mariadb

Commit Graph

Author	SHA1	Message	Date
Marko Mäkelä	947b0b5722	Implement innodb_evict_tables_on_commit_debug Some bugs are detected only after a table definition has been evicted and then reloaded to the InnoDB data dictionary cache. For debug builds, introduce the settable Boolean configuration parameter innodb_evict_tables_on_commit_debug that can be set to request InnoDB to attempt to evict table definitions from the data dictionary cache whenever a transaction is committed. This has been tested on 10.3 and 10.4 with the following: ./mysql-test-run.pl --mysqld=--loose-innodb-evict-tables-on-commit-debug You can also use the following: SET GLOBAL innodb_evict_tables_on_commit_debug=ON; SET GLOBAL innodb_evict_tables_on_commit_debug=OFF; The parameter affects the commit (or rollback or abort) of transactions that have modified persistent InnoDB tables.	6 years ago
Marko Mäkelä	25af2a183b	MDEV-15326/MDEV-16136 dead code removal Revert part of `fa2a74e08d`. trx_reference(): Remove, and merge the relevant part to the only caller trx_rw_is_active(). If the statements trx = NULL; were ever executed, the function would have dereferenced a NULL pointer and crashed in trx_mutex_exit(trx). Hence, those statements must have been unreachable, and they can be replaced with debug assertions. trx_rw_is_active(): Avoid unnecessary acquisition and release of trx->mutex when do_ref_count=false. lock_trx_release_locks(): Do not reset trx->id=0. Had the statement been necessary, we would have experienced crashes in trx_reference().	6 years ago
Marko Mäkelä	0c7c61019d	Remove the wrappers ut_time(), ut_difftime(), ib_time_t	6 years ago
Marko Mäkelä	10727b6953	Always initialize trx_t::start_time_micro This affects the function has_higher_priority() for internal or recovered transactions.	6 years ago
Vicențiu Ciorbaru	c0ac0b8860	Update FSF address	7 years ago
Marko Mäkelä	3db94d2403	MDEV-19346: Remove dummy InnoDB log checkpoints log_checkpoint(), log_make_checkpoint_at(): Remove the parameter write_always. It seems that the primary purpose of this parameter was to ensure in the function recv_reset_logs() that both checkpoint header pages will be overwritten, when the function is called from the never-enabled function recv_recovery_from_archive_start(). create_log_files(): Merge recv_reset_logs() to its only caller. Debug instrumentation: Prefer to flush the redo log, instead of triggering a redo log checkpoint. page_header_set_field(): Disable a debug assertion that will always fail due to MDEV-19344, now that we no longer initiate a redo log checkpoint before an injected crash. In recv_reset_logs() there used to be two calls to log_make_checkpoint_at(). The apparent purpose of this was to ensure that both InnoDB redo log checkpoint header pages will be initialized or overwritten. The second call was removed (without any explanation) in MySQL 5.6.3: mysql/mysql-server@4ca37968da54ddc6b3b6628f41428ddba1c79bb8 In MySQL 5.6.8 WL#6494, starting with mysql/mysql-server@00a0ba8ad92569fcf08212b3b8cf046dc8a0ce10 the function recv_reset_logs() was not only invoked during InnoDB data file initialization, but also during a regular startup when the redo log is being resized. mysql/mysql-server@45e91679832219e2593c77185342f11f85232b58 in MySQL 5.7.2 removed the UNIV_LOG_ARCHIVE code, but still did not remove the parameter write_always.	7 years ago
Marko Mäkelä	d0116e10a5	Revert MDEV-18464 and MDEV-12009 This reverts commit `21b2fada7a` and commit `81d71ee6b2`. The MDEV-18464 change introduces a few data race issues. Contrary to the documentation, the field trx_t::victim is not always being protected by lock_sys_t::mutex and trx_t::mutex. Most importantly, it seems that KILL QUERY could wrongly avoid acquiring both mutexes when invoking lock_trx_handle_wait_low(), in case another thread had already set trx->victim=true. We also revert MDEV-12009, because it should depend on the MDEV-18464 fix being present.	7 years ago
Thirunarayanan Balathandayuthapani	0623cc7c16	MDEV-19051 Avoid unnecessary writing MLOG_INDEX_LOAD 1) Avoid writing of MLOG_INDEX_LOAD redo log record during inplace alter table when the table is empty and also for spatial index. 2) Avoid creation of temporary merge file for spatial index during index creation process.	7 years ago
