src/plugin.c: Make plugin_load() idempotent, i.e. don't load plugins twice.

[collectd.git] / src / plugin.c

diff --git a/src/plugin.c b/src/plugin.c
index b2a8b86..386be32 100644 (file)
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -81,6 +81,8 @@ struct write_queue_s
 /*
  * Private variables
  */
+static c_avl_tree_t *plugins_loaded = NULL;
+
 static llist_t *list_init;
 static llist_t *list_write;
 static llist_t *list_flush;
@@ -831,8 +833,52 @@ void plugin_set_dir (const char *dir)
        }
 }
 
+static _Bool plugin_is_loaded (char const *name)
+{
+       int status;
+
+       if (plugins_loaded == NULL)
+               plugins_loaded = c_avl_create ((void *) strcasecmp);
+       assert (plugins_loaded != NULL);
+
+       status = c_avl_get (plugins_loaded, name, /* ret_value = */ NULL);
+       return (status == 0);
+}
+
+static int plugin_mark_loaded (char const *name)
+{
+       char *name_copy;
+       int status;
+
+       name_copy = strdup (name);
+       if (name_copy == NULL)
+               return (ENOMEM);
+
+       status = c_avl_insert (plugins_loaded,
+                       /* key = */ name_copy, /* value = */ NULL);
+       return (status);
+}
+
+static void plugin_free_loaded ()
+{
+       void *key;
+       void *value;
+
+       if (plugins_loaded == NULL)
+               return;
+
+       while (c_avl_pick (plugins_loaded, &key, &value) == 0)
+       {
+               sfree (key);
+               assert (value == NULL);
+       }
+
+       c_avl_destroy (plugins_loaded);
+       plugins_loaded = NULL;
+}
+
 #define BUFSIZE 512
-int plugin_load (const char *type, uint32_t flags)
+int plugin_load (char const *plugin_name, uint32_t flags)
 {
        DIR  *dh;
        const char *dir;
@@ -844,15 +890,23 @@ int plugin_load (const char *type, uint32_t flags)
        struct dirent *de;
        int status;
 
+       if (plugin_name == NULL)
+               return (EINVAL);
+
+       /* Check if plugin is already loaded and don't do anything in this
+        * case. */
+       if (plugin_is_loaded (plugin_name))
+               return (0);
+
        dir = plugin_get_dir ();
        ret = 1;
 
        /* `cpu' should not match `cpufreq'. To solve this we add `.so' to the
         * type when matching the filename */
-       status = ssnprintf (typename, sizeof (typename), "%s.so", type);
+       status = ssnprintf (typename, sizeof (typename), "%s.so", plugin_name);
        if ((status < 0) || ((size_t) status >= sizeof (typename)))
        {
-               WARNING ("plugin_load: Filename too long: \"%s.so\"", type);
+               WARNING ("plugin_load: Filename too long: \"%s.so\"", plugin_name);
                return (-1);
        }
        typename_len = strlen (typename);
@@ -899,13 +953,14 @@ int plugin_load (const char *type, uint32_t flags)
                if (status == 0)
                {
                        /* success */
+                       plugin_mark_loaded (plugin_name);
                        ret = 0;
                        break;
                }
                else
                {
                        ERROR ("plugin_load: Load plugin \"%s\" failed with "
-                                       "status %i.", type, status);
+                                       "status %i.", plugin_name, status);
                }
        }
 
@@ -913,7 +968,7 @@ int plugin_load (const char *type, uint32_t flags)
 
        if (filename[0] == 0)
                ERROR ("plugin_load: Could not find plugin \"%s\" in %s",
-                               type, dir);
+                               plugin_name, dir);
 
        return (ret);
 }
@@ -1658,6 +1713,8 @@ void plugin_shutdown_all (void)
        destroy_all_callbacks (&list_notification);
        destroy_all_callbacks (&list_shutdown);
        destroy_all_callbacks (&list_log);
+
+       plugin_free_loaded ();
 } /* void plugin_shutdown_all */
 
 int plugin_dispatch_missing (const value_list_t *vl) /* {{{ */