lock0lock.cc File Reference

The transaction lock system. More...

#include <mysql/service_thd_engine_lock.h>
#include <sys/types.h>
#include <algorithm>
#include <bit>
#include <set>
#include <unordered_map>
#include <vector>
#include "btr0btr.h"
#include "current_thd.h"
#include "debug_sync.h"
#include "dict0boot.h"
#include "dict0mem.h"
#include "ha_prototypes.h"
#include "lock0lock.h"
#include "lock0priv.h"
#include "os0thread.h"
#include "pars0pars.h"
#include "row0mysql.h"
#include "row0sel.h"
#include "srv0mon.h"
#include "trx0purge.h"
#include "trx0sys.h"
#include "usr0sess.h"
#include "ut0bitset.h"
#include "ut0new.h"
#include "ut0vec.h"
#include "my_dbug.h"
#include "my_psi_config.h"
#include "mysql/plugin.h"
#include "mysql/psi/psi_thread.h"

Classes
class	Deadlock_notifier
	A static class for reporting notifications about deadlocks. More...
struct	locksys::Conflicting
struct	PrintNotStarted
	Functor to print not-started transaction from the mysql_trx_list. More...
class	TrxLockIterator
	Iterate over a transaction's locks. More...
class	TrxListIterator
	This iterates over RW trx_sys lists only. More...

Namespaces
namespace	locksys

Macros
#define	LOCK_MODULE_IMPLEMENTATION
#define	PRINT_NUM_OF_LOCK_STRUCTS

Typedefs
template<typename T >
using	Locks = std::vector< T, mem_heap_allocator< T > >

Enumerations
enum class	locksys::Conflict { locksys::HAS_TO_WAIT , locksys::NO_CONFLICT , locksys::CAN_BYPASS }

