X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fplugin.c;h=0ae6e44a7f401cf293958d1f7951be684d26e339;hb=5a7145dd5626503f411a4aed87f30fc0f9689c90;hp=f1333f1d43ce8fa8a347d8fc0e112479615f1563;hpb=7699c3ec722a9414f3342d6cd31b7be440a5da6f;p=collectd.git

diff --git a/src/plugin.c b/src/plugin.c
index f1333f1d..6139baf0 100644
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -1,6 +1,6 @@
 /**
  * collectd - src/plugin.c
- * Copyright (C) 2005,2006  Florian octo Forster
+ * Copyright (C) 2005-2009  Florian octo Forster
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -17,9 +17,11 @@
  *
  * Authors:
  *   Florian octo Forster <octo at verplant.org>
+ *   Sebastian Harl <sh at tokkee.org>
  **/
 
 #include "collectd.h"
+#include "utils_complain.h"
 
 #include <ltdl.h>
 
@@ -32,18 +34,35 @@
 #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
 struct read_func_s
 {
-	int wait_time;
-	int wait_left;
-	int (*callback) (void);
-	enum { DONE = 0, TODO = 1, ACTIVE = 2 } needs_read;
+	/* `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;
 
@@ -51,16 +70,20 @@ typedef struct read_func_s read_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;
 static llist_t *list_log;
 static llist_t *list_notification;
 
+static fc_chain_t *pre_cache_chain = NULL;
+static fc_chain_t *post_cache_chain = NULL;
+
 static c_avl_tree_t *data_sets;
 
 static char *plugindir = NULL;
 
+static c_heap_t       *read_heap = NULL;
 static int             read_loop = 1;
 static pthread_mutex_t read_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t  read_cond = PTHREAD_COND_INITIALIZER;
@@ -78,26 +101,101 @@ 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);
 		}
 
@@ -105,27 +203,65 @@ 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 int create_register_callback (llist_t **list, /* {{{ */
+		const char *name, void *callback, user_data_t *ud)
+{
+	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)
+	{
+		cf->cf_udata.data = NULL;
+		cf->cf_udata.free_func = NULL;
+	}
+	else
+	{
+		cf->cf_udata = *ud;
+	}
 
-static int plugin_unregister (llist_t *list, const char *name)
+	return (register_callback (list, name, cf));
+} /* }}} int create_register_callback */
+
+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
@@ -146,14 +282,14 @@ static int plugin_load_file (char *file)
 	{
 		const char *error = lt_dlerror ();
 
-		ERROR ("lt_dlopen failed: %s", error);
-		fprintf (stderr, "lt_dlopen failed: %s\n", error);
+		ERROR ("lt_dlopen (%s) failed: %s", file, error);
+		fprintf (stderr, "lt_dlopen (%s) failed: %s\n", file, error);
 		return (1);
 	}
 
 	if ((reg_handle = (void (*) (void)) lt_dlsym (dlh, "module_register")) == NULL)
 	{
-		WARNING ("Couldn't find symbol ``module_register'' in ``%s'': %s\n",
+		WARNING ("Couldn't find symbol `module_register' in `%s': %s\n",
 				file, lt_dlerror ());
 		lt_dlclose (dlh);
 		return (-1);
@@ -164,80 +300,146 @@ static int plugin_load_file (char *file)
 	return (0);
 }
 
-static void *plugin_read_thread (void *args)
+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;
 
-		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;
+		}
 
-			status = rf->callback ();
-			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);
+		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;
+		}
+
+		DEBUG ("plugin_read_thread: Handling `%s'.", rf->rf_name);
+
+		if (rf->rf_type == RF_SIMPLE)
+		{
+			int (*callback) (void);
+
+			callback = rf->rf_callback;
+			status = (*callback) ();
+		}
+		else
+		{
+			plugin_read_cb callback;
+
+			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);
 } /* void *plugin_read_thread */
 
-static void start_threads (int num)
+static void start_read_threads (int num)
 {
 	int i;
 
@@ -247,7 +449,7 @@ static void start_threads (int num)
 	read_threads = (pthread_t *) calloc (num, sizeof (pthread_t));
 	if (read_threads == NULL)
 	{
-		ERROR ("plugin: start_threads: calloc failed.");
+		ERROR ("plugin: start_read_threads: calloc failed.");
 		return;
 	}
 
