| 1 | /* |
| 2 | * SPDX-License-Identifier: MIT |
| 3 | * |
| 4 | * Copyright 2017-2018 Philippe Proulx <pproulx@efficios.com> |
| 5 | * Copyright 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 6 | */ |
| 7 | |
| 8 | #ifndef BABELTRACE_LIB_OBJECT_H |
| 9 | #define BABELTRACE_LIB_OBJECT_H |
| 10 | |
| 11 | #include "common/assert.h" |
| 12 | #include <stdbool.h> |
| 13 | |
| 14 | struct bt_object; |
| 15 | |
| 16 | typedef void (*bt_object_release_func)(struct bt_object *); |
| 17 | typedef void (*bt_object_parent_is_owner_listener_func)( |
| 18 | struct bt_object *); |
| 19 | |
| 20 | static inline |
| 21 | void bt_object_get_ref_no_null_check(const void *obj); |
| 22 | |
| 23 | static inline |
| 24 | void bt_object_put_ref_no_null_check(const void *obj); |
| 25 | |
| 26 | /* |
| 27 | * Babeltrace object base. |
| 28 | * |
| 29 | * All objects publicly exposed by Babeltrace APIs must contain this |
| 30 | * object as their first member. |
| 31 | */ |
| 32 | struct bt_object { |
| 33 | /* |
| 34 | * True if this object is shared, that is, it has a reference |
| 35 | * count. |
| 36 | */ |
| 37 | bool is_shared; |
| 38 | |
| 39 | /* |
| 40 | * Current reference count. |
| 41 | */ |
| 42 | unsigned long long ref_count; |
| 43 | |
| 44 | /* |
| 45 | * Release function called when the object's reference count |
| 46 | * falls to zero. For an object with a parent, this function is |
| 47 | * bt_object_with_parent_release_func(), which calls |
| 48 | * `spec_release_func` below if there's no current parent. |
| 49 | */ |
| 50 | bt_object_release_func release_func; |
| 51 | |
| 52 | /* |
| 53 | * Specific release function called by |
| 54 | * bt_object_with_parent_release_func() or directly by a |
| 55 | * parent object. |
| 56 | */ |
| 57 | bt_object_release_func spec_release_func; |
| 58 | |
| 59 | /* |
| 60 | * Optional callback for an object with a parent, called by |
| 61 | * bt_object_with_parent_release_func() to indicate to the |
| 62 | * object that its parent is its owner. |
| 63 | */ |
| 64 | bt_object_parent_is_owner_listener_func |
| 65 | parent_is_owner_listener_func; |
| 66 | |
| 67 | /* |
| 68 | * Optional parent object. |
| 69 | */ |
| 70 | struct bt_object *parent; |
| 71 | }; |
| 72 | |
| 73 | static inline |
| 74 | unsigned long long bt_object_get_ref_count(const struct bt_object *c_obj) |
| 75 | { |
| 76 | struct bt_object *obj = (void *) c_obj; |
| 77 | |
| 78 | BT_ASSERT_DBG(obj); |
| 79 | BT_ASSERT_DBG(obj->is_shared); |
| 80 | return obj->ref_count; |
| 81 | } |
| 82 | |
| 83 | static inline |
| 84 | struct bt_object *bt_object_borrow_parent(const struct bt_object *c_obj) |
| 85 | { |
| 86 | struct bt_object *obj = (void *) c_obj; |
| 87 | |
| 88 | BT_ASSERT_DBG(obj); |
| 89 | BT_ASSERT_DBG(obj->is_shared); |
| 90 | return obj->parent; |
| 91 | } |
| 92 | |
| 93 | static inline |
| 94 | struct bt_object *bt_object_get_parent(const struct bt_object *c_obj) |
| 95 | { |
| 96 | struct bt_object *obj = (void *) c_obj; |
| 97 | struct bt_object *parent = bt_object_borrow_parent(obj); |
| 98 | |
| 99 | if (parent) { |
| 100 | bt_object_get_ref_no_null_check(parent); |
| 101 | } |
| 102 | |
| 103 | return parent; |
| 104 | } |
| 105 | |
| 106 | static inline |
| 107 | void bt_object_set_parent(struct bt_object *child, struct bt_object *parent) |
| 108 | { |
| 109 | BT_ASSERT_DBG(child); |
| 110 | BT_ASSERT_DBG(child->is_shared); |
| 111 | |
| 112 | #ifdef BT_LOGT |
| 113 | BT_LOGT("Setting object's parent: addr=%p, parent-addr=%p", |
| 114 | child, parent); |
| 115 | #endif |
| 116 | |
| 117 | /* |
| 118 | * It is assumed that a "child" having a parent is publicly |
| 119 | * reachable. Therefore, a reference to its parent must be |
