[FFmpeg-devel] [PATCH 1/3] avutil: add staticpool
Muhammad Faiz
mfcc64 at gmail.com
Sat Jan 20 06:29:13 EET 2018
Help avoiding malloc-free cycles when allocating-freeing common
structures.
Signed-off-by: Muhammad Faiz <mfcc64 at 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
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