/src/ffmpeg/libavutil/refstruct.h
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1 | | /* |
2 | | * This file is part of FFmpeg. |
3 | | * |
4 | | * FFmpeg is free software; you can redistribute it and/or |
5 | | * modify it under the terms of the GNU Lesser General Public |
6 | | * License as published by the Free Software Foundation; either |
7 | | * version 2.1 of the License, or (at your option) any later version. |
8 | | * |
9 | | * FFmpeg is distributed in the hope that it will be useful, |
10 | | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | | * Lesser General Public License for more details. |
13 | | * |
14 | | * You should have received a copy of the GNU Lesser General Public |
15 | | * License along with FFmpeg; if not, write to the Free Software |
16 | | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
17 | | */ |
18 | | |
19 | | #ifndef AVUTIL_REFSTRUCT_H |
20 | | #define AVUTIL_REFSTRUCT_H |
21 | | |
22 | | #include <stddef.h> |
23 | | |
24 | | /** |
25 | | * RefStruct is an API for creating reference-counted objects |
26 | | * with minimal overhead. The API is designed for objects, |
27 | | * not buffers like the AVBuffer API. The main differences |
28 | | * to the AVBuffer API are as follows: |
29 | | * |
30 | | * - It uses void* instead of uint8_t* as its base type due to |
31 | | * its focus on objects. |
32 | | * - There are no equivalents of AVBuffer and AVBufferRef. |
33 | | * E.g. there is no way to get the usable size of the object: |
34 | | * The user is supposed to know what is at the other end of |
35 | | * the pointer. It also avoids one level of indirection. |
36 | | * - Custom allocators are not supported. This allows to simplify |
37 | | * the implementation and reduce the amount of allocations. |
38 | | * - It also has the advantage that the user's free callback need |
39 | | * only free the resources owned by the object, but not the |
40 | | * object itself. |
41 | | * - Because referencing (and replacing) an object managed by the |
42 | | * RefStruct API does not involve allocations, they can not fail |
43 | | * and therefore need not be checked. |
44 | | * |
45 | | * @note Referencing and unreferencing the buffers is thread-safe and thus |
46 | | * may be done from multiple threads simultaneously without any need for |
47 | | * additional locking. |
48 | | */ |
49 | | |
50 | | /** |
51 | | * This union is used for all opaque parameters in this API to spare the user |
52 | | * to cast const away in case the opaque to use is const-qualified. |
53 | | * |
54 | | * The functions provided by this API with an AVRefStructOpaque come in pairs |
55 | | * named foo_c and foo. The foo function accepts void* as opaque and is just |
56 | | * a wrapper around the foo_c function; "_c" means "(potentially) const". |
57 | | */ |
58 | | typedef union { |
59 | | void *nc; |
60 | | const void *c; |
61 | | } AVRefStructOpaque; |
62 | | |
63 | | /** |
64 | | * If this flag is set in av_refstruct_alloc_ext_c(), the object will not |
65 | | * be initially zeroed. |
66 | | */ |
67 | 0 | #define AV_REFSTRUCT_FLAG_NO_ZEROING (1 << 0) |
68 | | |
69 | | /** |
70 | | * Allocate a refcounted object of usable size `size` managed via |
71 | | * the RefStruct API. |
72 | | * |
73 | | * By default (in the absence of flags to the contrary), |
74 | | * the returned object is initially zeroed. |
75 | | * |
76 | | * @param size Desired usable size of the returned object. |
77 | | * @param flags A bitwise combination of AV_REFSTRUCT_FLAG_* flags. |
78 | | * @param opaque A pointer that will be passed to the free_cb callback. |
79 | | * @param free_cb A callback for freeing this object's content |
80 | | * when its reference count reaches zero; |
81 | | * it must not free the object itself. |
82 | | * @return A pointer to an object of the desired size or NULL on failure. |
83 | | */ |
84 | | void *av_refstruct_alloc_ext_c(size_t size, unsigned flags, AVRefStructOpaque opaque, |
85 | | void (*free_cb)(AVRefStructOpaque opaque, void *obj)); |
86 | | |
87 | | /** |
88 | | * A wrapper around av_refstruct_alloc_ext_c() for the common case |