Functions
bool	locksys::owns_exclusive_global_latch ()
	Tests if lock_sys latch is exclusively owned by the current thread. More...
bool	locksys::owns_shared_global_latch ()
	Tests if lock_sys latch is owned in shared mode by the current thread. More...
bool	locksys::owns_page_shard (const page_id_t &page_id)
	Tests if given page shard can be safely accessed by the current thread. More...
bool	locksys::owns_table_shard (const dict_table_t &table)
	Test if given table shard can be safely accessed by the current thread. More...
bool	locksys::owns_lock_shard (const lock_t *lock)
	Checks if shard which contains lock is latched (or that an exclusive latch on whole lock_sys is held) by current thread. More...
static void	lock_rec_validate_page (const buf_block_t *block)
	Validates the record lock queues on a page. More...
void	lock_report_trx_id_insanity (trx_id_t trx_id, const rec_t *rec, const dict_index_t *index, const ulint *offsets, trx_id_t next_trx_id)
	Reports that a transaction id is insensible, i.e., in the future. More...
bool	lock_check_trx_id_sanity (trx_id_t trx_id, const rec_t *rec, const dict_index_t *index, const ulint *offsets)
	Checks that a transaction id is sensible, i.e., not in the future. More...
bool	lock_clust_rec_cons_read_sees (const rec_t *rec, dict_index_t *index, const ulint *offsets, ReadView *view)
	Checks that a record is seen in a consistent read. More...
bool	lock_sec_rec_cons_read_sees (const rec_t *rec, const dict_index_t *index, const ReadView *view)
	Checks that a non-clustered index record is seen in a consistent read. More...
void	lock_sys_create (ulint n_cells)
	Creates the lock system at database start. More...
static uint64_t	lock_rec_lock_hash_value (const lock_t *lock)
	Calculates the hash value of a lock: used in migrating the hash table. More...
void	lock_sys_resize (ulint n_cells)
	Resize the lock hash tables. More...
void	lock_sys_close (void)
	Closes the lock system at database shutdown. More...
ulint	lock_get_size (void)
	Gets the size of a lock struct. More...
bool	lock_is_waiting (const lock_t &lock)
	Checks if the lock is waiting (as opposed to granted). More...
static void	lock_set_lock_and_trx_wait (lock_t *lock)
	Sets the wait flag of a lock and the back pointer in trx to lock. More...
static ulint	lock_rec_get_gap (const lock_t *lock)
	Gets the gap flag of a record lock. More...
static ulint	lock_rec_get_rec_not_gap (const lock_t *lock)
	Gets the LOCK_REC_NOT_GAP flag of a record lock. More...
static ulint	lock_rec_get_insert_intention (const lock_t *lock)
	Gets the waiting insert flag of a record lock. More...
static Conflict	locksys::rec_lock_check_conflict (const trx_t *trx, ulint type_mode, const lock_t *lock2, bool lock_is_on_supremum, Trx_locks_cache &trx_locks_cache)
	Checks if a new request for a record lock has to wait for existing request. More...
static bool	locksys::rec_lock_has_to_wait (const lock_t *lock1, const lock_t *lock2, Trx_locks_cache &lock1_cache)
	Checks if a record lock request lock1 has to wait for request lock2. More...
bool	locksys::has_to_wait (const lock_t *lock1, const lock_t *lock2, Trx_locks_cache &lock1_cache)
	Checks if a lock request lock1 has to wait for request lock2. More...
bool	lock_has_to_wait (const lock_t *lock1, const lock_t *lock2)
	Checks if a lock request lock1 has to wait for request lock2. More...
ulint	lock_rec_find_set_bit (const lock_t *lock)
	Looks for a set bit in a record lock bitmap. More...
ulint	lock_rec_find_next_set_bit (const lock_t *lock, ulint heap_no)
	Looks for the next set bit in the record lock bitmap. More...
static byte	lock_rec_reset_nth_bit (lock_t *lock, ulint i)
	Reset the nth bit of a record lock. More...
bool	lock_rec_clear_request_no_wakeup (lock_t *lock, uint16_t heap_no)
	Reset the nth bit of a record lock. More...
static bool	lock_rec_has_any (Locks_hashtable &hash, page_id_t page_id)
static bool	lock_rec_has_any (Locks_hashtable &hash, page_id_t page_id, uint16_t heap_no)
bool	lock_rec_expl_exist_on_page (const page_id_t &page_id)
	Determines if there are explicit record locks on a page. More...
static void	lock_rec_bitmap_reset (lock_t *lock)
	Resets the record lock bitmap to zero. More...
static lock_t *	lock_rec_copy (const lock_t *lock, mem_heap_t *heap)
	Copies a record lock to heap. More...
static const lock_t *	lock_rec_has_expl (ulint precise_mode, const page_id_t page_id, uint32_t heap_no, const trx_t *trx)
	Checks if a transaction has a GRANTED explicit lock on rec stronger or equal to precise_mode. More...
static const lock_t *	lock_rec_has_expl (ulint precise_mode, const buf_block_t *block, ulint heap_no, const trx_t *trx)
static const lock_t *	lock_rec_other_has_expl_req (lock_mode mode, const buf_block_t *block, bool wait, ulint heap_no, const trx_t *trx)
	Checks if some other transaction has a lock request in the queue. More...
static locksys::Conflicting	lock_rec_other_has_conflicting (ulint mode, const buf_block_t *block, ulint heap_no, const trx_t *trx)
	Checks if some other transaction has a conflicting explicit lock request in the queue, so that we have to wait. More...
static bool	can_older_trx_be_still_active (trx_id_t max_old_active_id)
	Checks if the (-infinity,max_old_active_id] range contains an id of a currently active transaction which has modified a record. More...
static trx_t *	lock_sec_rec_some_has_impl (const rec_t *rec, dict_index_t *index, const ulint *offsets)
	Checks if some transaction has an implicit x-lock on a record in a secondary index. More...
static bool	lock_rec_other_trx_holds_expl (ulint precise_mode, const trx_t *trx, const rec_t *rec, const buf_block_t *block)
	Checks if some transaction, other than given trx_id, has an explicit lock on the given rec, in the given precise_mode. More...
ulint	lock_number_of_rows_locked (const trx_lock_t *trx_lock)
	Return approximate number or record locks (bits set in the bitmap) for this transaction. More...
ulint	lock_number_of_tables_locked (const trx_t *trx)
	Return the number of table locks for a transaction. More...
static void	lock_rec_insert_to_waiting (Locks_hashtable &lock_hash, lock_t *lock, const RecID &rec_id)
	Insert lock record to the tail of the queue where the WAITING locks reside. More...
static void	lock_rec_insert_to_granted (Locks_hashtable &lock_hash, lock_t *lock, const RecID &rec_id)
	Insert lock record to the head of the queue where the GRANTED locks reside. More...
static void	locksys::add_to_trx_locks (lock_t *lock)
	Adds the lock to the list of trx's locks. More...
static void	locksys::remove_from_trx_locks (lock_t *lock)
	Removes the lock from the list of trx's locks. More...
static void	lock_mark_trx_for_rollback (hit_list_t &hit_list, trx_id_t hp_trx_id, trx_t *trx)
	Collect the transactions that will need to be rolled back asynchronously. More...
static bool	lock_edge_may_survive_prepare (const lock_t *waiting_lock, const lock_t *blocking_lock)
	Checks if the waits-for edge between waiting_lock and blocking_lock may survive PREPARE of the blocking_lock->trx. More...
static void	lock_report_wait_for_edge_to_server (const lock_t *waiting_lock, const lock_t *blocking_lock)
static void	lock_create_wait_for_edge (const lock_t *waiting_lock, const lock_t *blocking_lock)
	Creates a new edge in wait-for graph, from waiter to blocker. More...
static void	lock_rec_move_granted_to_front (lock_t *lock, const RecID &rec_id)
	Moves a granted lock to the front of the queue for a given record by removing it adding it to the front. More...
static void	lock_rec_add_to_queue (ulint type_mode, const buf_block_t *block, const ulint heap_no, dict_index_t *index, trx_t *trx, const bool we_own_trx_mutex=false)
	Adds a record lock request in the record queue. More...
static lock_rec_req_status	lock_rec_lock_fast (bool impl, ulint mode, const buf_block_t *block, ulint heap_no, dict_index_t *index, que_thr_t *thr)
	This is a fast routine for locking a record in the most common cases: there are no explicit locks on the page, or there is just one lock, owned by this transaction, and of the right type_mode. More...
static void	lock_reuse_for_next_key_lock (const lock_t *held_lock, ulint mode, const buf_block_t *block, ulint heap_no, dict_index_t *index, trx_t *trx)
	A helper function for lock_rec_lock_slow(), which grants a Next Key Lock (either LOCK_X or LOCK_S as specified by mode) on <block,heap_no> in the index to the trx, assuming that it already has a granted held_lock, which is at least as strong as mode|LOCK_REC_NOT_GAP. More...
static dberr_t	lock_rec_lock_slow (bool impl, select_mode sel_mode, ulint mode, const buf_block_t *block, ulint heap_no, dict_index_t *index, que_thr_t *thr)
	This is the general, and slower, routine for locking a record. More...
static dberr_t	lock_rec_lock (bool impl, select_mode sel_mode, ulint mode, const buf_block_t *block, ulint heap_no, dict_index_t *index, que_thr_t *thr)
	Tries to lock the specified record in the mode requested. More...
static const lock_t *	lock_rec_has_to_wait_in_queue (const lock_t *wait_lock, const trx_t *blocking_trx=nullptr)
	Checks if a waiting record lock request still has to wait in a queue. More...
static void	lock_grant (lock_t *lock)
	Grants a lock to a waiting lock request and releases the waiting transaction. More...
void	lock_make_trx_hit_list (trx_t *hp_trx, hit_list_t &hit_list)
	Iterate over the granted locks which conflict with trx->lock.wait_lock and prepare the hit list for ASYNC Rollback. More...
static void	lock_rec_cancel (lock_t *lock)
	Cancels a waiting record lock request and releases the waiting transaction that requested it. More...
static void	lock_update_wait_for_edge (const lock_t *waiting_lock, const lock_t *blocking_lock)
	Given a waiting_lock, and blocking_lock which is the reason it has to wait, makes sure that the (only) edge in the wait-for graph outgoing from the waiting_lock->trx points to blocking_lock->trx. More...
template<typename Container >
static const lock_t *	lock_rec_has_to_wait_for_granted (const typename Container::value_type &wait_lock, const Container &granted, const size_t new_granted_index)
	Checks if a waiting record lock request still has to wait for granted locks. More...
static void	lock_rec_grant_by_heap_no (lock_t *in_lock, ulint heap_no)
	Grant a lock to waiting transactions. More...
static const lock_t *	lock_has_to_wait_in_queue (const lock_t *wait_lock, const trx_t *blocking_trx)
	Checks if a waiting lock request still has to wait in a queue. More...
static void	lock_grant_or_update_wait_for_edge (lock_t *lock)
	Given a lock, which was found in waiting queue, checks if it still has to wait in queue, and either grants it, or makes sure that the reason it has to wait is reflected in the wait-for graph. More...
static void	lock_grant_or_update_wait_for_edge_if_waiting (lock_t *lock, const trx_t *releasing_trx)
	Given a lock, and a transaction which is releasing another lock from the same queue, makes sure that if the lock was waiting for this transaction, then it will either be granted, or another reason for waiting is reflected in the wait-for graph. More...
static void	lock_rec_grant (lock_t *in_lock)
	Grant lock to waiting requests that no longer conflicts. More...
static void	lock_rec_dequeue_from_page (lock_t *in_lock)
	Removes a record lock request, waiting or granted, from the queue and grants locks to other transactions in the queue if they now are entitled to a lock. More...
void	lock_rec_discard (lock_t *in_lock)
	Removes a record lock request, waiting or granted, from the queue. More...
static const lock_t *	lock_find_record_lock_by_guid (Locks_hashtable &lock_hash, page_id_t page_id, const lock_guid_t &guid)
const lock_t *	lock_find_record_lock_by_guid (page_id_t page_id, const lock_guid_t &guid)
	Inspect the lock queues associated with the given page_id in search for a lock which has guid equal to the given one. More...
static void	lock_rec_free_all_from_discard_page_low (page_id_t page_id, Locks_hashtable &lock_hash)
	Removes record lock objects set on an index page which is discarded. More...
void	lock_rec_free_all_from_discard_page (const buf_block_t *block)
	Removes record lock objects set on an index page which is discarded. More...
static void	lock_rec_reset_and_release_wait_low (Locks_hashtable &hash, const buf_block_t *block, ulint heap_no)
	Resets the lock bits for a single record. More...
static void	lock_rec_reset_and_release_wait (const buf_block_t *block, ulint heap_no)
	Resets the lock bits for a single record. More...
void	lock_on_statement_end (trx_t *trx)
	Called to inform lock-sys that a statement processing for a trx has just finished. More...
static void	lock_protect_locks_till_statement_end (que_thr_t *thr)
static void	lock_rec_inherit_to_gap (const buf_block_t *heir_block, const buf_block_t *block, ulint heir_heap_no, ulint heap_no)
	Makes a record to inherit the locks (except LOCK_INSERT_INTENTION type) of another record as gap type locks, but does not reset the lock bits of the other record. More...
static void	lock_rec_inherit_to_gap_if_gap_lock (const buf_block_t *block, uint16_t heir_heap_no, uint16_t heap_no)
	Makes a record to inherit the gap locks (except LOCK_INSERT_INTENTION type) of another record as gap type locks, but does not reset the lock bits of the other record. More...
static void	lock_rec_move (const buf_block_t *receiver, const buf_block_t *donator, ulint receiver_heap_no, ulint donator_heap_no)
	Moves the locks of a record to another record and resets the lock bits of the donating record. More...
static void	lock_move_granted_locks_to_front (trx_lock_list_t &lock_list)
	Move all the granted locks to the front of the given lock list. More...
void	lock_move_reorganize_page (const buf_block_t *block, const buf_block_t *oblock)
	Updates the lock table when we have reorganized a page. More...
void	lock_move_rec_list_end (const buf_block_t *new_block, const buf_block_t *block, const rec_t *rec)
	Moves the explicit locks on user records to another page if a record list end is moved to another page. More...
void	lock_move_rec_list_start (const buf_block_t *new_block, const buf_block_t *block, const rec_t *rec, const rec_t *old_end)
	Moves the explicit locks on user records to another page if a record list start is moved to another page. More...
void	lock_rtr_move_rec_list (const buf_block_t *new_block, const buf_block_t *block, rtr_rec_move_t *rec_move, ulint num_move)
	Moves the explicit locks on user records to another page if a record list start is moved to another page. More...
void	lock_update_split_right (const buf_block_t *right_block, const buf_block_t *left_block)
	Updates the lock table when a page is split to the right. More...
void	lock_update_merge_right (const buf_block_t *right_block, const rec_t *orig_succ, const buf_block_t *left_block)
	Updates the lock table when a page is merged to the right. More...
void	lock_update_root_raise (const buf_block_t *block, const buf_block_t *root)
	Updates the lock table when the root page is copied to another in btr_root_raise_and_insert. More...
void	lock_update_copy_and_discard (const buf_block_t *new_block, const buf_block_t *block)
	Updates the lock table when a page is copied to another and the original page is removed from the chain of leaf pages, except if page is the root! More...
void	lock_update_split_point (const buf_block_t *right_block, const buf_block_t *left_block)
	Requests the Lock System to update record locks regarding the gap between the last record of the left_page and the first record of the right_page when the caller is about to prepended a new record as the first record on the right page, even though it should "naturally" be inserted as the last record of the left_page according to the information in the higher levels of the index. More...
void	lock_update_split_left (const buf_block_t *right_block, const buf_block_t *left_block)
	Updates the lock table when a page is split to the left. More...
void	lock_update_merge_left (const buf_block_t *left_block, const rec_t *orig_pred, const buf_block_t *right_block)
	Updates the lock table when a page is merged to the left. More...
void	lock_rec_reset_and_inherit_gap_locks (const buf_block_t *heir_block, const buf_block_t *block, ulint heir_heap_no, ulint heap_no)
	Resets the original locks on heir and replaces them with gap type locks inherited from rec. More...
void	lock_update_discard (const buf_block_t *heir_block, ulint heir_heap_no, const buf_block_t *block)
	Updates the lock table when a page is discarded. More...
void	lock_update_insert (const buf_block_t *block, const rec_t *rec)
	Updates the lock table when a new user record is inserted. More...
void	lock_update_delete (const buf_block_t *block, const rec_t *rec)
	Updates the lock table when a record is removed. More...
void	lock_rec_store_on_page_infimum (const buf_block_t *block, const rec_t *rec)
	Stores on the page infimum record the explicit locks of another record. More...
void	lock_rec_restore_from_page_infimum (const buf_block_t *block, const rec_t *rec, const buf_block_t *donator)
	Restores the state of explicit lock requests on a single record, where the state was stored on the infimum of the page. More...
static lock_t *	lock_table_create (dict_table_t *table, ulint type_mode, trx_t *trx)
	Creates a table lock object and adds it as the last in the lock queue of the table. More...
static void	lock_table_pop_autoinc_locks (trx_t *trx)
	Pops autoinc lock requests from the transaction's autoinc_locks. More...
static void	lock_table_remove_autoinc_lock (lock_t *lock, trx_t *trx)
	Removes an autoinc lock request from the transaction's autoinc_locks. More...
const lock_t *	lock_find_table_lock_by_guid (const dict_table_t *table, const lock_guid_t &guid)
	Inspect the lock queue associated with the given table in search for a lock which has guid equal to the given one. More...
static void	lock_table_remove_low (lock_t *lock)
	Removes a table lock request from the queue and the trx list of locks; this is a low-level function which does NOT check if waiting requests can now be granted. More...
static dberr_t	lock_table_enqueue_waiting (ulint mode, dict_table_t *table, que_thr_t *thr, const lock_t *blocking_lock)
	Enqueues a waiting request for a table lock which cannot be granted immediately. More...
static const lock_t *	lock_table_other_has_incompatible (const trx_t *trx, ulint wait, const dict_table_t *table, lock_mode mode)
	Checks if other transactions have an incompatible mode lock request in the lock queue. More...
dberr_t	lock_table (ulint flags, dict_table_t *table, lock_mode mode, que_thr_t *thr)
	Locks the specified database table in the mode given. More...
void	lock_table_ix_resurrect (dict_table_t *table, trx_t *trx)
	Creates a table IX lock object for a resurrected transaction. More...
static const lock_t *	lock_table_has_to_wait_in_queue (const lock_t *wait_lock, const trx_t *blocking_trx=nullptr)
	Checks if a waiting table lock request still has to wait in a queue. More...
static void	lock_table_dequeue (lock_t *in_lock)
	Removes a table lock request, waiting or granted, from the queue and grants locks to other transactions in the queue, if they now are entitled to a lock. More...
dberr_t	lock_table_for_trx (dict_table_t *table, trx_t *trx, enum lock_mode mode)
	Sets a lock on a table based on the given mode. More...
static void	lock_rec_release (lock_t *lock, ulint heap_no)
	Grant a lock to waiting transactions. More...
void	lock_rec_unlock (trx_t *trx, const buf_block_t *block, const rec_t *rec, lock_mode lock_mode)
	Removes a granted record lock of a transaction from the queue and grants locks to other transactions waiting in the queue if they now are entitled to a lock. More...
static void	lock_release_gap_lock (lock_t *lock)
	Unlock the GAP Lock part of a Next Key Lock and grant it to waiters (if any) More...
static bool	lock_release_read_lock (lock_t *lock, bool only_gap)
	Used to release a lock during PREPARE. More...
template<typename F >
static bool	locksys::try_relatch_trx_and_shard_and_do (const lock_t *lock, F &&f)
	A helper function which solves a chicken-and-egg problem occurring when one needs to iterate over trx's locks and perform some actions on them. More...
static bool	locksys::try_release_read_locks_in_s_mode (trx_t *trx, bool only_gap)
	Tries to release read locks of a transaction without latching the whole lock sys. More...
static bool	locksys::try_release_read_locks_in_x_mode (trx_t *trx, bool only_gap)
	Release read locks of a transaction latching the whole lock-sys in exclusive mode, which is a bit too expensive to do by default. More...
void	lock_trx_release_read_locks (trx_t *trx, bool only_gap)
	Release read locks of a transaction. More...
static bool	locksys::try_release_all_locks (trx_t *trx)
	Releases transaction locks, and releases possible other transactions waiting because of these locks. More...
static bool	IS_LOCK_S_OR_X (lock_t *lock)
static void	lock_remove_all_on_table_for_trx (dict_table_t *table, trx_t *trx, bool remove_also_table_sx_locks)
	Removes locks of a transaction on a table to be dropped. More...
static ulint	lock_remove_recovered_trx_record_locks (dict_table_t *table)
	Remove any explicit record locks held by recovering transactions on the table. More...
void	lock_remove_all_on_table (dict_table_t *table, bool remove_also_table_sx_locks)
	Removes locks on a table to be dropped. More...
static void	lock_table_print (FILE *file, const lock_t *lock)
	Prints info of a table lock. More...
static void	lock_rec_print (FILE *file, const lock_t *lock)
	Prints info of a record lock. More...
static size_t	lock_get_n_rec_locks (void)
	Calculates the number of record lock structs in the record lock hash table. More...
void	lock_print_info_summary (FILE *file)
	Prints info of locks for all transactions. More...
void	lock_trx_print_wait_and_mvcc_state (FILE *file, const trx_t *trx)
	Prints transaction lock wait and MVCC state. More...
static bool	lock_rec_fetch_page (const lock_t *lock)
	Reads the page containing the record protected by the given lock. More...
static bool	lock_trx_print_locks (FILE *file, const trx_t *trx, TrxLockIterator &iter, bool load_block)
	Prints info of locks for a transaction. More...
void	lock_print_info_all_transactions (FILE *file)
	Prints info of locks for each transaction. More...
static bool	lock_table_queue_validate (const dict_table_t *table)
	Validates the lock queue on a table. More...
static void	locksys::rec_queue_validate_latched (const buf_block_t *block, const rec_t *rec, const dict_index_t *index, const ulint *offsets)
	Validates the lock queue on a single record. More...
static void	locksys::rec_queue_latch_and_validate (const buf_block_t *block, const rec_t *rec, const dict_index_t *index, const ulint *offsets)
	Validates the lock queue on a single record. More...
static void	locksys::rec_queue_latch_and_validate (const buf_block_t *block, const rec_t *rec, const dict_index_t *index)
	Validates the lock queue on a single record. More...
static void	lock_validate_table_locks ()
	Validates the table locks. More...
static void	lock_rec_block_validate (const page_id_t &page_id)
	Validate a record lock's block. More...
bool	lock_validate ()
	Validates the lock system. More...
dberr_t	lock_rec_insert_check_and_lock (ulint flags, const rec_t *rec, buf_block_t *block, dict_index_t *index, que_thr_t *thr, mtr_t *mtr, bool *inherit)
	Checks if locks of other transactions prevent an immediate insert of a record. More...
static void	lock_rec_convert_impl_to_expl_for_trx (const buf_block_t *block, const rec_t *rec, dict_index_t *index, const ulint *offsets, trx_t *trx, ulint heap_no)
	Creates an explicit record lock for a running transaction that currently only has an implicit lock on the record. More...
void	lock_rec_convert_impl_to_expl (const buf_block_t *block, const rec_t *rec, dict_index_t *index, const ulint *offsets)
	If a transaction has an implicit x-lock on a record, but no explicit x-lock set on the record, sets one for it. More...
dberr_t	lock_clust_rec_modify_check_and_lock (ulint flags, const buf_block_t *block, const rec_t *rec, dict_index_t *index, const ulint *offsets, que_thr_t *thr)
	Checks if locks of other transactions prevent an immediate modify (update, delete mark, or delete unmark) of a clustered index record. More...
dberr_t	lock_sec_rec_modify_check_and_lock (ulint flags, buf_block_t *block, const rec_t *rec, dict_index_t *index, que_thr_t *thr, mtr_t *mtr)
	Checks if locks of other transactions prevent an immediate modify (delete mark or delete unmark) of a secondary index record. More...
dberr_t	lock_sec_rec_read_check_and_lock (const lock_duration_t duration, const buf_block_t *block, const rec_t *rec, dict_index_t *index, const ulint *offsets, const select_mode sel_mode, const lock_mode mode, const ulint gap_mode, que_thr_t *thr)
	Like lock_clust_rec_read_check_and_lock(), but reads a secondary index record. More...
dberr_t	lock_clust_rec_read_check_and_lock (const lock_duration_t duration, const buf_block_t *block, const rec_t *rec, dict_index_t *index, const ulint *offsets, const select_mode sel_mode, const lock_mode mode, const ulint gap_mode, que_thr_t *thr)
	Checks if locks of other transactions prevent an immediate read, or passing over by a read cursor, of a clustered index record. More...
dberr_t	lock_clust_rec_read_check_and_lock_alt (const buf_block_t *block, const rec_t *rec, dict_index_t *index, lock_mode mode, ulint gap_mode, que_thr_t *thr)
	Checks if locks of other transactions prevent an immediate read, or passing over by a read cursor, of a clustered index record. More...
static void	lock_release_autoinc_last_lock (trx_t *trx)
	Release the last lock from the transaction's autoinc locks. More...
static bool	lock_trx_holds_autoinc_locks (const trx_t *trx)
	Check if a transaction holds any autoinc locks. More...
static void	lock_release_autoinc_locks (trx_t *trx)
	Release all the transaction's autoinc locks. More...
uint32_t	lock_get_type (const lock_t *lock)
	Gets the type of a lock. More...
trx_id_t	lock_get_trx_id (const lock_t *lock)
	Gets the id of the transaction owning a lock. More...
void	lock_get_psi_event (const lock_t *lock, ulonglong *thread_id, ulonglong *event_id)
	Get the performance schema event (thread_id, event_id) that created the lock. More...
const char *	lock_get_mode_str (const lock_t *lock)
	Gets the mode of a lock in a human readable string. More...
const char *	lock_get_type_str (const lock_t *lock)
	Gets the type of a lock in a human readable string. More...
static dict_table_t *	lock_get_table (const lock_t *lock)
	Gets the table on which the lock is. More...
table_id_t	lock_get_table_id (const lock_t *lock)
	Gets the id of the table on which the lock is. More...
const table_name_t &	lock_get_table_name (const lock_t *lock)
	Determine which table a lock is associated with. More...
const dict_index_t *	lock_rec_get_index (const lock_t *lock)
	For a record lock, gets the index on which the lock is. More...
const char *	lock_rec_get_index_name (const lock_t *lock)
	For a record lock, gets the name of the index on which the lock is. More...
page_id_t	lock_rec_get_page_id (const lock_t *lock)
	For a record lock, gets the tablespace number and page number on which the lock is. More...
void	lock_cancel_waiting_and_release (trx_t *trx)
	Cancels a waiting lock request and releases possible other transactions waiting behind it. More...
void	lock_unlock_table_autoinc (trx_t *trx)
	Unlocks AUTO_INC type locks that were possibly reserved by a trx. More...
void	lock_trx_release_locks (trx_t *trx)
	Releases a transaction's locks, and releases possible other transactions waiting because of these locks. More...
bool	lock_cancel_if_waiting_and_release (const TrxVersion trx_version)
	Cancels the waiting lock request of the trx, if any. More...
static const lock_t *	lock_table_locks_lookup (const dict_table_t *table)
	Scans all locks of all transactions in the rw_trx_list searching for any lock (table or rec) against the table. More...
bool	lock_table_has_locks (const dict_table_t *table)
	Check if there are any locks (table or rec) against table. More...
void	lock_set_timeout_event ()
	Set the lock system timeout event. More...
bool	lock_trx_has_rec_x_lock (que_thr_t *thr, const dict_table_t *table, const buf_block_t *block, ulint heap_no)
	Check if the transaction holds an exclusive lock on a record. More...
void	lock_trx_alloc_locks (trx_t *trx)
	Allocate cached locks for the transaction. More...
void	lock_notify_about_deadlock (const ut::vector< const trx_t * > &trxs_on_cycle, const trx_t *victim_trx)
	Handles writing the information about found deadlock to the log files and caches it for future lock_latest_err_file() calls (for example used by SHOW ENGINE INNODB STATUS) More...