Jan Lindström	21b2fada7a	MDEV-18464: Port kill_one_trx fixes from 10.4 to 10.1 Pushed the decision for innodb transaction and system locking down to lock0lock.cc level. With this, we can avoid releasing these mutexes for executions where these mutexes were acquired upfront. This patch will also fix BF aborting of native threads, e.g. threads which have declared wsrep_on=OFF. Earlier, we have used, for innodb trx locks, was_chosen_as_deadlock_victim flag, for marking inodb transactions, which are victims for wsrep BF abort. With native threads (wsrep_on==OFF), re-using was_chosen_as_deadlock_victim flag may lead to inteference with real deadlock, and to deal with this, the patch has added new flag for marking wsrep BF aborts only: victim=true Similar way if replication decides to abort one of the threads we mark victim by: victim=true innobase_kill_query Remove lock sys and trx mutex handling. wsrep_innobase_kill_one_trx Mark victim trx with victim=true trx0trx.h Remove trx_abort_t type and abort type variable from trx struct. Add victim variable to trx. wsrep_kill_victim Remove abort_type lock_report_waiters_to_mysql Take also trx mutex and mark trx as a victim for replication abort. lock_trx_handle_wait_low New low level function to check whether the transaction has already been rolled back because it was selected as a deadlock victim, or if it has to wait then cancel the wait lock. lock_trx_handle_wait If transaction is not marked as victim take lock sys and trx mutex before calling lock_trx_handle_wait_low and release them after that. row_search_for_mysql Remove lock sys and trx mutex taking and releasing. trx_rollback_to_savepoint_for_mysql_low trx_commit_in_memory Clean up victim variable.	7 years ago
Jan Lindström	1d56d875fe	MDEV-15740: InnoDB does not flush redo log when it shoul During database recovery, a transaction with wsrep XID is recovered from InnoDB in prepared state. However, when the transaction is looked up with trx_get_trx_by_xid() in innobase_commit_by_xid(), trx->xid gets cleared in trx_get_trx_by_xid_low() and commit time serialization history write does not update the wsrep XID in trx sys header for that recovered trx. As a result the transaction gets committed during recovery but the wsrep position does not get updated appropriately. As a fix, we preserve trx->xid for Galera over transaction commit in recovery phase. Fix authored by: Teemu Ollakka (GaleraCluster) and Marko Mäkelä. modified: mysql-test/suite/galera/disabled.def modified: mysql-test/suite/galera/r/galera_gcache_recover_full_gcache.result modified: mysql-test/suite/galera/r/galera_gcache_recover_manytrx.result modified: mysql-test/suite/galera/t/galera_gcache_recover_full_gcache.test modified: mysql-test/suite/galera/t/galera_gcache_recover_manytrx.test modified: storage/innobase/trx/trx0trx.cc modified: storage/xtradb/trx/trx0trx.cc	7 years ago
Marko Mäkelä	b9824074a6	MDEV-17851 Assertion failure srv_undo_tablespaces > 1 trx_assign_rseg_low(): Skip dedicated undo tablespaces if innodb_undo_tablespaces=0 has been set after the database was created.	7 years ago
Marko Mäkelä	ff88e4bb8a	Remove many redundant #include from InnoDB	7 years ago
Marko Mäkelä	abcd09c95a	mtr_t::start(): Remove unused parameters The parameters bool sync=true, bool read_only=false of mtr_t::start() were added in `eca5b0fc17` (MySQL 5.7.3). The parameter read_only was never used anywhere. The parameter sync was only copied around, and would be returned by the unused function mtr_t::is_async(). We do not need this dead code in MariaDB.	7 years ago
Marko Mäkelä	75f8e86f57	MDEV-17158 TRUNCATE is not atomic after MDEV-13564 It turned out that ha_innobase::truncate() would prematurely commit the transaction already before the completion of the ha_innobase::create(). All of this must be atomic. innodb.truncate_crash: Use the correct DEBUG_SYNC point, and tolerate non-truncation of the table, because the redo log for the TRUNCATE transaction commit might be flushed due to some InnoDB background activity. dict_build_tablespace_for_table(): Merge to the function dict_build_table_def_step(). dict_build_table_def_step(): If a table is being created during an already started data dictionary transaction (such as TRUNCATE), persistently write the table_id to the undo log header before creating any file. In this way, the recovery of TRUNCATE will be able to delete the new file before rolling back the rename