89 | | * of a non-const qualified opaque. |
90 | | * |
91 | | * @see av_refstruct_alloc_ext_c() |
92 | | */ |
93 | | static inline |
94 | | void *av_refstruct_alloc_ext(size_t size, unsigned flags, void *opaque, |
95 | | void (*free_cb)(AVRefStructOpaque opaque, void *obj)) |
96 | 0 | { |
97 | 0 | return av_refstruct_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque}, |
98 | 0 | free_cb); |
99 | 0 | } Unexecuted instantiation: format.c:av_refstruct_alloc_ext Unexecuted instantiation: ops.c:av_refstruct_alloc_ext Unexecuted instantiation: avcodec.c:av_refstruct_alloc_ext Unexecuted instantiation: decode.c:av_refstruct_alloc_ext Unexecuted instantiation: get_buffer.c:av_refstruct_alloc_ext Unexecuted instantiation: pthread_frame.c:av_refstruct_alloc_ext Unexecuted instantiation: utils.c:av_refstruct_alloc_ext Unexecuted instantiation: container_fifo.c:av_refstruct_alloc_ext Unexecuted instantiation: frame.c:av_refstruct_alloc_ext Unexecuted instantiation: refstruct.c:av_refstruct_alloc_ext |
100 | | |
101 | | /** |
102 | | * Equivalent to av_refstruct_alloc_ext(size, 0, NULL, NULL) |
103 | | */ |
104 | | static inline |
105 | | void *av_refstruct_allocz(size_t size) |
106 | 0 | { |
107 | 0 | return av_refstruct_alloc_ext(size, 0, NULL, NULL); |
108 | 0 | } Unexecuted instantiation: format.c:av_refstruct_allocz Unexecuted instantiation: ops.c:av_refstruct_allocz Unexecuted instantiation: avcodec.c:av_refstruct_allocz Unexecuted instantiation: decode.c:av_refstruct_allocz Unexecuted instantiation: get_buffer.c:av_refstruct_allocz Unexecuted instantiation: pthread_frame.c:av_refstruct_allocz Unexecuted instantiation: utils.c:av_refstruct_allocz Unexecuted instantiation: container_fifo.c:av_refstruct_allocz Unexecuted instantiation: frame.c:av_refstruct_allocz Unexecuted instantiation: refstruct.c:av_refstruct_allocz |
109 | | |
110 | | /** |
111 | | * Decrement the reference count of the underlying object and automatically |
112 | | * free the object if there are no more references to it. |
113 | | * |
114 | | * `*objp == NULL` is legal and a no-op. |
115 | | * |
116 | | * @param objp Pointer to a pointer that is either NULL or points to an object |
117 | | * managed via this API. `*objp` is set to NULL on return. |
118 | | */ |
119 | | void av_refstruct_unref(void *objp); |
120 | | |
121 | | /** |
122 | | * Create a new reference to an object managed via this API, |
123 | | * i.e. increment the reference count of the underlying object |
124 | | * and return obj. |
125 | | * @return a pointer equal to obj. |
126 | | */ |
127 | | void *av_refstruct_ref(void *obj); |
128 | | |
129 | | /** |
130 | | * Analog of av_refstruct_ref(), but for constant objects. |
131 | | * @see av_refstruct_ref() |
132 | | */ |
133 | | const void *av_refstruct_ref_c(const void *obj); |
134 | | |
135 | | /** |
136 | | * Ensure `*dstp` refers to the same object as src. |
137 | | * |
138 | | * If `*dstp` is already equal to src, do nothing. Otherwise unreference `*dstp` |
139 | | * and replace it with a new reference to src in case `src != NULL` (this |
140 | | * involves incrementing the reference count of src's underlying object) or |
141 | | * with NULL otherwise. |
142 | | * |
143 | | * @param dstp Pointer to a pointer that is either NULL or points to an object |
144 | | * managed via this API. |
145 | | * @param src A pointer to an object managed via this API or NULL. |
146 | | */ |
147 | | void av_refstruct_replace(void *dstp, const void *src); |
148 | | |
149 | | /** |
150 | | * Check whether the reference count of an object managed |
151 | | * via this API is 1. |
152 | | * |
153 | | * @param obj A pointer to an object managed via this API. |
154 | | * @return 1 if the reference count of obj is 1; 0 otherwise. |
155 | | */ |
156 | | int av_refstruct_exclusive(const void *obj); |
157 | | |
158 | | /** |
159 | | * AVRefStructPool is an API for a thread-safe pool of objects managed |
160 | | * via the RefStruct API. |
161 | | * |
162 | | * Frequently allocating and freeing large or complicated objects may be slow |
