X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Futils_cache.c;h=20b12375d8ebfc159de13f520c46b89052ae1e97;hb=83077c18c3e78739c2d2d18debf99875944eaa72;hp=241aa726c55bf775159f96b7b448b68f574ae8fe;hpb=e628f39838a67b40d52dfb8425b4d8474fbd0550;p=collectd.git

diff --git a/src/utils_cache.c b/src/utils_cache.c
index 241aa726..20b12375 100644
--- a/src/utils_cache.c
+++ b/src/utils_cache.c
@@ -25,6 +25,7 @@
 #include "utils_avltree.h"
 #include "utils_cache.h"
 #include "utils_threshold.h"
+#include "meta_data.h"
 
 #include <assert.h>
 #include <pthread.h>
@@ -34,17 +35,33 @@ typedef struct cache_entry_s
 	char name[6 * DATA_MAX_NAME_LEN];
 	int        values_num;
 	gauge_t   *values_gauge;
-	counter_t *values_counter;
+	value_t   *values_raw;
 	/* Time contained in the package
 	 * (for calculating rates) */
-	time_t last_time;
+	cdtime_t last_time;
 	/* Time according to the local clock
 	 * (for purging old entries) */
-	time_t last_update;
+	cdtime_t last_update;
 	/* Interval in which the data is collected
 	 * (for purding old entries) */
-	int interval;
+	cdtime_t interval;
 	int state;
+	int hits;
+
+	/*
+	 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+	 * !  0  !  1  !  2  !  3  !  4  !  5  !  6  !  7  !  8  ! ...
+	 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+	 * ! ds0 ! ds1 ! ds2 ! ds0 ! ds1 ! ds2 ! ds0 ! ds1 ! ds2 ! ...
+	 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+	 * !      t = 0      !      t = 1      !      t = 2      ! ...
+	 * +-----------------+-----------------+-----------------+----
+	 */
+	gauge_t *history;
+	size_t   history_index; /* points to the next position to write to. */
+	size_t   history_length;
+
+	meta_data_t *meta;
 } cache_entry_t;
 
 static c_avl_tree_t   *cache_tree = NULL;
@@ -69,17 +86,21 @@ static cache_entry_t *cache_alloc (int values_num)
   memset (ce, '\0', sizeof (cache_entry_t));
   ce->values_num = values_num;
 
-  ce->values_gauge = (gauge_t *) calloc (values_num, sizeof (gauge_t));
-  ce->values_counter = (counter_t *) calloc (values_num, sizeof (counter_t));
-  if ((ce->values_gauge == NULL) || (ce->values_counter == NULL))
+  ce->values_gauge = calloc (values_num, sizeof (*ce->values_gauge));
+  ce->values_raw   = calloc (values_num, sizeof (*ce->values_raw));
+  if ((ce->values_gauge == NULL) || (ce->values_raw == NULL))
   {
     sfree (ce->values_gauge);
-    sfree (ce->values_counter);
+    sfree (ce->values_raw);
     sfree (ce);
     ERROR ("utils_cache: cache_alloc: calloc failed.");
     return (NULL);
   }
 
+  ce->history = NULL;
+  ce->history_length = 0;
+  ce->meta = NULL;
+
   return (ce);
 } /* cache_entry_t *cache_alloc */
 
@@ -89,7 +110,13 @@ static void cache_free (cache_entry_t *ce)
     return;
 
   sfree (ce->values_gauge);
-  sfree (ce->values_counter);
+  sfree (ce->values_raw);
+  sfree (ce->history);
+  if (ce->meta != NULL)
+  {
+    meta_data_destroy (ce->meta);
+    ce->meta = NULL;
+  }
   sfree (ce);
 } /* void cache_free */
 
@@ -137,7 +164,7 @@ static int uc_send_notification (const char *name)
    * acquiring the lock takes and we will use this time later to decide
    * whether or not the state is OKAY.
    */
-  n.time = time (NULL);
+  n.time = cdtime ();
 
   status = c_avl_get (cache_tree, name, (void *) &ce);
   if (status != 0)
@@ -148,7 +175,7 @@ static int uc_send_notification (const char *name)
   }
     
