light: show runtime connection status information

kernel/Kconfig

@@ -196,6 +196,32 @@ config MARS_LOADAVG_LIMIT
 	---help---
 	Normally ON.
 
+config MARS_SHOW_CONNECTIONS
+	bool "show connection status symlinks"
+	depends on MARS
+	default n
+	---help---
+	Normally OFF.
+
+	When enabled, the status of all current network connections is
+	written to /mars/resource-$resource/local-$host/connect-*
+	showing the current status of all network connections by
+	the following encoding:
+
+	  -1 = connection is closed (not intended to start)
+	   0 = connection is interrupted / not established
+	   1 = connection is established at TCP level
+
+	Warning! the symlinks are not deleted by the kernel. You have
+	to cleanup old symlinks by yourself in userspace.
+
+	When you forget the cleanup in regular intervals, you may
+	end up with thoundands of symlinks accumulating in the
+	/mars/resource-$resource/local-$host/ directory over a
+	longer time.
+
+	If unsure, say N here.
+
 #config MARS_HUNG
 #	bool "hangup on kernel stacktrace (EXPERIMENTAL!!!)"
 #	depends on MARS && MARS_BIGMODULE!=m

kernel/mars_client.c

@@ -31,6 +31,7 @@ static void _kill_thread(struct client_threadinfo *ti, const char *name)
 
 static void _kill_socket(struct client_output *output)
 {
+	output->brick->connection_state = 1;
 	if (mars_socket_is_alive(&output->socket)) {
 		MARS_DBG("shutdown socket\n");
 		mars_shutdown_socket(&output->socket);
@@ -485,6 +486,7 @@ static int sender_thread(void *data)
 				_do_timeout(output, &output->mref_list, false);
 				continue;
 			}
+			brick->connection_state = 2;
 			do_kill = true;
 			/* Re-Submit any waiting requests
 			 */
@@ -584,6 +586,7 @@ static int client_switch(struct client_brick *brick)
 	if (brick->power.button) {
 		mars_power_led_off((void*)brick, false);
 		if (!output->sender.thread) {
+			brick->connection_state = 1;
 			output->sender.thread = brick_thread_create(sender_thread, output, "mars_sender%d", thread_count++);
 			if (unlikely(!output->sender.thread)) {
 				MARS_ERR("cannot start sender thread\n");
@@ -597,6 +600,7 @@ static int client_switch(struct client_brick *brick)
 	} else {
 		mars_power_led_on((void*)brick, false);
 		_kill_thread(&output->sender, "sender");
+		brick->connection_state = 0;
 		if (!output->sender.thread) {
 			mars_power_led_off((void*)brick, !output->sender.thread);
 		}

kernel/mars_client.h

@@ -26,6 +26,8 @@ struct client_brick {
 	int max_flying; // limit on parallelism
 	int io_timeout;    // > 0: report IO errors after timeout (in seconds)
 	bool limit_mode;
+	// readonly from outside
+	int connection_state; // 0 = switched off, 1 = not connected, 2 = connected
 };
 
 struct client_input {

kernel/sy_old/mars_proc.c

@@ -204,6 +204,7 @@ ctl_table mars_table[] = {
 #ifdef CONFIG_MARS_DEBUG
 	INT_ENTRY("show_debug_messages",  brick_say_debug,        0600),
 	INT_ENTRY("show_statistics",      global_show_statist,    0600),
+	INT_ENTRY("show_connections",     global_show_connections, 0600),
 #endif
 	INT_ENTRY("logger_completion_semantics", trans_logger_completion_semantics, 0600),
 	INT_ENTRY("logger_do_crc",        trans_logger_do_crc,    0600),

kernel/sy_old/strategy.h

@@ -164,6 +164,7 @@ extern int  mars_power_button_recursive(struct mars_brick *brick, bool val, bool
 // statistics
 
 extern int global_show_statist;
+extern int global_show_connections;
 
 void show_statistics(struct mars_global *global, const char *class);
 

kernel/sy_old/sy_generic.c

@@ -1571,6 +1571,25 @@ EXPORT_SYMBOL_GPL(make_brick_all);
 
 /////////////////////////////////////////////////////////////////////////
 
+// generic symlink updates
+
+void update_client_links(struct client_brick *brick)
+{
+	char val[8];
+	const char *name;
+
+	name = backskip_replace(brick->brick_path, '/', true, "/local-%s/connection-", my_id());
+	if (unlikely(!name))
+		return; // silently
+
+	sprintf(val, "%d", brick->connection_state - 1);
+	mars_symlink(val, name, NULL, 0);
+
+	brick_string_free(name);
+}
+
+/////////////////////////////////////////////////////////////////////////
+
 // statistics
 
 int global_show_statist =
@@ -1581,6 +1600,14 @@ int global_show_statist =
 #endif
 EXPORT_SYMBOL_GPL(global_show_statist);
 
+int global_show_connections =
+#ifdef CONFIG_MARS_SHOW_CONNECTIONS
+	1;
+#else
+	0;
+#endif
+EXPORT_SYMBOL_GPL(global_show_connections);
+
 static
 void _show_one(struct mars_brick *test, int *brick_count)
 {
@@ -1637,6 +1664,19 @@ void show_statistics(struct mars_global *global, const char *class)
 	int dent_count = 0;
 	int brick_count = 0;
 
+	// update all connection state symlinks
+	if (global_show_connections) {
+		down_read(&global->brick_mutex);
+		for (tmp = global->brick_anchor.next; tmp != &global->brick_anchor; tmp = tmp->next) {
+			struct mars_brick *test;
+			test = container_of(tmp, struct mars_brick, global_brick_link);
+			if (test->type == (void*)&client_brick_type) {
+				update_client_links((void*)test);
+			}
+		}
+		up_read(&global->brick_mutex);
+	}
+
 	if (!global_show_statist)
 		return; // silently
 	

userspace/marsadm

@@ -633,6 +633,7 @@ sub create_res {
   mkdir("$tmp/userspace") unless -d "$tmp/userspace";
   mkdir("$tmp/defaults") unless -d "$tmp/defaults";
   mkdir("$tmp/defaults-$host");
+  mkdir("$tmp/local-$host");
   mkdir("$tmp/actual-$host");
   my $todo = "$tmp/todo-$host";
   mkdir($todo);