src/plugin.c: plugin_log: Print to stderr if no log plugin has been loaded.
[collectd.git] / src / plugin.c
index 41a816f..24e5e01 100644 (file)
@@ -34,6 +34,7 @@
 #include "configfile.h"
 #include "utils_avltree.h"
 #include "utils_llist.h"
+#include "utils_heap.h"
 #include "utils_cache.h"
 #include "utils_threshold.h"
 #include "filter_chain.h"
 /*
  * Private structures
  */
+struct callback_func_s
+{
+       void *cf_callback;
+       user_data_t cf_udata;
+};
+typedef struct callback_func_s callback_func_t;
+
 #define RF_SIMPLE  0
 #define RF_COMPLEX 1
+#define RF_REMOVE  65535
 struct read_func_s
 {
-       int wait_time;
-       int wait_left;
-       int type;
-       union
-       {
-               int (*cb_simple) (void);
-               plugin_read_cb cb_complex;
-       } callback;
-       enum { DONE = 0, TODO = 1, ACTIVE = 2 } needs_read;
-       user_data_t udata;
+       /* `read_func_t' "inherits" from `callback_func_t'.
+        * The `rf_super' member MUST be the first one in this structure! */
+#define rf_callback rf_super.cf_callback
+#define rf_udata rf_super.cf_udata
+       callback_func_t rf_super;
+       char rf_name[DATA_MAX_NAME_LEN];
+       int rf_type;
+       struct timespec rf_interval;
+       struct timespec rf_effective_interval;
+       struct timespec rf_next_read;
 };
 typedef struct read_func_s read_func_t;
 
-struct write_func_s
-{
-       plugin_write_cb callback;
-       user_data_t udata;
-};
-typedef struct write_func_s write_func_t;
-
-struct flush_func_s
-{
-       plugin_flush_cb callback;
-       user_data_t udata;
-};
-typedef struct flush_func_s flush_func_t;
-
-struct log_func_s
-{
-       plugin_log_cb callback;
-       user_data_t udata;
-};
-typedef struct log_func_s log_func_t;
-
 /*
  * Private variables
  */
 static llist_t *list_init;
-static llist_t *list_read;
 static llist_t *list_write;
 static llist_t *list_flush;
 static llist_t *list_shutdown;
@@ -97,6 +84,8 @@ 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;
@@ -114,26 +103,101 @@ static const char *plugin_get_dir (void)
                return (plugindir);
 }
 
-static int register_callback (llist_t **list, const char *name, void *callback)
+static void destroy_callback (callback_func_t *cf) /* {{{ */
+{
+       if (cf == NULL)
+               return;
+
+       if ((cf->cf_udata.data != NULL) && (cf->cf_udata.free_func != NULL))
+       {
+               cf->cf_udata.free_func (cf->cf_udata.data);
+               cf->cf_udata.data = NULL;
+               cf->cf_udata.free_func = NULL;
+       }
+       sfree (cf);
+} /* }}} void destroy_callback */
+
+static void destroy_all_callbacks (llist_t **list) /* {{{ */
+{
+       llentry_t *le;
+
+       if (*list == NULL)
+               return;
+
+       le = llist_head (*list);
+       while (le != NULL)
+       {
+               llentry_t *le_next;
+
+               le_next = le->next;
+
+               sfree (le->key);
+               destroy_callback (le->value);
+               le->value = NULL;
+
+               le = le_next;
+       }
+
+       llist_destroy (*list);
+       *list = NULL;
+} /* }}} void destroy_all_callbacks */
+
+static void destroy_read_heap (void) /* {{{ */
+{
+       if (read_heap == NULL)
+               return;
+
+       while (42)
+       {
+               callback_func_t *cf;
+
+               cf = c_head_get_root (read_heap);
+               if (cf == NULL)
+                       break;
+
+               destroy_callback (cf);
+       }
+
+       c_heap_destroy (read_heap);
+       read_heap = NULL;
+} /* }}} void destroy_read_heap */
+
+static int register_callback (llist_t **list, /* {{{ */
+               const char *name, callback_func_t *cf)
 {
        llentry_t *le;
        char *key;
 
-       if ((*list == NULL)
-                       && ((*list = llist_create ()) == NULL))
+       if (*list == NULL)
+       {
+               *list = llist_create ();
+               if (*list == NULL)
+               {
+                       ERROR ("plugin: create_register_callback: "
+                                       "llist_create failed.");
+                       destroy_callback (cf);
+                       return (-1);
+               }
+       }
+
+       key = strdup (name);
+       if (key == NULL)
+       {
+               ERROR ("plugin: create_register_callback: strdup failed.");
+               destroy_callback (cf);
                return (-1);
+       }
 
        le = llist_search (*list, name);
        if (le == NULL)
        {
-               key = strdup (name);
-               if (key == NULL)
-                       return (-1);
-
-               le = llentry_create (key, callback);
+               le = llentry_create (key, cf);
                if (le == NULL)
                {
+                       ERROR ("plugin: create_register_callback: "
+                                       "llentry_create failed.");
                        free (key);
+                       destroy_callback (cf);
                        return (-1);
                }
 
