Help avoiding malloc-free cycles when allocating-freeing common structures.
Signed-off-by: Muhammad Faiz <mfc...@gmail.com> --- libavutil/staticpool.h | 117 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 libavutil/staticpool.h diff --git a/libavutil/staticpool.h b/libavutil/staticpool.h new file mode 100644 index 0000000000..9c9b2784bc --- /dev/null +++ b/libavutil/staticpool.h @@ -0,0 +1,117 @@ +/* + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVUTIL_STATICPOOL_H +#define AVUTIL_STATICPOOL_H + +#include <stdatomic.h> +#include "avassert.h" +#include "mem.h" + +/** + * FF_STATICPOOL allocate memory without av_malloc if possible + * @param size must be 2^n between 64 and 4096 + */ +#define FF_STATICPOOL_DECLARE(type, size) \ +typedef struct type##_StaticPoolWrapper { \ + type buf; \ + unsigned index; \ + atomic_uint next; \ +} type##_StaticPoolWrapper; \ + \ +static atomic_uint type##_staticpool_next; \ +static atomic_uint type##_staticpool_last; \ +static type##_StaticPoolWrapper type##_staticpool_table[size]; \ + \ +static type *type##_staticpool_malloc(void) \ +{ \ + unsigned val, index, serial, new_val; \ + \ + av_assert0((size) >= 64 && (size) <= 4096 && !((size) & ((size) - 1))); \ + \ + /* use serial, avoid spinlock */ \ + /* acquire, so we don't get stalled table[index].next */ \ + val = atomic_load_explicit(&type##_staticpool_next, memory_order_acquire); \ + do { \ + index = val & ((size) - 1); \ + serial = val & ~((size) - 1); \ + new_val = atomic_load_explicit(&type##_staticpool_table[index].next, memory_order_relaxed) | (serial + (size)); \ + } while (!atomic_compare_exchange_strong_explicit(&type##_staticpool_next, &val, new_val, \ + memory_order_acquire, memory_order_acquire)); \ + \ + index = val & ((size) - 1); \ + if (index) \ + return &type##_staticpool_table[index].buf; \ + \ + index = atomic_fetch_add_explicit(&type##_staticpool_last, 1, memory_order_relaxed) + 1; \ + if (index < (size)) { \ + type##_staticpool_table[index].index = index; \ + return &type##_staticpool_table[index].buf; \ + } \ + \ + atomic_fetch_add_explicit(&type##_staticpool_last, -1, memory_order_relaxed); \ + return av_malloc(sizeof(type)); \ +} \ + \ +static inline type *type##_staticpool_mallocz(void) \ +{ \ + type *ptr = type##_staticpool_malloc(); \ + if (ptr) \ + memset(ptr, 0, sizeof(*ptr)); \ + return ptr; \ +} \ + \ +static void type##_staticpool_free(type *ptr) \ +{ \ + type##_StaticPoolWrapper *entry = (type##_StaticPoolWrapper *) ptr; \ + unsigned val, serial, index, new_val; \ + \ + if ((uintptr_t)ptr <= (uintptr_t)(type##_staticpool_table) || \ + (uintptr_t)ptr >= (uintptr_t)(type##_staticpool_table + size)) { \ + av_free(ptr); \ + return; \ + } \ + \ + if (CONFIG_MEMORY_POISONING) \ + memset(&entry->buf, FF_MEMORY_POISON, sizeof(entry->buf)); \ + \ + val = atomic_load_explicit(&type##_staticpool_next, memory_order_relaxed); \ + do { \ + index = val & ((size) - 1); \ + serial = val & ~((size) - 1); \ + atomic_store_explicit(&entry->next, index, memory_order_relaxed); \ + new_val = entry->index | (serial + (size)); \ + } while (!atomic_compare_exchange_strong_explicit(&type##_staticpool_next, &val, new_val, \ + memory_order_release, memory_order_relaxed)); \ +} \ + \ +static inline void type##_staticpool_freep(type **ptr) \ +{ \ + if (ptr) { \ + type##_staticpool_free(*ptr); \ + *ptr = NULL; \ + } \ +} \ +/* FF_STATICPOOL_DECLARE */ + +#define FF_STATICPOOL_MALLOC(type) type##_staticpool_malloc() +#define FF_STATICPOOL_MALLOCZ(type) type##_staticpool_mallocz() +#define FF_STATICPOOL_FREE(type, v) type##_staticpool_free(v) +#define FF_STATICPOOL_FREEP(type, v) type##_staticpool_freep(v) + +#endif -- 2.13.2 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel