src/plugin.c: Make `plugin_unregister_read' functional again.

diff --git a/src/plugin.c b/src/plugin.c
index 6139baf..70e0c0f 100644 (file)
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -51,6 +51,7 @@ typedef struct callback_func_s callback_func_t;
 
 #define RF_SIMPLE  0
 #define RF_COMPLEX 1
+#define RF_REMOVE  65535
 struct read_func_s
 {
        /* `read_func_t' "inherits" from `callback_func_t'.
@@ -84,6 +85,7 @@ static c_avl_tree_t *data_sets;
 static char *plugindir = NULL;
 
 static c_heap_t       *read_heap = NULL;
+static llist_t        *read_list;
 static int             read_loop = 1;
 static pthread_mutex_t read_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t  read_cond = PTHREAD_COND_INITIALIZER;
@@ -307,6 +309,7 @@ static void *plugin_read_thread (void __attribute__((unused)) *args)
                read_func_t *rf;
                struct timeval now;
                int status;
+               int rf_type;
 
                /* Get the read function that needs to be read next. */
                rf = c_head_get_root (read_heap);
@@ -344,6 +347,8 @@ static void *plugin_read_thread (void __attribute__((unused)) *args)
                pthread_mutex_lock (&read_lock);
                pthread_cond_timedwait (&read_cond, &read_lock,
                                &rf->rf_next_read);
+               /* Must hold `real_lock' when accessing `rf->rf_type'. */
+               rf_type = rf->rf_type;
                pthread_mutex_unlock (&read_lock);
 
                /* Check if we're supposed to stop.. This may have interrupted
@@ -355,9 +360,22 @@ static void *plugin_read_thread (void __attribute__((unused)) *args)
                        break;
                }
 
+               /* The entry has been marked for deletion. The linked list
+                * entry has already been removed by `plugin_unregister_read'.
+                * All we have to do here is free the `read_func_t' and
+                * continue. */
+               if (rf_type == RF_REMOVE)
+               {
+                       DEBUG ("plugin_read_thread: Destroying the `%s' "
+                                       "callback.", rf->rf_name);
+                       destroy_callback ((callback_func_t *) rf);
+                       rf = NULL;
+                       continue;
+               }
+
                DEBUG ("plugin_read_thread: Handling `%s'.", rf->rf_name);
 
-               if (rf->rf_type == RF_SIMPLE)
+               if (rf_type == RF_SIMPLE)
                {
                        int (*callback) (void);
 
@@ -368,6 +386,8 @@ static void *plugin_read_thread (void __attribute__((unused)) *args)
                {
                        plugin_read_cb callback;
 
+                       assert (rf_type == RF_COMPLEX);
+
                        callback = rf->rf_callback;
                        status = (*callback) (&rf->rf_udata);
                }
@@ -641,22 +661,67 @@ static int plugin_compare_read_func (const void *arg0, const void *arg1)
                return (0);
 } /* int plugin_compare_read_func */
 
-int plugin_register_read (const char *name,
-               int (*callback) (void))
+/* Add a read function to both, the heap and a linked list. The linked list if
+ * used to look-up read functions, especially for the remove function. The heap
+ * is used to determine which plugin to read next. */
+static int plugin_insert_read (read_func_t *rf)
 {
-       read_func_t *rf;
+       int status;
+       llentry_t *le;
+
+       pthread_mutex_lock (&read_lock);
+
+       if (read_list == NULL)
+       {
+               read_list = llist_create ();
+               if (read_list == NULL)
+               {
+                       pthread_mutex_unlock (&read_lock);
+                       ERROR ("plugin_insert_read: read_list failed.");
+                       return (-1);
+               }
+       }
 
        if (read_heap == NULL)
        {
                read_heap = c_heap_create (plugin_compare_read_func);
                if (read_heap == NULL)
                {
-                       ERROR ("plugin_register_read: "
-                                       "c_heap_create failed.");
+                       pthread_mutex_unlock (&read_lock);
+                       ERROR ("plugin_insert_read: c_heap_create failed.");
                        return (-1);
                }
        }
 
