Re: [Tarantool-patches] [PATCH v2 2/2] vinyl: clean-up unprocessed read views in *_build_read_views()

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Hi! Thanks for the patch!

See 2 comments below.

> diff --git a/src/box/vy_write_iterator.c b/src/box/vy_write_iterator.c
> index 7a6a20627..910e5a062 100644
> --- a/src/box/vy_write_iterator.c
> +++ b/src/box/vy_write_iterator.c
> @@ -790,8 +790,11 @@ next_lsn:
>  	 * statement around if this is major compaction, because
>  	 * there's no tuple it could overwrite.
>  	 */
> -	if (rc == 0 && stream->is_last_level &&
> -	    stream->deferred_delete_stmt != NULL) {
> +	if (rc != 0) {
> +		for (int i = 0; i < stream->rv_count; ++i)
> +			stream->read_views[i].history = NULL;

1. Why are we sure it is safe to nullify the read view histories in
case of a fail? Looks like they can keep tuples which should be
unreferenced. If it would be enough to nullify them, we could
just do the same in vy_write_iterator_stop(). But it calls
vy_write_history_destroy() before nullification.

Why is not it called here? The same question for vy_read_view_merge().

> +	} else if (stream->is_last_level &&
> +		   stream->deferred_delete_stmt != NULL) {
>  		vy_stmt_unref_if_possible(stream->deferred_delete_stmt);
>  		stream->deferred_delete_stmt = NULL;
>  	}
> @@ -834,6 +837,15 @@ vy_read_view_merge(struct vy_write_iterator *stream, struct tuple *hint,
>  		rv->history = NULL;
>  		return 0;
>  	}
> +#ifndef NDEBUG
> +	struct errinj *inj =
> +		errinj(ERRINJ_VY_READ_VIEW_MERGE_FAIL, ERRINJ_BOOL);
> +	if (inj != NULL && inj->bparam) {
> +			inj->bparam = false;
> +			diag_set(OutOfMemory, 666, "malloc", "struct vy_stmt");
> +			return -1;
> +		}

2. Indentation is too big.

> +#endif
> @@ -983,8 +995,13 @@ vy_write_iterator_build_read_views(struct vy_write_iterator *stream, int *count)
>  		if (rv->history == NULL)
>  			continue;
>  		if (vy_read_view_merge(stream, hint, rv,
> -				       is_first_insert) != 0)
> +				       is_first_insert) != 0) {
> +			while (rv >= &stream->read_views[0]) {
> +				rv->history = NULL;
> +				rv--;
> +			}
>  			goto error;
> +		}
>  		assert(rv->history == NULL);
>  		if (rv->tuple == NULL)
>  			continue;