Allow res_calendar to be unloaded

The calendaring tech modules depend on res_calendar and initially
res_calendar just bumped the use count so that it couldn't be unloaded.
res_calendar can potentially create many threads and I've seen issues
where the Asterisk shutdown has failed where it looked like these
threads could be the culprit.

This patch adds unload support for res_calendar. Unloading res_calendar
will also unload the dependant tech modules as well.

(closes issue ASTERISK-16744)
Review: https://reviewboard.asterisk.org/r/1657/
........

Merged revisions 353502 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 353503 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@353504 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_calendar.c

@@ -216,6 +216,7 @@ static pthread_t refresh_thread = AST_PTHREADT_NULL;
 static ast_mutex_t refreshlock;
 static ast_cond_t refresh_condition;
 static ast_mutex_t reloadlock;
+static int module_unloading;
 
 static void event_notification_destroy(void *data);
 static void *event_notification_duplicate(void *data);
@@ -1013,9 +1014,9 @@ void ast_calendar_merge_events(struct ast_calendar *cal, struct ao2_container *n
 }
 
 
-static int load_config(void *data)
+static int load_config(int reload)
 {
-	struct ast_flags config_flags = { CONFIG_FLAG_FILEUNCHANGED };
+	struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };
 	struct ast_config *tmpcfg;
 
 	if (!(tmpcfg = ast_config_load2("calendar.conf", "calendar", config_flags)) ||
@@ -1734,7 +1735,7 @@ static int reload(void)
 
 	/* Mark existing calendars for deletion */
 	ao2_callback(calendars, OBJ_NODATA | OBJ_MULTIPLE, cb_pending_deletion, NULL);
-	load_config(NULL);
+	load_config(1);
 
 	AST_LIST_LOCK(&techs);
 	AST_LIST_TRAVERSE(&techs, iter, list) {
@@ -1761,15 +1762,21 @@ static void *do_refresh(void *data)
 
 		ast_mutex_lock(&refreshlock);
 
-		if ((wait = ast_sched_wait(sched)) < 0) {
-			wait = 1000;
-		}
-
-		ts.tv_sec = (now.tv_sec + wait / 1000) + 1;
-		ast_cond_timedwait(&refresh_condition, &refreshlock, &ts);
+		while (!module_unloading) {
+			if ((wait = ast_sched_wait(sched)) < 0) {
+				wait = 1000;
+			}
 
+			ts.tv_sec = (now.tv_sec + wait / 1000) + 1;
+			if (ast_cond_timedwait(&refresh_condition, &refreshlock, &ts) == ETIMEDOUT) {
+				break;
+			}
+		}
 		ast_mutex_unlock(&refreshlock);
 
+		if (module_unloading) {
+			break;
+		}
 		ast_sched_runq(sched);
 	}
 
@@ -1792,12 +1799,22 @@ static int unload_module(void)
 	/* Remove all calendars */
 	ao2_callback(calendars, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, NULL, NULL);
 
+	ast_mutex_lock(&refreshlock);
+	module_unloading = 1;
+	ast_cond_signal(&refresh_condition);
+	ast_mutex_unlock(&refreshlock);
+	pthread_join(refresh_thread, NULL);
+
 	AST_LIST_LOCK(&techs);
-	AST_LIST_TRAVERSE(&techs, tech, list) {
+	AST_LIST_TRAVERSE_SAFE_BEGIN(&techs, tech, list) {
 		ast_unload_resource(tech->module, 0);
 	}
+	AST_LIST_TRAVERSE_SAFE_END;
 	AST_LIST_UNLOCK(&techs);
 
+	ast_config_destroy(calendar_config);
+	calendar_config = NULL;
+
 	return 0;
 }
 
@@ -1808,7 +1825,7 @@ static int load_module(void)
 		return AST_MODULE_LOAD_FAILURE;
 	}
 
-	if (load_config(NULL)) {
+	if (load_config(0)) {
 		/* We don't have calendar support enabled */
 		return AST_MODULE_LOAD_DECLINE;
 	}
@@ -1835,9 +1852,6 @@ static int load_module(void)
 
 	ast_devstate_prov_add("Calendar", calendarstate);
 
-	/* Since other modules depend on this, disable unloading */
-	ast_module_ref(ast_module_info->self);
-
 	return AST_MODULE_LOAD_SUCCESS;
 }
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "Asterisk Calendar integration",