163 | | * and wasteful. This API is meant to solve this in cases when the caller |
164 | | * needs a set of interchangeable objects. |
165 | | * |
166 | | * At the beginning, the user must call allocate the pool via |
167 | | * av_refstruct_pool_alloc() or its analogue av_refstruct_pool_alloc_ext(). |
168 | | * Then whenever an object is needed, call av_refstruct_pool_get() to |
169 | | * get a new or reused object from the pool. This new object works in all |
170 | | * aspects the same way as the ones created by av_refstruct_alloc_ext(). |
171 | | * However, when the last reference to this object is unreferenced, it is |
172 | | * (optionally) reset and returned to the pool instead of being freed and |
173 | | * will be reused for subsequent av_refstruct_pool_get() calls. |
174 | | * |
175 | | * When the caller is done with the pool and no longer needs to create any new |
176 | | * objects, av_refstruct_pool_uninit() must be called to mark the pool as |
177 | | * freeable. Then entries returned to the pool will then be freed. |
178 | | * Once all the entries are freed, the pool will automatically be freed. |
179 | | * |
180 | | * Allocating and releasing objects with this API is thread-safe as long as |
181 | | * the user-supplied callbacks (if provided) are thread-safe. |
182 | | */ |
183 | | |
184 | | /** |
185 | | * The buffer pool. This structure is opaque and not meant to be accessed |
186 | | * directly. It is allocated with the allocators below and freed with |
187 | | * av_refstruct_pool_uninit(). |
188 | | */ |
189 | | typedef struct AVRefStructPool AVRefStructPool; |
190 | | |
191 | | /** |
192 | | * If this flag is not set, every object in the pool will be zeroed before |
193 | | * the init callback is called or before it is turned over to the user |
194 | | * for the first time if no init callback has been provided. |
195 | | */ |
196 | 0 | #define AV_REFSTRUCT_POOL_FLAG_NO_ZEROING AV_REFSTRUCT_FLAG_NO_ZEROING |
197 | | /** |
198 | | * If this flag is set and both init_cb and reset_cb callbacks are provided, |
199 | | * then reset_cb will be called if init_cb fails. |
200 | | * The object passed to reset_cb will be in the state left by init_cb. |
201 | | */ |
202 | 0 | #define AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR (1 << 16) |
203 | | /** |
204 | | * If this flag is set and both init_cb and free_entry_cb callbacks are |
205 | | * provided, then free_cb will be called if init_cb fails. |
206 | | * |
207 | | * It will be called after reset_cb in case reset_cb and the |
208 | | * AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR flag are also set. |
209 | | * |
210 | | * The object passed to free_cb will be in the state left by |
211 | | * the callbacks applied earlier (init_cb potentially followed by reset_cb). |
212 | | */ |
213 | 0 | #define AV_REFSTRUCT_POOL_FLAG_FREE_ON_INIT_ERROR (1 << 17) |
214 | | /** |
215 | | * If this flag is set, the entries will be zeroed before |
216 | | * being returned to the user (after the init or reset callbacks |
217 | | * have been called (if provided)). Furthermore, to avoid zeroing twice |
218 | | * it also makes the pool behave as if the AV_REFSTRUCT_POOL_FLAG_NO_ZEROING |
219 | | * flag had been provided. |
220 | | */ |
221 | 0 | #define AV_REFSTRUCT_POOL_FLAG_ZERO_EVERY_TIME (1 << 18) |
222 | | |
223 | | /** |
224 | | * Equivalent to av_refstruct_pool_alloc(size, flags, NULL, NULL, NULL, NULL, NULL) |
225 | | */ |
226 | | AVRefStructPool *av_refstruct_pool_alloc(size_t size, unsigned flags); |
227 | | |
228 | | /** |
229 | | * Allocate an AVRefStructPool, potentially using complex callbacks. |
230 | | * |
231 | | * @param size size of the entries of the pool |
232 | | * @param flags a bitwise combination of AV_REFSTRUCT_POOL_FLAG_* flags |
233 | | * @param opaque A pointer that will be passed to the callbacks below. |
234 | | * @param init A callback that will be called directly after a new entry |
235 | | * has been allocated. obj has already been zeroed unless |
236 | | * the AV_REFSTRUCT_POOL_FLAG_NO_ZEROING flag is in use. |