   /* Check if the entry has been updated in the meantime */
-  if ((n.time - ce->last_update) < (2 * ce->interval))
+  if ((n.time - ce->last_update) < (timeout_g * ce->interval))
   {
     ce->state = STATE_OKAY;
     pthread_mutex_unlock (&cache_lock);
@@ -157,8 +184,8 @@ static int uc_send_notification (const char *name)
   }
 
   ssnprintf (n.message, sizeof (n.message),
-      "%s has not been updated for %i seconds.", name,
-      (int) (n.time - ce->last_update));
+      "%s has not been updated for %.3f seconds.", name,
+      CDTIME_T_TO_DOUBLE (n.time - ce->last_update));
 
   pthread_mutex_unlock (&cache_lock);
 
@@ -167,6 +194,21 @@ static int uc_send_notification (const char *name)
   return (0);
 } /* int uc_send_notification */
 
+static void uc_check_range (const data_set_t *ds, cache_entry_t *ce)
+{
+  int i;
+
+  for (i = 0; i < ds->ds_num; i++)
+  {
+    if (isnan (ce->values_gauge[i]))
+      continue;
+    else if (ce->values_gauge[i] < ds->ds[i].min)
+      ce->values_gauge[i] = NAN;
+    else if (ce->values_gauge[i] > ds->ds[i].max)
+      ce->values_gauge[i] = NAN;
+  }
+} /* void uc_check_range */
+
 static int uc_insert (const data_set_t *ds, const value_list_t *vl,
     const char *key)
 {
@@ -186,6 +228,7 @@ static int uc_insert (const data_set_t *ds, const value_list_t *vl,
   ce = cache_alloc (ds->ds_num);
   if (ce == NULL)
   {
+    sfree (key_copy);
     ERROR ("uc_insert: cache_alloc (%i) failed.", ds->ds_num);
     return (-1);
   }
@@ -194,19 +237,44 @@ static int uc_insert (const data_set_t *ds, const value_list_t *vl,
 
   for (i = 0; i < ds->ds_num; i++)
   {
-    if (ds->ds[i].type == DS_TYPE_COUNTER)
-    {
-      ce->values_gauge[i] = NAN;
-      ce->values_counter[i] = vl->values[i].counter;
-    }
-    else /* if (ds->ds[i].type == DS_TYPE_GAUGE) */
+    switch (ds->ds[i].type)
     {
-      ce->values_gauge[i] = vl->values[i].gauge;
-    }
+      case DS_TYPE_COUNTER:
+	ce->values_gauge[i] = NAN;
+	ce->values_raw[i].counter = vl->values[i].counter;
+	break;
+
+      case DS_TYPE_GAUGE:
+	ce->values_gauge[i] = vl->values[i].gauge;
+	ce->values_raw[i].gauge = vl->values[i].gauge;
+	break;
+
+      case DS_TYPE_DERIVE:
+	ce->values_gauge[i] = NAN;
+	ce->values_raw[i].derive = vl->values[i].derive;
+	break;
+
+      case DS_TYPE_ABSOLUTE:
+	ce->values_gauge[i] = NAN;
+	if (vl->interval > 0)
+	  ce->values_gauge[i] = ((double) vl->values[i].absolute)
+	    / CDTIME_T_TO_DOUBLE (vl->interval);
+	ce->values_raw[i].absolute = vl->values[i].absolute;
+	break;
+	
+      default:
+	/* This shouldn't happen. */
+	ERROR ("uc_insert: Don't know how to handle data source type %i.",
+	    ds->ds[i].type);
+	return (-1);
+    } /* switch (ds->ds[i].type) */
   } /* for (i) */
 
+  /* Prune invalid gauge data */
+  uc_check_range (ds, ce);
+
   ce->last_time = vl->time;
-  ce->last_update = time (NULL);
+  ce->last_update = cdtime ();
   ce->interval = vl->interval;
   ce->state = STATE_OKAY;
 
@@ -232,7 +300,7 @@ int uc_init (void)
 
 int uc_check_timeout (void)
 {
-  time_t now;
+  cdtime_t now;
   cache_entry_t *ce;
 
   char **keys = NULL;
@@ -244,14 +312,14 @@ int uc_check_timeout (void)
   
   pthread_mutex_lock (&cache_lock);
 
-  now = time (NULL);
+  now = cdtime ();
 
   /* Build a list of entries to be flushed */
   iter = c_avl_get_iterator (cache_tree);
   while (c_avl_iterator_next (iter, (void *) &key, (void *) &ce) == 0)
   {
     /* If entry has not been updated, add to `keys' array */
-    if ((now - ce->last_update) >= (2 * ce->interval))
+    if ((now - ce->last_update) >= (ce->interval * timeout_g))
     {
       char **tmp;
 