Variables
bool	innobase_deadlock_detect = true
static const ulint	REC_LOCK_CACHE = 8
	Total number of cached record locks. More...
static const ulint	REC_LOCK_SIZE = sizeof(ib_lock_t) + 256
	Maximum record lock size in bytes. More...
static const ulint	TABLE_LOCK_CACHE = 8
	Total number of cached table locks. More...
static const ulint	TABLE_LOCK_SIZE = sizeof(ib_lock_t)
	Size in bytes, of the table lock instance. More...
static const std::map< uint, const char * >	lock_constant_names
	Used by lock_get_mode_str to build a lock mode description. More...
static std::unordered_map< uint, const char * >	lock_cached_lock_mode_names
	Used by lock_get_mode_str to cache results. More...
static std::mutex	lock_cached_lock_mode_names_mutex
	Mutex protecting access to lock_cached_lock_mode_names. More...
lock_sys_t *	lock_sys = nullptr
	The lock system. More...
static bool	lock_deadlock_found = false
	We store info on the latest deadlock error to this buffer. More...
static FILE *	lock_latest_err_file
	Only created if !srv_read_only_mode. More...
constexpr auto	locksys::MAX_CS_DURATION = std::chrono::seconds{1}
	We don't want to hold the Global latch for too long, even in S mode, not to starve threads waiting for X-latch on it such as lock_wait_timeout_thread(). More...

Detailed Description

The transaction lock system.

Created 5/7/1996 Heikki Tuuri

Macro Definition Documentation

LOCK_MODULE_IMPLEMENTATION

#define LOCK_MODULE_IMPLEMENTATION

PRINT_NUM_OF_LOCK_STRUCTS

#define PRINT_NUM_OF_LOCK_STRUCTS

Typedef Documentation

Locks

template<typename T >

using Locks = std::vector<T, mem_heap_allocator<T> >

Function Documentation

can_older_trx_be_still_active()

static bool can_older_trx_be_still_active ( trx_id_t  max_old_active_id )

static

Checks if the (-infinity,max_old_active_id] range contains an id of a currently active transaction which has modified a record.

The premise is that the caller has seen a record modified by a trx with trx->id <= max_old_active_id, and wants to know if it might be still active. It may err on the safe side.

Remarks

The difficulties to keep in mind here:

• the caller doesn't hold trx_sys mutex, nor can prevent any transaction from committing or starting before the start and after the end of execution of this function. Thus the result of this function has to be interpreted as if it could have a "one sided error", even if the return value is exact during the execution
• the transactions are assigned ids from increasing sequence, but they are added to various structures like lists and shards out of order. This means that the answer this function gives only makes sense in the context that the caller already saw an effect of the trx modifying some row, which means it had to be already added to these structures. In other words, calling this function twice for the same number can give false then true. Still the false from the first call is "correct" for the purpose of the caller (as it must mean that the trx which modified the record had to be removed from the structures already, hence is not active anymore). Also the true from the second call is "correct" in that indeed some smaller transaction id had to be added to the structures meanwhile, even if it's not the one which modified the record in question - error on the safe side.

Parameters

[in]

max_old_active_id

The end of the range inclusive. For example found in the PAGE_MAX_TRX_ID field of a header of a secondary index page.

Return values

false	the caller may assume that if before the call it saw a record modified by trx_id, and trx_id < max_old_active_id, then it is no longer active
true	the caller should double check in a synchronized way if the seen trx_id is still active or not

IS_LOCK_S_OR_X()

static bool IS_LOCK_S_OR_X ( lock_t *  lock )

inlinestatic

lock_cancel_if_waiting_and_release()

bool lock_cancel_if_waiting_and_release

(

TrxVersion

trx_version

)

Cancels the waiting lock request of the trx, if any.

If the transaction has already committed (trx->version has changed) or is no longer waiting for a lock (trx->lock.blocking_trx is nullptr) this function will not cancel the waiting lock.

Note

There is a possibility of ABA in which a waiting lock request was already granted or canceled and then the trx requested another lock and started waiting for it - in such case this function might either cancel or not the second request depending on timing. Currently all usages of this function ensure that this is impossible:

• innodb_kill_connection ensures trx_is_interrupted(trx), thus upon first wake up it will realize it has to report an error and rollback
• HP transaction marks the trx->in_innodb & TRX_FORCE_ROLLBACK flag which is checked when the trx attempts RecLock::add_to_waitq and reports DB_DEADLOCK

Parameters

[in]

trx_version

The trx we want to wake up and its expected version

Returns

true iff the function did release a waiting lock

lock_cancel_waiting_and_release()

void lock_cancel_waiting_and_release

(

trx_t *

trx

)

Cancels a waiting lock request and releases possible other transactions waiting behind it.

Parameters

[in,out]

trx

The transaction waiting for a lock

lock_check_trx_id_sanity()

bool lock_check_trx_id_sanity	(	trx_id_t	trx_id,
		const rec_t *	rec,
		const dict_index_t *	index,
		const ulint *	offsets
	)

Checks that a transaction id is sensible, i.e., not in the future.

Emits an error otherwise.

Parameters

[in]	trx_id	The trx id to check, found in user record or secondary index page header
[in]	rec	The user record which contained the trx_id in its header or in header of its page
[in]	index	The index which contained the rec
[in]	offsets	The result of rec_get_offsets(rec, index)

Returns

true iff ok

lock_clust_rec_cons_read_sees()

bool lock_clust_rec_cons_read_sees	(	const rec_t *	rec,
		dict_index_t *	index,
		const ulint *	offsets,
		ReadView *	view
	)

Checks that a record is seen in a consistent read.

Returns

true if sees, or false if an earlier version of the record should be retrieved

Parameters

rec	in: user record which should be read or passed over by a read cursor
index	in: clustered index
offsets	in: rec_get_offsets(rec, index)
view	in: consistent read view

lock_clust_rec_modify_check_and_lock()

dberr_t lock_clust_rec_modify_check_and_lock	(	ulint	flags,
		const buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		const ulint *	offsets,
		que_thr_t *	thr
	)

Checks if locks of other transactions prevent an immediate modify (update, delete mark, or delete unmark) of a clustered index record.

If they do, first tests if the query thread should anyway be suspended for some reason; if not, then puts the transaction and the query thread to the lock wait state and inserts a waiting request for a record x-lock to the lock queue.

Returns

DB_SUCCESS, DB_LOCK_WAIT, or DB_DEADLOCK

Parameters

flags	in: if BTR_NO_LOCKING_FLAG bit is set, does nothing
block	in: buffer block of rec
rec	in: record which should be modified
index	in: clustered index
offsets	in: rec_get_offsets(rec, index)
thr	in: query thread

lock_clust_rec_read_check_and_lock()

dberr_t lock_clust_rec_read_check_and_lock	(	lock_duration_t	duration,
		const buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		const ulint *	offsets,
		select_mode	sel_mode,
		lock_mode	mode,
		ulint	gap_mode,
		que_thr_t *	thr
	)

Checks if locks of other transactions prevent an immediate read, or passing over by a read cursor, of a clustered index record.

If they do, first tests if the query thread should anyway be suspended for some reason; if not, then puts the transaction and the query thread to the lock wait state and inserts a waiting request for a record lock to the lock queue. Sets the requested mode lock on the record.