| 120 | * taken. The reference to the parent will be released once the |
| 121 | * object's reference count falls to zero. |
| 122 | */ |
| 123 | if (parent) { |
| 124 | BT_ASSERT_DBG(!child->parent); |
| 125 | child->parent = parent; |
| 126 | bt_object_get_ref_no_null_check(parent); |
| 127 | } else { |
| 128 | if (child->parent) { |
| 129 | bt_object_put_ref_no_null_check(child->parent); |
| 130 | } |
| 131 | |
| 132 | child->parent = NULL; |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | static inline |
| 137 | void bt_object_try_spec_release(struct bt_object *obj) |
| 138 | { |
| 139 | BT_ASSERT_DBG(obj); |
| 140 | BT_ASSERT_DBG(obj->is_shared); |
| 141 | BT_ASSERT_DBG(obj->spec_release_func); |
| 142 | |
| 143 | if (bt_object_get_ref_count(obj) == 0) { |
| 144 | obj->spec_release_func(obj); |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | static inline |
| 149 | void bt_object_with_parent_release_func(struct bt_object *obj) |
| 150 | { |
| 151 | if (obj->parent) { |
| 152 | /* |
| 153 | * Keep our own copy of the parent address because `obj` |
| 154 | * could be destroyed in |
| 155 | * obj->parent_is_owner_listener_func(). |
| 156 | */ |
| 157 | struct bt_object *parent = obj->parent; |
| 158 | |
| 159 | #ifdef BT_LOGT |
| 160 | BT_LOGT("Releasing parented object: addr=%p, ref-count=%llu, " |
| 161 | "parent-addr=%p, parent-ref-count=%llu", |
| 162 | obj, obj->ref_count, |
| 163 | parent, parent->ref_count); |
| 164 | #endif |
| 165 | |
| 166 | if (obj->parent_is_owner_listener_func) { |
| 167 | /* |
| 168 | * Object has a chance to destroy itself here |
| 169 | * under certain conditions and notify its |
| 170 | * parent. At this point the parent is |
| 171 | * guaranteed to exist because it's not put yet. |
| 172 | */ |
| 173 | obj->parent_is_owner_listener_func(obj); |
| 174 | } |
| 175 | |
| 176 | /* The release function will be invoked by the parent. */ |
| 177 | bt_object_put_ref_no_null_check(parent); |
| 178 | } else { |
| 179 | bt_object_try_spec_release(obj); |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | static inline |
| 184 | void bt_object_init(struct bt_object *obj, bool is_shared, |
| 185 | bt_object_release_func release_func) |
| 186 | { |
| 187 | BT_ASSERT_DBG(obj); |
| 188 | BT_ASSERT_DBG(!is_shared || release_func); |
| 189 | obj->is_shared = is_shared; |
| 190 | obj->release_func = release_func; |
| 191 | obj->parent_is_owner_listener_func = NULL; |
| 192 | obj->spec_release_func = NULL; |
| 193 | obj->parent = NULL; |
| 194 | obj->ref_count = 1; |
| 195 | } |
| 196 | |
| 197 | static inline |
| 198 | void bt_object_init_shared(struct bt_object *obj, |
| 199 | bt_object_release_func release_func) |
| 200 | { |
| 201 | bt_object_init(obj, true, release_func); |
| 202 | } |
| 203 | |
| 204 | static inline |
| 205 | void bt_object_init_unique(struct bt_object *obj) |
| 206 | { |
| 207 | bt_object_init(obj, false, NULL); |
| 208 | } |
| 209 | |
| 210 | static inline |
| 211 | void bt_object_init_shared_with_parent(struct bt_object *obj, |
| 212 | bt_object_release_func spec_release_func) |
| 213 | { |
| 214 | BT_ASSERT_DBG(obj); |
| 215 | BT_ASSERT_DBG(spec_release_func); |
| 216 | bt_object_init_shared(obj, bt_object_with_parent_release_func); |
| 217 | obj->spec_release_func = spec_release_func; |
| 218 | } |
| 219 | |
| 220 | static inline |
| 221 | void bt_object_set_parent_is_owner_listener_func(struct bt_object *obj, |
| 222 | bt_object_parent_is_owner_listener_func func) |
| 223 | { |
| 224 | BT_ASSERT_DBG(obj); |
| 225 | BT_ASSERT_DBG(obj->is_shared); |
| 226 | BT_ASSERT_DBG(obj->spec_release_func); |
| 227 | ((struct bt_object *) obj)->parent_is_owner_listener_func = func; |
| 228 | } |
| 229 | |
| 230 | static inline |