of the original table. dict_table_rename_in_cache(): Add the parameter replace_new_file, used as part of rolling back a TRUNCATE operation. fil_rename_tablespace_check(): Add the parameter replace_new. If the parameter is set and a file identified by new_path exists, remove a possible tablespace and also the file. create_table_info_t::create_table_def(): Remove some debug assertions that no longer hold. During TRUNCATE, the transaction will already have been started (and performed a rename operation) before the table is created. Also, remove a call to dict_build_tablespace_for_table(). create_table_info_t::create_table(): Add the parameter create_fk=true. During TRUNCATE TABLE, do not add FOREIGN KEY constraints to the InnoDB data dictionary, because they will also not be removed. row_table_add_foreign_constraints(): If trx=NULL, do not modify the InnoDB data dictionary, but only load the FOREIGN KEY constraints from the data dictionary. ha_innobase::create(): Lock the InnoDB data dictionary cache only if no transaction was passed by the caller. Unlock it in any case. innobase_rename_table(): Add the parameter commit = true. If !commit, do not lock or unlock the data dictionary cache. ha_innobase::truncate(): Lock the data dictionary before invoking rename or create, and let ha_innobase::create() unlock it and also commit or roll back the transaction. trx_undo_mark_as_dict(): Renamed from trx_undo_mark_as_dict_operation() and declared global instead of static. row_undo_ins_parse_undo_rec(): If table_id is set, this must be rolling back the rename operation in TRUNCATE TABLE, and therefore replace_new_file=true.	7 years ago
Marko Mäkelä	fa2a74e08d	MDEV-16136: Prevent wrong reuse in trx_reference() If trx_free() and trx_create_low() were called while a call to trx_reference() was pending, we could get a reference to a wrong transaction object. trx_reference(): Return NULL if the trx->id no longer matches. lock_trx_release_locks(): Assign trx->id = 0, so that trx_reference() will not return a reference to this object. trx_cleanup_at_db_startup(): Assign trx->id = 0. assert_trx_is_free(): Assert !trx->n_ref. Assert trx->id == 0, now that it will be cleared as part of a transaction commit.	7 years ago
Marko Mäkelä	6583506570	Rename lock_pool_t to lock_list Also, replace reverse iteration with forward iteration. lock_table_has(): Remove a redundant condition.	7 years ago
Marko Mäkelä	3ce8a0fc49	MDEV-16136: Simplify trx_lock_t memory management Allocate trx->lock.rec_pool and trx->lock.table_pool directly from trx_t. Remove unnecessary use of std::vector. In order to do this, move some definitions from lock0priv.h to lock0types.h, so that ib_lock_t will not be an opaque type.	7 years ago
Marko Mäkelä	769f6d2db7	Fix -Wclass-memaccess in WSREP,InnoDB,XtraDB	7 years ago
Marko Mäkelä	9dfef6e29b	Fix -Wclass-memaccess warnings in InnoDB,XtraDB	7 years ago
Sergey Vojtovich	a1b2336199	Optimized away excessive condition trx_set_rw_mode() is never called for read-only transactions, this is guarded by callers. Removing this condition from critical section immediately gives 5% scalability improvement in OLTP index updates benchmark.	8 years ago
Marko Mäkelä	d17e9a02c4	Fix InnoDB/XtraDB warnings by GCC 8.2.0	7 years ago
Marko Mäkelä	1748a31ae8	MDEV-16675 Unnecessary explicit lock acquisition during UPDATE or DELETE In InnoDB, an INSERT will not create an explicit lock object. Instead, the inserted record is initially implicitly locked by the transaction that wrote its trx_t::id to the hidden system column DB_TRX_ID. (Other transactions would check if DB_TRX_ID is referring to a transaction that has not been committed.) If a record was inserted in the current transaction, it would be implicitly locked by that transaction. Only if some other transaction is requesting access to the record, the implicit lock should be converted to an explicit one, so that the waits-for graph can be constructed for detecting deadlocks and lock wait timeouts. Before this fix, InnoDB would convert implicit locks to explicit ones, even if no conflict exists. lock_rec_convert_impl_to_expl(): Return whether caller_trx already holds an explicit lock that covers the record. row_vers_impl_x_locked_low(): Avoid a lookup if the record matches caller_trx->id. lock_trx_has_expl_x_lock(): Renamed from lock_trx_has_rec_x_lock(). row_upd_clust_step(): In a debug assertion, check for implicit lock before invoking lock_trx_has_expl_x_lock(). rw_trx_hash_t::find(): Make do_ref_count a mandatory parameter. Assert that trx_id is not 0 (the caller should check it). trx_sys_t::is_registered(): Only invoke find() if id != 0. trx_sys_t::find(): Add the optional parameter do_ref_count. lock_rec_queue_validate(): Avoid lookup for trx_id == 0.	8 years ago
