_type_map[] = {
 	{"SERVER_DOWN",         EVENT_HDL_SUB_SERVER_DOWN},
 	{"SERVER_STATE",        EVENT_HDL_SUB_SERVER_STATE},
 	{"SERVER_ADMIN",        EVENT_HDL_SUB_SERVER_ADMIN},
+	{"SERVER_CHECK",        EVENT_HDL_SUB_SERVER_CHECK},
 };
 
 /* internal types (only used in this file) */

src/server.c

@@ -262,6 +262,27 @@ static void srv_event_hdl_publish(struct event_hdl_sub_type event,
 	_srv_event_hdl_publish(event, cb_data, srv);
 }
 
+/* Publish SERVER_CHECK event
+ *
+ * This special event will contain extra hints related to the check itself
+ *
+ * Must be called with server lock held
+ */
+void srv_event_hdl_publish_check(struct server *srv, struct check *check)
+{
+	struct event_hdl_cb_data_server_check cb_data;
+
+	/* check event provides additional info about the server check */
+	_srv_event_hdl_prepare_checkres(&cb_data.safe.res, check);
+
+	cb_data.unsafe.ptr = check;
+
+	/* prepare event data (common server data) */
+	_srv_event_hdl_prepare((struct event_hdl_cb_data_server *)&cb_data, srv, 0);
+
+	_srv_event_hdl_publish(EVENT_HDL_SUB_SERVER_CHECK, cb_data, srv);
+}
+
 /*
  * Check that we did not get a hash collision.
  * Unlikely, but it can happen. The server's proxy must be at least