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/babeltrace-internal.h>
  31 #include <babeltrace/ref-internal.h>
  32 #include <babeltrace/ref.h>
  33 #include <babeltrace/assert-internal.h>
  34 #include <stdbool.h>
  35
  36 /**
  37  * All objects publicly exposed by Babeltrace APIs must contain this structure
  38  * as their first member. This allows the unification of all ref counting
  39  * mechanisms and may be used to provide more base functionality to all
  40  * objects.
  41  */
  42 struct bt_object {
  43         struct bt_ref ref_count;
  44         /* Class-specific, optional release function. */
  45         bt_object_release_func release;
  46         /* Class-specific, optional "parent is owner" notification listener. */
  47         bt_object_release_func parent_is_owner_listener;
  48         /* @see doc/ref-counting.md */
  49         struct bt_object *parent;
  50
  51         /*
  52          * True if this object is shared, that is, it uses reference
  53          * counting. Only used in developer mode.
  54          */
  55         bool is_shared;
  56 };
  57
  58 static inline
  59 long bt_object_get_ref_count(const void *ptr)
  60 {
  61         const struct bt_object *obj = ptr;
  62
  63         return obj->ref_count.count;
  64 }
  65
  66 static inline
  67 void bt_object_release(void *ptr)
  68 {
  69         struct bt_object *obj = ptr;
  70
  71 #ifdef BT_LOGV
  72         BT_LOGV("Releasing object: addr=%p, ref-count=%lu", ptr,
  73                 obj->ref_count.count);
  74 #endif
  75
  76         if (obj && obj->release && bt_object_get_ref_count(obj) == 0) {
  77                 obj->release(obj);
  78         }
  79 }
  80
  81 static inline
  82 void generic_release(struct bt_object *obj)
  83 {
  84         if (obj->parent) {
  85                 struct bt_object *parent = obj->parent;
  86
  87 #ifdef BT_LOGV
  88                 BT_LOGV("Releasing parented object: addr=%p, ref-count=%lu, "
  89                         "parent-addr=%p, parent-ref-count=%lu",
  90                         obj, obj->ref_count.count,
  91                         parent, parent->ref_count.count);
  92 #endif
  93
  94                 if (obj->parent_is_owner_listener) {
  95                         /*
  96                          * Object has a chance to destroy itself here
  97                          * under certain conditions and notify its
  98                          * parent. At this point the parent is
  99                          * guaranteed to exist because it's not put yet.
 100                          */
 101                         obj->parent_is_owner_listener(obj);
 102                 }
 103
 104                 /* The release function will be invoked by the parent. */
 105                 bt_put(parent);
 106         } else {
 107                 bt_object_release(obj);
 108         }
 109 }
 110
 111 static inline
 112 struct bt_object *bt_object_borrow_parent(void *ptr)
 113 {
 114         struct bt_object *obj = ptr;
 115
 116         return obj ? obj->parent : NULL;
 117 }
 118
 119 static inline
 120 struct bt_object *bt_object_get_parent(void *ptr)
 121 {
 122         return bt_get(bt_object_borrow_parent(ptr));
 123 }
 124
 125 static inline
 126 void bt_object_set_parent(void *child_ptr, void *parent)
 127 {
 128         struct bt_object *child = child_ptr;
 129
 130         if (!child) {
 131                 return;
 132         }
 133
 134 #ifdef BT_LOGV
 135         BT_LOGV("Setting object's parent: addr=%p, parent-addr=%p",
 136                 child_ptr, parent);
 137 #endif
 138
 139         /*
 140          * It is assumed that a "child" being "parented" is publicly reachable.
 141          * Therefore, a reference to its parent must be taken. The reference
 142          * to the parent will be released once the object's reference count
 143          * falls to zero.
 144          */
 145         BT_PUT(child->parent);
 146         child->parent = bt_get(parent);
 147 }
 148
 149 #ifdef BT_DEV_MODE
 150 static inline
 151 void _bt_object_set_is_shared(struct bt_object *obj, bool is_shared)
 152 {
 153         obj->is_shared = is_shared;
 154 }
 155
 156 # define bt_object_set_is_shared        _bt_object_set_is_shared
 157 #else
 158 # define bt_object_set_is_shared(_obj, _is_shared)
 159 #endif
 160
 161 static inline
 162 void bt_object_init(void *ptr, bt_object_release_func release)
 163 {
 164         struct bt_object *obj = ptr;
 165
 166         obj->release = release;
 167         obj->parent = NULL;
 168         bt_object_set_is_shared(obj, true);
 169         bt_ref_init(&obj->ref_count, generic_release);
 170 }
 171
 172 static inline
 173 void bt_object_set_parent_is_owner_listener(void *obj,
 174                 bt_object_release_func cb)
 175 {
 176         BT_ASSERT(obj);
 177         ((struct bt_object *) obj)->parent_is_owner_listener = cb;
 178 }
 179
 180 #endif /* BABELTRACE_OBJECT_INTERNAL_H */