@@ -141,37 +205,65 @@ static int register_callback (llist_t **list, const char *name, void *callback)
        }
        else
        {
-               le->value = callback;
+               callback_func_t *old_cf;
+
+               old_cf = le->value;
+               le->value = cf;
+
+               destroy_callback (old_cf);
+               sfree (key);
        }
 
        return (0);
-} /* int register_callback */
+} /* }}} int register_callback */
 
-static void plugin_user_data_destroy (user_data_t *ud)
+static int create_register_callback (llist_t **list, /* {{{ */
+               const char *name, void *callback, user_data_t *ud)
 {
-       if ((ud != NULL) && (ud->data != NULL) && (ud->free_func != NULL))
+       callback_func_t *cf;
+
+       cf = (callback_func_t *) malloc (sizeof (*cf));
+       if (cf == NULL)
+       {
+               ERROR ("plugin: create_register_callback: malloc failed.");
+               return (-1);
+       }
+       memset (cf, 0, sizeof (*cf));
+
+       cf->cf_callback = callback;
+       if (ud == NULL)
        {
-               ud->free_func (ud->data);
-               ud->data = NULL;
-               ud->free_func = NULL;
+               cf->cf_udata.data = NULL;
+               cf->cf_udata.free_func = NULL;
        }
-} /* void plugin_user_data_destroy */
+       else
+       {
+               cf->cf_udata = *ud;
+       }
+
+       return (register_callback (list, name, cf));
+} /* }}} int create_register_callback */
 
-static int plugin_unregister (llist_t *list, const char *name)
+static int plugin_unregister (llist_t *list, const char *name) /* {{{ */
 {
        llentry_t *e;
 
-       e = llist_search (list, name);
+       if (list == NULL)
+               return (-1);
 
+       e = llist_search (list, name);
        if (e == NULL)
                return (-1);
 
        llist_remove (list, e);
-       free (e->key);
+
+       sfree (e->key);
+       destroy_callback (e->value);
+
        llentry_destroy (e);
 
        return (0);
-} /* int plugin_unregister */
+} /* }}} int plugin_unregister */
 
 /*
  * (Try to) load the shared object `file'. Won't complain if it isn't a shared
@@ -212,80 +304,156 @@ static int plugin_load_file (char *file)
 
 static void *plugin_read_thread (void __attribute__((unused)) *args)
 {
-       llentry_t   *le;
-       read_func_t *rf;
-       int          status;
-       int          done;
-
-       pthread_mutex_lock (&read_lock);
-
        while (read_loop != 0)
        {
-               le = llist_head (list_read);
-               done = 0;
+               read_func_t *rf;
+               struct timeval now;
+               int status;
+               int rf_type;
 
-               while ((read_loop != 0) && (le != NULL))
+               /* Get the read function that needs to be read next. */
+               rf = c_head_get_root (read_heap);
+               if (rf == NULL)
                {
-                       rf = (read_func_t *) le->value;
+                       struct timespec abstime;
 
-                       if (rf->needs_read != TODO)
-                       {
-                               le = le->next;
-                               continue;
-                       }
+                       gettimeofday (&now, /* timezone = */ NULL);
 
-                       /* We will do this read function */
-                       rf->needs_read = ACTIVE;
+                       abstime.tv_sec = now.tv_sec + interval_g;
+                       abstime.tv_nsec = 1000 * now.tv_usec;
 
-                       DEBUG ("[thread #%5lu] plugin: plugin_read_thread: Handling %s",
-                                       (unsigned long int) pthread_self (), le->key);
+                       pthread_mutex_lock (&read_lock);
+                       pthread_cond_timedwait (&read_cond, &read_lock,
+                                       &abstime);
                        pthread_mutex_unlock (&read_lock);
+                       continue;
+               }
 
-                       if (rf->type == RF_SIMPLE)
-                       {
-                               status = rf->callback.cb_simple ();
-                       }
-                       else
-                       {
-                               assert (rf->type == RF_COMPLEX);
-                               status = rf->callback.cb_complex (&rf->udata);
-                       }
-                       done++;
+               if ((rf->rf_interval.tv_sec == 0) && (rf->rf_interval.tv_nsec == 0))
+               {
+                       gettimeofday (&now, /* timezone = */ NULL);
 
