/****************************************************** The transaction lock system (c) 1996 Innobase Oy Created 5/7/1996 Heikki Tuuri *******************************************************/ #include "lock0lock.h" #ifdef UNIV_NONINL #include "lock0lock.ic" #endif #include "usr0sess.h" /* When releasing transaction locks, this specifies how often we release the kernel mutex for a moment to give also others access to it */ #define LOCK_RELEASE_KERNEL_INTERVAL 1000 /* Safety margin when creating a new record lock: this many extra records can be inserted to the page without need to create a lock with a bigger bitmap */ #define LOCK_PAGE_BITMAP_MARGIN 64 /* An explicit record lock affects both the record and the gap before it. An implicit x-lock does not affect the gap, it only locks the index record from read or update. If a transaction has modified or inserted an index record, then it owns an implicit x-lock on the record. On a secondary index record, a transaction has an implicit x-lock also if it has modified the clustered index record, the max trx id of the page where the secondary index record resides is >= trx id of the transaction (or database recovery is running), and there are no explicit non-gap lock requests on the secondary index record. This complicated definition for a secondary index comes from the implementation: we want to be able to determine if a secondary index record has an implicit x-lock, just by looking at the present clustered index record, not at the historical versions of the record. The complicated definition can be explained to the user so that there is nondeterminism in the access path when a query is answered: we may, or may not, access the clustered index record and thus may, or may not, bump into an x-lock set there. Different transaction can have conflicting locks set on the gap at the same time. The locks on the gap are purely inhibitive: an insert cannot be made, or a select cursor may have to wait, if a different transaction has a conflicting lock on the gap. An x-lock on the gap does not give the right to insert into the gap if there are conflicting locks granted on the gap at the same time. An explicit lock can be placed on a user record or the supremum record of a page. The locks on the supremum record are always thought to be of the gap type, though the gap bit is not set. When we perform an update of a record where the size of the record changes, we may temporarily store its explicit locks on the infimum record of the page, though the infimum otherwise never carries locks. A waiting record lock can also be of the gap type. A waiting lock request can be granted when there is no conflicting mode lock request by another transaction ahead of it in the explicit lock queue. ------------------------------------------------------------------------- RULE 1: If there is an implicit x-lock on a record, and there are non-gap ------- lock requests waiting in the queue, then the transaction holding the implicit x-lock also has an explicit non-gap record x-lock. Therefore, as locks are released, we can grant locks to waiting lock requests purely by looking at the explicit lock requests in the queue. RULE 2: Granted non-gap locks on a record are always ahead in the queue ------- of waiting non-gap locks on a record. RULE 3: Different transactions cannot have conflicting granted non-gap locks ------- on a record at the same time. However, they can have conflicting granted gap locks. RULE 4: If a there is a waiting lock request in a queue, no lock request, ------- gap or not, can be inserted ahead of it in the queue. In record deletes and page splits, new gap type locks can be created by the database manager for a transaction, and without rule 4, the waits-for graph of transactions might become cyclic without the database noticing it, as the deadlock check is only performed when a transaction itself requests a lock! ------------------------------------------------------------------------- An insert is allowed to a gap if there are no explicit lock requests by other transactions on the next record. It does not matter if these lock requests are granted or waiting, gap bit set or not. On the other hand, an implicit x-lock by another transaction does not prevent an insert, which allows for more concurrency when using an Oracle-style sequence number generator for the primary key with many transactions doing inserts concurrently. A modify of a record is allowed if the transaction has an x-lock on the record, or if other transactions do not have any non-gap lock requests on the record. A read of a single user record with a cursor is allowed if the transaction has a non-gap explicit, or an implicit lock on the record, or if the other transactions have no x-lock requests on the record. At a page supremum a read is always allowed. In summary, an implicit lock is seen as a granted x-lock only on the record, not on the gap. An explicit lock with no gap bit set is a lock both on the record and the gap. If the gap bit is set, the lock is only on the gap. Different transaction cannot own conflicting locks on the record at the same time, but they may own conflicting locks on the gap. Granted locks on a record give an access right to the record, but gap type locks just inhibit operations. NOTE: Finding out if some transaction has an implicit x-lock on a secondary index record can be cumbersome. We may have to look at previous versions of the corresponding clustered index record to find out if a delete marked secondary index record was delete marked by an active transaction, not by a committed one. FACT A: If a transaction