[Tarantool-patches] [PATCH] box: do not reset region on select
Alexander V. Tikhonov
avtikhon at tarantool.org
Tue Dec 29 11:52:38 MSK 2020
Hi All, thanks for the patch, as I see no new degradation found in
gitlab-ci testing commit criteria pipeline [1], patch LGTM.
[1] - https://gitlab.com/tarantool/tarantool/-/pipelines/235247720
On Tue, Dec 29, 2020 at 04:46:35AM +0300, Alexander Turenko wrote:
> From: Mergen Imeev <imeevma at gmail.com>
>
> A read only transaction should not invalidate the fiber region.
>
> The problem was found in context of calling a Lua function from SQL on
> tarantool 2.* (#5427).
>
> Another problem (#5623) was fixed by this commit on tarantool 2.*. Since
> 2.2.0-469-g707e58a3f ('box: rework box_lua_{call, eval} to use input
> port') arguments for a C stored procedure is allocated on a fiber
> region. The region is truncated at the end of the call. When the
> procedure performs a read only transaction, fiber_gc() may be called
> and so region_truncate() will fail on assertion (on Debug build).
>
> Despite that all found cases are specific for tarantool 2.*, it is
> possible to be hit by the problem on 1.10 as well. It is enough to
> allocate something on a region (explicitly or implicitly) and perform a
> read only transaction.
>
> So it looks worthful to backport the fix to 1.10 as well.
>
> (cherry picked from commit d0d668fa014763adefb71bfeddab1ae5a5350fce)
>
> The original commit message:
>
> | sql: do not reset region on select
> |
> | Prior to this patch, region on fiber was reset during select(), get(),
> | count(), max(), or min(). This would result in an error if one of these
> | operations was used in a user-defined function in SQL. After this patch,
> | these functions truncate region instead of resetting it.
> |
> | Closes #5427
> ---
>
> Hi!
>
> Mergen, Vlad, Alexander, Kirill,
>
> I want to fix the problem on 1.10 as well, prior to 1.10.9 release. Are
> there any objections?
>
> The patch is cherry picked without changes, except removed src/box/sql
> files, removed test (it is SQL specific) and rewritten commit message.
>
> https://github.com/tarantool/tarantool/issues/5427
> https://github.com/tarantool/tarantool/issues/5623
> https://github.com/tarantool/tarantool/tree/Totktonada/gh-5427-ro-txn-dont-invalidate-fiber-region-1.10
>
> Fails on GitHub Actions runners on
> app-tap/gh-4983-tnt-e-assert-false-hangs.test.lua are expected (and we
> work on them).
>
> @ChangeLog (somewhere in 'Core'): Don't invalidate the fiber region
> (the box region) on a read only transaction (gh-5427, gh-5623).
>
> src/box/box.cc | 5 +++--
> src/box/index.cc | 25 +++++++++++++++----------
> src/box/txn.h | 23 ++++++++++++++++++++---
> 3 files changed, 38 insertions(+), 15 deletions(-)
>
> diff --git a/src/box/box.cc b/src/box/box.cc
> index 58011d44c..0f6761cf6 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -1070,7 +1070,8 @@ box_select(uint32_t space_id, uint32_t index_id,
> });
>
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return -1;
>
> struct iterator *it = index_create_iterator(index, type,
> @@ -1104,7 +1105,7 @@ box_select(uint32_t space_id, uint32_t index_id,
> txn_rollback_stmt();
> return -1;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> return 0;
> }
>
> diff --git a/src/box/index.cc b/src/box/index.cc
> index 9c4acec1d..bb218061f 100644
> --- a/src/box/index.cc
> +++ b/src/box/index.cc
> @@ -246,13 +246,14 @@ box_index_get(uint32_t space_id, uint32_t index_id, const char *key,
> return -1;
> /* Start transaction in the engine. */
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return -1;
> if (index_get(index, key, part_count, result) != 0) {
> txn_rollback_stmt();