Parameters

[in]	duration	If equal to AT_LEAST_STATEMENT, then makes sure that the lock will be kept around and inherited for at least the duration of current statement. If equal to REGULAR the life-cycle of the lock will depend on isolation level rules.
[in]	block	buffer block of rec
[in]	rec	user record or page supremum record which should be read or passed over by a read cursor
[in]	index	secondary index
[in]	offsets	rec_get_offsets(rec, index)
[in]	sel_mode	select mode: SELECT_ORDINARY, SELECT_SKIP_LOKCED, or SELECT_NO_WAIT
[in]	mode	mode of the lock which the read cursor should set on records: LOCK_S or LOCK_X; the latter is possible in SELECT FOR UPDATE
[in]	gap_mode	LOCK_ORDINARY, LOCK_GAP, or LOCK_REC_NOT_GAP
[in,out]	thr	query thread

Returns

DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK, DB_SKIP_LOCKED, or DB_LOCK_NOWAIT

lock_clust_rec_read_check_and_lock_alt()

dberr_t lock_clust_rec_read_check_and_lock_alt	(	const buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		lock_mode	mode,
		ulint	gap_mode,
		que_thr_t *	thr
	)

Checks if locks of other transactions prevent an immediate read, or passing over by a read cursor, of a clustered index record.

If they do, first tests if the query thread should anyway be suspended for some reason; if not, then puts the transaction and the query thread to the lock wait state and inserts a waiting request for a record lock to the lock queue. Sets the requested mode lock on the record. This is an alternative version of lock_clust_rec_read_check_and_lock() that does not require the parameter "offsets".

Returns

DB_SUCCESS, DB_LOCK_WAIT, or DB_DEADLOCK

Parameters

block	in: buffer block of rec
rec	in: user record or page supremum record which should be read or passed over by a read cursor
index	in: clustered index
mode	in: mode of the lock which the read cursor should set on records: LOCK_S or LOCK_X; the latter is possible in SELECT FOR UPDATE
gap_mode	in: LOCK_ORDINARY, LOCK_GAP, or LOCK_REC_NOT_GAP
thr	in: query thread

lock_create_wait_for_edge()

static void lock_create_wait_for_edge ( const lock_t *  waiting_lock, const lock_t *  blocking_lock  )

static

Creates a new edge in wait-for graph, from waiter to blocker.

Parameters

[in]	waiting_lock	A lock waiting in queue, blocked by blocking_lock
[in]	blocking_lock	A lock which is a reason the waiting_lock has to wait

lock_edge_may_survive_prepare()

static bool lock_edge_may_survive_prepare ( const lock_t *  waiting_lock, const lock_t *  blocking_lock  )

static

Checks if the waits-for edge between waiting_lock and blocking_lock may survive PREPARE of the blocking_lock->trx.

For transactions in low isolation levels we release some of the locks during PREPARE.

Parameters

[in]	waiting_lock	A lock waiting in queue, blocked by blocking_lock
[in]	blocking_lock	A lock which is a reason the waiting_lock has to wait

Returns

if the waiting_lock->trx MAY have to wait for blocking_lock->trx even if blocking_lock->trx PREPAREs. The nondeterminism comes from situations like when X lock conflicts with S lock on a delete-marked record - purgining it might convert both to non-conflicitng gap locks

Return values

true	the waiting_lock->trx MAY have to wait for blocking_lock->trx even if blocking_lock->trx PREPAREs.
false	the waiting_lock->trx CERTAINLY will not have to wait for blocking_lock->trx for this particular reason.

lock_find_record_lock_by_guid() [1/2]

static const lock_t * lock_find_record_lock_by_guid ( Locks_hashtable &  lock_hash, page_id_t  page_id, const lock_guid_t &  guid  )

static

lock_find_record_lock_by_guid() [2/2]

const lock_t * lock_find_record_lock_by_guid	(	page_id_t	page_id,
		const lock_guid_t &	guid
	)

Inspect the lock queues associated with the given page_id in search for a lock which has guid equal to the given one.

Caller should hold a latch on shard containing locks for this page.

Parameters

[in]	page_id	the id of the page, for which we expect the lock
[in]	guid	the guid of the lock we seek for

Returns

the lock with a given guid or nullptr if no such lock

lock_find_table_lock_by_guid()

const lock_t * lock_find_table_lock_by_guid	(	const dict_table_t *	table,
		const lock_guid_t &	guid
	)

Inspect the lock queue associated with the given table in search for a lock which has guid equal to the given one.

Caller should hold a latch on the shard containing this table's locks.

Parameters

[in]	table	the table, for which we expect the lock
[in]	guid	the guid of the lock we seek for

Returns

the lock with a given guid or nullptr if no such lock

lock_get_mode_str()

const char * lock_get_mode_str

(

const lock_t *

lock

)

Gets the mode of a lock in a human readable string.

The string should not be free()'d or modified. This functions is a bit complex for following reasons:

• the way it is used in performance schema requires that the memory pointed by the return value is accessible for a long time
• the caller never frees the memory
• so, we need to maintain a pool of these strings or use string literals
• there are many possible combinations of flags and thus it is impractical to maintain the list of all possible literals and if/else logic
• moreover, sometimes performance_schema.data_locks is used precisely to investigate some unexpected situation, thus limiting output of this function only to expected combinations of flags might be misleading

  Returns

  lock mode

Parameters

lock

in: lock

lock_get_n_rec_locks()

static size_t lock_get_n_rec_locks ( void  )

static

Calculates the number of record lock structs in the record lock hash table.

Returns

number of record locks

lock_get_psi_event()

void lock_get_psi_event	(	const lock_t *	lock,
		ulonglong *	thread_id,
		ulonglong *	event_id
	)

Get the performance schema event (thread_id, event_id) that created the lock.

Parameters

[in]	lock	Lock
[out]	thread_id	Thread ID that created the lock
[out]	event_id	Event ID that created the lock

lock_get_size()

ulint lock_get_size

(

void

)

Gets the size of a lock struct.

Returns

size in bytes

lock_get_table()

static dict_table_t * lock_get_table ( const lock_t *  lock )

inlinestatic

Gets the table on which the lock is.

Returns

table

Parameters

lock

in: lock

lock_get_table_id()

table_id_t lock_get_table_id

(

const lock_t *

lock

)

Gets the id of the table on which the lock is.

Returns

id of the table

Parameters

lock

in: lock

lock_get_table_name()

const table_name_t & lock_get_table_name

(

const lock_t *

lock

)

Determine which table a lock is associated with.

Parameters

[in]

lock

the lock

Returns

name of the table

lock_get_trx_id()

trx_id_t lock_get_trx_id

(

const lock_t *

lock

)

Gets the id of the transaction owning a lock.

Parameters

[in]

lock

A lock of the transaction we are interested in

Returns

the transaction's id

lock_get_type()

uint32_t lock_get_type

(

const lock_t *

lock

)

Gets the type of a lock.

Non-inline version for using outside of the lock module.

Returns

LOCK_TABLE or LOCK_REC

Parameters

lock

in: lock

lock_get_type_str()

const char * lock_get_type_str

(

const lock_t *

lock

)

Gets the type of a lock in a human readable string.

The string should not be free()'d or modified.

Returns

lock type

Parameters

lock

in: lock

lock_grant()

static void lock_grant ( lock_t *  lock )

static

Grants a lock to a waiting lock request and releases the waiting transaction.

The caller must hold lock_sys latch for the shard containing the lock, but not the lock->trx->mutex.

Parameters

[in,out]

lock

waiting lock request

lock_grant_or_update_wait_for_edge()

static void lock_grant_or_update_wait_for_edge ( lock_t *  lock )

static

Given a lock, which was found in waiting queue, checks if it still has to wait in queue, and either grants it, or makes sure that the reason it has to wait is reflected in the wait-for graph.

Parameters

[in]

lock

A lock in WAITING state, which perhaps can be granted now

lock_grant_or_update_wait_for_edge_if_waiting()

static void lock_grant_or_update_wait_for_edge_if_waiting ( lock_t *  lock, const trx_t *  releasing_trx  )

static

Given a lock, and a transaction which is releasing another lock from the same queue, makes sure that if the lock was waiting for this transaction, then it will either be granted, or another reason for waiting is reflected in the wait-for graph.

lock_has_to_wait()

bool lock_has_to_wait	(	const lock_t *	lock1,
		const lock_t *	lock2
	)

Checks if a lock request lock1 has to wait for request lock2.

Parameters

[in]	lock1	A waiting lock
[in]	lock2	Another lock; NOTE that it is assumed that this has a lock bit set on the same record as in lock1 if the locks are record lock

Returns

true if lock1 has to wait for lock2 to be removed

lock_has_to_wait_in_queue()

static const lock_t * lock_has_to_wait_in_queue ( const lock_t *  wait_lock, const trx_t *  blocking_trx  )

static

Checks if a waiting lock request still has to wait in a queue.

Parameters

[in]	wait_lock	Waiting lock
[in]	blocking_trx	If not nullptr, it restricts the search to only the locks held by the blocking_trx, which is useful in case when there might be multiple reasons for waiting in queue, but we need to report the specific one. Useful when reporting a deadlock cycle.

Returns

The conflicting lock which is the reason wait_lock has to wait or nullptr if it can be granted now

lock_is_waiting()

bool lock_is_waiting

(

const lock_t &

lock

)

Checks if the lock is waiting (as opposed to granted).

Caller should hold a latch on shard containging the lock in order for this check to be meaningful.

Parameters

[in]

lock

the lock to inspect

Returns

true iff the lock is waiting

lock_make_trx_hit_list()

void lock_make_trx_hit_list	(	trx_t *	trx,
		hit_list_t &	hit_list
	)

Iterate over the granted locks which conflict with trx->lock.wait_lock and prepare the hit list for ASYNC Rollback.

If the transaction is waiting for some other lock then wake up with deadlock error. Currently we don't mark following transactions for ASYNC Rollback.

1. Read only transactions
2. Background transactions
3. Other High priority transactions

   Parameters

   [in]	trx	High Priority transaction
   [in,out]	hit_list	List of transactions which need to be rolled back

lock_mark_trx_for_rollback()

static void lock_mark_trx_for_rollback ( hit_list_t &  hit_list, trx_id_t  hp_trx_id, trx_t *  trx  )

static

Collect the transactions that will need to be rolled back asynchronously.

Parameters

[in,out]	hit_list	The list of transactions to be rolled back, to which the trx should be appended.
[in]	hp_trx_id	The id of the blocked High Priority Transaction
[in,out]	trx	The blocking transaction to be rolled back

lock_move_granted_locks_to_front()

static void lock_move_granted_locks_to_front ( trx_lock_list_t &  lock_list )

static

Move all the granted locks to the front of the given lock list.

All the waiting locks will be at the end of the list.

Parameters

[in,out]

lock_list

the given lock list.

lock_move_rec_list_end()

void lock_move_rec_list_end	(	const buf_block_t *	new_block,
		const buf_block_t *	block,
		const rec_t *	rec
	)

Moves the explicit locks on user records to another page if a record list end is moved to another page.

Parameters

[in]	new_block	Index page to move to
[in]	block	Index page
[in,out]	rec	Record on page: this is the first record moved

lock_move_rec_list_start()

void lock_move_rec_list_start	(	const buf_block_t *	new_block,
		const buf_block_t *	block,
		const rec_t *	rec,
		const rec_t *	old_end
	)

Moves the explicit locks on user records to another page if a record list start is moved to another page.

Parameters

[in]	new_block	Index page to move to
[in]	block	Index page
[in,out]	rec	Record on page: this is the first record not copied
[in]	old_end	Old previous-to-last record on new_page before the records were copied

lock_move_reorganize_page()

void lock_move_reorganize_page	(	const buf_block_t *	block,
		const buf_block_t *	oblock
	)

Updates the lock table when we have reorganized a page.

NOTE: we copy also the locks set on the infimum of the page; the infimum may carry locks if an update of a record is occurring on the page, and its locks were temporarily stored on the infimum.

Parameters

block	in: old index page, now reorganized
oblock	in: copy of the old, not reorganized page

lock_notify_about_deadlock()

void lock_notify_about_deadlock	(	const ut::vector< const trx_t * > &	trxs_on_cycle,
		const trx_t *	victim_trx
	)

Handles writing the information about found deadlock to the log files and caches it for future lock_latest_err_file() calls (for example used by SHOW ENGINE INNODB STATUS)

Parameters

[in]	trxs_on_cycle	trxs causing deadlock, i-th waits for i+1-th
[in]	victim_trx	the trx from trx_on_cycle which will be rolled back

lock_number_of_rows_locked()

ulint lock_number_of_rows_locked

(

const trx_lock_t *

trx_lock

)

Return approximate number or record locks (bits set in the bitmap) for this transaction.