@@ -259,8 +327,10 @@ int uc_check_timeout (void)
 	  (keys_len + 1) * sizeof (char *));
       if (tmp == NULL)
       {
-	ERROR ("uc_purge: realloc failed.");
+	ERROR ("uc_check_timeout: realloc failed.");
 	c_avl_iterator_destroy (iter);
+	sfree (keys);
+	pthread_mutex_unlock (&cache_lock);
 	return (-1);
       }
 
@@ -275,6 +345,8 @@ int uc_check_timeout (void)
     }
   } /* while (c_avl_iterator_next) */
 
+  ce = NULL;
+
   for (i = 0; i < keys_len; i++)
   {
     int status;
@@ -285,12 +357,13 @@ int uc_check_timeout (void)
     {
       ERROR ("uc_check_timeout: ut_check_interesting failed.");
       sfree (keys[i]);
+      continue;
     }
     else if (status == 0) /* ``service'' is uninteresting */
     {
-      ce = NULL;
       DEBUG ("uc_check_timeout: %s is missing but ``uninteresting''",
 	  keys[i]);
+      ce = NULL;
       status = c_avl_remove (cache_tree, keys[i],
 	  (void *) &key, (void *) &ce);
       if (status != 0)
@@ -299,21 +372,36 @@ int uc_check_timeout (void)
       }
       sfree (keys[i]);
       sfree (key);
-      cache_free (ce);
+      if (ce != NULL)
+        cache_free (ce);
+      continue;
     }
-    else if (status == 1) /* persist */
+
+    /* If we get here, the value is ``interesting''. Query the record from the
+     * cache and update the state field. */
+    if (c_avl_get (cache_tree, keys[i], (void *) &ce) != 0)
+    {
+      ERROR ("uc_check_timeout: cannot get data for %s from cache", keys[i]);
+      /* Do not free `keys[i]' so a notification is sent further down. */
+      continue;
+    }
+    assert (ce != NULL);
+
+    if (status == 2) /* persist */
     {
       DEBUG ("uc_check_timeout: %s is missing, sending notification.",
 	  keys[i]);
       ce->state = STATE_MISSING;
+      /* Do not free `keys[i]' so a notification is sent further down. */
     }
-    else if (status == 2) /* do not persist */
+    else if (status == 1) /* do not persist */
     {
       if (ce->state == STATE_MISSING)
       {
 	DEBUG ("uc_check_timeout: %s is missing but "
 	    "notification has already been sent.",
 	    keys[i]);
+	/* Set `keys[i]' to NULL to no notification is sent. */
 	sfree (keys[i]);
       }
       else /* (ce->state != STATE_MISSING) */
@@ -321,6 +409,7 @@ int uc_check_timeout (void)
 	DEBUG ("uc_check_timeout: %s is missing, sending one notification.",
 	    keys[i]);
 	ce->state = STATE_MISSING;
+	/* Do not free `keys[i]' so a notification is sent further down. */
       }
     }
     else
@@ -328,7 +417,12 @@ int uc_check_timeout (void)
       WARNING ("uc_check_timeout: ut_check_interesting (%s) returned "
 	  "invalid status %i.",
 	  keys[i], status);
+      sfree (keys[i]);
     }
+
+    /* Make really sure the next iteration doesn't work with this pointer.
+     * There have been too many bugs in the past.. :/  -- octo */
+    ce = NULL;
   } /* for (keys[i]) */
 
   c_avl_iterator_destroy (iter);
@@ -354,12 +448,12 @@ int uc_update (const data_set_t *ds, const value_list_t *vl)
   char name[6 * DATA_MAX_NAME_LEN];
   cache_entry_t *ce = NULL;
   int send_okay_notification = 0;
-  time_t update_delay = 0;
+  cdtime_t update_delay = 0;
   notification_t n;
   int status;
   int i;
 
-  if (FORMAT_VL (name, sizeof (name), vl, ds) != 0)
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
   {
     ERROR ("uc_update: FORMAT_VL failed.");
     return (-1);
@@ -381,9 +475,11 @@ int uc_update (const data_set_t *ds, const value_list_t *vl)
   if (ce->last_time >= vl->time)
   {
     pthread_mutex_unlock (&cache_lock);
-    NOTICE ("uc_update: Value too old: name = %s; value time = %u; "
-	"last cache update = %u;",
-	name, (unsigned int) vl->time, (unsigned int) ce->last_time);
+    NOTICE ("uc_update: Value too old: name = %s; value time = %.3f; "
+	"last cache update = %.3f;",
+	name,
+	CDTIME_T_TO_DOUBLE (vl->time),
+	CDTIME_T_TO_DOUBLE (ce->last_time));
     return (-1);
   }
 