Marko Mäkelä	cd15e764a8	MDEV-16159 Use atomic memory access for purge_sys Thanks to Sergey Vojtovich for feedback and many ideas. purge_state_t: Remove. The states are replaced with purge_sys_t::enabled() and purge_sys_t::paused() as follows: PURGE_STATE_INIT, PURGE_STATE_EXIT, PURGE_STATE_DISABLED: !enabled(). PURGE_STATE_RUN, PURGE_STATE_STOP: paused() distinguishes these. purge_sys_t::m_paused: Renamed from purge_sys_t::n_stop. Protected by atomic memory access only, not purge_sys_t::latch. purge_sys_t::m_enabled: An atomically updated Boolean that replaces purge_sys_t::state. purge_sys_t:🏃 Remove, because it duplicates srv_sys.n_threads_active[SRV_PURGE]. purge_sys_t::running(): Accessor for srv_sys.n_threads_active[SRV_PURGE]. purge_sys_t::stop(): Renamed from trx_purge_stop(). purge_sys_t::resume(): Renamed from trx_purge_run(). Do not acquire latch; solely rely on atomics. purge_sys_t::is_initialised(), purge_sys_t::m_initialised: Remove. purge_sys_t::create(), purge_sys_t::close(): Instead of invoking is_initialised(), check whether event is NULL. purge_sys_t::event: Move before latch, so that fields that are protected by latch can reside on the same cache line with latch. srv_start_wait_for_purge_to_start(): Merge to the only caller srv_start().	8 years ago
Marko Mäkelä	ba19764209	Fix most -Wsign-conversion in InnoDB Change innodb_buffer_pool_size, innodb_fill_factor to unsigned.	8 years ago
Marko Mäkelä	83bd4dd1ee	MDEV-15914: Remove trx_t::undo_mutex The trx_t::undo_mutex covered both some main-memory data structures (trx_undo_t) and access to undo pages. The trx_undo_t is only accessed by the thread that is associated with a running transaction. Likewise, each transaction has its private set of undo pages. The thread that is associated with an active transaction may lock multiple undo pages concurrently, but no other thread may lock multiple pages of a foreign transaction. Concurrent access to the undo logs of an active transaction is possible, but trx_undo_get_undo_rec_low() only locks one undo page at a time, without ever holding any undo_mutex. It seems that the trx_t::undo_mutex would have been necessary if multi-threaded execution or rollback of a single transaction had been implemented in InnoDB.	8 years ago
Marko Mäkelä	ff0000cdd2	MDEV-15914: Remove trx_undo_t::empty Use the value trx_undo_t::top_undo_no == IB_ID_MAX for indicating that an undo log is empty.	8 years ago
Marko Mäkelä	e3fb8e9569	Remove trx_t::undo_rseg_space The field undo_rseg_space was only used in a debug check. trx_roll_check_undo_rec_ordering(): Remove.	8 years ago
Marko Mäkelä	7b5543b21d	MDEV-15030 Add ASAN instrumentation to trx_t Pool Pool::mem_free(): Poison the freed memory. Assert that it was fully initialized, because the reuse of trx_t objects will assume that the objects were previously initialized. Pool::~Pool(), Pool::get(): Unpoison the allocated memory, and mark it initialized. trx_free(): After invoking Pool::mem_free(), unpoison trx_t::mutex and trx_t::undo_mutex, because MutexMonitor will access these even for freed trx_t objects.	8 years ago
Marko Mäkelä	dd127799bc	MDEV-15832 With innodb_fast_shutdown=3, skip the rollback of connected transactions row_undo_step(): If innodb_fast_shutdown=3 has been requested, abort the rollback of any non-DDL transactions. Starting with MDEV-12323, we aborted the rollback of recovered transactions. The transactions would be rolled back on subsequent server startup. trx_roll_report_progress(): Renamed from trx_roll_must_shutdown(), now that the shutdown check has been moved to the only caller. trx_commit_low(): Allow mtr=NULL for transactions that are aborted on rollback. trx_rollback_finish(): Clean up aborted transactions to avoid assertion failures and memory leaks on shutdown. This code was previously in trx_rollback_active(). trx_rollback_to_savepoint_low(), trx_rollback_for_mysql_low(): Remove some redundant assertions.	8 years ago