has inserted a row, it can delete it any time without need to wait for locks. PROOF: The transaction has an implicit x-lock on every index record inserted for the row, and can thus modify each record without the need to wait. Q.E.D. FACT B: If a transaction has read some result set with a cursor, it can read it again, and retrieves the same result set, if it has not modified the result set in the meantime. Hence, there is no phantom problem. If the biggest record, in the alphabetical order, touched by the cursor is removed, a lock wait may occur, otherwise not. PROOF: When a read cursor proceeds, it sets an s-lock on each user record it passes, and a gap type s-lock on each page supremum. The cursor must wait until it has these locks granted. Then no other transaction can have a granted x-lock on any of the user records, and therefore cannot modify the user records. Neither can any other transaction insert into the gaps which were passed over by the cursor. Page splits and merges, and removal of obsolete versions of records do not affect this, because when a user record or a page supremum is removed, the next record inherits its locks as gap type locks, and therefore blocks inserts to the same gap. Also, if a page supremum is inserted, it inherits its locks from the successor record. When the cursor is positioned again at the start of the result set, the records it will touch on its course are either records it touched during the last pass or new inserted page supremums. It can immediately access all these records, and when it arrives at the biggest record, it notices that the result set is complete. If the biggest record was removed, lock wait can occur because the next record only inherits a gap type lock, and a wait may be needed. Q.E.D. */ /* If an index record should be changed or a new inserted, we must check the lock on the record or the next. When a read cursor starts reading, we will set a record level s-lock on each record it passes, except on the initial record on which the cursor is positioned before we start to fetch records. Our index tree search has the convention that the B-tree cursor is positioned BEFORE the first possibly matching record in the search. Optimizations are possible here: if the record is searched on an equality condition to a unique key, we could actually set a special lock on the record, a lock which would not prevent any insert before this record. In the next key locking an x-lock set on a record also prevents inserts just before that record. There are special infimum and supremum records on each page. A supremum record can be locked by a read cursor. This records cannot be updated but the lock prevents insert of a user record to the end of the page. Next key locks will prevent the phantom problem where new rows could appear to SELECT result sets after the select operation has been performed. Prevention of phantoms ensures the serilizability of transactions. What should we check if an insert of a new record is wanted? Only the lock on the next record on the same page, because also the supremum record can carry a lock. An s-lock prevents insertion, but what about an x-lock? If it was set by a searched update, then there is implicitly an s-lock, too, and the insert should be prevented. What if our transaction owns an x-lock to the next record, but there is a waiting s-lock request on the next record? If this s-lock was placed by a read cursor moving in the ascending order in the index, we cannot do the insert immediately, because when we finally commit our transaction, the read cursor should see also the new inserted record. So we should move the read cursor backward from the the next record for it to pass over the new inserted record. This move backward may be too cumbersome to implement. If we in this situation just enqueue a second x-lock request for our transaction on the next record, then the deadlock mechanism notices a deadlock between our transaction and the s-lock request transaction. This seems to be an ok solution. We could have the convention that granted explicit record locks, lock the corresponding records from changing, and also lock the gaps before them from inserting. A waiting explicit lock request locks the gap before from inserting. Implicit record x-locks, which we derive from the transaction id in the clustered index record, only lock the record itself from modification, not the gap before it from inserting. How should we store update locks? If the search is done by a unique key, we could just modify the record trx id. Otherwise, we could put a record x-lock on the record. If the update changes ordering fields of the clustered index record, the inserted new record needs no record lock in lock table, the trx id is enough. The same holds for a secondary index record. Searched delete is similar to update. PROBLEM: What about waiting lock requests? If a transaction is waiting to make an update to a record which another modified, how does the other transaction know to send the end-lock-wait signal to the waiting transaction? If we have the convention that a transaction may wait for just one lock at a time, how do we preserve it if lock wait ends? PROBLEM: Checking the trx id label of a secondary index record. In the case of a modification, not an insert, is this necessary? A secondary index record is modified only by setting or resetting its deleted flag. A secondary index record contains fields to uniquely determine the corresponding clustered index record. A secondary index record is therefore only modified if we also modify the clustered index record, and the trx id checking is done on the clustered index record, before we come to modify the secondary index record. So, in the case of delete marking or unmarking a secondary index record, we do not have to care about trx ids, only the locks in the lock table must be checked. In the case of a select from a secondary index, the trx id is relevant, and in this case we may have to search the clustered index record. PROBLEM: How to update record locks when page is split or merged, or -------------------------------------------------------------------- a record is deleted or updated? If the size of fields in a record changes, we perform the update by a delete followed by an insert. How can we retain the locks set or waiting on the record? Because a record lock is indexed in the bitmap by the heap number of the record, when we remove the record from the record list, it is possible still to keep the lock bits. If the page is reorganized, we could make a table of old and new heap numbers, and permute the bitmaps in the locks accordingly. We can add to the table a row telling where the updated record ended. If the update does not require a reorganization of the page, we can simply move the lock bits for the updated record to the position determined by its new heap number (we may have to allocate a new lock, if we run out of the bitmap in the old one). A more complicated case is the one where the reinsertion of the updated record is done pessimistically, because the structure of the tree may change. PROBLEM: If a supremum record is removed in a page merge, or a record --------------------------------------------------------------------- removed in a purge, what to do to the waiting lock requests? In a split to the right, we just move the lock requests to the new supremum. If a record is removed, we could move the waiting lock request to its inheritor, the next record in the index. But, the next record may already have lock requests on its own queue. A new deadlock check should be made then. Maybe it is easier just to release the waiting transactions. They can then enqueue new lock requests on appropriate records. PROBLEM: When a record is inserted, what locks should it inherit from the ------------------------------------------------------------------------- upper neighbor? An insert of a new supremum record in a page split is always possible, but an insert of a new user record requires that the upper neighbor does not have any lock requests by other transactions, granted or waiting, in its lock queue. Solution: We can copy the locks as gap type locks, so that also the waiting locks are transformed to granted gap type locks on the inserted record. */ ibool lock_print_waits = FALSE; /* The lock system */ lock_sys_t* lock_sys = NULL; /* A table lock */ typedef struct lock_table_struct lock_table_t; struct lock_table_struct{ dict_table_t* table; /* database table in dictionary cache */ UT_LIST_NODE_T(lock_t) locks; /* list of locks on the same table */ }; /* Record lock for a page */ typedef struct lock_rec_struct lock_rec_t; struct lock_rec_struct{ ulint space; /* space id */ ulint page_no; /* page number */ ulint n_bits; /* number of bits in the lock bitmap */ /* NOTE: the lock bitmap is placed immediately after the lock struct */ }; /* Lock struct */ struct lock_struct{ trx_t* trx; /* transaction owning the lock */ UT_LIST_NODE_T(lock_t) trx_locks; /* list of the locks of the transaction */ ulint type_mode; /* lock type, mode, gap flag, and wait flag, ORed */ hash_node_t hash; /* hash chain node for a record lock */ dict_index_t* index; /* index for a record lock */ union { lock_table_t tab_lock;/* table lock */ lock_rec_t rec_lock;/* record lock */ } un_member; }; /************************************************************************ Checks if a lock request results in a deadlock. */ static ibool lock_deadlock_occurs( /*=================*/ /* out: TRUE if a deadlock was detected */ lock_t* lock, /* in: lock the transaction is requesting */ trx_t* trx); /* in: transaction */ /************************************************************************ Looks recursively for a deadlock. */ static ibool lock_deadlock_recursive( /*====================*/ /* out: TRUE if a deadlock was detected */ trx_t* start, /* in: recursion starting point */ trx_t* trx, /* in: a transaction waiting for a lock */ lock_t* wait_lock); /* in: the lock trx is waiting to be granted */ /************************************************************************* Reserves the kernel mutex. This function is used in this module to allow monitoring the contention degree on the kernel mutex caused by the lock operations. */ UNIV_INLINE void lock_mutex_enter_kernel(void) /*=========================*/ { mutex_enter(&kernel_mutex); } /************************************************************************* Releses the kernel mutex. This function is used in this module to allow monitoring the contention degree on the kernel mutex caused by the lock operations. */ UNIV_INLINE void lock_mutex_exit_kernel(void) /*=========================*/ { mutex_exit(&kernel_mutex); } #ifdef notdefined /************************************************************************* Gets the mutex protecting record locks for a page in the buffer pool. */ UNIV_INLINE mutex_t* lock_rec_get_mutex( /*===============*/ byte* ptr) /* in: pointer to somewhere within a buffer frame */ { return(buf_frame_get_lock_mutex(ptr)); } /************************************************************************* Reserves the mutex protecting record locks for a page in the buffer pool. */ UNIV_INLINE void