-                       if (status != 0)
-                       {
-                               if (rf->wait_time < interval_g)
-                                       rf->wait_time = interval_g;
-                               rf->wait_left = rf->wait_time;
-                               rf->wait_time = rf->wait_time * 2;
-                               if (rf->wait_time > 86400)
-                                       rf->wait_time = 86400;
-
-                               NOTICE ("read-function of plugin `%s' "
-                                               "failed. Will suspend it for %i "
-                                               "seconds.", le->key, rf->wait_left);
-                       }
-                       else
+                       rf->rf_interval.tv_sec = interval_g;
+                       rf->rf_interval.tv_nsec = 0;
+
+                       rf->rf_effective_interval = rf->rf_interval;
+
+                       rf->rf_next_read.tv_sec = now.tv_sec;
+                       rf->rf_next_read.tv_nsec = 1000 * now.tv_usec;
+               }
+
+               /* sleep until this entry is due,
+                * using pthread_cond_timedwait */
+               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
+                * the sleep, too. */
+               if (read_loop == 0)
+               {
+                       /* Insert `rf' again, so it can be free'd correctly */
+                       c_heap_insert (read_heap, rf);
+                       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_type == RF_SIMPLE)
+               {
+                       int (*callback) (void);
+
+                       callback = rf->rf_callback;
+                       status = (*callback) ();
+               }
+               else
+               {
+                       plugin_read_cb callback;
+
+                       assert (rf_type == RF_COMPLEX);
+
+                       callback = rf->rf_callback;
+                       status = (*callback) (&rf->rf_udata);
+               }
+
+               /* If the function signals failure, we will increase the
+                * intervals in which it will be called. */
+               if (status != 0)
+               {
+                       rf->rf_effective_interval.tv_sec *= 2;
+                       rf->rf_effective_interval.tv_nsec *= 2;
+                       NORMALIZE_TIMESPEC (rf->rf_effective_interval);
+
+                       if (rf->rf_effective_interval.tv_sec >= 86400)
                        {
-                               rf->wait_left = 0;
-                               rf->wait_time = interval_g;
+                               rf->rf_effective_interval.tv_sec = 86400;
+                               rf->rf_effective_interval.tv_nsec = 0;
                        }
 
-                       pthread_mutex_lock (&read_lock);
-
-                       rf->needs_read = DONE;
-                       le = le->next;
-               } /* while (le != NULL) */
+                       NOTICE ("read-function of plugin `%s' failed. "
+                                       "Will suspend it for %i seconds.",
+                                       rf->rf_name,
+                                       (int) rf->rf_effective_interval.tv_sec);
+               }
+               else
+               {
+                       /* Success: Restore the interval, if it was changed. */
+                       rf->rf_effective_interval = rf->rf_interval;
+               }
 
-               if ((read_loop != 0) && (done == 0))
+               /* update the ``next read due'' field */
+               gettimeofday (&now, /* timezone = */ NULL);
+
+               DEBUG ("plugin_read_thread: Effective interval of the "
+                               "%s plugin is %i.%09i.",
+                               rf->rf_name,
+                               (int) rf->rf_effective_interval.tv_sec,
+                               (int) rf->rf_effective_interval.tv_nsec);
+
+               /* Calculate the next (absolute) time at which this function
+                * should be called. */
+               rf->rf_next_read.tv_sec = rf->rf_next_read.tv_sec
+                       + rf->rf_effective_interval.tv_sec;
+               rf->rf_next_read.tv_nsec = rf->rf_next_read.tv_nsec
+                       + rf->rf_effective_interval.tv_nsec;
+               NORMALIZE_TIMESPEC (rf->rf_next_read);
+
+               /* Check, if `rf_next_read' is in the past. */
+               if ((rf->rf_next_read.tv_sec < now.tv_sec)
+                               || ((rf->rf_next_read.tv_sec == now.tv_sec)
+                                       && (rf->rf_next_read.tv_nsec < (1000 * now.tv_usec))))
                {
-                       DEBUG ("[thread #%5lu] plugin: plugin_read_thread: Waiting on read_cond.",
-                                       (unsigned long int) pthread_self ());
-                       pthread_cond_wait (&read_cond, &read_lock);
+                       /* `rf_next_read' is in the past. Insert `now'
+                        * so this value doesn't trail off into the
+                        * past too much. */
+                       rf->rf_next_read.tv_sec = now.tv_sec;
+                       rf->rf_next_read.tv_nsec = 1000 * now.tv_usec;
                }
-       } /* while (read_loop) */
 
-       pthread_mutex_unlock (&read_lock);
+               DEBUG ("plugin_read_thread: Next read of the %s plugin at %i.%09i.",
+                               rf->rf_name,
+                               (int) rf->rf_next_read.tv_sec,
+                               (int) rf->rf_next_read.tv_nsec);
+
+               /* Re-insert this read function into the heap again. */
+               c_heap_insert (read_heap, rf);
+       } /* while (read_loop) */
 
        pthread_exit (NULL);
        return ((void *) 0);
@@ -328,6 +496,8 @@ static void stop_read_threads (void)
        if (read_threads == NULL)
                return;
 