@@ -261,19 +463,24 @@ static void start_threads (int num)
 		}
 		else
 		{
-			ERROR ("plugin: start_threads: pthread_create failed.");
+			ERROR ("plugin: start_read_threads: pthread_create failed.");
 			return;
 		}
 	} /* for (i) */
-} /* void start_threads */
+} /* void start_read_threads */
 
-static void stop_threads (void)
+static void stop_read_threads (void)
 {
 	int i;
 
+	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_threads: Signalling `read_cond'");
+	DEBUG ("plugin: stop_read_threads: Signalling `read_cond'");
 	pthread_cond_broadcast (&read_cond);
 	pthread_mutex_unlock (&read_lock);
 
@@ -281,13 +488,13 @@ static void stop_threads (void)
 	{
 		if (pthread_join (read_threads[i], NULL) != 0)
 		{
-			ERROR ("plugin: stop_threads: pthread_join failed.");
+			ERROR ("plugin: stop_read_threads: pthread_join failed.");
 		}
 		read_threads[i] = (pthread_t) 0;
 	}
 	sfree (read_threads);
 	read_threads_num = 0;
-} /* void stop_threads */
+} /* void stop_read_threads */
 
 /*
  * Public functions
@@ -318,6 +525,7 @@ int plugin_load (const char *type)
 	int   ret;
 	struct stat    statbuf;
 	struct dirent *de;
+	int status;
 
 	DEBUG ("type = %s", type);
 
@@ -326,7 +534,8 @@ int plugin_load (const char *type)
 
 	/* `cpu' should not match `cpufreq'. To solve this we add `.so' to the
 	 * type when matching the filename */
-	if (snprintf (typename, BUFSIZE, "%s.so", type) >= BUFSIZE)
+	status = ssnprintf (typename, sizeof (typename), "%s.so", type);
+	if ((status < 0) || ((size_t) status >= sizeof (typename)))
 	{
 		WARNING ("snprintf: truncated: `%s.so'", type);
 		return (-1);
@@ -346,7 +555,9 @@ int plugin_load (const char *type)
 		if (strncasecmp (de->d_name, typename, typename_len))
 			continue;
 
-		if (snprintf (filename, BUFSIZE, "%s/%s", dir, de->d_name) >= BUFSIZE)
+		status = ssnprintf (filename, sizeof (filename),
+				"%s/%s", dir, de->d_name);
+		if ((status < 0) || ((size_t) status >= sizeof (filename)))
 		{
 			WARNING ("snprintf: truncated: `%s/%s'", dir, de->d_name);
 			continue;
@@ -362,6 +573,7 @@ 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;
 		}
 
@@ -405,14 +617,46 @@ 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 */
+
 int plugin_register_read (const char *name,
 		int (*callback) (void))
 {
 	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)
 	{
@@ -422,25 +666,86 @@ int plugin_register_read (const char *name,
 		return (-1);
 	}
 
-	memset (rf, '\0', sizeof (read_func_t));
-	rf->wait_time = interval_g;
-	rf->wait_left = 0;
-	rf->callback = callback;
-	rf->needs_read = DONE;
-
-	return (register_callback (&list_read, name, (void *) rf));
+	memset (rf, 0, sizeof (read_func_t));
+	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 (c_heap_insert (read_heap, rf));
 } /* int plugin_register_read */
 
+int plugin_register_complex_read (const char *name,
+		plugin_read_cb callback,
+		const struct timespec *interval,
+		user_data_t *user_data)
+{
+	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)
+	{
+		ERROR ("plugin_register_complex_read: malloc failed.");
+		return (-1);
+	}
+
+	memset (rf, 0, sizeof (read_func_t));
+	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->rf_udata.data = NULL;
+		rf->rf_udata.free_func = NULL;
+	}
+	else
+	{
+		rf->rf_udata = *user_data;
+	}
+
+	return (c_heap_insert (read_heap, rf));
+} /* int plugin_register_complex_read */
+
 int plugin_register_write (const char *name,
-		int (*callback) (const data_set_t *ds, const value_list_t *vl))
+		plugin_write_cb callback, user_data_t *ud)
 {
-	return (register_callback (&list_write, name, (void *) callback));
+	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 *ud)
+{
+	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)
@@ -480,16 +785,18 @@ int plugin_register_data_set (const data_set_t *ds)
 	return (c_avl_insert (data_sets, (void *) ds_copy->type, (void *) ds_copy));
 } /* int plugin_register_data_set */
 