Since delete-marked records may be removed, the record count will not be precise. The caller must be holding exclusive global lock_sys latch.

Parameters

[in]

trx_lock

transaction locks

lock_number_of_tables_locked()

ulint lock_number_of_tables_locked

(

const trx_t *

trx

)

Return the number of table locks for a transaction.

The caller must be holding trx->mutex.

Parameters

[in]

trx

the transaction for which we want the number of table locks

lock_on_statement_end()

void lock_on_statement_end

(

trx_t *

trx

)

Called to inform lock-sys that a statement processing for a trx has just finished.

Parameters

[in]

trx

transaction which has finished processing a statement

lock_print_info_all_transactions()

void lock_print_info_all_transactions

(

FILE *

file

)

Prints info of locks for each transaction.

This function assumes that the caller holds the exclusive global latch and more importantly it may release and reacquire it on behalf of the caller. (This should be fixed in the future).

Parameters

[in,out]

file

the file where to print

lock_print_info_summary()

void lock_print_info_summary

(

FILE *

file

)

Prints info of locks for all transactions.

Parameters

[in]

file

file where to print

lock_protect_locks_till_statement_end()

static void lock_protect_locks_till_statement_end ( que_thr_t *  thr )

inlinestatic

lock_rec_add_to_queue()

static void lock_rec_add_to_queue ( ulint  type_mode, const buf_block_t *  block, const ulint  heap_no, dict_index_t *  index, trx_t *  trx, const bool  we_own_trx_mutex = false  )

static

Adds a record lock request in the record queue.

The request is normally added as the last in the queue, but if the request to be added is not a waiting request, we can reuse a suitable record lock object already existing on the same page, just setting the appropriate bit in its bitmap. This is a low-level function which does NOT check for deadlocks or lock compatibility!

Parameters

[in]	type_mode	lock mode, wait, gap etc. flags; type is ignored and replaced by LOCK_REC
[in]	block	buffer block containing the record
[in]	heap_no	heap number of the record
[in]	index	index of record
[in,out]	trx	transaction
[in]	we_own_trx_mutex	true iff the caller own trx->mutex (optional). Defaults to false.

lock_rec_bitmap_reset()

static void lock_rec_bitmap_reset ( lock_t *  lock )

static

Resets the record lock bitmap to zero.

NOTE: does not touch the wait_lock pointer in the transaction! This function is used in lock object creation and resetting.

Parameters

lock	in: record lock

lock_rec_block_validate()

static void lock_rec_block_validate ( const page_id_t &  page_id )

static

Validate a record lock's block.

lock_rec_cancel()

static void lock_rec_cancel ( lock_t *  lock )

static

Cancels a waiting record lock request and releases the waiting transaction that requested it.

NOTE: does NOT check if waiting lock requests behind this one can now be granted!

Parameters

lock	in: waiting record lock request

lock_rec_clear_request_no_wakeup()

bool lock_rec_clear_request_no_wakeup	(	lock_t *	lock,
		uint16_t	heap_no
	)

Reset the nth bit of a record lock.

If this was a wait lock clears the wait flag on it, and marks that the trx no longer waits on it, but doesn't wake up the transaction. This function is meant to be used when lock requests are moved from one place to another, and thus a new (equivalent) lock request will be soon created for the transaction, so there's no point in waking it up.

Parameters

[in,out]	lock	record lock
[in]	heap_no	index of the bit that will be reset

Returns

false iff the bit was already cleared before the call

lock_rec_convert_impl_to_expl()

void lock_rec_convert_impl_to_expl	(	const buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		const ulint *	offsets
	)

If a transaction has an implicit x-lock on a record, but no explicit x-lock set on the record, sets one for it.

Parameters

[in]	block	buffer block of rec
[in]	rec	user record on page
[in]	index	index of record
[in]	offsets	rec_get_offsets(rec, index)

lock_rec_convert_impl_to_expl_for_trx()

static void lock_rec_convert_impl_to_expl_for_trx ( const buf_block_t *  block, const rec_t *  rec, dict_index_t *  index, const ulint *  offsets, trx_t *  trx, ulint  heap_no  )

static

Creates an explicit record lock for a running transaction that currently only has an implicit lock on the record.

The transaction instance must have a reference count > 0 so that it can't be committed and freed before this function has completed.

Parameters

block	in: buffer block of rec
rec	in: user record on page
index	in: index of record
offsets	in: rec_get_offsets(rec, index)
trx	in/out: active transaction
heap_no	in: rec heap number to lock

lock_rec_copy()

static lock_t * lock_rec_copy ( const lock_t *  lock, mem_heap_t *  heap  )

static

Copies a record lock to heap.

Returns

copy of lock

Parameters

lock	in: record lock
heap	in: memory heap

lock_rec_dequeue_from_page()

static void lock_rec_dequeue_from_page ( lock_t *  in_lock )

static

Removes a record lock request, waiting or granted, from the queue and grants locks to other transactions in the queue if they now are entitled to a lock.

NOTE: all record locks contained in in_lock are removed.

Parameters

[in,out]

in_lock

record lock object: all record locks which are contained in this lock object are removed; transactions waiting behind will get their lock requests granted, if they are now qualified to it

lock_rec_discard()

void lock_rec_discard

(

lock_t *

in_lock

)

Removes a record lock request, waiting or granted, from the queue.

Parameters

[in]

in_lock

record lock object: all record locks which are contained in this lock object are removed

lock_rec_expl_exist_on_page()

bool lock_rec_expl_exist_on_page

(

const page_id_t &

page_id

)

Determines if there are explicit record locks on a page.

Parameters

[in]

page_id

space id and page number

Returns

true iff an explicit record lock on the page exists

lock_rec_fetch_page()

static bool lock_rec_fetch_page ( const lock_t *  lock )

static

Reads the page containing the record protected by the given lock.

This function will temporarily release the exclusive global latch and the trx_sys_t::mutex if the page was read from disk.

Parameters

[in]

lock

the record lock

Returns

true if a page was successfully read from the tablespace

lock_rec_find_next_set_bit()

ulint lock_rec_find_next_set_bit	(	const lock_t *	lock,
		ulint	heap_no
	)

Looks for the next set bit in the record lock bitmap.

Parameters

[in]	lock	record lock with at least one bit set
[in]	heap_no	current set bit

Returns

The next bit index == heap number following heap_no, or ULINT_UNDEFINED if none found

lock_rec_find_set_bit()

ulint lock_rec_find_set_bit

(

const lock_t *

lock

)

Looks for a set bit in a record lock bitmap.

Returns ULINT_UNDEFINED, if none found.

Parameters

[in]

lock

A record lock

Returns

bit index == heap number of the record, or ULINT_UNDEFINED if none found

lock_rec_free_all_from_discard_page()

void lock_rec_free_all_from_discard_page

(

const buf_block_t *

block

)

Removes record lock objects set on an index page which is discarded.

This function does not move locks, or check for waiting locks, therefore the lock bitmaps must already be reset when this function is called.

Parameters

block

in: page to be discarded

lock_rec_free_all_from_discard_page_low()

static void lock_rec_free_all_from_discard_page_low ( page_id_t  page_id, Locks_hashtable &  lock_hash  )

static

Removes record lock objects set on an index page which is discarded.

This function does not move locks, or check for waiting locks, therefore the lock bitmaps must already be reset when this function is called.

lock_rec_get_gap()

static ulint lock_rec_get_gap ( const lock_t *  lock )

inlinestatic

Gets the gap flag of a record lock.

Returns

LOCK_GAP or 0

Parameters

lock	in: record lock

lock_rec_get_index()

const dict_index_t * lock_rec_get_index

(

const lock_t *

lock

)

For a record lock, gets the index on which the lock is.

Returns

index

Parameters

lock

in: lock

lock_rec_get_index_name()

const char * lock_rec_get_index_name

(

const lock_t *

lock

)

For a record lock, gets the name of the index on which the lock is.

The string should not be free()'d or modified.

Returns

name of the index

Parameters

lock

in: lock

lock_rec_get_insert_intention()

static ulint lock_rec_get_insert_intention ( const lock_t *  lock )

inlinestatic

Gets the waiting insert flag of a record lock.

Returns

LOCK_INSERT_INTENTION or 0

Parameters

lock	in: record lock

lock_rec_get_page_id()

page_id_t lock_rec_get_page_id

(

const lock_t *

lock

)

For a record lock, gets the tablespace number and page number on which the lock is.

Returns

tablespace number in: lock

lock_rec_get_rec_not_gap()

static ulint lock_rec_get_rec_not_gap ( const lock_t *  lock )

inlinestatic

Gets the LOCK_REC_NOT_GAP flag of a record lock.

Returns

LOCK_REC_NOT_GAP or 0

Parameters

lock	in: record lock

lock_rec_grant()

static void lock_rec_grant ( lock_t *  in_lock )

static

Grant lock to waiting requests that no longer conflicts.

The in_lock might be modified before call to this function by clearing some flag (see for example lock_trx_release_read_locks). It also might already be removed from the hash cell (a.k.a. waiting queue) or still reside in it. However the content of bitmap should not be changed prior to calling this function, as the bitmap will be inspected to see which heap_no at all were blocked by this in_lock, and only locks waiting for those heap_no's will be checked.

Parameters

[in,out]

in_lock

record lock object: grant all non-conflicting locks waiting behind this lock object

lock_rec_grant_by_heap_no()

static void lock_rec_grant_by_heap_no ( lock_t *  in_lock, ulint  heap_no  )

static

Grant a lock to waiting transactions.

This function scans the queue of locks in which in_lock resides (or resided) paying attention only to locks on heap_no-th bit. For each waiting lock which was blocked by in_lock->trx it checks if it can be granted now. It iterates on waiting locks in order favoring high-priority transactions and then transactions of high trx->lock.schedule_weight.

Parameters

[in]	in_lock	Lock which was released, or partially released by modifying its type/mode (see lock_trx_release_read_locks) or resetting heap_no-th bit in the bitmap (see lock_rec_release)
[in]	heap_no	Heap number within the page on which the lock was (or still is) held

lock_rec_has_any() [1/2]

static bool lock_rec_has_any ( Locks_hashtable &  hash, page_id_t  page_id  )

static

lock_rec_has_any() [2/2]

static bool lock_rec_has_any ( Locks_hashtable &  hash, page_id_t  page_id, uint16_t  heap_no  )

static

lock_rec_has_expl() [1/2]

static const lock_t * lock_rec_has_expl ( ulint  precise_mode, const buf_block_t *  block, ulint  heap_no, const trx_t *  trx  )

inlinestatic

lock_rec_has_expl() [2/2]

static const lock_t * lock_rec_has_expl ( ulint  precise_mode, const page_id_t  page_id, uint32_t  heap_no, const trx_t *  trx  )

inlinestatic

Checks if a transaction has a GRANTED explicit lock on rec stronger or equal to precise_mode.

Parameters

[in]	precise_mode	LOCK_S or LOCK_X possibly ORed to LOCK_GAP or LOCK_REC_NOT_GAP, for a supremum record we regard this always a gap type request
[in]	page_id	id of the page containing the record
[in]	heap_no	heap number of the record
[in]	trx	transaction

Returns

lock or NULL

lock_rec_has_to_wait_for_granted()

template<typename Container >

static const lock_t * lock_rec_has_to_wait_for_granted ( const typename Container::value_type &  wait_lock, const Container &  granted, const size_t  new_granted_index  )

static

Checks if a waiting record lock request still has to wait for granted locks.

Parameters

[in]	wait_lock	Waiting record lock
[in]	granted	Granted record locks
[in]	new_granted_index	Start of new granted locks

Returns

The conflicting lock which is the reason wait_lock has to wait or nullptr if it can be granted now

lock_rec_has_to_wait_in_queue()

static const lock_t * lock_rec_has_to_wait_in_queue ( const lock_t *  wait_lock, const trx_t *  blocking_trx = nullptr  )

static

Checks if a waiting record lock request still has to wait in a queue.

Parameters

[in]	wait_lock	Waiting record lock
[in]	blocking_trx	If not nullptr, it restricts the search to only the locks held by the blocking_trx, which is useful in case when there might be multiple reasons for waiting in queue, but we need to report the specific one. Useful when reporting a deadlock cycle. (optional)

Returns

The conflicting lock which is the reason wait_lock has to wait or nullptr if it can be granted now

lock_rec_inherit_to_gap()

static void lock_rec_inherit_to_gap ( const buf_block_t *  heir_block, const buf_block_t *  block, ulint  heir_heap_no, ulint  heap_no  )

static

Makes a record to inherit the locks (except LOCK_INSERT_INTENTION type) of another record as gap type locks, but does not reset the lock bits of the other record.