+       INFO ("collectd: Stopping %i read threads.", read_threads_num);
+
        pthread_mutex_lock (&read_lock);
        read_loop = 0;
        DEBUG ("plugin: stop_read_threads: Signalling `read_cond'");
@@ -346,36 +516,6 @@ static void stop_read_threads (void)
        read_threads_num = 0;
 } /* void stop_read_threads */
 
-static int remove_read_functions (void)
-{
-       llentry_t *this;
-
-       if (list_read == NULL)
-               return (0);
-
-       this = llist_head (list_read);
-       while (this != NULL)
-       {
-               llentry_t *next;
-               read_func_t *rf;
-
-               next = this->next;
-               rf = (read_func_t *) this->value;
-
-               free (this->key);
-
-               plugin_user_data_destroy (&rf->udata);
-               free (rf);
-
-               this = next;
-       }
-
-       llist_destroy (list_read);
-       list_read = NULL;
-
-       return (0);
-} /* }}} int remove_read_functions */
-
 /*
  * Public functions
  */
@@ -453,6 +593,7 @@ int plugin_load (const char *type)
                else if (!S_ISREG (statbuf.st_mode))
                {
                        /* don't follow symlinks */
+                       WARNING ("stat %s: not a regular file", filename);
                        continue;
                }
 
@@ -496,9 +637,86 @@ int plugin_register_complex_config (const char *type,
 int plugin_register_init (const char *name,
                int (*callback) (void))
 {
-       return (register_callback (&list_init, name, (void *) callback));
+       return (create_register_callback (&list_init, name, (void *) callback,
+                               /* user_data = */ NULL));
 } /* plugin_register_init */
 
+static int plugin_compare_read_func (const void *arg0, const void *arg1)
+{
+       const read_func_t *rf0;
+       const read_func_t *rf1;
+
+       rf0 = arg0;
+       rf1 = arg1;
+
+       if (rf0->rf_next_read.tv_sec < rf1->rf_next_read.tv_sec)
+               return (-1);
+       else if (rf0->rf_next_read.tv_sec > rf1->rf_next_read.tv_sec)
+               return (1);
+       else if (rf0->rf_next_read.tv_nsec < rf1->rf_next_read.tv_nsec)
+               return (-1);
+       else if (rf0->rf_next_read.tv_nsec > rf1->rf_next_read.tv_nsec)
+               return (1);
+       else
+               return (0);
+} /* int plugin_compare_read_func */
+
+/* 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)
+{
+       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)
+               {
+                       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))
 {
@@ -514,19 +732,22 @@ int plugin_register_read (const char *name,
        }
 
        memset (rf, 0, sizeof (read_func_t));
-       rf->wait_time = interval_g;
-       rf->wait_left = 0;
-       rf->type = RF_SIMPLE;
-       rf->callback.cb_simple = callback;
-       rf->needs_read = DONE;
-       rf->udata.data = NULL;
-       rf->udata.free_func = NULL;
-
-       return (register_callback (&list_read, name, (void *) rf));
+       rf->rf_callback = (void *) callback;
+       rf->rf_udata.data = NULL;
+       rf->rf_udata.free_func = NULL;
+       sstrncpy (rf->rf_name, name, sizeof (rf->rf_name));
+       rf->rf_type = RF_SIMPLE;
+       rf->rf_interval.tv_sec = 0;
+       rf->rf_interval.tv_nsec = 0;
+       rf->rf_effective_interval = rf->rf_interval;
+
+       return (plugin_insert_read (rf));
 } /* int plugin_register_read */
 
 int plugin_register_complex_read (const char *name,
-               plugin_read_cb callback, user_data_t *user_data)
+               plugin_read_cb callback,
+               const struct timespec *interval,
+               user_data_t *user_data)
 {
        read_func_t *rf;
 
@@ -538,84 +759,48 @@ int plugin_register_complex_read (const char *name,
        }
 
        memset (rf, 0, sizeof (read_func_t));
-       rf->wait_time = interval_g;
-       rf->wait_left = 0;
-       rf->type = RF_COMPLEX;
-       rf->callback.cb_complex = callback;
-       rf->needs_read = DONE;
+       rf->rf_callback = (void *) callback;
+       sstrncpy (rf->rf_name, name, sizeof (rf->rf_name));
+       rf->rf_type = RF_COMPLEX;
+       if (interval != NULL)
+       {
+               rf->rf_interval = *interval;
+       }
+       rf->rf_effective_interval = rf->rf_interval;
 
        /* Set user data */
        if (user_data == NULL)
        {
-               rf->udata.data = NULL;
-               rf->udata.free_func = NULL;
+               rf->rf_udata.data = NULL;
+               rf->rf_udata.free_func = NULL;
        }
        else
        {
-               rf->udata = *user_data;
+               rf->rf_udata = *user_data;
        }
 
