Also fix query_plans_by_table

[collectd.git] / src / meta_data.c

diff --git a/src/meta_data.c b/src/meta_data.c
index 80b6dd1..d220784 100644 (file)
--- a/src/meta_data.c
+++ b/src/meta_data.c
@@ -1,6 +1,6 @@
 /**
  * collectd - src/meta_data.c
- * Copyright (C) 2008,2009  Florian octo Forster
+ * Copyright (C) 2008-2011  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
@@ -101,6 +101,26 @@ static meta_entry_t *md_entry_alloc (const char *key) /* {{{ */
   return (e);
 } /* }}} meta_entry_t *md_entry_alloc */
 
+static meta_entry_t *md_entry_clone (const meta_entry_t *orig) /* {{{ */
+{
+  meta_entry_t *copy;
+
+  if (orig == NULL)
+    return (NULL);
+
+  copy = md_entry_alloc (orig->key);
+  if (copy == NULL)
+    return (NULL);
+  copy->type = orig->type;
+  if (copy->type == MD_TYPE_STRING)
+    copy->value.mv_string = strdup (orig->value.mv_string);
+  else
+    copy->value = orig->value;
+
+  copy->next = md_entry_clone (orig->next);
+  return (copy);
+} /* }}} meta_entry_t *md_entry_clone */
+
 static void md_entry_free (meta_entry_t *e) /* {{{ */
 {
   if (e == NULL)
@@ -189,6 +209,17 @@ static meta_entry_t *md_entry_lookup (meta_data_t *md, /* {{{ */
 } /* }}} meta_entry_t *md_entry_lookup */
 
 /*
+ * Each value_list_t*, as it is going through the system, is handled by exactly
+ * one thread. Plugins which pass a value_list_t* to another thread, e.g. the
+ * rrdtool plugin, must create a copy first. The meta data within a
+ * value_list_t* is not thread safe and doesn't need to be.
+ *
+ * The meta data associated with cache entries are a different story. There, we
+ * need to ensure exclusive locking to prevent leaks and other funky business.
+ * This is ensured by the uc_meta_data_get_*() functions.
+ */
+
+/*
  * Public functions
  */
 meta_data_t *meta_data_create (void) /* {{{ */
@@ -209,12 +240,31 @@ meta_data_t *meta_data_create (void) /* {{{ */
   return (md);
 } /* }}} meta_data_t *meta_data_create */
 
+meta_data_t *meta_data_clone (meta_data_t *orig) /* {{{ */
+{
+  meta_data_t *copy;
+
+  if (orig == NULL)
+    return (NULL);
+
+  copy = meta_data_create ();
+  if (copy == NULL)
+    return (NULL);
+
+  pthread_mutex_lock (&orig->lock);
+  copy->head = md_entry_clone (orig->head);
+  pthread_mutex_unlock (&orig->lock);
+
+  return (copy);
+} /* }}} meta_data_t *meta_data_clone */
+
 void meta_data_destroy (meta_data_t *md) /* {{{ */
 {
   if (md == NULL)
     return;
 
   md_entry_free (md->head);
+  pthread_mutex_destroy (&md->lock);
   free (md);
 } /* }}} void meta_data_destroy */
 
@@ -245,7 +295,7 @@ int meta_data_type (meta_data_t *md, const char *key) /* {{{ */
   meta_entry_t *e;
 
   if ((md == NULL) || (key == NULL))
-    return 0;
+    return -EINVAL;
 
   pthread_mutex_lock (&md->lock);
 
@@ -268,14 +318,20 @@ int meta_data_toc (meta_data_t *md, char ***toc) /* {{{ */
   meta_entry_t *e;
 
   if ((md == NULL) || (toc == NULL))
-    return -1;
+    return -EINVAL;
 
   pthread_mutex_lock (&md->lock);
 
   for (e = md->head; e != NULL; e = e->next)
     ++count;    
 
-  *toc = malloc(count * sizeof(**toc));
+  if (count == 0)
+  {
+    pthread_mutex_unlock (&md->lock);
+    return (count);
+  }
+
+  *toc = calloc(count, sizeof(**toc));
   for (e = md->head; e != NULL; e = e->next)
     (*toc)[i++] = strdup(e->key);
   
@@ -445,7 +501,7 @@ int meta_data_get_string (meta_data_t *md, /* {{{ */
 
   if (e->type != MD_TYPE_STRING)
   {
-    ERROR ("meta_data_get_signed_int: Type mismatch for key `%s'", e->key);
+    ERROR ("meta_data_get_string: Type mismatch for key `%s'", e->key);
     pthread_mutex_unlock (&md->lock);
     return (-ENOENT);
   }