237 | | * @param reset A callback that will be called after an entry has been |
238 | | * returned to the pool and before it is reused. |
239 | | * @param free_entry A callback that will be called when an entry is freed |
240 | | * after the pool has been marked as to be uninitialized. |
241 | | * @param free A callback that will be called when the pool itself is |
242 | | * freed (after the last entry has been returned and freed). |
243 | | */ |
244 | | AVRefStructPool *av_refstruct_pool_alloc_ext_c(size_t size, unsigned flags, |
245 | | AVRefStructOpaque opaque, |
246 | | int (*init_cb)(AVRefStructOpaque opaque, void *obj), |
247 | | void (*reset_cb)(AVRefStructOpaque opaque, void *obj), |
248 | | void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj), |
249 | | void (*free_cb)(AVRefStructOpaque opaque)); |
250 | | |
251 | | /** |
252 | | * A wrapper around av_refstruct_pool_alloc_ext_c() for the common case |
253 | | * of a non-const qualified opaque. |
254 | | * |
255 | | * @see av_refstruct_pool_alloc_ext_c() |
256 | | */ |
257 | | static inline |
258 | | AVRefStructPool *av_refstruct_pool_alloc_ext(size_t size, unsigned flags, |
259 | | void *opaque, |
260 | | int (*init_cb)(AVRefStructOpaque opaque, void *obj), |
261 | | void (*reset_cb)(AVRefStructOpaque opaque, void *obj), |
262 | | void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj), |
263 | | void (*free_cb)(AVRefStructOpaque opaque)) |
264 | 0 | { |
265 | 0 | return av_refstruct_pool_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque}, |
266 | 0 | init_cb, reset_cb, free_entry_cb, free_cb); |
267 | 0 | } Unexecuted instantiation: format.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: ops.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: avcodec.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: decode.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: get_buffer.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: pthread_frame.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: utils.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: container_fifo.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: frame.c:av_refstruct_pool_alloc_ext Unexecuted instantiation: refstruct.c:av_refstruct_pool_alloc_ext |
268 | | |
269 | | /** |
270 | | * Get an object from the pool, reusing an old one from the pool when |
271 | | * available. |
272 | | * |
273 | | * Every call to this function must happen before av_refstruct_pool_uninit(). |
274 | | * Otherwise undefined behaviour may occur. |
275 | | * |
276 | | * @param pool the pool from which to get the object |
277 | | * @return a reference to the object on success, NULL on error. |
278 | | */ |
279 | | void *av_refstruct_pool_get(AVRefStructPool *pool); |
280 | | |
281 | | /** |
282 | | * Mark the pool as being available for freeing. It will actually be freed |
283 | | * only once all the allocated buffers associated with the pool are released. |
284 | | * Thus it is safe to call this function while some of the allocated buffers |
285 | | * are still in use. |
286 | | * |
287 | | * It is illegal to try to get a new entry after this function has been called. |
288 | | * |
289 | | * @param poolp pointer to a pointer to either NULL or a pool to be freed. |
290 | | * `*poolp` will be set to NULL. |
291 | | */ |
292 | | static inline void av_refstruct_pool_uninit(AVRefStructPool **poolp) |
293 | 0 | { |
294 | 0 | av_refstruct_unref(poolp); |
295 | 0 | } Unexecuted instantiation: format.c:av_refstruct_pool_uninit Unexecuted instantiation: ops.c:av_refstruct_pool_uninit Unexecuted instantiation: avcodec.c:av_refstruct_pool_uninit Unexecuted instantiation: decode.c:av_refstruct_pool_uninit Unexecuted instantiation: get_buffer.c:av_refstruct_pool_uninit Unexecuted instantiation: pthread_frame.c:av_refstruct_pool_uninit Unexecuted instantiation: utils.c:av_refstruct_pool_uninit Unexecuted instantiation: container_fifo.c:av_refstruct_pool_uninit Unexecuted instantiation: frame.c:av_refstruct_pool_uninit Unexecuted instantiation: refstruct.c:av_refstruct_pool_uninit |
296 | | |
297 | | #endif /* AVUTIL_REFSTRUCT_H */ |