From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp46.i.mail.ru (smtp46.i.mail.ru [94.100.177.106]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id ABF994765E0 for ; Tue, 29 Dec 2020 04:46:24 +0300 (MSK) From: Alexander Turenko Date: Tue, 29 Dec 2020 04:46:35 +0300 Message-Id: <59789e72543d71f8b66dff8f02866af52508aa8b.1609205150.git.alexander.turenko@tarantool.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH] box: do not reset region on select List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mergen Imeev , Vladislav Shpilevoy , "Alexander V . Tikhonov" , Kirill Yukhin Cc: Mergen Imeev , tarantool-patches@dev.tarantool.org From: Mergen Imeev 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