| 231 | void bt_object_inc_ref_count(const struct bt_object *c_obj) |
| 232 | { |
| 233 | struct bt_object *obj = (void *) c_obj; |
| 234 | |
| 235 | BT_ASSERT_DBG(obj); |
| 236 | BT_ASSERT_DBG(obj->is_shared); |
| 237 | obj->ref_count++; |
| 238 | BT_ASSERT_DBG(obj->ref_count != 0); |
| 239 | } |
| 240 | |
| 241 | static inline |
| 242 | void bt_object_get_ref_no_null_check_no_parent_check(const struct bt_object *c_obj) |
| 243 | { |
| 244 | struct bt_object *obj = (void *) c_obj; |
| 245 | |
| 246 | BT_ASSERT_DBG(obj); |
| 247 | BT_ASSERT_DBG(obj->is_shared); |
| 248 | |
| 249 | #ifdef BT_LOGT |
| 250 | BT_LOGT("Incrementing object's reference count: %llu -> %llu: " |
| 251 | "addr=%p, cur-count=%llu, new-count=%llu", |
| 252 | obj->ref_count, obj->ref_count + 1, |
| 253 | obj, obj->ref_count, obj->ref_count + 1); |
| 254 | #endif |
| 255 | |
| 256 | bt_object_inc_ref_count(obj); |
| 257 | } |
| 258 | |
| 259 | static inline |
| 260 | void bt_object_get_ref_no_null_check(const void *c_obj) |
| 261 | { |
| 262 | struct bt_object *obj = (void *) c_obj; |
| 263 | |
| 264 | BT_ASSERT_DBG(obj); |
| 265 | BT_ASSERT_DBG(obj->is_shared); |
| 266 | |
| 267 | if (G_UNLIKELY(obj->parent && bt_object_get_ref_count(obj) == 0)) { |
| 268 | #ifdef BT_LOGT |
| 269 | BT_LOGT("Incrementing object's parent's reference count: " |
| 270 | "addr=%p, parent-addr=%p", obj, obj->parent); |
| 271 | #endif |
| 272 | |
| 273 | bt_object_get_ref_no_null_check(obj->parent); |
| 274 | } |
| 275 | |
| 276 | #ifdef BT_LOGT |
| 277 | BT_LOGT("Incrementing object's reference count: %llu -> %llu: " |
| 278 | "addr=%p, cur-count=%llu, new-count=%llu", |
| 279 | obj->ref_count, obj->ref_count + 1, |
| 280 | obj, obj->ref_count, obj->ref_count + 1); |
| 281 | #endif |
| 282 | |
| 283 | bt_object_inc_ref_count(obj); |
| 284 | } |
| 285 | |
| 286 | static inline |
| 287 | void bt_object_put_ref_no_null_check(const void *c_obj) |
| 288 | { |
| 289 | struct bt_object *obj = (void *) c_obj; |
| 290 | |
| 291 | BT_ASSERT_DBG(obj); |
| 292 | BT_ASSERT_DBG(obj->is_shared); |
| 293 | BT_ASSERT_DBG(obj->ref_count > 0); |
| 294 | |
| 295 | #ifdef BT_LOGT |
| 296 | BT_LOGT("Decrementing object's reference count: %llu -> %llu: " |
| 297 | "addr=%p, cur-count=%llu, new-count=%llu", |
| 298 | obj->ref_count, obj->ref_count - 1, |
| 299 | obj, obj->ref_count, obj->ref_count - 1); |
| 300 | #endif |
| 301 | |
| 302 | obj->ref_count--; |
| 303 | |
| 304 | if (obj->ref_count == 0) { |
| 305 | BT_ASSERT_DBG(obj->release_func); |
| 306 | obj->release_func(obj); |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | static inline |
| 311 | void bt_object_get_ref(const void *ptr) |
| 312 | { |
| 313 | struct bt_object *obj = (void *) ptr; |
| 314 | |
| 315 | if (G_UNLIKELY(!obj)) { |
| 316 | return; |
| 317 | } |
| 318 | |
| 319 | BT_ASSERT_DBG(obj->is_shared); |
| 320 | bt_object_get_ref_no_null_check(obj); |
| 321 | } |
| 322 | |
| 323 | static inline |
| 324 | void bt_object_put_ref(const void *ptr) |
| 325 | { |
| 326 | struct bt_object *obj = (void *) ptr; |
| 327 | |
| 328 | if (G_UNLIKELY(!obj)) { |
| 329 | return; |
| 330 | } |
| 331 | |
| 332 | BT_ASSERT_DBG(obj->is_shared); |
| 333 | BT_ASSERT_DBG(bt_object_get_ref_count(obj) > 0); |
| 334 | bt_object_put_ref_no_null_check(obj); |
| 335 | } |
| 336 | |
| 337 | #define BT_OBJECT_PUT_REF_AND_RESET(_var) \ |
| 338 | do { \ |
| 339 | bt_object_put_ref(_var); \ |
| 340 | (_var) = NULL; \ |
| 341 | } while (0) |
| 342 | |
| 343 | #define BT_OBJECT_MOVE_REF(_var_dst, _var_src) \ |
| 344 | do { \ |
| 345 | bt_object_put_ref(_var_dst); \ |
| 346 | (_var_dst) = (_var_src); \ |
| 347 | (_var_src) = NULL; \ |
| 348 | } while (0) |
| 349 | |
| 350 | #endif /* BABELTRACE_LIB_OBJECT_H */ |