Also waiting lock requests on rec are inherited as GRANTED gap locks.

Parameters

heir_block	in: block containing the record which inherits
block	in: block containing the record from which inherited; does NOT reset the locks on this record
heir_heap_no	in: heap_no of the inheriting record
heap_no	in: heap_no of the donating record

lock_rec_inherit_to_gap_if_gap_lock()

static void lock_rec_inherit_to_gap_if_gap_lock ( const buf_block_t *  block, uint16_t  heir_heap_no, uint16_t  heap_no  )

static

Makes a record to inherit the gap locks (except LOCK_INSERT_INTENTION type) of another record as gap type locks, but does not reset the lock bits of the other record.

Also waiting lock requests are inherited as GRANTED gap locks.

Parameters

block	in: buffer block
heir_heap_no	in: heap_no of record which inherits
heap_no	in: heap_no of record from which inherited; does NOT reset the locks on this record

lock_rec_insert_check_and_lock()

dberr_t lock_rec_insert_check_and_lock	(	ulint	flags,
		const rec_t *	rec,
		buf_block_t *	block,
		dict_index_t *	index,
		que_thr_t *	thr,
		mtr_t *	mtr,
		bool *	inherit
	)

Checks if locks of other transactions prevent an immediate insert of a record.

If they do, first tests if the query thread should anyway be suspended for some reason; if not, then puts the transaction and the query thread to the lock wait state and inserts a waiting request for a gap x-lock to the lock queue.

Returns

DB_SUCCESS, DB_LOCK_WAIT, or DB_DEADLOCK

Parameters

flags	in: if BTR_NO_LOCKING_FLAG bit is set, does nothing
rec	in: record after which to insert
block	in/out: buffer block of rec
index	in: index
thr	in: query thread
mtr	in/out: mini-transaction
inherit	out: set to true if the new inserted record maybe should inherit LOCK_GAP type locks from the successor record

lock_rec_insert_to_granted()

static void lock_rec_insert_to_granted ( Locks_hashtable &  lock_hash, lock_t *  lock, const RecID &  rec_id  )

static

Insert lock record to the head of the queue where the GRANTED locks reside.

Parameters

[in,out]	lock_hash	Hash table containing the locks
[in,out]	lock	Record lock instance to insert
[in]	rec_id	Record being locked

lock_rec_insert_to_waiting()

static void lock_rec_insert_to_waiting ( Locks_hashtable &  lock_hash, lock_t *  lock, const RecID &  rec_id  )

static

Insert lock record to the tail of the queue where the WAITING locks reside.

Parameters

[in,out]	lock_hash	Hash table containing the locks
[in,out]	lock	Record lock instance to insert
[in]	rec_id	Record being locked

lock_rec_lock()

static dberr_t lock_rec_lock ( bool  impl, select_mode  sel_mode, ulint  mode, const buf_block_t *  block, ulint  heap_no, dict_index_t *  index, que_thr_t *  thr  )

static

Tries to lock the specified record in the mode requested.

If not immediately possible, enqueues a waiting lock request. This is a low-level function which does NOT look at implicit locks! Checks lock compatibility within explicit locks. This function sets a normal next-key lock, or in the case of a page supremum record, a gap type lock.

Parameters

[in]	impl	if true, no lock is set if no wait is necessary: we assume that the caller will set an implicit lock
[in]	sel_mode	select mode: SELECT_ORDINARY, SELECT_SKIP_LOCKED, or SELECT_NO_WAIT
[in]	mode	lock mode: LOCK_X or LOCK_S possibly ORed to either LOCK_GAP or LOCK_REC_NOT_GAP
[in]	block	buffer block containing the record
[in]	heap_no	heap number of record
[in]	index	index of record
[in,out]	thr	query thread

Returns

DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK, DB_SKIP_LOCKED, or DB_LOCK_NOWAIT

lock_rec_lock_fast()

static lock_rec_req_status lock_rec_lock_fast ( bool  impl, ulint  mode, const buf_block_t *  block, ulint  heap_no, dict_index_t *  index, que_thr_t *  thr  )

inlinestatic

This is a fast routine for locking a record in the most common cases: there are no explicit locks on the page, or there is just one lock, owned by this transaction, and of the right type_mode.

This is a low-level function which does NOT look at implicit locks! Checks lock compatibility within explicit locks. This function sets a normal next-key lock, or in the case of a page supremum record, a gap type lock.

Returns

whether the locking succeeded LOCK_REC_SUCCESS, LOCK_REC_SUCCESS_CREATED, LOCK_REC_FAIL

Parameters

impl	in: if true, no lock is set if no wait is necessary: we assume that the caller will set an implicit lock
mode	in: lock mode: LOCK_X or LOCK_S possibly ORed to either LOCK_GAP or LOCK_REC_NOT_GAP
block	in: buffer block containing the record
heap_no	in: heap number of record
index	in: index of record
thr	in: query thread

lock_rec_lock_hash_value()

static uint64_t lock_rec_lock_hash_value ( const lock_t *  lock )

static

Calculates the hash value of a lock: used in migrating the hash table.

Parameters

[in]

lock

record lock object

Returns

hashed value

lock_rec_lock_slow()

static dberr_t lock_rec_lock_slow ( bool  impl, select_mode  sel_mode, ulint  mode, const buf_block_t *  block, ulint  heap_no, dict_index_t *  index, que_thr_t *  thr  )

static

This is the general, and slower, routine for locking a record.

This is a low-level function which does NOT look at implicit locks! Checks lock compatibility within explicit locks. This function sets a normal next-key lock, or in the case of a page supremum record, a gap type lock.

Parameters

[in]	impl	if true, no lock might be set if no wait is necessary: we assume that the caller will set an implicit lock
[in]	sel_mode	select mode: SELECT_ORDINARY, SELECT_SKIP_LOCKED, or SELECT_NO_WAIT
[in]	mode	lock mode: LOCK_X or LOCK_S possibly ORed to either LOCK_GAP or LOCK_REC_NOT_GAP
[in]	block	buffer block containing the record
[in]	heap_no	heap number of record
[in]	index	index of record
[in,out]	thr	query thread

Returns

DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK, DB_SKIP_LOCKED, or DB_LOCK_NOWAIT

lock_rec_move()

static void lock_rec_move ( const buf_block_t *  receiver, const buf_block_t *  donator, ulint  receiver_heap_no, ulint  donator_heap_no  )

static

Moves the locks of a record to another record and resets the lock bits of the donating record.

Parameters

receiver	in: buffer block containing the receiving record
donator	in: buffer block containing the donating record
receiver_heap_no	in: heap_no of the record which gets the locks; there must be no lock requests on it!
donator_heap_no	in: heap_no of the record which gives the locks

lock_rec_move_granted_to_front()

static void lock_rec_move_granted_to_front ( lock_t *  lock, const RecID &  rec_id  )

static

Moves a granted lock to the front of the queue for a given record by removing it adding it to the front.

As a single lock can correspond to multiple rows (and thus: queues) this function moves it to the front of whole hash cell.

Parameters

[in]	lock	a granted lock to be moved
[in]	rec_id	record id which specifies particular queue and hash cell

lock_rec_other_has_conflicting()

static locksys::Conflicting lock_rec_other_has_conflicting ( ulint  mode, const buf_block_t *  block, ulint  heap_no, const trx_t *  trx  )

static

Checks if some other transaction has a conflicting explicit lock request in the queue, so that we have to wait.

Parameters

[in]	mode	LOCK_S or LOCK_X, possibly ORed to LOCK_GAP or LOC_REC_NOT_GAP, LOCK_INSERT_INTENTION
[in]	block	buffer block containing the record
[in]	heap_no	heap number of the record
[in]	trx	our transaction

Returns

a pair, where: the first element is a conflicting lock or null if no conflicting lock found, the second element indicates if the trx has bypassed one of waiting locks.

lock_rec_other_has_expl_req()

static const lock_t * lock_rec_other_has_expl_req ( lock_mode  mode, const buf_block_t *  block, bool  wait, ulint  heap_no, const trx_t *  trx  )

static

Checks if some other transaction has a lock request in the queue.

Returns

lock or NULL

Parameters

mode	in: LOCK_S or LOCK_X
block	in: buffer block containing the record
wait	in: whether also waiting locks are taken into account
heap_no	in: heap number of the record
trx	in: transaction, or NULL if requests by all transactions are taken into account

lock_rec_other_trx_holds_expl()

static bool lock_rec_other_trx_holds_expl ( ulint  precise_mode, const trx_t *  trx, const rec_t *  rec, const buf_block_t *  block  )

static

Checks if some transaction, other than given trx_id, has an explicit lock on the given rec, in the given precise_mode.

Parameters

[in]	precise_mode	LOCK_S or LOCK_X possibly ORed to LOCK_GAP or LOCK_REC_NOT_GAP.
[in]	trx	the trx holding implicit lock on rec
[in]	rec	user record
[in]	block	buffer block containing the record

Returns

true iff there's a transaction, whose id is not equal to trx_id, that has an explicit lock on the given rec, in the given precise_mode.

lock_rec_print()

static void lock_rec_print ( FILE *  file, const lock_t *  lock  )

static

Prints info of a record lock.

Parameters

file	in: file where to print
lock	in: record type lock

lock_rec_release()

static void lock_rec_release ( lock_t *  lock, ulint  heap_no  )

static

Grant a lock to waiting transactions.

Parameters

[in]	lock	Lock that was unlocked
[in]	heap_no	Heap no within the page for the lock.

lock_rec_reset_and_inherit_gap_locks()

void lock_rec_reset_and_inherit_gap_locks	(	const buf_block_t *	heir_block,
		const buf_block_t *	block,
		ulint	heir_heap_no,
		ulint	heap_no
	)

Resets the original locks on heir and replaces them with gap type locks inherited from rec.

Parameters

[in]	heir_block	Block containing the record which inherits
[in]	block	Block containing the record from which inherited; does not reset the locks on this record
[in]	heir_heap_no	Heap_no of the inheriting record
[in]	heap_no	Heap_no of the donating record

lock_rec_reset_and_release_wait()

static void lock_rec_reset_and_release_wait ( const buf_block_t *  block, ulint  heap_no  )

static

Resets the lock bits for a single record.

Releases transactions waiting for lock requests here.

Parameters

block	in: buffer block containing the record
heap_no	in: heap number of record

lock_rec_reset_and_release_wait_low()

static void lock_rec_reset_and_release_wait_low ( Locks_hashtable &  hash, const buf_block_t *  block, ulint  heap_no  )

static

Resets the lock bits for a single record.

Releases transactions waiting for lock requests here.

Parameters

hash	in: hash table
block	in: buffer block containing the record
heap_no	in: heap number of record

lock_rec_reset_nth_bit()

static byte lock_rec_reset_nth_bit ( lock_t *  lock, ulint  i  )

inlinestatic

Reset the nth bit of a record lock.

Parameters

[in,out]	lock	record lock
[in]	i	index of the bit that will be reset

Returns

previous value of the bit

lock_rec_restore_from_page_infimum()

void lock_rec_restore_from_page_infimum	(	const buf_block_t *	block,
		const rec_t *	rec,
		const buf_block_t *	donator
	)

Restores the state of explicit lock requests on a single record, where the state was stored on the infimum of the page.

Parameters

[in]	block	Buffer block containing rec
[in]	rec	Record whose lock state is restored
[in]	donator	Page (rec is not necessarily on this page) whose infimum stored the lock state; lock bits are reset on the infimum

lock_rec_store_on_page_infimum()

void lock_rec_store_on_page_infimum	(	const buf_block_t *	block,
		const rec_t *	rec
	)

Stores on the page infimum record the explicit locks of another record.

This function is used to store the lock state of a record when it is updated and the size of the record changes in the update. The record is moved in such an update, perhaps to another page. The infimum record acts as a dummy carrier record, taking care of lock releases while the actual record is being moved.

Parameters

block	in: buffer block containing rec
rec	in: record whose lock state is stored on the infimum record of the same page; lock bits are reset on the record

lock_rec_unlock()

void lock_rec_unlock	(	trx_t *	trx,
		const buf_block_t *	block,
		const rec_t *	rec,
		lock_mode	lock_mode
	)

Removes a granted record lock of a transaction from the queue and grants locks to other transactions waiting in the queue if they now are entitled to a lock.