@@ -393,43 +489,91 @@ int uc_update (const data_set_t *ds, const value_list_t *vl)
   {
     send_okay_notification = 1;
     ce->state = STATE_OKAY;
-    update_delay = time (NULL) - ce->last_update;
+    update_delay = cdtime () - ce->last_update;
   }
 
   for (i = 0; i < ds->ds_num; i++)
   {
-    if (ds->ds[i].type == DS_TYPE_COUNTER)
+    switch (ds->ds[i].type)
     {
-      counter_t diff;
+      case DS_TYPE_COUNTER:
+	{
+	  counter_t diff;
+
+	  /* check if the counter has wrapped around */
+	  if (vl->values[i].counter < ce->values_raw[i].counter)
+	  {
+	    if (ce->values_raw[i].counter <= 4294967295U)
+	      diff = (4294967295U - ce->values_raw[i].counter)
+		+ vl->values[i].counter;
+	    else
+	      diff = (18446744073709551615ULL - ce->values_raw[i].counter)
+		+ vl->values[i].counter;
+	  }
+	  else /* counter has NOT wrapped around */
+	  {
+	    diff = vl->values[i].counter - ce->values_raw[i].counter;
+	  }
+
+	  ce->values_gauge[i] = ((double) diff)
+	    / (CDTIME_T_TO_DOUBLE (vl->time - ce->last_time));
+	  ce->values_raw[i].counter = vl->values[i].counter;
+	}
+	break;
 
-      /* check if the counter has wrapped around */
-      if (vl->values[i].counter < ce->values_counter[i])
-      {
-	if (ce->values_counter[i] <= 4294967295U)
-	  diff = (4294967295U - ce->values_counter[i])
-	    + vl->values[i].counter;
-	else
-	  diff = (18446744073709551615ULL - ce->values_counter[i])
-	    + vl->values[i].counter;
-      }
-      else /* counter has NOT wrapped around */
-      {
-	diff = vl->values[i].counter - ce->values_counter[i];
-      }
+      case DS_TYPE_GAUGE:
+	ce->values_raw[i].gauge = vl->values[i].gauge;
+	ce->values_gauge[i] = vl->values[i].gauge;
+	break;
+
+      case DS_TYPE_DERIVE:
+	{
+	  derive_t diff;
+
+	  diff = vl->values[i].derive - ce->values_raw[i].derive;
+
+	  ce->values_gauge[i] = ((double) diff)
+	    / (CDTIME_T_TO_DOUBLE (vl->time - ce->last_time));
+	  ce->values_raw[i].derive = vl->values[i].derive;
+	}
+	break;
+
+      case DS_TYPE_ABSOLUTE:
+	ce->values_gauge[i] = ((double) vl->values[i].absolute)
+	  / (CDTIME_T_TO_DOUBLE (vl->time - ce->last_time));
+	ce->values_raw[i].absolute = vl->values[i].absolute;
+	break;
+
+      default:
+	/* This shouldn't happen. */
+	pthread_mutex_unlock (&cache_lock);
+	ERROR ("uc_update: Don't know how to handle data source type %i.",
+	    ds->ds[i].type);
+	return (-1);
+    } /* switch (ds->ds[i].type) */
 
-      ce->values_gauge[i] = ((double) diff)
-	/ ((double) (vl->time - ce->last_time));
-      ce->values_counter[i] = vl->values[i].counter;
-    }
-    else /* if (ds->ds[i].type == DS_TYPE_GAUGE) */
-    {
-      ce->values_gauge[i] = vl->values[i].gauge;
-    }
     DEBUG ("uc_update: %s: ds[%i] = %lf", name, i, ce->values_gauge[i]);
   } /* for (i) */
 