lock_rec_mutex_enter( /*=================*/ byte* ptr) /* in: pointer to somewhere within a buffer frame */ { mutex_enter(lock_rec_get_mutex(ptr)); } /************************************************************************* Releases the mutex protecting record locks for a page in the buffer pool. */ UNIV_INLINE void lock_rec_mutex_exit( /*================*/ byte* ptr) /* in: pointer to somewhere within a buffer frame */ { mutex_exit(lock_rec_get_mutex(ptr)); } /************************************************************************* Checks if the caller owns the mutex to record locks of a page. Works only in the debug version. */ UNIV_INLINE ibool lock_rec_mutex_own( /*===============*/ /* out: TRUE if the current OS thread has reserved the mutex */ byte* ptr) /* in: pointer to somewhere within a buffer frame */ { return(mutex_own(lock_rec_get_mutex(ptr))); } /************************************************************************* Gets the mutex protecting record locks on a given page address. */ mutex_t* lock_rec_get_mutex_for_addr( /*========================*/ ulint space, /* in: space id */ ulint page_no)/* in: page number */ { return(hash_get_mutex(lock_sys->rec_hash, lock_rec_fold(space, page_no))); } /************************************************************************* Checks if the caller owns the mutex to record locks of a page. Works only in the debug version. */ UNIV_INLINE ibool lock_rec_mutex_own_addr( /*====================*/ ulint space, /* in: space id */ ulint page_no)/* in: page number */ { return(mutex_own(lock_rec_get_mutex_for_addr(space, page_no))); } /************************************************************************* Reserves all the mutexes protecting record locks. */ UNIV_INLINE void lock_rec_mutex_enter_all(void) /*==========================*/ { hash_table_t* table; ulint n_mutexes; ulint i; table = lock_sys->rec_hash; n_mutexes = table->n_mutexes; for (i = 0; i < n_mutexes; i++) { mutex_enter(hash_get_nth_mutex(table, i)); } } /************************************************************************* Releases all the mutexes protecting record locks. */ UNIV_INLINE void lock_rec_mutex_exit_all(void) /*=========================*/ { hash_table_t* table; ulint n_mutexes; ulint i; table = lock_sys->rec_hash; n_mutexes = table->n_mutexes; for (i = 0; i < n_mutexes; i++) { mutex_exit(hash_get_nth_mutex(table, i)); } } /************************************************************************* Checks that the current OS thread owns all the mutexes protecting record locks. */ UNIV_INLINE ibool lock_rec_mutex_own_all(void) /*========================*/ /* out: TRUE if owns all */ { hash_table_t* table; ulint n_mutexes; ibool owns_yes = TRUE; ulint i; table = lock_sys->rec_hash; n_mutexes = table->n_mutexes; for (i = 0; i < n_mutexes; i++) { if (!mutex_own(hash_get_nth_mutex(table, i))) { owns_yes = FALSE; } } return(owns_yes); } #endif /************************************************************************* Checks that a record is seen in a consistent read. */ ibool lock_clust_rec_cons_read_sees( /*==========================*/ /* out: TRUE if sees, or FALSE if an earlier version of the record should be retrieved */ rec_t* rec, /* in: user record which should be read or passed over by a read cursor */ dict_index_t* index, /* in: clustered index */ read_view_t* view) /* in: consistent read view */ { dulint trx_id; ut_ad(index->type & DICT_CLUSTERED); ut_ad(page_rec_is_user_rec(rec)); trx_id = row_get_rec_trx_id(rec, index); if (read_view_sees_trx_id(view, trx_id)) { return(TRUE); } return(FALSE); } /************************************************************************* Checks that a non-clustered index record is seen in a consistent read. */ ulint lock_sec_rec_cons_read_sees( /*========================*/ /* out: TRUE if certainly sees, or FALSE if an earlier version of the clustered index record might be needed: 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 */ rec_t* rec, /* in: user record which should be read or passed over by a read cursor */ dict_index_t* index, /* in: non-clustered index */ read_view_t* view) /* in: consistent read view */ { dulint max_trx_id; ut_ad(!(index->type & DICT_CLUSTERED)); ut_ad(page_rec_is_user_rec(rec)); if (recv_recovery_is_on()) { return(FALSE); } max_trx_id = page_get_max_trx_id(buf_frame_align(rec)); if (ut_dulint_cmp(max_trx_id, view->up_limit_id) >= 0) { return(FALSE); } return(TRUE); } /************************************************************************* Creates the lock system at database start. */ void lock_sys_create( /*============*/ ulint n_cells) /* in: number of slots in lock hash table */ { lock_sys = mem_alloc(sizeof(lock_sys_t)); lock_sys->rec_hash = hash_create(n_cells); /* hash_create_mutexes(lock_sys->rec_hash, 2, SYNC_REC_LOCK); */ } /************************************************************************* Gets the mode of a lock. */ UNIV_INLINE ulint lock_get_mode( /*==========*/ /* out: mode */ lock_t* lock) /* in: lock */ { ut_ad(lock); return(lock->type_mode & LOCK_MODE_MASK); } /************************************************************************* Gets the type of a lock. */ UNIV_INLINE ulint lock_get_type( /*==========*/ /* out: LOCK_TABLE or LOCK_RECa */ lock_t* lock) /* in: lock */ { ut_ad(lock); return(lock->type_mode & LOCK_TYPE_MASK); } /************************************************************************* Gets the wait flag of a lock. */ UNIV_INLINE ibool lock_get_wait( /*==========*/ /* out: TRUE if waiting */ lock_t* lock) /* in: lock */ { ut_ad(lock); if (lock->type_mode & LOCK_WAIT) { return(TRUE); } return(FALSE); } /************************************************************************* Sets the wait flag of a lock and the back pointer in trx to lock. */ UNIV_INLINE void lock_set_lock_and_trx_wait( /*=======================*/ lock_t* lock, /* in: lock */ trx_t* trx) /* in: trx */ { ut_ad(lock); ut_ad(trx->wait_lock == NULL); trx->wait_lock = lock; lock->type_mode = lock->type_mode | LOCK_WAIT; } /************************************************************************** The back pointer to a waiting lock request in the transaction is set to NULL and the wait bit in lock type_mode is reset. */ UNIV_INLINE void lock_reset_lock_and_trx_wait( /*=========================*/ lock_t* lock) /* in: record lock */ { ut_ad((lock->trx)->wait_lock == lock); ut_ad(lock_get_wait(lock)); /* Reset the back pointer in trx to this waiting lock request */ (lock->trx)->wait_lock = NULL; lock->type_mode = lock->type_mode & ~LOCK_WAIT; } /************************************************************************* Gets the gap flag of a record lock. */ UNIV_INLINE ibool lock_rec_get_gap( /*=============*/ /* out: TRUE if gap flag set */ lock_t* lock) /* in: record lock */ { ut_ad(lock); ut_ad(lock_get_type(lock) == LOCK_REC); if (lock->type_mode & LOCK_GAP) { return(TRUE); } return(FALSE); } /************************************************************************* Sets the gap flag of a record lock. */ UNIV_INLINE void lock_rec_set_gap( /*=============*/ lock_t* lock, /* in: record lock */ ibool val) /* in: value to set: TRUE or FALSE */ { ut_ad(lock); ut_ad((val == TRUE) || (val == FALSE)); ut_ad(lock_get_type(lock) == LOCK_REC); if (val) { lock->type_mode = lock->type_mode | LOCK_GAP; } else { lock->type_mode = lock->type_mode & ~LOCK_GAP; } } /************************************************************************* Calculates if lock mode 1 is stronger or equal to lock mode 2. */ UNIV_INLINE ibool lock_mode_stronger_or_eq( /*=====================*/ /* out: TRUE if mode1 stronger or equal to mode2 */ ulint mode1, /* in: lock mode */ ulint mode2) /* in: lock mode */ { ut_ad((mode1 == LOCK_X) || (mode1 == LOCK_S) || (mode1 == LOCK_IX) || (mode1 == LOCK_IS)); ut_ad((mode2 == LOCK_X) || (mode2 == LOCK_S) || (mode2 == LOCK_IX) || (mode2 == LOCK_IS)); if (mode1 == LOCK_X) { return(TRUE); } else if ((mode1 == LOCK_S) && ((mode2 == LOCK_S) || (mode2 == LOCK_IS))) { return(TRUE); } else if ((mode1 == LOCK_IS) && (mode2 == LOCK_IS)) { return(TRUE); } else if ((mode1 == LOCK_IX) && ((mode2 == LOCK_IX) || (mode2 == LOCK_IS))) { return(TRUE); } return(FALSE); } /************************************************************************* Calculates if lock mode 1 is compatible with lock mode 2. */ UNIV_INLINE ibool lock_mode_compatible( /*=================*/ /* out: TRUE if mode1 compatible with mode2 */ ulint mode1, /* in: lock mode */ ulint mode2) /* in: lock mode */ { ut_ad((mode1 == LOCK_X) || (mode1 == LOCK_S) || (mode1 == LOCK_IX) || (mode1 == LOCK_IS)); ut_ad((mode2 == LOCK_X) || (mode2 == LOCK_S) || (mode2 == LOCK_IX) || (mode2 == LOCK_IS)); if ((mode1 == LOCK_S) && ((mode2 == LOCK_IS) || (mode2 == LOCK_S))) { return(TRUE); } else if (mode1 == LOCK_X) { return(FALSE); } else if ((mode1 == LOCK_IS) && ((mode2 == LOCK_IS) || (mode2 == LOCK_IX) || (mode2 == LOCK_S))) { return(TRUE); } else if ((mode1 == LOCK_IX) && ((mode2 == LOCK_IS) || (mode2 == LOCK_IX))) { return(TRUE); } return(FALSE); } /************************************************************************* Returns LOCK_X if mode is LOCK_S, and vice versa. */ UNIV_INLINE ulint lock_get_confl_mode( /*================*/ /* out: conflicting basic lock mode */ ulint mode) /* in: LOCK_S or LOCK_X */ { ut_ad((mode == LOCK_X) || (mode == LOCK_S)); if (mode == LOCK_S) { return(LOCK_X); } return(LOCK_S); } /************************************************************************* Checks if a lock request lock1 has to wait for request lock2. NOTE that we, for simplicity, ignore the gap bits in locks, and treat gap type lock requests like non-gap lock requests. */ UNIV_INLINE ibool lock_has_to_wait( /*=============*/ /* out: TRUE if lock1 has to wait lock2 to be removed */ lock_t* lock1, /* in: waiting record lock */ lock_t* lock2) /* in: another lock; NOTE that it is assumed that this has a lock bit set on the same record as in lock1 */ { if ((lock1->trx != lock2->trx) && !lock_mode_compatible(lock_get_mode(lock1), lock_get_mode(lock2))) { return(TRUE); } return(FALSE); } /*============== RECORD LOCK BASIC FUNCTIONS ============================*/ /************************************************************************* Gets the number of bits in a record lock bitmap. */ UNIV_INLINE ulint lock_rec_get_n_bits( /*================*/ /* out: number of bits */ lock_t* lock) /* in: record lock */ { return(lock->un_member.rec_lock.n_bits); } /************************************************************************* Gets the nth bit of a record lock. */ UNIV_INLINE ibool lock_rec_get_nth_bit( /*=================*/ /* out: TRUE if bit set */ lock_t* lock, /* in: record lock */ ulint i) /* in: index of the bit */ { ulint byte_index; ulint bit_index; ulint b; ut_ad(lock); ut_ad(lock_get_type(lock) == LOCK_REC); if (i >= lock->un_member.rec_lock.n_bits) { return(FALSE); } byte_index = i / 8; bit_index = i % 8; b = (ulint)*((byte*)lock + sizeof(lock_t) + byte_index); return(ut_bit_get_nth(b, bit_index)); } /************************************************************************** Sets the nth bit of a record lock to TRUE. */ UNIV_INLINE void lock_rec_set_nth_bit( /*==================*/ lock_t* lock, /* in: record lock */ ulint i) /* in: index of the bit */ { ulint byte_index; ulint bit_index; byte* ptr; ulint b; ut_ad(lock); ut_ad(lock_get_type(lock) == LOCK_REC); ut_ad(i < lock->un_member.rec_lock.n_bits); byte_index = i / 8; bit_index = i % 8; ptr = (byte*)lock + sizeof(lock_t) + byte_index; b = (ulint)*ptr; b = ut_bit_set_nth(b, bit_index, TRUE); *ptr = (byte)b; } /************************************************************************** Looks for a set bit in a record lock bitmap. Returns ULINT_UNDEFINED, if none found. */ static ulint lock_rec_find_set_bit( /*==================*/ /* out: bit index == heap number of the record, or ULINT_UNDEFINED if none found */ lock_t* lock) /* in: record lock with at least one bit set */ { ulint i; for (i = 0; i < lock_rec_get_n_bits(lock); i++) { if (lock_rec_get_nth_bit(lock, i)) { return(i); } } return(ULINT_UNDEFINED); } /************************************************************************** Resets the nth bit of a record lock. */ UNIV_INLINE void lock_rec_reset_nth_bit( /*===================*/ lock_t* lock, /* in: record lock */ ulint i) /* in: index of the bit which must be set to TRUE when this function is called */ { ulint byte_index; ulint bit_index; byte* ptr; ulint b; ut_ad(lock); ut_ad(lock_get_type(lock) == LOCK_REC); ut_ad(i < lock->un_member.rec_lock.n_bits); byte_index = i / 8; bit_index = i % 8; ptr = (byte*)lock + sizeof(lock_t) + byte_index; b = (ulint)*ptr; b = ut_bit_set_nth(b, bit_index, FALSE); *ptr = (byte)b; } /************************************************************************* Gets the first or next record lock on a page. */ UNIV_INLINE lock_t* lock_rec_get_next_on_page( /*======================*/ /* out: next lock, NULL if none exists */ lock_t* lock) /* in: a record lock */ { ulint space; ulint page_no; ut_ad(mutex_own(&kernel_mutex)); space = lock->un_member.rec_lock.space; page_no = lock->un_member.rec_lock.page_no; for (;;) { lock = HASH_GET_NEXT(hash, lock); if (!lock) { break; } if ((lock->un_member.rec_lock.space == space) && (lock->un_member.rec_lock.page_no == page_no)) { break; } } return(lock); } /************************************************************************* Gets the first record lock on a page, where the page is identified by its file address. */ UNIV_INLINE lock_t* lock_rec_get_first_on_page_addr( /*============================*/ /* out: first lock, NULL if none exists */ ulint space, /* in: space */ ulint page_no)/* in: page number */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); lock = HASH_GET_FIRST(lock_sys->rec_hash, lock_rec_hash(space, page_no)); while (lock) { if ((lock->un_member.rec_lock.space == space) && (lock->un_member.rec_lock.page_no == page_no)) { break; } lock = HASH_GET_NEXT(hash, lock); } return(lock); } /************************************************************************* Returns TRUE if there are explicit record locks on a page. */ ibool lock_rec_expl_exist_on_page( /*========================*/ /* out: TRUE if there are explicit record locks on the page */ ulint space, /* in: space id */ ulint page_no)/* in: page number */ { ibool ret; mutex_enter(&kernel_mutex); if (lock_rec_get_first_on_page_addr(space, page_no)) { ret = TRUE; } else { ret = FALSE; } mutex_exit(&kernel_mutex); return(ret); } /************************************************************************* Gets the first record lock on a page, where the page is identified by a pointer to it. */ UNIV_INLINE lock_t* lock_rec_get_first_on_page( /*=======================*/ /* out: first lock, NULL if none exists */ byte* ptr) /* in: pointer to somewhere on the page */ { ulint hash; lock_t* lock; ulint space; ulint page_no; ut_ad(mutex_own(&kernel_mutex)); hash = buf_frame_get_lock_hash_val(ptr); lock = HASH_GET_FIRST(lock_sys->rec_hash, hash); while (lock) { space = buf_frame_get_space_id(ptr); page_no = buf_frame_get_page_no(ptr); if ((lock->un_member.rec_lock.space == space) && (lock->un_member.rec_lock.page_no == page_no)) { break; } lock = HASH_GET_NEXT(hash, lock); } return(lock); } /************************************************************************* Gets the next explicit lock request on a record. */ UNIV_INLINE lock_t* lock_rec_get_next( /*==============*/ /* out: next lock, NULL if none exists */ rec_t* rec, /* in: record on a page */ lock_t* lock) /* in: lock */ { ut_ad(mutex_own(&kernel_mutex)); for (;;) { lock = lock_rec_get_next_on_page(lock); if (lock == NULL) { return(NULL); } if (lock_rec_get_nth_bit(lock, rec_get_heap_no(rec))) { return(lock); } } } /************************************************************************* Gets the first explicit lock request on a record. */ UNIV_INLINE lock_t* lock_rec_get_first( /*===============*/ /* out: first lock, NULL if none exists */ rec_t* rec) /* in: record on a page */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); lock = lock_rec_get_first_on_page(rec); while (lock) { if (lock_rec_get_nth_bit(lock, rec_get_heap_no(rec))) { break; } lock = lock_rec_get_next_on_page(lock); } return(lock); } /************************************************************************* 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. */ static void lock_rec_bitmap_reset( /*==================*/ lock_t* lock) /* in: record lock */ { byte* ptr; ulint n_bytes; ulint i; /* Reset to zero the bitmap which resides immediately after the lock struct */ ptr = (byte*)lock + sizeof(lock_t); n_bytes = lock_rec_get_n_bits(lock) / 8; ut_ad((lock_rec_get_n_bits(lock) % 8) == 0); for (i = 0; i < n_bytes; i++) { *ptr = 0; ptr++; } } /************************************************************************* Copies