include/babeltrace/object-internal.h

   1 #ifndef BABELTRACE_OBJECT_INTERNAL_H
   2 #define BABELTRACE_OBJECT_INTERNAL_H
   3
   4 /*
   5  * Babeltrace - Base object
   6  *
   7  * Copyright 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   8  *
   9  * Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  27  * SOFTWARE.
  28  */
  29
  30 #include <babeltrace/ref-internal.h>
  31 #include <babeltrace/ref.h>
  32
  33 /**
  34  * All objects publicly exposed by Babeltrace APIs must contain this structure
  35  * as their first member. This allows the unification of all ref counting
  36  * mechanisms and may be used to provide more base functionality to all
  37  * objects.
  38  */
  39 struct bt_object {
  40         struct bt_ref ref_count;
  41         /* Class-specific release function. */
  42         bt_object_release_func release;
  43         /* @see doc/ref-counting.md */
  44         struct bt_object *parent;
  45 };
  46
  47 static inline
  48 long bt_object_get_ref_count(const void *ptr)
  49 {
  50         const struct bt_object *obj = ptr;
  51
  52         return obj->ref_count.count;
  53 }
  54
  55 static inline
  56 void bt_object_release(void *ptr)
  57 {
  58         struct bt_object *obj = ptr;
  59
  60         if (obj && obj->release && !bt_object_get_ref_count(obj)) {
  61                 obj->release(obj);
  62         }
  63 }
  64
  65 static inline
  66 void generic_release(struct bt_object *obj)
  67 {
  68         if (obj->parent) {
  69                 /* The release function will be invoked by the parent. */
  70                 bt_put(obj->parent);
  71         } else {
  72                 bt_object_release(obj);
  73         }
  74 }
  75
  76 static inline
  77 struct bt_object *bt_object_borrow_parent(void *ptr)
  78 {
  79         struct bt_object *obj = ptr;
  80
  81         return obj ? obj->parent : NULL;
  82 }
  83
  84 static inline
  85 struct bt_object *bt_object_get_parent(void *ptr)
  86 {
  87         return bt_get(bt_object_borrow_parent(ptr));
  88 }
  89
  90 static inline
  91 void bt_object_set_parent(void *child_ptr, void *parent)
  92 {
  93         struct bt_object *child = child_ptr;
  94
  95         if (!child) {
  96                 return;
  97         }
  98
  99         /*
 100          * It is assumed that a "child" being "parented" is publicly reachable.
 101          * Therefore, a reference to its parent must be taken. The reference
 102          * to the parent will be released once the object's reference count
 103          * falls to zero.
 104          */
 105         BT_PUT(child->parent);
 106         child->parent = bt_get(parent);
 107 }
 108
 109 static inline
 110 void bt_object_init(void *ptr, bt_object_release_func release)
 111 {
 112         struct bt_object *obj = ptr;
 113
 114         obj->release = release;
 115         obj->parent = NULL;
 116         bt_ref_init(&obj->ref_count, generic_release);
 117 }
 118
 119 #endif /* BABELTRACE_OBJECT_INTERNAL_H */