+  /* Update the history if it exists. */
+  if (ce->history != NULL)
+  {
+    assert (ce->history_index < ce->history_length);
+    for (i = 0; i < ce->values_num; i++)
+    {
+      size_t hist_idx = (ce->values_num * ce->history_index) + i;
+      ce->history[hist_idx] = ce->values_gauge[i];
+    }
+
+    assert (ce->history_length > 0);
+    ce->history_index = (ce->history_index + 1) % ce->history_length;
+  }
+
+  /* Prune invalid gauge data */
+  uc_check_range (ds, ce);
+
   ce->last_time = vl->time;
-  ce->last_update = time (NULL);
+  ce->last_update = cdtime ();
   ce->interval = vl->interval;
 
   pthread_mutex_unlock (&cache_lock);
@@ -472,16 +616,24 @@ int uc_get_rate_by_name (const char *name, gauge_t **ret_values, size_t *ret_val
   {
     assert (ce != NULL);
 
-    ret_num = ce->values_num;
-    ret = (gauge_t *) malloc (ret_num * sizeof (gauge_t));
-    if (ret == NULL)
+    /* remove missing values from getval */
+    if (ce->state == STATE_MISSING)
     {
-      ERROR ("utils_cache: uc_get_rate_by_name: malloc failed.");
       status = -1;
     }
     else
     {
-      memcpy (ret, ce->values_gauge, ret_num * sizeof (gauge_t));
+      ret_num = ce->values_num;
+      ret = (gauge_t *) malloc (ret_num * sizeof (gauge_t));
+      if (ret == NULL)
+      {
+        ERROR ("utils_cache: uc_get_rate_by_name: malloc failed.");
+        status = -1;
+      }
+      else
+      {
+        memcpy (ret, ce->values_gauge, ret_num * sizeof (gauge_t));
+      }
     }
   }
   else
@@ -508,9 +660,9 @@ gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl)
   size_t ret_num = 0;
   int status;
 
-  if (FORMAT_VL (name, sizeof (name), vl, ds) != 0)
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
   {
-    ERROR ("uc_insert: FORMAT_VL failed.");
+    ERROR ("utils_cache: uc_get_rate: FORMAT_VL failed.");
     return (NULL);
   }
 
@@ -520,7 +672,7 @@ gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl)
 
   /* This is important - the caller has no other way of knowing how many
    * values are returned. */
-  if (ret_num != ds->ds_num)
+  if (ret_num != (size_t) ds->ds_num)
   {
     ERROR ("utils_cache: uc_get_rate: ds[%s] has %i values, "
 	"but uc_get_rate_by_name returned %zu.",
@@ -532,14 +684,14 @@ gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl)
   return (ret);
 } /* gauge_t *uc_get_rate */
 
-int uc_get_names (char ***ret_names, time_t **ret_times, size_t *ret_number)
+int uc_get_names (char ***ret_names, cdtime_t **ret_times, size_t *ret_number)
 {
   c_avl_iterator_t *iter;
   char *key;
   cache_entry_t *value;
 
   char **names = NULL;
-  time_t *times = NULL;
+  cdtime_t *times = NULL;
   size_t number = 0;
 
   int status = 0;
@@ -554,11 +706,15 @@ int uc_get_names (char ***ret_names, time_t **ret_times, size_t *ret_number)
   {
     char **temp;
 
+    /* remove missing values when list values */
+    if (value->state == STATE_MISSING)
+      continue;
+
     if (ret_times != NULL)
     {
-      time_t *tmp_times;
+      cdtime_t *tmp_times;
 
-      tmp_times = (time_t *) realloc (times, sizeof (time_t) * (number + 1));
+      tmp_times = (cdtime_t *) realloc (times, sizeof (cdtime_t) * (number + 1));
       if (tmp_times == NULL)
       {
 	status = -1;
@@ -614,7 +770,7 @@ int uc_get_state (const data_set_t *ds, const value_list_t *vl)
   cache_entry_t *ce = NULL;
   int ret = STATE_ERROR;
 
-  if (FORMAT_VL (name, sizeof (name), vl, ds) != 0)
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
   {
     ERROR ("uc_get_state: FORMAT_VL failed.");
     return (STATE_ERROR);
@@ -639,7 +795,7 @@ int uc_set_state (const data_set_t *ds, const value_list_t *vl, int state)
   cache_entry_t *ce = NULL;
   int ret = -1;
 