-       return (register_callback (&list_read, name, (void *) rf));
+       return (plugin_insert_read (rf));
 } /* int plugin_register_complex_read */
 
 int plugin_register_write (const char *name,
-               plugin_write_cb callback, user_data_t *user_data)
+               plugin_write_cb callback, user_data_t *ud)
 {
-       write_func_t *wf;
-
-       wf = (write_func_t *) malloc (sizeof (*wf));
-       if (wf == NULL)
-       {
-               ERROR ("plugin_register_write: malloc failed.");
-               return (-1);
-       }
-       memset (wf, 0, sizeof (*wf));
-
-       wf->callback = callback;
-       if (user_data == NULL)
-       {
-               wf->udata.data = NULL;
-               wf->udata.free_func = NULL;
-       }
-       else
-       {
-               wf->udata = *user_data;
-       }
-
-       return (register_callback (&list_write, name, (void *) wf));
+       return (create_register_callback (&list_write, name,
+                               (void *) callback, ud));
 } /* int plugin_register_write */
 
 int plugin_register_flush (const char *name,
-               plugin_flush_cb callback, user_data_t *user_data)
+               plugin_flush_cb callback, user_data_t *ud)
 {
-       flush_func_t *ff;
-
-       ff = (flush_func_t *) malloc (sizeof (*ff));
-       if (ff == NULL)
-       {
-               ERROR ("plugin_register_flush: malloc failed.");
-               return (-1);
-       }
-       memset (ff, 0, sizeof (*ff));
-
-       ff->callback = callback;
-       if (user_data == NULL)
-       {
-               ff->udata.data = NULL;
-               ff->udata.free_func = NULL;
-       }
-       else
-       {
-               ff->udata = *user_data;
-       }
-
-       return (register_callback (&list_flush, name, (void *) ff));
+       return (create_register_callback (&list_flush, name,
+                               (void *) callback, ud));
 } /* int plugin_register_flush */
 
 int plugin_register_shutdown (char *name,
                int (*callback) (void))
 {
-       return (register_callback (&list_shutdown, name, (void *) callback));
+       return (create_register_callback (&list_shutdown, name,
+                               (void *) callback, /* user_data = */ NULL));
 } /* int plugin_register_shutdown */
 
 int plugin_register_data_set (const data_set_t *ds)
@@ -656,36 +841,17 @@ int plugin_register_data_set (const data_set_t *ds)
 } /* int plugin_register_data_set */
 
 int plugin_register_log (const char *name,
-               plugin_log_cb callback, user_data_t *user_data)
+               plugin_log_cb callback, user_data_t *ud)
 {
-       log_func_t *lf;
-
-       lf = (log_func_t *) malloc (sizeof (*lf));
-       if (lf == NULL)
-       {
-               ERROR ("plugin_register_log: malloc failed.");
-               return (-1);
-       }
-       memset (lf, 0, sizeof (*lf));
-
-       lf->callback = callback;
-       if (user_data == NULL)
-       {
-               lf->udata.data = NULL;
-               lf->udata.free_func = NULL;
-       }
-       else
-       {
-               lf->udata = *user_data;
-       }
-
-       return (register_callback (&list_log, name, (void *) lf));
+       return (create_register_callback (&list_log, name,
+                               (void *) callback, ud));
 } /* int plugin_register_log */
 
 int plugin_register_notification (const char *name,
-               int (*callback) (const notification_t *notif))
+               plugin_notification_cb callback, user_data_t *ud)
 {
-       return (register_callback (&list_notification, name, (void *) callback));
+       return (create_register_callback (&list_notification, name,
+                               (void *) callback, ud));
 } /* int plugin_register_log */
 
 int plugin_unregister_config (const char *name)
@@ -705,70 +871,54 @@ 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) /* {{{ */
 {
-       llentry_t *e;
+       llentry_t *le;
        read_func_t *rf;
 
-       e = llist_search (list_read, name);
+       if (name == NULL)
+               return (-ENOENT);
 
-       if (e == NULL)
-               return (-1);
-
-       llist_remove (list_read, e);
-
-       rf = (read_func_t *) e->value;
-       plugin_user_data_destroy (&rf->udata);
-       free (rf);
-       free (e->key);
-
-       llentry_destroy (e);
+       pthread_mutex_lock (&read_lock);
 
-       return (0);
-}
+       if (read_list == NULL)
+       {
+               pthread_mutex_unlock (&read_lock);
+               return (-ENOENT);
+       }
 
-int plugin_unregister_write (const char *name)
-{
-       llentry_t *e;
-       write_func_t *wf;
+       le = llist_search (read_list, name);
+       if (le == NULL)
+       {
+               pthread_mutex_unlock (&read_lock);
+               WARNING ("plugin_unregister_read: No such read function: %s",
+                               name);
+               return (-ENOENT);
+       }
 
-       e = llist_search (list_write, name);
+       llist_remove (read_list, le);
 
-       if (e == NULL)
-               return (-1);
+       rf = le->value;
+       assert (rf != NULL);
+       rf->rf_type = RF_REMOVE;
 
