Re: [tarantool-patches] [PATCH v4 4/9] txn: get rid of fiber_gc from txn_rollback

[Vladimir Davydov <vdavydov.dev@gmail.com>]

On Thu, Jun 20, 2019 at 12:23:11AM +0300, Georgy Kirichenko wrote:
> Don't touch a fiber gc storage on a transaction rollback explicitly.
> This relaxes dependencies between fiber and transaction life cycles.
> 
> Prerequisites: #1254
> ---
>  src/box/applier.cc     |  8 +++++---
>  src/box/box.cc         | 14 +++++++++-----
>  src/box/call.c         | 22 ++++++++++++++++------
>  src/box/memtx_engine.c |  3 ++-
>  src/box/txn.c          | 35 +++++++++++++++++------------------
>  src/box/txn.h          |  8 ++++++--
>  src/box/vy_scheduler.c | 10 +++++++---
>  7 files changed, 62 insertions(+), 38 deletions(-)
> 
> diff --git a/src/box/txn.c b/src/box/txn.c
> index 39b1ed773..21f7e98b4 100644
> --- a/src/box/txn.c
> +++ b/src/box/txn.c
> @@ -168,6 +168,10 @@ txn_new()
>  inline static void
>  txn_free(struct txn *txn)
>  {
> +	struct txn_stmt *stmt;
> +	stailq_foreach_entry(stmt, &txn->stmts, next)
> +		txn_stmt_unref_tuples(stmt);
> +

Clearly, this doesn't belong here. Should be a part of the previous
patch?

>  	/* Truncate region up to struct txn size. */
>  	region_truncate(&txn->region, sizeof(struct txn));
>  	stailq_add(&txn_cache, &txn->in_txn_cache);
> @@ -636,6 +634,7 @@ txn_on_stop(struct trigger *trigger, void *event)
>  {
>  	(void) trigger;
>  	(void) event;
> -	txn_rollback();                 /* doesn't yield or fail */
> +	txn_rollback(in_txn());                 /* doesn't yield or fail */
> +

Extra new line.

>  }
>  
> diff --git a/src/box/txn.h b/src/box/txn.h
> index 5a66f8e53..569978ce9 100644
> --- a/src/box/txn.h
> +++ b/src/box/txn.h
> @@ -267,6 +270,7 @@ txn_on_rollback(struct txn *txn, struct trigger *trigger)
>  
>  /**
>   * Start a new statement.
> + * Return a new statement or NULL in case of error.

Again, looks like a leftover from the prevoius patch.

Other than that the patch looks fine to me. I would rather remove
fiber_gc() altogether, but as Kostja pointed out, it's too risky
so fine - let it be.

>   */
>  struct txn_stmt *
>  txn_begin_stmt(struct txn *txn, struct space *space);