-  if (FORMAT_VL (name, sizeof (name), vl, ds) != 0)
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
   {
     ERROR ("uc_get_state: FORMAT_VL failed.");
     return (STATE_ERROR);
@@ -658,4 +814,273 @@ int uc_set_state (const data_set_t *ds, const value_list_t *vl, int state)
 
   return (ret);
 } /* int uc_set_state */
+
+int uc_get_history_by_name (const char *name,
+    gauge_t *ret_history, size_t num_steps, size_t num_ds)
+{
+  cache_entry_t *ce = NULL;
+  size_t i;
+  int status = 0;
+
+  pthread_mutex_lock (&cache_lock);
+
+  status = c_avl_get (cache_tree, name, (void *) &ce);
+  if (status != 0)
+  {
+    pthread_mutex_unlock (&cache_lock);
+    return (-ENOENT);
+  }
+
+  if (((size_t) ce->values_num) != num_ds)
+  {
+    pthread_mutex_unlock (&cache_lock);
+    return (-EINVAL);
+  }
+
+  /* Check if there are enough values available. If not, increase the buffer
+   * size. */
+  if (ce->history_length < num_steps)
+  {
+    gauge_t *tmp;
+    size_t i;
+
+    tmp = realloc (ce->history, sizeof (*ce->history)
+	* num_steps * ce->values_num);
+    if (tmp == NULL)
+    {
+      pthread_mutex_unlock (&cache_lock);
+      return (-ENOMEM);
+    }
+
+    for (i = ce->history_length * ce->values_num;
+	i < (num_steps * ce->values_num);
+	i++)
+      tmp[i] = NAN;
+
+    ce->history = tmp;
+    ce->history_length = num_steps;
+  } /* if (ce->history_length < num_steps) */
+
+  /* Copy the values to the output buffer. */
+  for (i = 0; i < num_steps; i++)
+  {
+    size_t src_index;
+    size_t dst_index;
+
+    if (i < ce->history_index)
+      src_index = ce->history_index - (i + 1);
+    else
+      src_index = ce->history_length + ce->history_index - (i + 1);
+    src_index = src_index * num_ds;
+
+    dst_index = i * num_ds;
+
+    memcpy (ret_history + dst_index, ce->history + src_index,
+	sizeof (*ret_history) * num_ds);
+  }
+
+  pthread_mutex_unlock (&cache_lock);
+
+  return (0);
+} /* int uc_get_history_by_name */
+
+int uc_get_history (const data_set_t *ds, const value_list_t *vl,
+    gauge_t *ret_history, size_t num_steps, size_t num_ds)
+{
+  char name[6 * DATA_MAX_NAME_LEN];
+
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
+  {
+    ERROR ("utils_cache: uc_get_history: FORMAT_VL failed.");
+    return (-1);
+  }
+
+  return (uc_get_history_by_name (name, ret_history, num_steps, num_ds));
+} /* int uc_get_history */
+
+int uc_get_hits (const data_set_t *ds, const value_list_t *vl)
+{
+  char name[6 * DATA_MAX_NAME_LEN];
+  cache_entry_t *ce = NULL;
+  int ret = STATE_ERROR;
+
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
+  {
+    ERROR ("uc_get_state: FORMAT_VL failed.");
+    return (STATE_ERROR);
+  }
+
+  pthread_mutex_lock (&cache_lock);
+
+  if (c_avl_get (cache_tree, name, (void *) &ce) == 0)
+  {
+    assert (ce != NULL);
+    ret = ce->hits;
+  }
+
+  pthread_mutex_unlock (&cache_lock);
+
+  return (ret);
+} /* int uc_get_hits */
+
+int uc_set_hits (const data_set_t *ds, const value_list_t *vl, int hits)
+{
+  char name[6 * DATA_MAX_NAME_LEN];
+  cache_entry_t *ce = NULL;
+  int ret = -1;
+
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
+  {
+    ERROR ("uc_get_state: FORMAT_VL failed.");
+    return (STATE_ERROR);
+  }
+
+  pthread_mutex_lock (&cache_lock);
+
+  if (c_avl_get (cache_tree, name, (void *) &ce) == 0)
+  {
+    assert (ce != NULL);
+    ret = ce->hits;
+    ce->hits = hits;
+  }
+
+  pthread_mutex_unlock (&cache_lock);
+
+  return (ret);
+} /* int uc_set_hits */
+
+int uc_inc_hits (const data_set_t *ds, const value_list_t *vl, int step)
+{
+  char name[6 * DATA_MAX_NAME_LEN];
