Re: [Tarantool-patches] [PATCH v4 4/5] sql: use parser's region of "index" array

[Nikita Pettik <korablev@tarantool.org>]

On 10 Nov 15:18, Roman Khabibov wrote:
> Hi! Thanks for the review.
> 
> > On Nov 6, 2020, at 01:26, Nikita Pettik <korablev@tarantool.org> wrote:
> > 
> > On 09 Oct 16:45, 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.
> > 
> > Would be nice pointing out where leak occured. Also realloc usage looks
> > better to me (27 lines vs 8 with straight execution flaw). 
> Vlad said that main point of the region - speed, and it is also harder
> to leave a memory leak, because the region is destroyed in the end of
> parsing entirely.

Region vs malloc allocation performance benefit is not a point at all
as we speak about parsing process (at least for DDL statements).
Ok, as you wish, let's leave patch as is.
 
> >> Needed for #2349
> >> ---
> >> src/box/sql/build.c | 48 +++++++++++++++++++++++++++++++++------------
> >> 1 file changed, 35 insertions(+), 13 deletions(-)
> >> 
> >> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> >> index 3b3c8099a..fd8e7ed1e 100644
> >> --- a/src/box/sql/build.c
> >> +++ b/src/box/sql/build.c
> >> @@ -2228,29 +2228,52 @@ 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 parse's region if needed.
> >> + *
> >>  * We follow convention that PK comes first in list.
> >>  *
> >> + * @param parse Parsing structure.
> >>  * @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)
> >> +static int
> >> +sql_space_add_index(struct Parse *parse, 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;
> >> +	struct region *region = &parse->region;
> >> +	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;
> >> 	/* 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 0;
> >> +
> >> +alloc_error:
> >> +	diag_set(OutOfMemory, size, "region_alloc_array", "idx");
> >> +	parse->is_aborted = true;
> >> +	return -1;
> >> }
> >> 
> >> int
> >> @@ -2717,9 +2740,8 @@ sql_create_index(struct Parse *parse) {
> >> 		sqlVdbeAddOp0(vdbe, OP_Expire);
> >> 	}
> >> 
> >> -	if (tbl_name != NULL)
> >> +	if (tbl_name != NULL || sql_space_add_index(parse, space, index) != 0)
> >> 		goto exit_create_index;
> >> -	table_add_index(space, index);
> >> 	index = NULL;
> >> 
> >> 	/* Clean up before exiting. */
> >> -- 
> >> 2.24.3 (Apple Git-128)
> >> 
> 
> commit 459410f559a1c2f36a2da8925565a32a4caf4ae3 (HEAD)
> Author: Roman Khabibov <roman.habibov@tarantool.org>
> Date:   Thu Sep 3 14:26:47 2020 +0300
> 
>     sql: use parser's region of "index" array
>     
>     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 for the index array of ephemeral
>     space. The memory was never released.
>     
>     Needed for #2349
> 
> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index 3b3c8099a..fd8e7ed1e 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -2228,29 +2228,52 @@ 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 parse's region if needed.
> + *
>   * We follow convention that PK comes first in list.
>   *
> + * @param parse Parsing structure.
>   * @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)
> +static int
> +sql_space_add_index(struct Parse *parse, 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;
> +	struct region *region = &parse->region;
> +	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;
>  	/* 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 0;
> +
> +alloc_error:
> +	diag_set(OutOfMemory, size, "region_alloc_array", "idx");
> +	parse->is_aborted = true;
> +	return -1;
>  }
>  
>  int
> @@ -2717,9 +2740,8 @@ sql_create_index(struct Parse *parse) {
>  		sqlVdbeAddOp0(vdbe, OP_Expire);
>  	}
>  
> -	if (tbl_name != NULL)
> +	if (tbl_name != NULL || sql_space_add_index(parse, space, index) != 0)
>  		goto exit_create_index;
> -	table_add_index(space, index);
>  	index = NULL;
>  
>  	/* Clean up before exiting. */
> 
>