This function is meant to be used only by row_try_unlock, and it assumes that the lock we are looking for has LOCK_REC_NOT_GAP flag.

Parameters

trx	in/out: transaction that has set a record lock
block	in: buffer block containing rec
rec	in: record
lock_mode	in: LOCK_S or LOCK_X

lock_rec_validate_page()

static void lock_rec_validate_page ( const buf_block_t *  block )

static

Validates the record lock queues on a page.

Parameters

[in]

block

A (possibly freed) block for which we want to validate all lock queues. If any of the queues is non-empty we additionally assert that the block was not freed.

Parameters

block

in: buffer block

lock_release_autoinc_last_lock()

static void lock_release_autoinc_last_lock ( trx_t *  trx )

inlinestatic

Release the last lock from the transaction's autoinc locks.

Parameters

[in]

trx

trx which vector of AUTOINC locks to modify

lock_release_autoinc_locks()

static void lock_release_autoinc_locks ( trx_t *  trx )

static

Release all the transaction's autoinc locks.

Parameters

trx	in/out: transaction

lock_release_gap_lock()

static void lock_release_gap_lock ( lock_t *  lock )

static

Unlock the GAP Lock part of a Next Key Lock and grant it to waiters (if any)

Parameters

[in,out]

lock

lock object

lock_release_read_lock()

static bool lock_release_read_lock ( lock_t *  lock, bool  only_gap  )

static

Used to release a lock during PREPARE.

The lock is only released if rules permit it.

Parameters

[in]	lock	the lock that we consider releasing
[in]	only_gap	true if we don't want to release records, just the gaps between them

Returns

true iff the function did release (maybe a part of) a lock

lock_remove_all_on_table()

void lock_remove_all_on_table	(	dict_table_t *	table,
		bool	remove_also_table_sx_locks
	)

Removes locks on a table to be dropped.

If remove_also_table_sx_locks is true then table-level S and X locks are also removed in addition to other table-level and record-level locks. No lock, that is going to be removed, is allowed to be a wait lock.

Parameters

table	in: table to be dropped or discarded
remove_also_table_sx_locks	in: also removes table S and X locks

lock_remove_all_on_table_for_trx()

static void lock_remove_all_on_table_for_trx ( dict_table_t *  table, trx_t *  trx, bool  remove_also_table_sx_locks  )

static

Removes locks of a transaction on a table to be dropped.

If remove_also_table_sx_locks is true then table-level S and X locks are also removed in addition to other table-level and record-level locks. No lock that is going to be removed is allowed to be a wait lock.

Parameters

table	in: table to be dropped
trx	in: a transaction
remove_also_table_sx_locks	in: also removes table S and X locks

lock_remove_recovered_trx_record_locks()

static ulint lock_remove_recovered_trx_record_locks ( dict_table_t *  table )

static

Remove any explicit record locks held by recovering transactions on the table.

Returns

number of recovered transactions examined

Parameters

table

in: check if there are any locks held on records in this table or on the table itself

lock_report_trx_id_insanity()

void lock_report_trx_id_insanity	(	trx_id_t	trx_id,
		const rec_t *	rec,
		const dict_index_t *	index,
		const ulint *	offsets,
		trx_id_t	next_trx_id
	)

Reports that a transaction id is insensible, i.e., in the future.

Parameters

[in]	trx_id	Trx id
[in]	rec	User record
[in]	index	Index
[in]	offsets	Rec_get_offsets(rec, index)
[in]	next_trx_id	value received from trx_sys_get_next_trx_id_or_no()

lock_report_wait_for_edge_to_server()

static void lock_report_wait_for_edge_to_server ( const lock_t *  waiting_lock, const lock_t *  blocking_lock  )

static

lock_reuse_for_next_key_lock()

static void lock_reuse_for_next_key_lock ( const lock_t *  held_lock, ulint  mode, const buf_block_t *  block, ulint  heap_no, dict_index_t *  index, trx_t *  trx  )

static

A helper function for lock_rec_lock_slow(), which grants a Next Key Lock (either LOCK_X or LOCK_S as specified by mode) on <block,heap_no> in the index to the trx, assuming that it already has a granted held_lock, which is at least as strong as mode|LOCK_REC_NOT_GAP.

It does so by either reusing the lock if it already covers the gap, or by ensuring a separate GAP Lock, which in combination with Record Lock satisfies the request.

Parameters

[in]	held_lock	a lock granted to trx which is at least as strong as mode|LOCK_REC_NOT_GAP
[in]	mode	requested lock mode: LOCK_X or LOCK_S
[in]	block	buffer block containing the record to be locked
[in]	heap_no	heap number of the record to be locked
[in]	index	index of record to be locked
[in]	trx	the transaction requesting the Next Key Lock

lock_rtr_move_rec_list()

void lock_rtr_move_rec_list	(	const buf_block_t *	new_block,
		const buf_block_t *	block,
		rtr_rec_move_t *	rec_move,
		ulint	num_move
	)

Moves the explicit locks on user records to another page if a record list start is moved to another page.

Parameters

[in]	new_block	Index page to move to
[in]	block	Index page
[in]	rec_move	Recording records moved
[in]	num_move	Num of rec to move

lock_sec_rec_cons_read_sees()

bool lock_sec_rec_cons_read_sees	(	const rec_t *	rec,
		const dict_index_t *	index,
		const ReadView *	view
	)

Checks that a non-clustered index record is seen in a consistent read.

NOTE that a non-clustered index page contains so little information on its modifications that also in the case false, the present version of rec may be the right, but we must check this from the clustered index record.

Returns

true if certainly sees, or false if an earlier version of the clustered index record might be needed

Parameters

rec	in: user record which should be read or passed over by a read cursor
index	in: index
view	in: consistent read view

lock_sec_rec_modify_check_and_lock()

dberr_t lock_sec_rec_modify_check_and_lock	(	ulint	flags,
		buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		que_thr_t *	thr,
		mtr_t *	mtr
	)

Checks if locks of other transactions prevent an immediate modify (delete mark or delete unmark) of a secondary index record.

Returns

DB_SUCCESS, DB_LOCK_WAIT, or DB_DEADLOCK

Parameters

flags	in: if BTR_NO_LOCKING_FLAG bit is set, does nothing
block	in/out: buffer block of rec
rec	in: record which should be modified; NOTE: as this is a secondary index, we always have to modify the clustered index record first: see the comment below
index	in: secondary index
thr	in: query thread (can be NULL if BTR_NO_LOCKING_FLAG)
mtr	in/out: mini-transaction

lock_sec_rec_read_check_and_lock()

dberr_t lock_sec_rec_read_check_and_lock	(	lock_duration_t	duration,
		const buf_block_t *	block,
		const rec_t *	rec,
		dict_index_t *	index,
		const ulint *	offsets,
		select_mode	sel_mode,
		lock_mode	mode,
		ulint	gap_mode,
		que_thr_t *	thr
	)

Like lock_clust_rec_read_check_and_lock(), but reads a secondary index record.

Parameters

[in]	duration	If equal to AT_LEAST_STATEMENT, then makes sure that the lock will be kept around and inherited for at least the duration of current statement. If equal to REGULAR the life-cycle of the lock will depend on isolation level rules.
[in]	block	buffer block of rec
[in]	rec	user record or page supremum record which should be read or passed over by a read cursor
[in]	index	secondary index
[in]	offsets	rec_get_offsets(rec, index)
[in]	sel_mode	select mode: SELECT_ORDINARY, SELECT_SKIP_LOKCED, or SELECT_NO_WAIT
[in]	mode	mode of the lock which the read cursor should set on records: LOCK_S or LOCK_X; the latter is possible in SELECT FOR UPDATE
[in]	gap_mode	LOCK_ORDINARY, LOCK_GAP, or LOCK_REC_NOT_GAP
[in,out]	thr	query thread

Returns

DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, DB_DEADLOCK, DB_SKIP_LOCKED, or DB_LOCK_NOWAIT

lock_sec_rec_some_has_impl()

static trx_t * lock_sec_rec_some_has_impl ( const rec_t *  rec, dict_index_t *  index, const ulint *  offsets  )

static

Checks if some transaction has an implicit x-lock on a record in a secondary index.

Parameters

[in]	rec	user record
[in]	index	secondary index
[in]	offsets	rec_get_offsets(rec, index)

Returns

transaction id of the transaction which has the x-lock, or 0; NOTE that this function can return false positives but never false negatives. The caller must confirm all positive results by checking if the trx is still active.

lock_set_lock_and_trx_wait()

static void lock_set_lock_and_trx_wait ( lock_t *  lock )

inlinestatic

Sets the wait flag of a lock and the back pointer in trx to lock.

Parameters

[in]

lock

The lock on which a transaction is waiting

lock_set_timeout_event()

void lock_set_timeout_event

(

)

Set the lock system timeout event.

lock_sys_close()

void lock_sys_close

(

void

)

Closes the lock system at database shutdown.

lock_sys_create()

void lock_sys_create

(

ulint

n_cells

)

Creates the lock system at database start.

in: number of slots in lock hash table

Parameters

n_cells

in: number of slots in lock hash table

lock_sys_resize()

void lock_sys_resize

(

ulint

n_cells

)

Resize the lock hash tables.

Parameters

[in]

n_cells

number of slots in lock hash table

lock_table()

dberr_t lock_table	(	ulint	flags,
		dict_table_t *	table,
		lock_mode	mode,
		que_thr_t *	thr
	)

Locks the specified database table in the mode given.

If the lock cannot be granted immediately, the query thread is put to wait.

Returns

DB_SUCCESS, DB_LOCK_WAIT, or DB_DEADLOCK

Parameters

flags	in: if BTR_NO_LOCKING_FLAG bit is set, does nothing
table	in/out: database table in dictionary cache
mode	in: lock mode
thr	in: query thread

lock_table_create()

static lock_t * lock_table_create ( dict_table_t *  table, ulint  type_mode, trx_t *  trx  )

inlinestatic

Creates a table lock object and adds it as the last in the lock queue of the table.

Does NOT check for deadlocks or lock compatibility.

Returns

own: new lock object

Parameters

table	in/out: database table in dictionary cache
type_mode	in: lock mode possibly ORed with LOCK_WAIT
trx	in: trx

lock_table_dequeue()

static void lock_table_dequeue ( lock_t *  in_lock )

static

Removes a table lock request, waiting or granted, from the queue and grants locks to other transactions in the queue, if they now are entitled to a lock.

Parameters

in_lock

in/out: table lock object; transactions waiting behind will get their lock requests granted, if they are now qualified to it

lock_table_enqueue_waiting()

static dberr_t lock_table_enqueue_waiting ( ulint  mode, dict_table_t *  table, que_thr_t *  thr, const lock_t *  blocking_lock  )

static

Enqueues a waiting request for a table lock which cannot be granted immediately.

Checks for deadlocks.

Parameters

[in]	mode	lock mode this transaction is requesting
[in]	table	the table to be locked
[in]	thr	the query thread requesting the lock
[in]	blocking_lock	the lock which is the reason this request has to wait

Returns

DB_LOCK_WAIT or DB_DEADLOCK

lock_table_for_trx()

dberr_t lock_table_for_trx	(	dict_table_t *	table,
		trx_t *	trx,
		enum lock_mode	mode
	)

Sets a lock on a table based on the given mode.

Parameters

[in]	table	table to lock
[in,out]	trx	transaction
[in]	mode	LOCK_X or LOCK_S

Returns

error code or DB_SUCCESS.

lock_table_has_locks()

bool lock_table_has_locks

(

const dict_table_t *

table

)

Check if there are any locks (table or rec) against table.

Returned value might be obsolete.

Parameters

[in]

table

the table

Returns

true if there were any locks held on records in this table or on the table itself at some point in time during the call

The n_rec_locks field might be modified by operation on any page shard. This function is called in contexts where we believe that the number of locks should either be zero or decreasing. For such scenario of usage, we can read the n_rec_locks without any latch and restrict latch just to the table's shard and release it before return, which means true could be a false-positive, but false is certain.

lock_table_has_to_wait_in_queue()

static const lock_t * lock_table_has_to_wait_in_queue ( const lock_t *  wait_lock, const trx_t *  blocking_trx = nullptr  )

static

Checks if a waiting table lock request still has to wait in a queue.