a record lock to heap. */ static lock_t* lock_rec_copy( /*==========*/ /* out: copy of lock */ lock_t* lock, /* in: record lock */ mem_heap_t* heap) /* in: memory heap */ { lock_t* dupl_lock; ulint size; size = sizeof(lock_t) + lock_rec_get_n_bits(lock) / 8; dupl_lock = mem_heap_alloc(heap, size); ut_memcpy(dupl_lock, lock, size); return(dupl_lock); } /************************************************************************* Gets the previous record lock set on a record. */ static lock_t* lock_rec_get_prev( /*==============*/ /* out: previous lock on the same record, NULL if none exists */ lock_t* in_lock,/* in: record lock */ ulint heap_no)/* in: heap number of the record */ { lock_t* lock; ulint space; ulint page_no; lock_t* found_lock = NULL; ut_ad(mutex_own(&kernel_mutex)); ut_ad(lock_get_type(in_lock) == LOCK_REC); space = in_lock->un_member.rec_lock.space; page_no = in_lock->un_member.rec_lock.page_no; lock = lock_rec_get_first_on_page_addr(space, page_no); for (;;) { ut_ad(lock); if (lock == in_lock) { return(found_lock); } if (lock_rec_get_nth_bit(lock, heap_no)) { found_lock = lock; } lock = lock_rec_get_next_on_page(lock); } } /*============= FUNCTIONS FOR ANALYZING TABLE LOCK QUEUE ================*/ /************************************************************************* Checks if a transaction has the specified table lock, or stronger. */ UNIV_INLINE lock_t* lock_table_has( /*===========*/ /* out: lock or NULL */ trx_t* trx, /* in: transaction */ dict_table_t* table, /* in: table */ ulint mode) /* in: lock mode */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); /* Look for stronger locks the same trx already has on the table */ lock = UT_LIST_GET_LAST(table->locks); while (lock != NULL) { if ((lock->trx == trx) && (lock_mode_stronger_or_eq(lock_get_mode(lock), mode))) { /* The same trx already has locked the table in a mode stronger or equal to the mode given */ ut_ad(!lock_get_wait(lock)); return(lock); } lock = UT_LIST_GET_PREV(un_member.tab_lock.locks, lock); } return(NULL); } /*============= FUNCTIONS FOR ANALYZING RECORD LOCK QUEUE ================*/ /************************************************************************* Checks if a transaction has a GRANTED explicit non-gap lock on rec, stronger or equal to mode. */ UNIV_INLINE lock_t* lock_rec_has_expl( /*==============*/ /* out: lock or NULL */ ulint mode, /* in: lock mode */ rec_t* rec, /* in: record */ trx_t* trx) /* in: transaction */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); ut_ad((mode == LOCK_X) || (mode == LOCK_S)); lock = lock_rec_get_first(rec); while (lock) { if ((lock->trx == trx) && lock_mode_stronger_or_eq(lock_get_mode(lock), mode) && !lock_get_wait(lock) && !(lock_rec_get_gap(lock) || page_rec_is_supremum(rec))) { return(lock); } lock = lock_rec_get_next(rec, lock); } return(NULL); } /************************************************************************* Checks if some other transaction has an explicit lock request stronger or equal to mode on rec or gap, waiting or granted, in the lock queue. */ UNIV_INLINE lock_t* lock_rec_other_has_expl_req( /*========================*/ /* out: lock or NULL */ ulint mode, /* in: lock mode */ ulint gap, /* in: LOCK_GAP if also gap locks are taken into account, or 0 if not */ ulint wait, /* in: LOCK_WAIT if also waiting locks are taken into account, or 0 if not */ rec_t* rec, /* in: record to look at */ trx_t* trx) /* in: transaction, or NULL if requests by any transaction are wanted */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); ut_ad((mode == LOCK_X) || (mode == LOCK_S)); lock = lock_rec_get_first(rec); while (lock) { if ((lock->trx != trx) && (gap || !(lock_rec_get_gap(lock) || page_rec_is_supremum(rec))) && (wait || !lock_get_wait(lock)) && lock_mode_stronger_or_eq(lock_get_mode(lock), mode)) { return(lock); } lock = lock_rec_get_next(rec, lock); } return(NULL); } /************************************************************************* Looks for a suitable type record lock struct by the same trx on the same page. This can be used to save space when a new record lock should be set on a page: no new struct is needed, if a suitable old is found. */ UNIV_INLINE lock_t* lock_rec_find_similar_on_page( /*==========================*/ /* out: lock or NULL */ ulint type_mode, /* in: lock type_mode field */ rec_t* rec, /* in: record */ trx_t* trx) /* in: transaction */ { lock_t* lock; ulint heap_no; ut_ad(mutex_own(&kernel_mutex)); heap_no = rec_get_heap_no(rec); lock = lock_rec_get_first_on_page(rec); while (lock != NULL) { if ((lock->trx == trx) && (lock->type_mode == type_mode) && (lock_rec_get_n_bits(lock) > heap_no)) { return(lock); } lock = lock_rec_get_next_on_page(lock); } return(NULL); } /************************************************************************* Checks if some transaction has an implicit x-lock on a record in a secondary index. */ trx_t* lock_sec_rec_some_has_impl_off_kernel( /*==================================*/ /* out: transaction which has the x-lock, or NULL */ rec_t* rec, /* in: user record */ dict_index_t* index) /* in: secondary index */ { page_t* page; ut_ad(mutex_own(&kernel_mutex)); ut_ad(!(index->type & DICT_CLUSTERED)); ut_ad(page_rec_is_user_rec(rec)); page = buf_frame_align(rec); /* Some transaction may have an implicit x-lock on the record only if the max trx id for the page >= min trx id for the trx list, or database recovery is running. We do not write the changes of a page max trx id to the log, and therefore during recovery, this value for a page may be incorrect. */ if (!