-int plugin_register_log (char *name,
-		void (*callback) (int priority, const char *msg))
+int plugin_register_log (const char *name,
+		plugin_log_cb callback, user_data_t *ud)
 {
-	return (register_callback (&list_log, name, (void *) callback));
+	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)
@@ -511,19 +818,9 @@ int plugin_unregister_init (const char *name)
 
 int plugin_unregister_read (const char *name)
 {
-	llentry_t *e;
-
-	e = llist_search (list_read, name);
-
-	if (e == NULL)
-		return (-1);
-
-	llist_remove (list_read, e);
-	free (e->value);
-	free (e->key);
-	llentry_destroy (e);
-
-	return (0);
+	/* TODO: Implement removal of a specific key from the heap. */
+	assert (0);
+	return (-1);
 }
 
 int plugin_unregister_write (const char *name)
@@ -531,6 +828,11 @@ int plugin_unregister_write (const char *name)
 	return (plugin_unregister (list_write, name));
 }
 
+int plugin_unregister_flush (const char *name)
+{
+	return (plugin_unregister (list_flush, name));
+}
+
 int plugin_unregister_shutdown (const char *name)
 {
 	return (plugin_unregister (list_shutdown, name));
@@ -564,14 +866,21 @@ int plugin_unregister_notification (const char *name)
 
 void plugin_init_all (void)
 {
-	int (*callback) (void);
+	const char *chain_name;
 	llentry_t *le;
 	int status;
 
 	/* Init the value cache */
 	uc_init ();
 
-	if ((list_init == NULL) && (list_read == NULL))
+	chain_name = global_option_get ("PreCacheChain");
+	pre_cache_chain = fc_chain_get_by_name (chain_name);
+
+	chain_name = global_option_get ("PostCacheChain");
+	post_cache_chain = fc_chain_get_by_name (chain_name);
+
+
+	if ((list_init == NULL) && (read_heap == NULL))
 		return;
 
 	/* Calling all init callbacks before checking if read callbacks
@@ -580,7 +889,11 @@ 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)
@@ -600,69 +913,202 @@ void plugin_init_all (void)
 	}
 
 	/* Start read-threads */
-	if (list_read != NULL)
+	if (read_heap != NULL)
 	{
 		const char *rt;
 		int num;
 		rt = global_option_get ("ReadThreads");
 		num = atoi (rt);
-		start_threads ((num > 0) ? num : 5);
+		if (num != -1)
+			start_read_threads ((num > 0) ? num : 5);
 	}
 } /* 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;
+	return;
+} /* void plugin_read_all */
 
-	pthread_mutex_lock (&read_lock);
+/* Read function called when the `-T' command line argument is given. */
+int plugin_read_all_once (void)
+{
+	int status;
+	int return_status = 0;
 
-	le = llist_head (list_read);
-	while (le != NULL)
+	if (read_heap == NULL)
+	{
+		NOTICE ("No read-functions are registered.");
+		return (0);
+	}
+
+	while (42)
 	{
-		rf = (read_func_t *) le->value;
+		read_func_t *rf;
 
-		if (rf->needs_read != DONE)
+		rf = c_head_get_root (read_heap);
+		if (rf == NULL)
+			break;
+
+		if (rf->rf_type == RF_SIMPLE)
 		{
-			le = le->next;
-			continue;
+			int (*callback) (void);
+
+			callback = rf->rf_callback;
+			status = (*callback) ();
 		}
+		else
+		{
+			plugin_read_cb callback;
 
-		if (rf->wait_left > 0)
-			rf->wait_left -= interval_g;
+			callback = rf->rf_callback;
+			status = (*callback) (&rf->rf_udata);
+		}
 
-		if (rf->wait_left <= 0)
+		if (status != 0)
 		{
-			rf->needs_read = TODO;
+			NOTICE ("read-function of plugin `%s' failed.",
+					rf->rf_name);
+			return_status = -1;
 		}
 