+  cache_entry_t *ce = NULL;
+  int ret = -1;
+
+  if (FORMAT_VL (name, sizeof (name), vl) != 0)
+  {
+    ERROR ("uc_get_state: FORMAT_VL failed.");
+    return (STATE_ERROR);
+  }
+
+  pthread_mutex_lock (&cache_lock);
+
+  if (c_avl_get (cache_tree, name, (void *) &ce) == 0)
+  {
+    assert (ce != NULL);
+    ret = ce->hits;
+    ce->hits = ret + step;
+  }
+
+  pthread_mutex_unlock (&cache_lock);
+
+  return (ret);
+} /* int uc_inc_hits */
+
+/*
+ * Meta data interface
+ */
+/* XXX: This function will acquire `cache_lock' but will not free it! */
+static meta_data_t *uc_get_meta (const value_list_t *vl) /* {{{ */
+{
+  char name[6 * DATA_MAX_NAME_LEN];
+  cache_entry_t *ce = NULL;
+  int status;
+
+  status = FORMAT_VL (name, sizeof (name), vl);
+  if (status != 0)
+  {
+    ERROR ("utils_cache: uc_get_meta: FORMAT_VL failed.");
+    return (NULL);
+  }
+
+  pthread_mutex_lock (&cache_lock);
+
+  status = c_avl_get (cache_tree, name, (void *) &ce);
+  if (status != 0)
+  {
+    pthread_mutex_unlock (&cache_lock);
+    return (NULL);
+  }
+  assert (ce != NULL);
+
+  if (ce->meta == NULL)
+    ce->meta = meta_data_create ();
+
+  if (ce->meta == NULL)
+    pthread_mutex_unlock (&cache_lock);
+
+  return (ce->meta);
+} /* }}} meta_data_t *uc_get_meta */
+
+/* Sorry about this preprocessor magic, but it really makes this file much
+ * shorter.. */
+#define UC_WRAP(wrap_function) { \
+  meta_data_t *meta; \
+  int status; \
+  meta = uc_get_meta (vl); \
+  if (meta == NULL) return (-1); \
+  status = wrap_function (meta, key); \
+  pthread_mutex_unlock (&cache_lock); \
+  return (status); \
+}
+int uc_meta_data_exists (const value_list_t *vl, const char *key)
+  UC_WRAP (meta_data_exists)
+
+int uc_meta_data_delete (const value_list_t *vl, const char *key)
+  UC_WRAP (meta_data_delete)
+#undef UC_WRAP
+
+/* We need a new version of this macro because the following functions take
+ * two argumetns. */
+#define UC_WRAP(wrap_function) { \
+  meta_data_t *meta; \
+  int status; \
+  meta = uc_get_meta (vl); \
+  if (meta == NULL) return (-1); \
+  status = wrap_function (meta, key, value); \
+  pthread_mutex_unlock (&cache_lock); \
+  return (status); \
+}
+int uc_meta_data_add_string (const value_list_t *vl,
+    const char *key,
+    const char *value)
+  UC_WRAP(meta_data_add_string)
+int uc_meta_data_add_signed_int (const value_list_t *vl,
+    const char *key,
+    int64_t value)
+  UC_WRAP(meta_data_add_signed_int)
+int uc_meta_data_add_unsigned_int (const value_list_t *vl,
+    const char *key,
+    uint64_t value)
+  UC_WRAP(meta_data_add_unsigned_int)
+int uc_meta_data_add_double (const value_list_t *vl,
+    const char *key,
+    double value)
+  UC_WRAP(meta_data_add_double)
+int uc_meta_data_add_boolean (const value_list_t *vl,
+    const char *key,
+    _Bool value)
+  UC_WRAP(meta_data_add_boolean)
+
+int uc_meta_data_get_string (const value_list_t *vl,
+    const char *key,
+    char **value)
+  UC_WRAP(meta_data_get_string)
+int uc_meta_data_get_signed_int (const value_list_t *vl,
+    const char *key,
+    int64_t *value)
+  UC_WRAP(meta_data_get_signed_int)
+int uc_meta_data_get_unsigned_int (const value_list_t *vl,
+    const char *key,
+    uint64_t *value)
+  UC_WRAP(meta_data_get_unsigned_int)
+int uc_meta_data_get_double (const value_list_t *vl,
+    const char *key,
+    double *value)
+  UC_WRAP(meta_data_get_double)
+int uc_meta_data_get_boolean (const value_list_t *vl,
+    const char *key,
+    _Bool *value)
+  UC_WRAP(meta_data_get_boolean)
+#undef UC_WRAP
+
 /* vim: set sw=2 ts=8 sts=2 tw=78 : */