From b9390e53e68f70cac2a6b5122214a86bfb51ae65 Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@collectd.org>
Date: Sun, 7 Oct 2012 09:42:28 +0200
Subject: [PATCH] rc/utils_cache.c: Allocate most of the memory required by
 uc_get_names() at once.

strdup() will still require additional memory, but no more memory movement like
required when doing realloc() a lot.

This fixes Github issue #148.
---
 src/utils_cache.c | 50 +++++++++++++++++++++++++-------------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/src/utils_cache.c b/src/utils_cache.c
index 82567f33..539545ac 100644
--- a/src/utils_cache.c
+++ b/src/utils_cache.c
@@ -593,47 +593,47 @@ int uc_get_names (char ***ret_names, cdtime_t **ret_times, size_t *ret_number)
 
   pthread_mutex_lock (&cache_lock);
 
+  size_arrays = (size_t) c_avl_size (cache_tree);
+  if (size_arrays < 1)
+  {
+    /* Handle the "no values" case here, to avoid the error message when
+     * calloc() returns NULL. */
+    pthread_mutex_lock (&cache_lock);
+    return (0);
+  }
+
+  names = calloc (size_arrays, sizeof (*names));
+  times = calloc (size_arrays, sizeof (*times));
+  if ((names == NULL) || (times == NULL))
+  {
+    ERROR ("uc_get_names: calloc failed.");
+    sfree (names);
+    sfree (times);
+    pthread_mutex_lock (&cache_lock);
+    return (ENOMEM);
+  }
+
   iter = c_avl_get_iterator (cache_tree);
   while (c_avl_iterator_next (iter, (void *) &key, (void *) &value) == 0)
   {
-    char **temp;
-
     /* remove missing values when list values */
     if (value->state == STATE_MISSING)
       continue;
 
+    /* c_avl_size does not return a number smaller than the number of elements
+     * returned by c_avl_iterator_next. */
+    assert (number < size_arrays);
+
     if (ret_times != NULL)
-    {
-      cdtime_t *tmp_times;
-
-      if(number <= size_arrays)  {
-        tmp_times = (cdtime_t *) realloc (times, sizeof (cdtime_t) * (size_arrays + LISTVAL_INCREASE));
-        if (tmp_times == NULL)
-        {
-          status = -1;
-          break;
-        }
-        times = tmp_times;
-      }
       times[number] = value->last_time;
-    }
 
-    if(number <= size_arrays)  {
-      temp = (char **) realloc (names, sizeof (char *) * (size_arrays + LISTVAL_INCREASE));
-      if (temp == NULL)
-      {
-        status = -1;
-        break;
-      }
-      names = temp;
-      size_arrays += LISTVAL_INCREASE;
-    }
     names[number] = strdup (key);
     if (names[number] == NULL)
     {
       status = -1;
       break;
     }
+
     number++;
   } /* while (c_avl_iterator_next) */
 
-- 
2.11.0