-		le = le->next;
+		destroy_callback ((void *) rf);
 	}
 
-	DEBUG ("plugin: plugin_read_all: Signalling `read_cond'");
-	pthread_cond_broadcast (&read_cond);
-	pthread_mutex_unlock (&read_lock);
-} /* void plugin_read_all */
+	return (return_status);
+} /* int plugin_read_all_once */
+
+int plugin_write (const char *plugin, /* {{{ */
+		const data_set_t *ds, const value_list_t *vl)
+{
+  llentry_t *le;
+  int status;
+
+  if (vl == NULL)
+    return (EINVAL);
+
+  if (list_write == NULL)
+    return (ENOENT);
+
+  if (ds == NULL)
+  {
+    ds = plugin_get_ds (vl->type);
+    if (ds == NULL)
+    {
+      ERROR ("plugin_write: Unable to lookup type `%s'.", vl->type);
+      return (ENOENT);
+    }
+  }
+
+  if (plugin == NULL)
+  {
+    int success = 0;
+    int failure = 0;
+
+    le = llist_head (list_write);
+    while (le != NULL)
+    {
+      callback_func_t *cf = le->value;
+      plugin_write_cb callback;
+
+      DEBUG ("plugin: plugin_write: Writing values via %s.", le->key);
+      callback = cf->cf_callback;
+      status = (*callback) (ds, vl, &cf->cf_udata);
+      if (status != 0)
+        failure++;
+      else
+        success++;
+
+      le = le->next;
+    }
+
+    if ((success == 0) && (failure != 0))
+      status = -1;
+    else
+      status = 0;
+  }
+  else /* plugin != NULL */
+  {
+    callback_func_t *cf;
+    plugin_write_cb callback;
+
+    le = llist_head (list_write);
+    while (le != NULL)
+    {
+      if (strcasecmp (plugin, le->key) == 0)
+        break;
+
+      le = le->next;
+    }
+
+    if (le == NULL)
+      return (ENOENT);
+
+    cf = le->value;
+
+    DEBUG ("plugin: plugin_write: Writing values via %s.", le->key);
+    callback = cf->cf_callback;
+    status = (*callback) (ds, vl, &cf->cf_udata);
+  }
+
+  return (status);
+} /* }}} int plugin_write */
+
+int plugin_flush (const char *plugin, int timeout, const char *identifier)
+{
+  llentry_t *le;
+
+  if (list_flush == NULL)
+    return (0);
+
+  le = llist_head (list_flush);
+  while (le != NULL)
+  {
+    callback_func_t *cf;
+    plugin_flush_cb callback;
+
+    if ((plugin != NULL)
+        && (strcmp (plugin, le->key) != 0))
+    {
+      le = le->next;
+      continue;
+    }
+
+    cf = le->value;
+    callback = cf->cf_callback;
+
+    (*callback) (timeout, identifier, &cf->cf_udata);
+
+    le = le->next;
+  }
+  return (0);
+} /* int plugin_flush */
 
 void plugin_shutdown_all (void)
 {
-	int (*callback) (void);
 	llentry_t *le;
 
-	stop_threads ();
+	stop_read_threads ();
 
-	if (list_shutdown == NULL)
-		return;
+	destroy_all_callbacks (&list_init);
+	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
@@ -672,22 +1118,37 @@ 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 (const char *name, value_list_t *vl)
+int plugin_dispatch_values (value_list_t *vl)
 {
-	int (*callback) (const data_set_t *, const value_list_t *);
+	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;
-	llentry_t *le;
 
-	if (list_write == NULL)
+	if ((vl == NULL) || (vl->type[0] == 0)
+			|| (vl->values == NULL) || (vl->values_len < 1))
 	{
-		ERROR ("plugin_dispatch_values: No write callback has been "
-				"registered. Please load at least one plugin "
-				"that provides a write function.");
+		ERROR ("plugin_dispatch_values: Invalid value list.");
 		return (-1);
 	}
 
+	if (list_write == NULL)
+		c_complain_once (LOG_WARNING, &no_write_complaint,
+				"plugin_dispatch_values: No write callback has been "
+				"registered. Please load at least one output plugin, "
+				"if you want the collected data to be stored.");
+
 	if (data_sets == NULL)
 	{
 		ERROR ("plugin_dispatch_values: No data sets registered. "
@@ -696,12 +1157,18 @@ int plugin_dispatch_values (const char *name, value_list_t *vl)
 		return (-1);
 	}
 
-	if (c_avl_get (data_sets, name, (void *) &ds) != 0)
+	if (c_avl_get (data_sets, vl->type, (void *) &ds) != 0)
 	{
-		INFO ("plugin_dispatch_values: Dataset not found: %s", name);
+		INFO ("plugin_dispatch_values: Dataset not found: %s", vl->type);
 		return (-1);
 	}
 