+       le = llentry_create (rf->rf_name, rf);
+       if (le == NULL)
+       {
+               pthread_mutex_unlock (&read_lock);
+               ERROR ("plugin_insert_read: llentry_create failed.");
+               return (-1);
+       }
+
+       status = c_heap_insert (read_heap, rf);
+       if (status != 0)
+       {
+               pthread_mutex_unlock (&read_lock);
+               ERROR ("plugin_insert_read: c_heap_insert failed.");
+               llentry_destroy (le);
+               return (-1);
+       }
+
+       /* This does not fail. */
+       llist_append (read_list, le);
+
+       pthread_mutex_unlock (&read_lock);
+       return (0);
+} /* int plugin_insert_read */
+
+int plugin_register_read (const char *name,
+               int (*callback) (void))
+{
+       read_func_t *rf;
+
        rf = (read_func_t *) malloc (sizeof (read_func_t));
        if (rf == NULL)
        {
@@ -676,7 +741,7 @@ int plugin_register_read (const char *name,
        rf->rf_interval.tv_nsec = 0;
        rf->rf_effective_interval = rf->rf_interval;
 
-       return (c_heap_insert (read_heap, rf));
+       return (plugin_insert_read (rf));
 } /* int plugin_register_read */
 
 int plugin_register_complex_read (const char *name,
@@ -686,16 +751,6 @@ int plugin_register_complex_read (const char *name,
 {
        read_func_t *rf;
 
-       if (read_heap == NULL)
-       {
-               read_heap = c_heap_create (plugin_compare_read_func);
-               if (read_heap == NULL)
-               {
-                       ERROR ("plugin_register_read: c_heap_create failed.");
-                       return (-1);
-               }
-       }
-
        rf = (read_func_t *) malloc (sizeof (read_func_t));
        if (rf == NULL)
        {
@@ -724,7 +779,7 @@ int plugin_register_complex_read (const char *name,
                rf->rf_udata = *user_data;
        }
 
-       return (c_heap_insert (read_heap, rf));
+       return (plugin_insert_read (rf));
 } /* int plugin_register_complex_read */
 
 int plugin_register_write (const char *name,
@@ -816,12 +871,37 @@ int plugin_unregister_init (const char *name)
        return (plugin_unregister (list_init, name));
 }
 
-int plugin_unregister_read (const char *name)
+int plugin_unregister_read (const char *name) /* {{{ */
 {
-       /* TODO: Implement removal of a specific key from the heap. */
-       assert (0);
-       return (-1);
-}
+       llentry_t *le;
+       read_func_t *rf;
+
+       if (name == NULL)
+               return (-ENOENT);
+
+       pthread_mutex_lock (&read_lock);
+
+       if (read_list == NULL)
+       {
+               pthread_mutex_unlock (&read_lock);
+               return (-ENOENT);
+       }
+
+       le = llist_search (read_list, name);
+       llist_remove (read_list, le);
+
+       rf = le->value;
+       assert (rf != NULL);
+       rf->rf_type = RF_REMOVE;
+
+       pthread_mutex_unlock (&read_lock);
+
+       llentry_destroy (le);
+
+       DEBUG ("plugin_unregister_read: Marked `%s' for removal.", name);
+
+       return (0);
+} /* }}} int plugin_unregister_read */
 
 int plugin_unregister_write (const char *name)
 {
@@ -1093,6 +1173,12 @@ void plugin_shutdown_all (void)
        stop_read_threads ();
 
        destroy_all_callbacks (&list_init);
+
+       pthread_mutex_lock (&read_lock);
+       llist_destroy (read_list);
+       read_list = NULL;
+       pthread_mutex_unlock (&read_lock);
+
        destroy_read_heap ();
 
        plugin_flush (/* plugin = */ NULL, /* timeout = */ -1,