-       llist_remove (list_write, e);
+       pthread_mutex_unlock (&read_lock);
 
-       wf = (write_func_t *) e->value;
-       plugin_user_data_destroy (&wf->udata);
-       free (wf);
-       free (e->key);
+       llentry_destroy (le);
 
-       llentry_destroy (e);
+       DEBUG ("plugin_unregister_read: Marked `%s' for removal.", name);
 
        return (0);
+} /* }}} int plugin_unregister_read */
+
+int plugin_unregister_write (const char *name)
+{
+       return (plugin_unregister (list_write, name));
 }
 
 int plugin_unregister_flush (const char *name)
 {
-       llentry_t *e;
-       flush_func_t *ff;
-
-       e = llist_search (list_flush, name);
-
-       if (e == NULL)
-               return (-1);
-
-       llist_remove (list_flush, e);
-
-       ff = (flush_func_t *) e->value;
-       plugin_user_data_destroy (&ff->udata);
-       free (ff);
-       free (e->key);
-
-       llentry_destroy (e);
-
-       return (0);
+       return (plugin_unregister (list_flush, name));
 }
 
 int plugin_unregister_shutdown (const char *name)
@@ -794,24 +944,7 @@ int plugin_unregister_data_set (const char *name)
 
 int plugin_unregister_log (const char *name)
 {
-       llentry_t *e;
-       log_func_t *lf;
-
-       e = llist_search (list_log, name);
-
-       if (e == NULL)
-               return (-1);
-
-       llist_remove (list_log, e);
-
-       lf = (log_func_t *) e->value;
-       plugin_user_data_destroy (&lf->udata);
-       free (lf);
-       free (e->key);
-
-       llentry_destroy (e);
-
-       return (0);
+       return (plugin_unregister (list_log, name));
 }
 
 int plugin_unregister_notification (const char *name)
@@ -822,7 +955,6 @@ int plugin_unregister_notification (const char *name)
 void plugin_init_all (void)
 {
        const char *chain_name;
-       int (*callback) (void);
        llentry_t *le;
        int status;
 
@@ -836,7 +968,7 @@ void plugin_init_all (void)
        post_cache_chain = fc_chain_get_by_name (chain_name);
 
 
-       if ((list_init == NULL) && (list_read == NULL))
+       if ((list_init == NULL) && (read_heap == NULL))
                return;
 
        /* Calling all init callbacks before checking if read callbacks
@@ -845,7 +977,11 @@ void plugin_init_all (void)
        le = llist_head (list_init);
        while (le != NULL)
        {
-               callback = (int (*) (void)) le->value;
+               callback_func_t *cf;
+               plugin_init_cb callback;
+
+               cf = le->value;
+               callback = cf->cf_callback;
                status = (*callback) ();
 
                if (status != 0)
@@ -865,7 +1001,7 @@ void plugin_init_all (void)
        }
 
        /* Start read-threads */
-       if (list_read != NULL)
+       if (read_heap != NULL)
        {
                const char *rt;
                int num;
@@ -876,81 +1012,57 @@ void plugin_init_all (void)
        }
 } /* void plugin_init_all */
 
+/* TODO: Rename this function. */
 void plugin_read_all (void)
 {
-       llentry_t   *le;
-       read_func_t *rf;
-
        uc_check_timeout ();
 
-       if (list_read == NULL)
-               return;
-
-       pthread_mutex_lock (&read_lock);
-
-       le = llist_head (list_read);
-       while (le != NULL)
-       {
-               rf = (read_func_t *) le->value;
-
-               if (rf->needs_read != DONE)
-               {
-                       le = le->next;
-                       continue;
-               }
-
-               if (rf->wait_left > 0)
-                       rf->wait_left -= interval_g;
-
-               if (rf->wait_left <= 0)
-               {
-                       rf->needs_read = TODO;
-               }
-
-               le = le->next;
-       }
-
-       DEBUG ("plugin: plugin_read_all: Signalling `read_cond'");
-       pthread_cond_broadcast (&read_cond);
-       pthread_mutex_unlock (&read_lock);
+       return;
 } /* void plugin_read_all */
 
 /* Read function called when the `-T' command line argument is given. */
 int plugin_read_all_once (void)
 {
-       llentry_t   *le;
-       read_func_t *rf;
        int status;
        int return_status = 0;
 
-       if (list_read == NULL)
+       if (read_heap == NULL)
        {
                NOTICE ("No read-functions are registered.");
                return (0);
        }
 
-       for (le = llist_head (list_read);
-            le != NULL;
-            le = le->next)
+       while (42)
        {
-               rf = (read_func_t *) le->value;
+               read_func_t *rf;
+
+               rf = c_head_get_root (read_heap);
+               if (rf == NULL)
+                       break;
 