+	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; "
@@ -709,7 +1176,15 @@ int plugin_dispatch_values (const char *name, value_list_t *vl)
 			(unsigned int) vl->time, vl->interval,
 			vl->host,
 			vl->plugin, vl->plugin_instance,
-			ds->type, vl->type_instance);
+			vl->type, vl->type_instance);
+
+#if COLLECT_DEBUG
+	assert (0 == strcmp (ds->type, vl->type));
+#else
+	if (0 != strcmp (ds->type, vl->type))
+		WARNING ("plugin_dispatch_values: (ds->type = %s) != (vl->type = %s)",
+				ds->type, vl->type);
+#endif
 
 #if COLLECT_DEBUG
 	assert (ds->ds_num == vl->values_len);
@@ -727,19 +1202,85 @@ int plugin_dispatch_values (const char *name, value_list_t *vl)
 	escape_slashes (vl->host, sizeof (vl->host));
 	escape_slashes (vl->plugin, sizeof (vl->plugin));
 	escape_slashes (vl->plugin_instance, sizeof (vl->plugin_instance));
+	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);
+		if (status < 0)
+		{
+			WARNING ("plugin_dispatch_values: Running the "
+					"pre-cache chain failed with "
+					"status %i (%#x).",
+					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);
 
-	le = llist_head (list_write);
-	while (le != NULL)
+	if (post_cache_chain != NULL)
 	{
-		callback = (int (*) (const data_set_t *, const value_list_t *)) le->value;
-		(*callback) (ds, vl);
+		status = fc_process_chain (ds, vl, post_cache_chain);
+		if (status < 0)
+		{
+			WARNING ("plugin_dispatch_values: Running the "
+					"post-cache chain failed with "
+					"status %i (%#x).",
+					status, status);
+		}
+	}
+	else
+		fc_default_action (ds, vl);
 
-		le = le->next;
+	/* 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);
@@ -747,7 +1288,6 @@ int plugin_dispatch_values (const char *name, value_list_t *vl)
 
 int plugin_dispatch_notification (const notification_t *notif)
 {
-	int (*callback) (const notification_t *);
 	llentry_t *le;
 	/* Possible TODO: Add flap detection here */
 
@@ -763,8 +1303,19 @@ 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;
 	}
@@ -774,10 +1325,8 @@ int plugin_dispatch_notification (const notification_t *notif)
 
 void plugin_log (int level, const char *format, ...)
 {
-	char msg[512];
+	char msg[1024];
 	va_list ap;
-
-	void (*callback) (int, const char *);
 	llentry_t *le;
 
 	if (list_log == NULL)
@@ -789,15 +1338,20 @@ void plugin_log (int level, const char *format, ...)
 #endif
 
 	va_start (ap, format);
-	vsnprintf (msg, 512, format, ap);
-	msg[511] = '\0';
+	vsnprintf (msg, sizeof (msg), format, ap);
+	msg[sizeof (msg) - 1] = '\0';
 	va_end (ap);
 
 	le = llist_head (list_log);
 	while (le != NULL)
 	{
-		callback = (void (*) (int, const char *)) le->value;
-		(*callback) (level, msg);
+		callback_func_t *cf;
+		plugin_log_cb callback;
+
+		cf = le->value;
+		callback = cf->cf_callback;
+
+		(*callback) (level, msg, &cf->cf_udata);
 
 		le = le->next;
 	}
@@ -815,3 +1369,180 @@ const data_set_t *plugin_get_ds (const char *name)
 
