rrdtool plugin: Use the AVL-tree to implement the cache.

diff --git a/src/rrdtool.c b/src/rrdtool.c
index beb5a73..1c7d662 100644 (file)
--- a/src/rrdtool.c
+++ b/src/rrdtool.c
@@ -22,7 +22,7 @@
 #include "collectd.h"
 #include "plugin.h"
 #include "common.h"
-#include "utils_llist.h"
+#include "utils_avltree.h"
 #include "utils_debug.h"
 
 /*
@@ -76,16 +76,18 @@ static int rra_types_num = 3;
 static const char *config_keys[] =
 {
        "CacheTimeout",
+       "CacheFlush",
        "DataDir",
        NULL
 };
-static int config_keys_num = 2;
+static int config_keys_num = 3;
 
 static char *datadir = NULL;
 
-static int      cache_timeout = 0;
-static time_t   cache_flush;
-static llist_t *cache = NULL;
+static int         cache_timeout = 0;
+static int         cache_flush_timeout = 0;
+static time_t      cache_flush_last;
+static avl_tree_t *cache = NULL;
 
 /* * * * * * * * * *
  * WARNING:  Magic *
@@ -410,14 +412,9 @@ static rrd_cache_t *rrd_cache_insert (const char *filename,
                const char *value)
 {
        rrd_cache_t *rc = NULL;
-       llentry_t   *le = NULL;
 
        if (cache != NULL)
-       {
-               le = llist_search (cache, filename);
-               if (le != NULL)
-                       rc = (rrd_cache_t *) le->value;
-       }
+               avl_get (cache, filename, (void *) &rc);
 
        if (rc == NULL)
        {
@@ -435,12 +432,13 @@ static rrd_cache_t *rrd_cache_insert (const char *filename,
        {
                syslog (LOG_ERR, "rrdtool plugin: realloc failed: %s",
                                strerror (errno));
-               free (rc);
-               if (le != NULL)
+               if (cache != NULL)
                {
-                       llist_remove (cache, le);
-                       llentry_destroy (le);
+                       void *cache_key = NULL;
+                       avl_remove (cache, filename, &cache_key, NULL);
+                       sfree (cache_key);
                }
+               free (rc);
                return (NULL);
        }
 
@@ -451,11 +449,21 @@ static rrd_cache_t *rrd_cache_insert (const char *filename,
        if (rc->values_num == 1)
                rc->first_value = time (NULL);
 
-       if ((cache != NULL) && (le == NULL))
+       /* Insert if this is the first value */
+       if ((cache != NULL) && (rc->values_num == 1))
        {
-               le = llentry_create (filename, (void *) rc);
-               if (le != NULL)
-                       llist_prepend (cache, le);
+               void *cache_key = strdup (filename);
+
+               if (cache_key == NULL)
+               {
+                       syslog (LOG_ERR, "rrdtool plugin: strdup failed: %s",
+                                       strerror (errno));
+                       sfree (rc->values);
+                       sfree (rc);
+                       return (NULL);
+               }
+
+               avl_insert (cache, cache_key, rc);
        }
 
        DBG ("rrd_cache_insert (%s, %s) = %p", filename, value, (void *) rc);
@@ -513,10 +521,16 @@ static int rrd_write_cache_entry (const char *filename, rrd_cache_t *rc)
 
 static void rrd_cache_flush (int timeout)
 {
-       llentry_t   *le;
        rrd_cache_t *rc;
        time_t       now;
 
+       char **keys = NULL;
+       int    keys_num = 0;
+
+       char *key;
+       avl_iterator_t *iter;
+       int i;
+
        if (cache == NULL)
                return;
 
@@ -524,34 +538,48 @@ static void rrd_cache_flush (int timeout)
 
        now = time (NULL);
 
