libvirtstats plugin: Fix typos and other mistakes.

[collectd.git] / src / utils_cache.c

diff --git a/src/utils_cache.c b/src/utils_cache.c
index 5ecb83cfa015cc6b4cb606c1ad499676d6ebb2f6..9349a1f4a1c9364f8b170a1e324011a818f34167 100644 (file)
--- a/src/utils_cache.c
+++ b/src/utils_cache.c
@@ -37,7 +37,7 @@ typedef struct cache_entry_s
 } cache_entry_t;
 
 static avl_tree_t     *cache_tree = NULL;
-static pthread_mutex_t cache_lock;
+static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;
 
 static int cache_compare (const cache_entry_t *a, const cache_entry_t *b)
 {
@@ -87,8 +87,24 @@ int uc_update (const data_set_t *ds, const value_list_t *vl)
     {
       if (ds->ds[i].type == DS_TYPE_COUNTER)
       {
-       ce->values_gauge[i] = ((double) (vl->values[i].counter
-           - ce->values_counter[i]))
+       counter_t diff;
+
+       /* 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];
+       }
+
+       ce->values_gauge[i] = ((double) diff)
          / ((double) (vl->time - ce->last_update));
        ce->values_counter[i] = vl->values[i].counter;
       }