 	return (ds);
 } /* data_set_t *plugin_get_ds */
+
+static int plugin_notification_meta_add (notification_t *n,
+    const char *name,
+    enum notification_meta_type_e type,
+    const void *value)
+{
+  notification_meta_t *meta;
+  notification_meta_t *tail;
+
+  if ((n == NULL) || (name == NULL) || (value == NULL))
+  {
+    ERROR ("plugin_notification_meta_add: A pointer is NULL!");
+    return (-1);
+  }
+
+  meta = (notification_meta_t *) malloc (sizeof (notification_meta_t));
+  if (meta == NULL)
+  {
+    ERROR ("plugin_notification_meta_add: malloc failed.");
+    return (-1);
+  }
+  memset (meta, 0, sizeof (notification_meta_t));
+
+  sstrncpy (meta->name, name, sizeof (meta->name));
+  meta->type = type;
+
+  switch (type)
+  {
+    case NM_TYPE_STRING:
+    {
+      meta->nm_value.nm_string = strdup ((const char *) value);
+      if (meta->nm_value.nm_string == NULL)
+      {
+        ERROR ("plugin_notification_meta_add: strdup failed.");
+        sfree (meta);
+        return (-1);
+      }
+      break;
+    }
+    case NM_TYPE_SIGNED_INT:
+    {
+      meta->nm_value.nm_signed_int = *((int64_t *) value);
+      break;
+    }
+    case NM_TYPE_UNSIGNED_INT:
+    {
+      meta->nm_value.nm_unsigned_int = *((uint64_t *) value);
+      break;
+    }
+    case NM_TYPE_DOUBLE:
+    {
+      meta->nm_value.nm_double = *((double *) value);
+      break;
+    }
+    case NM_TYPE_BOOLEAN:
+    {
+      meta->nm_value.nm_boolean = *((bool *) value);
+      break;
+    }
+    default:
+    {
+      ERROR ("plugin_notification_meta_add: Unknown type: %i", type);
+      sfree (meta);
+      return (-1);
+    }
+  } /* switch (type) */
+
+  meta->next = NULL;
+  tail = n->meta;
+  while ((tail != NULL) && (tail->next != NULL))
+    tail = tail->next;
+
+  if (tail == NULL)
+    n->meta = meta;
+  else
+    tail->next = meta;
+
+  return (0);
+} /* int plugin_notification_meta_add */
+
+int plugin_notification_meta_add_string (notification_t *n,
+    const char *name,
+    const char *value)
+{
+  return (plugin_notification_meta_add (n, name, NM_TYPE_STRING, value));
+}
+
+int plugin_notification_meta_add_signed_int (notification_t *n,
+    const char *name,
+    int64_t value)
+{
+  return (plugin_notification_meta_add (n, name, NM_TYPE_SIGNED_INT, &value));
+}
+
+int plugin_notification_meta_add_unsigned_int (notification_t *n,
+    const char *name,
+    uint64_t value)
+{
+  return (plugin_notification_meta_add (n, name, NM_TYPE_UNSIGNED_INT, &value));
+}
+
+int plugin_notification_meta_add_double (notification_t *n,
+    const char *name,
+    double value)
+{
+  return (plugin_notification_meta_add (n, name, NM_TYPE_DOUBLE, &value));
+}
+
+int plugin_notification_meta_add_boolean (notification_t *n,
+    const char *name,
+    bool value)
+{
+  return (plugin_notification_meta_add (n, name, NM_TYPE_BOOLEAN, &value));
+}
+
+int plugin_notification_meta_copy (notification_t *dst,
+    const notification_t *src)
+{
+  notification_meta_t *meta;
+
+  assert (dst != NULL);
+  assert (src != NULL);
+  assert (dst != src);
+  assert ((src->meta == NULL) || (src->meta != dst->meta));
+
+  for (meta = src->meta; meta != NULL; meta = meta->next)
+  {
+    if (meta->type == NM_TYPE_STRING)
+      plugin_notification_meta_add_string (dst, meta->name,
+          meta->nm_value.nm_string);
+    else if (meta->type == NM_TYPE_SIGNED_INT)
+      plugin_notification_meta_add_signed_int (dst, meta->name,
+          meta->nm_value.nm_signed_int);
+    else if (meta->type == NM_TYPE_UNSIGNED_INT)
+      plugin_notification_meta_add_unsigned_int (dst, meta->name,
+          meta->nm_value.nm_unsigned_int);
+    else if (meta->type == NM_TYPE_DOUBLE)
+      plugin_notification_meta_add_double (dst, meta->name,
+          meta->nm_value.nm_double);
+    else if (meta->type == NM_TYPE_BOOLEAN)
+      plugin_notification_meta_add_boolean (dst, meta->name,
+          meta->nm_value.nm_boolean);
+  }
+
+  return (0);
+} /* int plugin_notification_meta_copy */
+
+int plugin_notification_meta_free (notification_meta_t *n)
+{
+  notification_meta_t *this;
+  notification_meta_t *next;
+
+  if (n == NULL)
+  {
+    ERROR ("plugin_notification_meta_free: n == NULL!");
+    return (-1);
+  }
+
+  this = n;
+  while (this != NULL)
+  {
+    next = this->next;
+
+    if (this->type == NM_TYPE_STRING)
+    {
+      free ((char *)this->nm_value.nm_string);
+      this->nm_value.nm_string = NULL;
+    }
+    sfree (this);
+
+    this = next;
+  }
+
+  return (0);
+} /* int plugin_notification_meta_free */
+
+/* vim: set sw=8 ts=8 noet fdm=marker : */