Parameters

[in]	wait_lock	Waiting table lock
[in]	blocking_trx	If not nullptr, it restricts the search to only the locks held by the blocking_trx, which is useful in case when there might be multiple reasons for waiting in queue, but we need to report the specific one. Useful when reporting a deadlock cycle. (optional)

Returns

The conflicting lock which is the reason wait_lock has to wait or nullptr if it can be granted now

lock_table_ix_resurrect()

void lock_table_ix_resurrect	(	dict_table_t *	table,
		trx_t *	trx
	)

Creates a table IX lock object for a resurrected transaction.

Parameters

[in,out]	table	Table
[in,out]	trx	Transaction

lock_table_locks_lookup()

static const lock_t * lock_table_locks_lookup ( const dict_table_t *  table )

static

Scans all locks of all transactions in the rw_trx_list searching for any lock (table or rec) against the table.

Parameters

[in]

table

the table for which we perform the search

Returns

lock if found

lock_table_other_has_incompatible()

static const lock_t * lock_table_other_has_incompatible ( const trx_t *  trx, ulint  wait, const dict_table_t *  table, lock_mode  mode  )

inlinestatic

Checks if other transactions have an incompatible mode lock request in the lock queue.

Returns

lock or NULL

Parameters

trx	in: transaction, or NULL if all transactions should be included
wait	in: LOCK_WAIT if also waiting locks are taken into account, or 0 if not
table	in: table
mode	in: lock mode

lock_table_pop_autoinc_locks()

static void lock_table_pop_autoinc_locks ( trx_t *  trx )

inlinestatic

Pops autoinc lock requests from the transaction's autoinc_locks.

We handle the case where there are gaps in the array and they need to be popped off the stack.

Parameters

trx	in/out: transaction that owns the AUTOINC locks

lock_table_print()

static void lock_table_print ( FILE *  file, const lock_t *  lock  )

static

Prints info of a table lock.

Parameters

file	in: file where to print
lock	in: table type lock

lock_table_queue_validate()

static bool lock_table_queue_validate ( const dict_table_t *  table )

static

Validates the lock queue on a table.

Returns

true if ok

Parameters

table

in: table

lock_table_remove_autoinc_lock()

static void lock_table_remove_autoinc_lock ( lock_t *  lock, trx_t *  trx  )

inlinestatic

Removes an autoinc lock request from the transaction's autoinc_locks.

Parameters

lock	in: table lock
trx	in/out: transaction that owns the lock

lock_table_remove_low()

static void lock_table_remove_low ( lock_t *  lock )

inlinestatic

Removes a table lock request from the queue and the trx list of locks; this is a low-level function which does NOT check if waiting requests can now be granted.

Parameters

lock	in/out: table lock

lock_trx_alloc_locks()

void lock_trx_alloc_locks

(

trx_t *

trx

)

Allocate cached locks for the transaction.

Parameters

trx	allocate cached record locks for this transaction

lock_trx_has_rec_x_lock()

bool lock_trx_has_rec_x_lock	(	que_thr_t *	thr,
		const dict_table_t *	table,
		const buf_block_t *	block,
		ulint	heap_no
	)

Check if the transaction holds an exclusive lock on a record.

Parameters

[in]	thr	query thread of the transaction
[in]	table	table to check
[in]	block	buffer block of the record
[in]	heap_no	record heap number

Returns

whether the locks are held

lock_trx_holds_autoinc_locks()

static bool lock_trx_holds_autoinc_locks ( const trx_t *  trx )

static

Check if a transaction holds any autoinc locks.

Returns

true if the transaction holds any AUTOINC locks.

Parameters

trx	in: transaction

lock_trx_print_locks()

static bool lock_trx_print_locks ( FILE *  file, const trx_t *  trx, TrxLockIterator &  iter, bool  load_block  )

static

Prints info of locks for a transaction.

Returns

true if all printed, false if latches were released.

Parameters

file	in/out: File to write
trx	in: current transaction
iter	in: transaction lock iterator
load_block	in: if true then read block from disk

lock_trx_print_wait_and_mvcc_state()

void lock_trx_print_wait_and_mvcc_state	(	FILE *	file,
		const trx_t *	trx
	)

Prints transaction lock wait and MVCC state.

Parameters

[in,out]	file	file where to print
[in]	trx	transaction

lock_trx_release_locks()

void lock_trx_release_locks

(

trx_t *

trx

)

Releases a transaction's locks, and releases possible other transactions waiting because of these locks.

Change the state of the transaction to TRX_STATE_COMMITTED_IN_MEMORY.

Doing an implicit to explicit conversion should not be expensive.

Parameters

trx	in/out: transaction

lock_trx_release_read_locks()

void lock_trx_release_read_locks	(	trx_t *	trx,
		bool	only_gap
	)

Release read locks of a transaction.

It is called during XA prepare to release locks early.

Parameters

[in,out]	trx	transaction
[in]	only_gap	release only GAP locks

lock_unlock_table_autoinc()

void lock_unlock_table_autoinc

(

trx_t *

trx

)

Unlocks AUTO_INC type locks that were possibly reserved by a trx.

This function should be called at the the end of an SQL statement, by the connection thread that owns the transaction (trx->mysql_thd).

Parameters

trx	in/out: transaction

lock_update_copy_and_discard()

void lock_update_copy_and_discard	(	const buf_block_t *	new_block,
		const buf_block_t *	block
	)

Updates the lock table when a page is copied to another and the original page is removed from the chain of leaf pages, except if page is the root!

Parameters

[in]	new_block	Index page to which copied
[in]	block	Index page; not the root!

lock_update_delete()

void lock_update_delete	(	const buf_block_t *	block,
		const rec_t *	rec
	)

Updates the lock table when a record is removed.

Parameters

[in]	block	Buffer block containing rec
[in]	rec	The record to be removed

lock_update_discard()

void lock_update_discard	(	const buf_block_t *	heir_block,
		ulint	heir_heap_no,
		const buf_block_t *	block
	)

Updates the lock table when a page is discarded.

Parameters

[in]	heir_block	Index page which will inherit the locks
[in]	heir_heap_no	Heap_no of the record which will inherit the locks
[in]	block	Index page which will be discarded

lock_update_insert()

void lock_update_insert	(	const buf_block_t *	block,
		const rec_t *	rec
	)

Updates the lock table when a new user record is inserted.

Parameters

[in]	block	Buffer block containing rec
[in]	rec	The inserted record

Parameters

block	in: buffer block containing rec
rec	in: the inserted record

lock_update_merge_left()

void lock_update_merge_left	(	const buf_block_t *	left_block,
		const rec_t *	orig_pred,
		const buf_block_t *	right_block
	)

Updates the lock table when a page is merged to the left.

Parameters

[in]	left_block	Left page to which merged
[in]	orig_pred	Original predecessor of supremum on the left page before merge
[in]	right_block	Merged index page which will be discarded

lock_update_merge_right()

void lock_update_merge_right	(	const buf_block_t *	right_block,
		const rec_t *	orig_succ,
		const buf_block_t *	left_block
	)

Updates the lock table when a page is merged to the right.

Parameters

[in]	right_block	Right page to which merged
[in]	orig_succ	Original successor of infimum on the right page before merge
[in]	left_block	Merged index page which will be discarded

lock_update_root_raise()

void lock_update_root_raise	(	const buf_block_t *	block,
		const buf_block_t *	root
	)

Updates the lock table when the root page is copied to another in btr_root_raise_and_insert.

Note that we leave lock structs on the root page, even though they do not make sense on other than leaf pages: the reason is that in a pessimistic update the infimum record of the root page will act as a dummy carrier of the locks of the record to be updated.

Parameters

block	in: index page to which copied
root	in: root page

lock_update_split_left()

void lock_update_split_left	(	const buf_block_t *	right_block,
		const buf_block_t *	left_block
	)

Updates the lock table when a page is split to the left.

Parameters

[in]	right_block	Right page
[in]	left_block	Left page

lock_update_split_point()

void lock_update_split_point	(	const buf_block_t *	right_block,
		const buf_block_t *	left_block
	)

Requests the Lock System to update record locks regarding the gap between the last record of the left_page and the first record of the right_page when the caller is about to prepended a new record as the first record on the right page, even though it should "naturally" be inserted as the last record of the left_page according to the information in the higher levels of the index.

That is, we assume that the lowest common ancestor of the left_page and the right_page routes the key of the new record to the left_page, but a heuristic which tries to avoid overflowing the left_page has chosen to prepend the new record to the right_page instead. Said ancestor performs this routing by comparing the key of the record to a "split point" - the key associated with the right_page's subtree, such that all records larger than that split point are to be found in the right_page (or some even further page). Ideally this should be the minimum key in this whole subtree, however due to the way we optimize the DELETE and INSERT operations, we often do not update this information, so that such "split point" can actually be smaller than the real minimum. Still, even if not up-to-date, its value is always correct, in that it really separates the subtrees (keys smaller than "split point" are not in left_page and larger are not in right_page).

The reason this is important to Lock System, is that the gap between the last record on the left_page and the first record on the right_page is represented as two gaps:

1. The gap between the last record on the left_page and the "split point", represented as the gap before the supremum pseudo-record of the left_page.
2. The gap between the "split point" and the first record of the right_page, represented as the gap before the first user record of the right_page.

Thus, inserting the new record, and subsequently adjusting "split points" in its ancestors to values smaller or equal to the new records' key, will mean that gap will be sliced at a different place ("moved to the left"): fragment of the 1st gap will now become treated as 2nd. Therefore, Lock System must copy any GRANTED locks from 1st gap to the 2nd gap. Any WAITING locks must be of INSERT_INTENTION type (as no other GAP locks ever wait for anything) and can stay at 1st gap, as their only purpose is to notify the requester they can retry insertion, and there's no correctness requirement to avoid waking them up too soon.

Parameters

[in]	right_block	Right page
[in]	left_block	Left page

lock_update_split_right()

void lock_update_split_right	(	const buf_block_t *	right_block,
		const buf_block_t *	left_block
	)

Updates the lock table when a page is split to the right.

Parameters

[in]	right_block	Right page
[in]	left_block	Left page

lock_update_wait_for_edge()

static void lock_update_wait_for_edge ( const lock_t *  waiting_lock, const lock_t *  blocking_lock  )

static

Given a waiting_lock, and blocking_lock which is the reason it has to wait, makes sure that the (only) edge in the wait-for graph outgoing from the waiting_lock->trx points to blocking_lock->trx.

Parameters

[in]	waiting_lock	A lock waiting in queue, blocked by blocking_lock
[in]	blocking_lock	A lock which is a reason the waiting_lock has to wait

lock_validate()

bool lock_validate

(

)

Validates the lock system.

Returns

true if ok

lock_validate_table_locks()

static void lock_validate_table_locks ( )

static

Validates the table locks.

Variable Documentation

innobase_deadlock_detect

bool innobase_deadlock_detect = true

lock_cached_lock_mode_names

std::unordered_map<uint, const char *> lock_cached_lock_mode_names

static

Used by lock_get_mode_str to cache results.

Strings pointed by these pointers might be in use by performance schema and thus can not be freed until the very end. Protected by exclusive global lock_cached_lock_mode_names_mutex.

lock_cached_lock_mode_names_mutex

std::mutex lock_cached_lock_mode_names_mutex

static

Mutex protecting access to lock_cached_lock_mode_names.

lock_constant_names

const std::map<uint, const char *> lock_constant_names

static

Initial value:

{
    {LOCK_GAP, "GAP"},
    {LOCK_REC_NOT_GAP, "REC_NOT_GAP"},
    {LOCK_INSERT_INTENTION, "INSERT_INTENTION"},
    {LOCK_PREDICATE, "PREDICATE"},
    {LOCK_PRDT_PAGE, "PRDT_PAGE"},
}

Used by lock_get_mode_str to build a lock mode description.

lock_deadlock_found

bool lock_deadlock_found = false

static

We store info on the latest deadlock error to this buffer.

InnoDB Monitor will then fetch it and print

lock_latest_err_file

FILE* lock_latest_err_file

static

Only created if !srv_read_only_mode.

I/O operations on this file require exclusive lock_sys latch

lock_sys

lock_sys_t* lock_sys = nullptr

The lock system.

REC_LOCK_CACHE

const ulint REC_LOCK_CACHE = 8

static

Total number of cached record locks.

REC_LOCK_SIZE

const ulint REC_LOCK_SIZE = sizeof(ib_lock_t) + 256

static

Maximum record lock size in bytes.

TABLE_LOCK_CACHE

const ulint TABLE_LOCK_CACHE = 8

static

Total number of cached table locks.

TABLE_LOCK_SIZE

const ulint TABLE_LOCK_SIZE = sizeof(ib_lock_t)

static

Size in bytes, of the table lock instance.