Eugene Kosov	1513630d30	remove dead code	8 years ago
Sergey Vojtovich	e6a9ce2759	MDEV-15773 - Simplified away trx_sys_t::m_views Use trx_sys_t::trx_list instead.	8 years ago
Sergey Vojtovich	3d5f7ad23a	MDEV-15773 - Simplified away trx_free_for_(mysql\|background)	8 years ago
Sergey Vojtovich	0993d6b81b	MDEV-15773 - trx_sys.mysql_trx_list -> trx_sys.trx_list Replaced "list of transactions created for MySQL" with "list of all transactions". This simplifies code and allows further removal of trx_sys.m_views.	8 years ago
Sergey Vojtovich	061c767cce	MDEV-15773 - Simplified away trx_t::in_mysql_trx_list	8 years ago
Sergey Vojtovich	d6d58836bb	MDEV-15773 - trx_allocate_for_background() -> trx_create() trx_free_resurrected(): Remove, unused function	8 years ago
Marko Mäkelä	9043bec954	MDEV-12266: Make trx_rseg_t::space a pointer trx_rsegf_get(), trx_undo_get_first_rec(): Change the parameter to fil_space_t* so that fewer callers need to be adjusted. trx_undo_free_page(): Remove the redundant parameter 'space'.	8 years ago
Marko Mäkelä	39ed074317	MDEV-12266: Remove trx_undo_t::space	8 years ago
Sergey Vojtovich	4faf34ad63	Clean-up trx_sys.mutex misuse Currently trx_sys.mutex protects only trx_sys.mysql_trx_list and trx_sys.m_views, which are not accessed by lock0lock debug routines. Thus there's no need to bother trx_sys.mutex here. Removed trx_assert_started(): this assertion is fully covered by check_trx_state().	8 years ago
Marko Mäkelä	bd7ed1b923	MDEV-13935 INSERT stuck at state Unlocking tables Revert the dead code for MySQL 5.7 multi-master replication (GCS), also known as WL#6835: InnoDB: GCS Replication: Deterministic Deadlock Handling (High Prio Transactions in InnoDB). Also, make innodb_lock_schedule_algorithm=vats skip SPATIAL INDEX, because the code does not seem to be compatible with them. Add FIXME comments to some SPATIAL INDEX locking code. It looks like Galera write-set replication might not work with SPATIAL INDEX.	8 years ago
Sergey Vojtovich	131d9a5d0c	Allocate lock_sys statically There is only one lock_sys. Allocate it statically in order to avoid dereferencing a pointer whenever accessing it. Also, align some members to their own cache line in order to avoid false sharing. lock_sys_t::create(): The deferred constructor. lock_sys_t::close(): The early destructor.	8 years ago
Marko Mäkelä	fb335b48b5	Allocate purge_sys statically There is only one purge_sys. Allocate it statically in order to avoid dereferencing a pointer whenever accessing it. Also, align some members to their own cache line in order to avoid false sharing. purge_sys_t::create(): The deferred constructor. purge_sys_t::close(): The early destructor. undo::Truncate::create(): The deferred constructor. Because purge_sys.undo_trunc is constructed before the start-up parameters are parsed, the normal constructor would copy a wrong value of srv_purge_rseg_truncate_frequency. TrxUndoRsegsIterator: Do not forward-declare an inline constructor, because the static construction of purge_sys.rseg_iter would not have access to it.	8 years ago
Marko Mäkelä	6ae7fa6878	Simplify TrxUndoRsegs Construct directly from trx_rseg_t&. push_back(), size(): Remove.	8 years ago
Marko Mäkelä	947efe17ed	MDEV-15158 On commit, do not write to the TRX_SYS page This is based on a prototype by Thirunarayanan Balathandayuthapani <thiru@mariadb.com>. Binlog and Galera write-set replication information was written into TRX_SYS page on each commit. Instead of writing to the TRX_SYS during normal operation, InnoDB can make use of rollback segment header pages, which are already being written to during a commit. The following list of fields in rollback segment header page are added: TRX_RSEG_BINLOG_OFFSET TRX_RSEG_BINLOG_NAME (NUL-terminated; empty name = not present) TRX_RSEG_WSREP_XID_FORMAT (0=not present; 1=present) TRX_RSEG_WSREP_XID_GTRID TRX_RSEG_WSREP_XID_BQUAL TRX_RSEG_WSREP_XID_DATA trx_sys_t: Introduce the fields recovered_binlog_filename, recovered_binlog_offset, recovered_wsrep_xid. To facilitate upgrade from older mysql or mariaDB versions, we will read the information in TRX_SYS page. It will be overridden by the information that we find in rollback segment header pages. Mariabackup --prepare will read the metadata from the rollback segment header pages via trx_rseg_array_init(). It will still not read any undo log pages or recover any transactions.	8 years ago