> return -1;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> /* Count statistics. */
> rmean_collect(rmean_box, IPROTO_SELECT, 1);
> if (*result != NULL)
> @@ -280,13 +281,14 @@ box_index_min(uint32_t space_id, uint32_t index_id, const char *key,
> return -1;
> /* Start transaction in the engine. */
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return -1;
> if (index_min(index, key, part_count, result) != 0) {
> txn_rollback_stmt();
> return -1;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> if (*result != NULL)
> tuple_bless(*result);
> return 0;
> @@ -312,13 +314,14 @@ box_index_max(uint32_t space_id, uint32_t index_id, const char *key,
> return -1;
> /* Start transaction in the engine. */
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return -1;
> if (index_max(index, key, part_count, result) != 0) {
> txn_rollback_stmt();
> return -1;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> if (*result != NULL)
> tuple_bless(*result);
> return 0;
> @@ -345,14 +348,15 @@ box_index_count(uint32_t space_id, uint32_t index_id, int type,
> return -1;
> /* Start transaction in the engine. */
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return -1;
> ssize_t count = index_count(index, itype, key, part_count);
> if (count < 0) {
> txn_rollback_stmt();
> return -1;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> return count;
> }
>
> @@ -381,7 +385,8 @@ box_index_iterator(uint32_t space_id, uint32_t index_id, int type,
> if (key_validate(index->def, itype, key, part_count))
> return NULL;
> struct txn *txn;
> - if (txn_begin_ro_stmt(space, &txn) != 0)
> + struct txn_ro_savepoint svp;
> + if (txn_begin_ro_stmt(space, &txn, &svp) != 0)
> return NULL;
> struct iterator *it = index_create_iterator(index, itype,
> key, part_count);
> @@ -389,7 +394,7 @@ box_index_iterator(uint32_t space_id, uint32_t index_id, int type,
> txn_rollback_stmt();
> return NULL;
> }
> - txn_commit_ro_stmt(txn);
> + txn_commit_ro_stmt(txn, &svp);
> rmean_collect(rmean_box, IPROTO_SELECT, 1);
> return it;
> }
> diff --git a/src/box/txn.h b/src/box/txn.h
> index c366f3cab..822d5a7a9 100644
> --- a/src/box/txn.h
> +++ b/src/box/txn.h
> @@ -96,6 +96,20 @@ struct txn_savepoint {
> struct stailq_entry *stmt;
> };
>
> +/**
> + * Read-only transaction savepoint object. After completing a read-only
> + * transaction, we must clear the region. However, if we just reset the region,
> + * we may corrupt the data that was placed in the region before the read-only
> + * transaction began. To avoid this, we should use truncation. This structure
> + * contains the information required for truncation.
> + */
> +struct txn_ro_savepoint {
> + /** Region used during this transaction. */
> + struct region *region;
> + /** Savepoint for region. */
> + size_t region_used;
> +};
> +
> extern double too_long_threshold;
>
> struct txn {
> @@ -236,24 +250,27 @@ txn_begin_in_engine(struct engine *engine, struct txn *txn);
> * select.
> */
> static inline int
> -txn_begin_ro_stmt(struct space *space, struct txn **txn)
> +txn_begin_ro_stmt(struct space *space, struct txn **txn,
> + struct txn_ro_savepoint *svp)
> {
> *txn = in_txn();
> if (*txn != NULL) {
> struct engine *engine = space->engine;
> return txn_begin_in_engine(engine, *txn);
> }
> + svp->region = &fiber()->gc;
> + svp->region_used = region_used(svp->region);
> return 0;
> }
>
> static inline void
> -txn_commit_ro_stmt(struct txn *txn)
> +txn_commit_ro_stmt(struct txn *txn, struct txn_ro_savepoint *svp)
> {
> assert(txn == in_txn());
> if (txn) {
> /* nothing to do */
> } else {
> - fiber_gc();
> + region_truncate(svp->region, svp->region_used);
> }
> }
>
> --
> 2.25.0
>
More information about the Tarantool-patches
mailing list