-       /* Remove empty entries */
-       le = llist_head (cache);
-       while (le != NULL)
+       /* Build a list of entries to be flushed */
+       iter = avl_get_iterator (cache);
+       while (avl_iterator_next (iter, (void *) &key, (void *) &rc) == 0)
        {
-               llentry_t *next = le->next;
-               rc = (rrd_cache_t *) le->value;
-               if (rc->values_num == 0)
+               DBG ("key = %s; age = %i;", key, now - rc->first_value);
+               if ((now - rc->first_value) >= timeout)
                {
-                       DBG ("Removing cache entry for `%s'", le->key);
-                       free (rc->values);
-                       free (rc);
-                       llist_remove (cache, le);
+                       keys = (char **) realloc ((void *) keys,
+                                       (keys_num + 1) * sizeof (char *));
+                       if (keys == NULL)
+                       {
+                               DBG ("realloc failed: %s", strerror (errno));
+                               syslog (LOG_ERR, "rrdtool plugin: "
+                                               "realloc failed: %s",
+                                               strerror (errno));
+                               avl_iterator_destroy (iter);
+                               return;
+                       }
+                       keys[keys_num] = key;
+                       keys_num++;
                }
-               le = next;
-       }
-
-       /* Write timed out entries */
-       le = llist_head (cache);
-       while (le != NULL)
+       } /* while (avl_iterator_next) */
+       avl_iterator_destroy (iter);
+       
+       for (i = 0; i < keys_num; i++)
        {
-               rc = (rrd_cache_t *) le->value;
-               if ((now - rc->first_value) >= timeout)
-                       rrd_write_cache_entry (le->key, rc);
+               if (avl_remove (cache, keys[i], NULL, (void *) &rc) != 0)
+               {
+                       DBG ("avl_remove (%s) failed.", keys[i]);
+                       continue;
+               }
 
-               le = le->next;
-       }
+               rrd_write_cache_entry (keys[i], rc);
+               sfree (keys[i]); keys[i] = NULL;
+               sfree (rc->values);
+               sfree (rc);
+       } /* for (i = 0..keys_num) */
 
-       cache_flush = now;
+       free (keys);
+       DBG ("Flushed %i value(s)", keys_num);
+
+       cache_flush_last = now;
 } /* void rrd_cache_flush */
 
 static int rrd_write (const data_set_t *ds, const value_list_t *vl)
@@ -608,13 +636,13 @@ static int rrd_write (const data_set_t *ds, const value_list_t *vl)
        if ((now - rc->first_value) >= cache_timeout)
                rrd_write_cache_entry (filename, rc);
 
-       if ((time (NULL) - cache_flush) >= cache_timeout)
+       if ((now - cache_flush_last) >= cache_flush_timeout)
        {
-               rrd_cache_flush (cache_timeout);
+               rrd_cache_flush (cache_flush_timeout);
        }
 
        return (0);
-} /* int rrd_dispatch */
+} /* int rrd_write */
 
 static int rrd_config (const char *key, const char *val)
 {
@@ -629,6 +657,17 @@ static int rrd_config (const char *key, const char *val)
                }
                cache_timeout = tmp;
        }
+       else if (strcasecmp ("CacheFlush", key) == 0)
+       {
+               int tmp = atoi (val);
+               if (tmp < 0)
+               {
+                       fprintf (stderr, "rrdtool: `CacheFlush' must "
+                                       "be greater than 0.\n");
+                       return (1);
+               }
+               cache_flush_timeout = tmp;
+       }
        else if (strcasecmp ("DataDir", key) == 0)
        {
                if (datadir != NULL)
@@ -668,11 +707,15 @@ static int rrd_init (void)
        if (cache_timeout < 2)
        {
                cache_timeout = 0;
+               cache_flush_timeout = 0;
        }
        else
        {
-               cache = llist_create ();
-               cache_flush = time (NULL);
+               if (cache_flush_timeout < cache_timeout)
+                       cache_flush_timeout = 10 * cache_timeout;
+
+               cache = avl_create ((int (*) (const void *, const void *)) strcmp);
+               cache_flush_last = time (NULL);
                plugin_register_shutdown ("rrdtool", rrd_shutdown);
        }
        return (0);