mono/metadata/property-bag.c

   1 /**
   2  * \file
   3  * Linearizable property bag.
   4  *
   5  * Authors:
   6  *   Rodrigo Kumpera (kumpera@gmail.com)
   7  *
   8  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   9  */
  10 #include <mono/metadata/property-bag.h>
  11 #include <mono/utils/atomic.h>
  12 #include <mono/utils/mono-membar.h>
  13
  14 /*
  15  * mono_property_bag_get:
  16  *
  17  *   Return the value of the property with TAG or NULL.
  18  * This doesn't take any locks.
  19  */
  20 void*
  21 mono_property_bag_get (MonoPropertyBag *bag, int tag)
  22 {
  23         MonoPropertyBagItem *item;
  24
  25         for (item = bag->head; item && item->tag <= tag; item = item->next) {
  26                 if (item->tag == tag)
  27                         return item;
  28         }
  29         return NULL;
  30 }
  31
  32 /*
  33  * mono_property_bag_add:
  34  *
  35  *   Store VALUE in the property bag. Return the previous value
  36  * with the same tag, or NULL. VALUE should point to a structure
  37  * extending the MonoPropertyBagItem structure with the 'tag'
  38  * field set.
  39  * This doesn't take any locks.
  40  */
  41 void*
  42 mono_property_bag_add (MonoPropertyBag *bag, void *value)
  43 {
  44         MonoPropertyBagItem *cur, **prev, *item = (MonoPropertyBagItem*)value;
  45         int tag = item->tag;
  46         mono_memory_barrier (); //publish the values in value
  47
  48 retry:
  49         prev = &bag->head;
  50         while (1) {
  51                 cur = *prev;
  52                 if (!cur || cur->tag > tag) {
  53                         item->next = cur;
  54                         if (mono_atomic_cas_ptr ((void**)prev, item, cur) == cur)
  55                                 return item;
  56                         goto retry;
  57                 } else if (cur->tag == tag) {
  58                         return cur;
  59                 } else {
  60                         prev = &cur->next;
  61                 }
  62         }
  63         return value;
  64 }