Re: [FFmpeg-devel] [PATCH 1/6] lavu/mem: add av_realloc_reuse() as a replacement for av_fast_realloc()

["Rémi Denis-Courmont" <remi@remlab.net>]

Le 28 septembre 2022 13:51:43 GMT+03:00, "Rémi Denis-Courmont" <remi@remlab.net> a écrit :
>Le 28 septembre 2022 13:48:49 GMT+03:00, Anton Khirnov <anton@khirnov.net> a écrit :
>>It uses size_t rather than unsigned for the size and conforms to our
>>standard naming scheme.
>>---
>> configure           |  5 ++++-
>> doc/APIchanges      |  3 +++
>> libavutil/mem.c     | 30 ++++++++++++++++++++++++++++++
>> libavutil/mem.h     | 37 +++++++++++++++++++++++++++++++++++--
>> libavutil/version.h |  3 ++-
>> 5 files changed, 74 insertions(+), 4 deletions(-)
>>
>>diff --git a/configure b/configure
>>index 6712d045d9..fd0e6ae032 100755
>>--- a/configure
>>+++ b/configure
>>@@ -4360,7 +4360,10 @@ case "$toolchain" in
>>         target_exec_default="valgrind"
>>         case "$toolchain" in
>>             valgrind-massif)
>>-                target_exec_args="--tool=massif --alloc-fn=av_malloc --alloc-fn=av_mallocz --alloc-fn=av_calloc --alloc-fn=av_fast_padded_malloc --alloc-fn=av_fast_malloc --alloc-fn=av_realloc_f --alloc-fn=av_fast_realloc --alloc-fn=av_realloc"
>>+                target_exec_args="--tool=massif"
>>+                for func in av_malloc av_mallocz av_calloc av_fast_padded_malloc av_fast_malloc av_realloc_f av_fast_realloc av_realloc av_realloc_reuse; do
>>+                    target_exec_args="$target_exec_args --alloc-fn=$func"
>>+                done
>>                 ;;
>>             valgrind-memcheck)
>>                 target_exec_args="--error-exitcode=1 --malloc-fill=0x2a --track-origins=yes --leak-check=full --gen-suppressions=all --suppressions=$source_path/tests/fate-valgrind.supp"
>>diff --git a/doc/APIchanges b/doc/APIchanges
>>index b0a41c9e37..9a735c27e7 100644
>>--- a/doc/APIchanges
>>+++ b/doc/APIchanges
>>@@ -14,6 +14,9 @@ libavutil:     2021-04-27
>> 
>> API changes, most recent first:
>> 
>>+2022-xx-xx - xxxxxxxxxx - lavu 57.38.100 - mem.h
>>+  Add av_realloc_reuse(), deprecate av_fast_realloc().
>>+
>> 2022-09-26 - xxxxxxxxxx - lavc 59.48.100 - avcodec.h
>>   Deprecate avcodec_enum_to_chroma_pos() and avcodec_chroma_pos_to_enum().
>>   Use av_chroma_location_enum_to_pos() or av_chroma_location_pos_to_enum()
>>diff --git a/libavutil/mem.c b/libavutil/mem.c
>>index 18aff5291f..51fdc9155f 100644
>>--- a/libavutil/mem.c
>>+++ b/libavutil/mem.c
>>@@ -502,6 +502,35 @@ void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
>>     }
>> }
>> 
>>+void *av_realloc_reuse(void *ptr, size_t *size, size_t min_size)
>>+{
>>+    size_t max_size;
>>+
>>+    if (min_size <= *size)
>>+        return ptr;
>>+
>>+    max_size = atomic_load_explicit(&max_alloc_size, memory_order_relaxed);
>>+
>>+    if (min_size > max_size) {
>>+        *size = 0;
>>+        return NULL;
>
>Isn't this leaking the existing allocation?
>
>>+    }
>>+
>>+    min_size = FFMIN(max_size, FFMAX(min_size + min_size / 16 + 32, min_size));
>>+
>>+    ptr = av_realloc(ptr, min_size);
>>+    /* we could set this to the unmodified min_size but this is safer
>>+     * if the user lost the ptr and uses NULL now
>>+     */
>>+    if (!ptr)
>>+        min_size = 0;
>>+
>>+    *size = min_size;
>>+
>>+    return ptr;
>>+}
>>+
>>+#if FF_API_FAST_ALLOC
>> void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
>> {
>>     size_t max_size;
>>@@ -531,6 +560,7 @@ void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
>> 
>>     return ptr;
>> }
>>+#endif
>> 
>> static inline void fast_malloc(void *ptr, unsigned int *size, size_t min_size, int zero_realloc)
>> {
>>diff --git a/libavutil/mem.h b/libavutil/mem.h
>>index d91174196c..deb440ca1a 100644
>>--- a/libavutil/mem.h
>>+++ b/libavutil/mem.h