Marko Mäkelä	03400d974d	Dead code removal: sess_t The session object is not really needed for anything. We can directly create and free the dummy purge_sys->query->trx.	8 years ago
Marko Mäkelä	27ea2963fc	Dead code removal: sess_t The session object is not really needed for anything. We can directly create and free the dummy purge_sys->query->trx.	8 years ago
Sergey Vojtovich	b782971c58	MDEV-15246 - premature history data deletion This is regression after `bc7a1dc1fb` of MDEV-15104 - Optimise MVCC snapshot. Aforementioned revision removes mutex lock around ReadView creation, which allows views to be created concurrently. Effectively it invalidates "oldest view" approach: no single view can be considered oldest anymore. Instead we have to iterate trx_sys.m_views to find min(m_low_limit_no), min(m_low_limit_id) and all transaction ids below min(m_low_limit_id), which would form oldest view. Second regression comes from `c0d5d7c0ef` of MDEV-15104 - Optimise MVCC snapshot. It removes mutex protection around trx->no assignment, which opens up a gap between m_max_trx_id increment and transaction serialisation number becoming visible through rw_trx_hash. While we're in this gap concurrent thread may come and do MVCC snapshot without seeing allocated but not yet assigned serialisation number. Then at some point purge thread may clone this view. As a result it won't see newly allocated serialisation number and may remove "unnecessary" history data of this transaction from rollback segments.	8 years ago
Marko Mäkelä	c051eaba46	MDEV-14988 innodb_read_only tries to modify files if transactions were recovered in COMMITTED state lock_trx_release_locks(): Relax a debug assertion to allow recovered TRX_STATE_COMMITTED_IN_MEMORY transactions. trx_commit_in_memory(): Add DEBUG_SYNC instrumentation. trx_undo_insert_cleanup(): Skip persistent changes if innodb_read_only is set. This should only happen when a recovered committed transaction would be cleaned up at shutdown.	8 years ago
Sergey Vojtovich	bc7a1dc1fb	MDEV-15104 - Optimise MVCC snapshot With trx_sys_t::rw_trx_ids removal, MVCC snapshot overhead became slightly higher. That is instead of copying an array we now have to iterate LF_HASH. All this done under trx_sys.mutex protection. This patch moves MVCC snapshot out of trx_sys.mutex. Clean-ups: Removed MVCC: doesn't make too much sense to keep it in a separate class anymore. Refactored ReadView so that it now calls register()/deregister() routines (it was vice versa before). ReadView doesn't have friends anymore. :( Even less trx_sys.mutex references.	8 years ago
Sergey Vojtovich	c0d5d7c0ef	MDEV-15104 - Remove trx_sys_t::serialisation_list serialisation_list was supposed to instantly give minimum registered transaction serialisation number. However maintaining and accessing this list requires global mutex protection. Since we already take MVCC snapshot by iterating trx_sys_t::rw_trx_hash, it is cheap to integrate minimum registered transaction lookup into this iteration.	8 years ago
Sergey Vojtovich	53cc9aa5be	MDEV-15104 - Remove trx_sys_t::rw_trx_ids Take snapshot of registered read-write transaction identifiers directly from rw_trx_hash. It immediately saves one trx_sys.mutex lock, reduces size of another critical section protected by this mutex, and makes further optimisations like removing trx_sys_t::serialisation_list possible. Downside of this approach is bigger overhead for view opening, because iterating LF_HASH is more expensive compared to taking snapshot of an array. However for low concurrency overhead difference is negligible, while for high concurrency mutex is much bigger evil. Currently we still take trx_sys.mutex to serialise ReadView creation. This is required to keep serialisation_list ordered by trx->no as well as not to let purge thread to create more recent snapshot while another thread gets suspended during creation of older snapshot. This will become completely mutex free along with serialisation_list removal. Compared to previous implementation removing element from rw_trx_hash and serialisation_list is not atomic. We disregard all possible bad consequences (if there're any) since it will be solved along with serialisation_list removal.	8 years ago

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234 Commits (e41eb044f19e3ee9b881344565924dd6b9d20e1a)