From d17953b287e0fa9d61c9aada7e36c03403b2fd69 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Thu, 4 Aug 2022 10:16:51 +0200
Subject: lavu/buffer: convert to AVRefcount WIP

---
 libavutil/buffer.c          | 22 ++++++++++++----------
 libavutil/buffer_internal.h |  5 ++++-
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 54590be566..6612183094 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -24,6 +24,7 @@
 #include "buffer_internal.h"
 #include "common.h"
 #include "mem.h"
+#include "refcount.h"
 #include "thread.h"
 
 static AVBufferRef *buffer_create(AVBuffer *buf, uint8_t *data, size_t size,
@@ -37,7 +38,7 @@ static AVBufferRef *buffer_create(AVBuffer *buf, uint8_t *data, size_t size,
     buf->free     = free ? free : av_buffer_default_free;
     buf->opaque   = opaque;
 
-    atomic_init(&buf->refcount, 1);
+    av_refcount_init(&buf->rc, NULL, NULL);
 
     buf->flags = flags;
 
@@ -109,7 +110,7 @@ AVBufferRef *av_buffer_ref(const AVBufferRef *buf)
 
     *ret = *buf;
 
-    atomic_fetch_add_explicit(&buf->buffer->refcount, 1, memory_order_relaxed);
+    av_refcount_inc(&buf->buffer->rc);
 
     return ret;
 }
@@ -126,7 +127,7 @@ static void buffer_replace(AVBufferRef **dst, AVBufferRef **src)
     } else
         av_freep(dst);
 
-    if (atomic_fetch_sub_explicit(&b->refcount, 1, memory_order_acq_rel) == 1) {
+    if (!av_refcount_dec(&bc->rc)) {
         /* b->free below might already free the structure containing *b,
          * so we have to read the flag now to avoid use-after-free. */
         int free_avbuffer = !(b->flags_internal & BUFFER_FLAG_NO_FREE);
@@ -149,7 +150,7 @@ int av_buffer_is_writable(const AVBufferRef *buf)
     if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
         return 0;
 
-    return atomic_load(&buf->buffer->refcount) == 1;
+    return av_refcount_exclusive(&buf->buffer->rc);
 }
 
 void *av_buffer_get_opaque(const AVBufferRef *buf)
@@ -159,7 +160,8 @@ void *av_buffer_get_opaque(const AVBufferRef *buf)
 
 int av_buffer_get_ref_count(const AVBufferRef *buf)
 {
-    return atomic_load(&buf->buffer->refcount);
+    //return atomic_load(&buf->buffer->refcount);
+    return 1;
 }
 
 int av_buffer_make_writable(AVBufferRef **pbuf)
@@ -272,7 +274,7 @@ AVBufferPool *av_buffer_pool_init2(size_t size, void *opaque,
     pool->alloc     = av_buffer_alloc; // fallback
     pool->pool_free = pool_free;
 
-    atomic_init(&pool->refcount, 1);
+    av_refcount_init(&pool->rc, NULL, NULL);
 
     return pool;
 }
@@ -288,7 +290,7 @@ AVBufferPool *av_buffer_pool_init(size_t size, AVBufferRef* (*alloc)(size_t size
     pool->size     = size;
     pool->alloc    = alloc ? alloc : av_buffer_alloc;
 
-    atomic_init(&pool->refcount, 1);
+    av_refcount_init(&pool->rc, NULL, NULL);
 
     return pool;
 }
@@ -332,7 +334,7 @@ void av_buffer_pool_uninit(AVBufferPool **ppool)
     buffer_pool_flush(pool);
     ff_mutex_unlock(&pool->mutex);
 
-    if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
+    if (av_refcount_dec(&pool->rc) == 1)
         buffer_pool_free(pool);
 }
 
@@ -349,7 +351,7 @@ static void pool_release_buffer(void *opaque, uint8_t *data)
     pool->pool = buf;
     ff_mutex_unlock(&pool->mutex);
 
-    if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
+    if (!av_refcount_dec(&pool->rc))
         buffer_pool_free(pool);
 }
 
@@ -406,7 +408,7 @@ AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
     ff_mutex_unlock(&pool->mutex);
 
     if (ret)
-        atomic_fetch_add_explicit(&pool->refcount, 1, memory_order_relaxed);
+        av_refcount_inc(&pool->rc);
 
     return ret;
 }
diff --git a/libavutil/buffer_internal.h b/libavutil/buffer_internal.h
index adb916aaa2..29119b47ab 100644
--- a/libavutil/buffer_internal.h
+++ b/libavutil/buffer_internal.h
@@ -23,6 +23,7 @@
 #include <stdint.h>
 
 #include "buffer.h"
+#include "refcount.h"
 #include "thread.h"
 
 /**
@@ -39,6 +40,8 @@ struct AVBuffer {
     uint8_t *data; /**< data described by this buffer */
     size_t size; /**< size of data in bytes */
 
+    AVRefcount rc;
+
     /**
      *  number of existing AVBufferRef instances referring to this buffer
      */
@@ -98,7 +101,7 @@ struct AVBufferPool {
      * buffers have been released, then it's safe to free the pool and all
      * the buffers in it.
      */
-    atomic_uint refcount;
+    AVRefcount rc;
 
     size_t size;
     void *opaque;
-- 
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