>>@@ -264,7 +264,7 @@ void *av_mallocz_array(size_t nmemb, size_t size) av_malloc_attrib av_alloc_size
>>  * @warning Unlike av_malloc(), the returned pointer is not guaranteed to be
>>  *          correctly aligned. The returned pointer must be freed after even
>>  *          if size is zero.
>>- * @see av_fast_realloc()
>>+ * @see av_realloc_reuse()
>>  * @see av_reallocp()
>>  */
>> void *av_realloc(void *ptr, size_t size) av_alloc_size(2);
>>@@ -346,6 +346,35 @@ av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size)
>>  */
>> int av_reallocp_array(void *ptr, size_t nmemb, size_t size);
>> 
>>+/**
>>+ * Reallocate a data buffer, reusing the existing one if it is large enough.
>>+ *
>>+ * This function is similar to av_realloc(), but optimized for cases where the
>>+ * buffer may grow significantly and is not expected to shrink.
>>+ *
>>+ * @param[in] ptr Previously allocated buffer, or `NULL`. If `ptr` is `NULL`, a
>>+ * new uninitialized buffer is allocated. `ptr` is invalidated when this
>>+ * function returns non-`NULL` and must be replaced with its return value.
>>+ *
>>+ * @param[in,out] size Pointer to the allocated size of buffer `ptr`. This
>>+ * function updates `*size` to the new allocated size (which may be larger than
>>+ * `min_size`). `*size` is set to 0 on failure.
>>+ *
>>+ * @param[in] min_size Minimum size in bytes of the returned buffer.
>>+ *
>>+ * @return
>>+ * - An allocated buffer (to be freed with `av_free()`) that is large enough to
>>+ *   hold at least `min_size` bytes. The first `*size` (value on entry to this
>>+ *   function) bytes of the buffer remain the same as the data in `ptr`, the
>>+ *   rest is uninitialized.
>>+ * - `NULL` on failure, then `*size` is set to 0 and ptr remains untouched.
>>+ *
>>+ * @see av_realloc()
>>+ * @see av_fast_malloc()
>>+ */
>>+void *av_realloc_reuse(void *ptr, size_t *size, size_t min_size);
>>+
>>+#if FF_API_FAST_ALLOC
>> /**
>>  * Reallocate the given buffer if it is not large enough, otherwise do nothing.
>>  *
>>@@ -377,13 +406,17 @@ int av_reallocp_array(void *ptr, size_t nmemb, size_t size);
>>  *         error
>>  * @see av_realloc()
>>  * @see av_fast_malloc()
>>+ *
>>+ * @deprecated use av_realloc_reuse()
>>  */
>>+attribute_deprecated
>> void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);
>>+#endif
>> 
>> /**
>>  * Allocate a buffer, reusing the given one if large enough.
>>  *
>>- * Contrary to av_fast_realloc(), the current buffer contents might not be
>>+ * Contrary to av_realloc_reuse(), the current buffer contents might not be
>>  * preserved and on error the old buffer is freed, thus no special handling to
>>  * avoid memleaks is necessary.
>>  *
>>diff --git a/libavutil/version.h b/libavutil/version.h
>>index 9c44cef6aa..285a32f3d6 100644
>>--- a/libavutil/version.h
>>+++ b/libavutil/version.h
>>@@ -79,7 +79,7 @@
>>  */
>> 
>> #define LIBAVUTIL_VERSION_MAJOR  57
>>-#define LIBAVUTIL_VERSION_MINOR  37
>>+#define LIBAVUTIL_VERSION_MINOR  38
>> #define LIBAVUTIL_VERSION_MICRO 100
>> 
>> #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
>>@@ -115,6 +115,7 @@
>> #define FF_API_OLD_CHANNEL_LAYOUT       (LIBAVUTIL_VERSION_MAJOR < 58)
>> #define FF_API_AV_FOPEN_UTF8            (LIBAVUTIL_VERSION_MAJOR < 58)
>> #define FF_API_PKT_DURATION             (LIBAVUTIL_VERSION_MAJOR < 58)
>>+#define FF_API_FAST_ALLOC               (LIBAVUTIL_VERSION_MAJOR < 58)
>> 
>> /**
>>  * @}
>
>_______________________________________________
>ffmpeg-devel mailing list
>ffmpeg-devel@ffmpeg.org
>https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
>To unsubscribe, visit link above, or email
>ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

Nevermind. This follows the realloc() convention that the caller retains the reference on failure.
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".