Re: [Tarantool-patches] [PATCH v4 4/6] sql: use parser's region of "index" array

[Nikita Pettik <korablev@tarantool.org>]

On 12 Sep 00:51, Roman Khabibov wrote:
> Allocate memory for the "index" array of ephemeral space on the
> parser's region instead of a heap as it was before. Fixed a memory
> leak that realloc() generated.
> 
> Needed for #3075

Why it is related to 3075??

> ---
>  src/box/sql/build.c | 42 +++++++++++++++++++++++++++++++-----------
>  1 file changed, 31 insertions(+), 11 deletions(-)
> 
> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index 6cc76bb77..d1d240315 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -2226,29 +2226,49 @@ vdbe_emit_new_sec_index_id(struct Parse *parse, uint32_t space_id,
>  }
>  
>  /**
> - * Add new index to table's indexes list.
> + * Add new index to ephemeral @a space's "index" array. Reallocate
> + * memory on @a region if needed.
> + *
>   * We follow convention that PK comes first in list.
>   *
> + * @param region Region (on parser).
>   * @param space Space to which belongs given index.
>   * @param index Index to be added to list.
>   */
>  static void
> -table_add_index(struct space *space, struct index *index)
> +sql_space_add_index(struct region *region, struct space *space,
> +		    struct index *index)
>  {
>  	uint32_t idx_count = space->index_count;
> -	size_t indexes_sz = sizeof(struct index *) * (idx_count + 1);
> -	struct index **idx = (struct index **) realloc(space->index,
> -						       indexes_sz);
> -	if (idx == NULL) {
> -		diag_set(OutOfMemory, indexes_sz, "realloc", "idx");
> -		return;
> -	}
> -	space->index = idx;
> +	size_t size = 0;
> +	struct index **idx = NULL;
> +	if (idx_count == 0) {
> +		idx = region_alloc_array(region, typeof(struct index *), 1,
> +					 &size);
> +		if (idx == NULL)
> +			goto alloc_error;
> +	/*
> +	 * Reallocate each time the idx_count becomes equal to the
> +	 * power of two.
> +	 */
> +	} else if ((idx_count & (idx_count - 1)) == 0) {
> +		idx = region_alloc_array(region, typeof(struct index *),
> +					 idx_count * 2, &size);
> +		if (idx == NULL)
> +			goto alloc_error;
> +		memcpy(idx, space->index, idx_count * sizeof(struct index *));
> +	}
> +	if (idx != NULL)
> +		space->index = idx;

DOes it make any sense? Why not simply call ::free (in case there really
was memleak)?

>  	/* Make sure that PK always comes as first member. */
>  	if (index->def->iid == 0 && idx_count != 0)
>  		SWAP(space->index[0], index);
>  	space->index[space->index_count++] = index;
>  	space->index_id_max =  MAX(space->index_id_max, index->def->iid);;
> +	return;
> +
> +alloc_error:
> +	diag_set(OutOfMemory, size, "region_alloc_array", "idx");
>  }
>  
>  int
> @@ -2717,7 +2737,7 @@ sql_create_index(struct Parse *parse) {
>  
>  	if (tbl_name != NULL)
>  		goto exit_create_index;
> -	table_add_index(space, index);
> +	sql_space_add_index(&parse->region, space, index);
>  	index = NULL;
>  
>  	/* Clean up before exiting. */
> -- 
> 2.24.3 (Apple Git-128)
>