-               if (rf->type == RF_SIMPLE)
+               if (rf->rf_type == RF_SIMPLE)
                {
-                       status = rf->callback.cb_simple ();
+                       int (*callback) (void);
+
+                       callback = rf->rf_callback;
+                       status = (*callback) ();
                }
                else
                {
-                       assert (rf->type == RF_COMPLEX);
-                       status = rf->callback.cb_complex (&rf->udata);
+                       plugin_read_cb callback;
+
+                       callback = rf->rf_callback;
+                       status = (*callback) (&rf->rf_udata);
                }
 
                if (status != 0)
                {
                        NOTICE ("read-function of plugin `%s' failed.",
-                               le->key);
+                                       rf->rf_name);
                        return_status = -1;
                }
+
+               destroy_callback ((void *) rf);
        }
 
        return (return_status);
@@ -986,10 +1098,12 @@ int plugin_write (const char *plugin, /* {{{ */
     le = llist_head (list_write);
     while (le != NULL)
     {
-      write_func_t *wf = le->value;
+      callback_func_t *cf = le->value;
+      plugin_write_cb callback;
 
       DEBUG ("plugin: plugin_write: Writing values via %s.", le->key);
-      status = wf->callback (ds, vl, &wf->udata);
+      callback = cf->cf_callback;
+      status = (*callback) (ds, vl, &cf->cf_udata);
       if (status != 0)
         failure++;
       else
@@ -1005,7 +1119,9 @@ int plugin_write (const char *plugin, /* {{{ */
   }
   else /* plugin != NULL */
   {
-    write_func_t *wf;
+    callback_func_t *cf;
+    plugin_write_cb callback;
+
     le = llist_head (list_write);
     while (le != NULL)
     {
@@ -1018,10 +1134,11 @@ int plugin_write (const char *plugin, /* {{{ */
     if (le == NULL)
       return (ENOENT);
 
-    wf = le->value;
+    cf = le->value;
 
     DEBUG ("plugin: plugin_write: Writing values via %s.", le->key);
-    status = wf->callback (ds, vl, &wf->udata);
+    callback = cf->cf_callback;
+    status = (*callback) (ds, vl, &cf->cf_udata);
   }
 
   return (status);
@@ -1037,7 +1154,8 @@ int plugin_flush (const char *plugin, int timeout, const char *identifier)
   le = llist_head (list_flush);
   while (le != NULL)
   {
-    flush_func_t *ff;
+    callback_func_t *cf;
+    plugin_flush_cb callback;
 
     if ((plugin != NULL)
         && (strcmp (plugin, le->key) != 0))
@@ -1046,9 +1164,10 @@ int plugin_flush (const char *plugin, int timeout, const char *identifier)
       continue;
     }
 
-    ff = (flush_func_t *) le->value;
+    cf = le->value;
+    callback = cf->cf_callback;
 
-    ff->callback (timeout, identifier, &ff->udata);
+    (*callback) (timeout, identifier, &cf->cf_udata);
 
     le = le->next;
   }
@@ -1057,19 +1176,33 @@ int plugin_flush (const char *plugin, int timeout, const char *identifier)
 
 void plugin_shutdown_all (void)
 {
-       int (*callback) (void);
        llentry_t *le;
 
        stop_read_threads ();
-       remove_read_functions ();
 
-       if (list_shutdown == NULL)
-               return;
+       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,
+                       /* identifier = */ NULL);
+
+       le = NULL;
+       if (list_shutdown != NULL)
+               le = llist_head (list_shutdown);
 
-       le = llist_head (list_shutdown);
        while (le != NULL)
        {
-               callback = (int (*) (void)) le->value;
+               callback_func_t *cf;
+               plugin_shutdown_cb callback;
+
+               cf = le->value;
+               callback = cf->cf_callback;
 
                /* Advance the pointer before calling the callback allows
                 * shutdown functions to unregister themselves. If done the
@@ -1079,6 +1212,12 @@ void plugin_shutdown_all (void)
 
                (*callback) ();
        }
+
+       destroy_all_callbacks (&list_write);
+       destroy_all_callbacks (&list_flush);
+       destroy_all_callbacks (&list_notification);
+       destroy_all_callbacks (&list_shutdown);
+       destroy_all_callbacks (&list_log);
 } /* void plugin_shutdown_all */
 
 int plugin_dispatch_values (value_list_t *vl)
@@ -1086,9 +1225,14 @@ int plugin_dispatch_values (value_list_t *vl)
        int status;
        static c_complain_t no_write_complaint = C_COMPLAIN_INIT_STATIC;
 
+       value_t *saved_values;
+       int      saved_values_len;
+
        data_set_t *ds;
 
-       if ((vl == NULL) || (*vl->type == '\0')) {
+       if ((vl == NULL) || (vl->type[0] == 0)
+                       || (vl->values == NULL) || (vl->values_len < 1))
+       {
                ERROR ("plugin_dispatch_values: Invalid value list.");
                return (-1);
        }
@@ -1116,6 +1260,9 @@ int plugin_dispatch_values (value_list_t *vl)
        if (vl->time == 0)
                vl->time = time (NULL);
 
+       if (vl->interval <= 0)
+               vl->interval = interval_g;
+
        DEBUG ("plugin_dispatch_values: time = %u; interval = %i; "
                        "host = %s; "
                        "plugin = %s; plugin_instance = %s; "
@@ -1152,6 +1299,31 @@ int plugin_dispatch_values (value_list_t *vl)
        escape_slashes (vl->type, sizeof (vl->type));
        escape_slashes (vl->type_instance, sizeof (vl->type_instance));
 
+       /* Copy the values. This way, we can assure `targets' that they get
+        * dynamically allocated values, which they can free and replace if
+        * they like. */
+       if ((pre_cache_chain != NULL) || (post_cache_chain != NULL))
+       {
+               saved_values     = vl->values;
+               saved_values_len = vl->values_len;
+
+               vl->values = (value_t *) calloc (vl->values_len,
+                               sizeof (*vl->values));
+               if (vl->values == NULL)
+               {
+                       ERROR ("plugin_dispatch_values: calloc failed.");
+                       vl->values = saved_values;
+                       return (-1);
+               }
+               memcpy (vl->values, saved_values,
+                               vl->values_len * sizeof (*vl->values));
+       }
+       else /* if ((pre == NULL) && (post == NULL)) */
+       {
+               saved_values     = NULL;
+               saved_values_len = 0;
+       }
+
        if (pre_cache_chain != NULL)
        {
                status = fc_process_chain (ds, vl, pre_cache_chain);
@@ -1163,12 +1335,25 @@ int plugin_dispatch_values (value_list_t *vl)
                                        status, status);
                }
                else if (status == FC_TARGET_STOP)
+               {
+                       /* Restore the state of the value_list so that plugins
+                        * don't get confused.. */
+                       if (saved_values != NULL)
+                       {
+                               free (vl->values);
+                               vl->values     = saved_values;
+                               vl->values_len = saved_values_len;
+                       }
                        return (0);
+               }
        }
 
        /* Update the value cache */
        uc_update (ds, vl);
 
+       /* Initiate threshold checking */
+       ut_check_threshold (ds, vl);
+
        if (post_cache_chain != NULL)
        {
                status = fc_process_chain (ds, vl, post_cache_chain);
@@ -1183,12 +1368,20 @@ int plugin_dispatch_values (value_list_t *vl)
        else
                fc_default_action (ds, vl);
 
+       /* Restore the state of the value_list so that plugins don't get
+        * confused.. */
+       if (saved_values != NULL)
+       {
+               free (vl->values);
+               vl->values     = saved_values;
+               vl->values_len = saved_values_len;
+       }
+
        return (0);
 } /* int plugin_dispatch_values */
 
 int plugin_dispatch_notification (const notification_t *notif)
 {
-       int (*callback) (const notification_t *);
        llentry_t *le;
        /* Possible TODO: Add flap detection here */
 
@@ -1204,8 +1397,19 @@ int plugin_dispatch_notification (const notification_t *notif)
        le = llist_head (list_notification);
        while (le != NULL)
        {
-               callback = (int (*) (const notification_t *)) le->value;
-               (*callback) (notif);
+               callback_func_t *cf;
+               plugin_notification_cb callback;
+               int status;
+
+               cf = le->value;
+               callback = cf->cf_callback;
+               status = (*callback) (notif, &cf->cf_udata);
+               if (status != 0)
+               {
+                       WARNING ("plugin_dispatch_notification: Notification "
+                                       "callback %s returned %i.",
+                                       le->key, status);
+               }
 
                le = le->next;
        }
@@ -1220,7 +1424,12 @@ void plugin_log (int level, const char *format, ...)
        llentry_t *le;
 
        if (list_log == NULL)
+       {
+               va_start (ap, format);
+               vfprintf (stderr, format, ap);
+               va_end (ap);
                return;
+       }
 
 #if !COLLECT_DEBUG
        if (level >= LOG_DEBUG)
@@ -1235,11 +1444,13 @@ void plugin_log (int level, const char *format, ...)
        le = llist_head (list_log);
        while (le != NULL)
        {
-               log_func_t *lf;
+               callback_func_t *cf;
+               plugin_log_cb callback;
 
-               lf = (log_func_t *) le->value;
+               cf = le->value;
+               callback = cf->cf_callback;
 
-               lf->callback (level, msg, &lf->udata);
+               (*callback) (level, msg, &cf->cf_udata);
 
                le = le->next;
        }
@@ -1432,3 +1643,5 @@ int plugin_notification_meta_free (notification_meta_t *n)
 
   return (0);
 } /* int plugin_notification_meta_free */
+
+/* vim: set sw=8 ts=8 noet fdm=marker : */