(ut_dulint_cmp(page_get_max_trx_id(page), trx_list_get_min_trx_id()) >= 0) && !recv_recovery_is_on()) { return(NULL); } /* Ok, in this case it is possible that some transaction has an implicit x-lock. We have to look in the clustered index. */ return(row_vers_impl_x_locked_off_kernel(rec, index)); } /*============== RECORD LOCK CREATION AND QUEUE MANAGEMENT =============*/ /************************************************************************* Creates a new record lock and inserts it to the lock queue. Does NOT check for deadlocks or lock compatibility! */ static lock_t* lock_rec_create( /*============*/ /* out: created lock, NULL if out of memory */ ulint type_mode,/* in: lock mode and wait flag, type is ignored and replaced by LOCK_REC */ rec_t* rec, /* in: record on page */ dict_index_t* index, /* in: index of record */ trx_t* trx) /* in: transaction */ { page_t* page; lock_t* lock; ulint page_no; ulint heap_no; ulint space; ulint n_bits; ulint n_bytes; ut_ad(mutex_own(&kernel_mutex)); page = buf_frame_align(rec); space = buf_frame_get_space_id(page); page_no = buf_frame_get_page_no(page); heap_no = rec_get_heap_no(rec); /* If rec is the supremum record, then we reset the gap bit, as all locks on the supremum are automatically of the gap type, and we try to avoid unnecessary memory consumption of a new record lock struct for a gap type lock */ if (rec == page_get_supremum_rec(page)) { type_mode = type_mode & ~LOCK_GAP; } /* Make lock bitmap bigger by a safety margin */ n_bits = page_header_get_field(page, PAGE_N_HEAP) + LOCK_PAGE_BITMAP_MARGIN; n_bytes = 1 + n_bits / 8; lock = mem_heap_alloc(trx->lock_heap, sizeof(lock_t) + n_bytes); if (lock == NULL) { return(NULL); } UT_LIST_ADD_LAST(trx_locks, trx->trx_locks, lock); lock->trx = trx; lock->type_mode = (type_mode & ~LOCK_TYPE_MASK) | LOCK_REC; lock->index = index; lock->un_member.rec_lock.space = space; lock->un_member.rec_lock.page_no = page_no; lock->un_member.rec_lock.n_bits = n_bytes * 8; /* Reset to zero the bitmap which resides immediately after the lock struct */ lock_rec_bitmap_reset(lock); /* Set the bit corresponding to rec */ lock_rec_set_nth_bit(lock, heap_no); HASH_INSERT(lock_t, hash, lock_sys->rec_hash, lock_rec_fold(space, page_no), lock); if (type_mode & LOCK_WAIT) { lock_set_lock_and_trx_wait(lock, trx); } return(lock); } /************************************************************************* Enqueues a waiting request for a lock which cannot be granted immediately. Checks for deadlocks. */ static ulint lock_rec_enqueue_waiting( /*=====================*/ /* out: DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint type_mode,/* in: lock mode this transaction is requesting: LOCK_S or LOCK_X, ORed with LOCK_GAP if a gap lock is requested */ rec_t* rec, /* in: record */ dict_index_t* index, /* in: index of record */ que_thr_t* thr) /* in: query thread */ { lock_t* lock; trx_t* trx; ut_ad(mutex_own(&kernel_mutex)); /* Test if there already is some other reason to suspend thread: we do not enqueue a lock request if the query thread should be stopped anyway */ if (que_thr_stop(thr)) { return(DB_QUE_THR_SUSPENDED); } trx = thr_get_trx(thr); /* Enqueue the lock request that will wait to be granted */ lock = lock_rec_create(type_mode | LOCK_WAIT, rec, index, trx); /* Check if a deadlock occurs: if yes, remove the lock request and return an error code */ if (lock_deadlock_occurs(lock, trx)) { lock_reset_lock_and_trx_wait(lock); lock_rec_reset_nth_bit(lock, rec_get_heap_no(rec)); return(DB_DEADLOCK); } trx->que_state = TRX_QUE_LOCK_WAIT; ut_a(que_thr_stop(thr)); if (lock_print_waits) { printf("Lock wait for trx %lu in index %s\n", ut_dulint_get_low(trx->id), index->name); } return(DB_LOCK_WAIT); } /************************************************************************* Adds a record lock request in the record queue. The request is normally added as the last in the queue, but if there are no waiting lock requests on the record, and 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! */ static lock_t* lock_rec_add_to_queue( /*==================*/ /* out: lock where the bit was set, NULL if out of memory */ ulint type_mode,/* in: lock mode, wait, and gap flags; type is ignored and replaced by LOCK_REC */ rec_t* rec, /* in: record on page */ dict_index_t* index, /* in: index of record */ trx_t* trx) /* in: transaction */ { lock_t* lock; lock_t* similar_lock = NULL; ulint heap_no; page_t* page; ibool somebody_waits = FALSE; ut_ad(mutex_own(&kernel_mutex)); ut_ad((type_mode & (LOCK_WAIT | LOCK_GAP)) || ((type_mode & LOCK_MODE_MASK) != LOCK_S) || !lock_rec_other_has_expl_req(LOCK_X, 0, LOCK_WAIT, rec, trx)); ut_ad((type_mode & (LOCK_WAIT | LOCK_GAP)) || ((type_mode & LOCK_MODE_MASK) != LOCK_X) || !lock_rec_other_has_expl_req(LOCK_S, 0, LOCK_WAIT, rec, trx)); type_mode = type_mode | LOCK_REC; page = buf_frame_align(rec); /* If rec is the supremum record, then we can reset the gap bit, as all locks on the supremum are automatically of the gap type, and we try to avoid unnecessary memory consumption of a new record lock struct for a gap type lock */ if (rec == page_get_supremum_rec(page)) { type_mode = type_mode & ~LOCK_GAP; } /* Look for a waiting lock request on the same record, or for a similar record lock on the same page */ heap_no = rec_get_heap_no(rec); lock = lock_rec_get_first_on_page(rec); while (lock != NULL) { if (lock_get_wait(lock) && (lock_rec_get_nth_bit(lock, heap_no))) { somebody_waits = TRUE; } lock = lock_rec_get_next_on_page(lock); } similar_lock = lock_rec_find_similar_on_page(type_mode, rec, trx); if (similar_lock && !somebody_waits && !(type_mode & LOCK_WAIT)) { lock_rec_set_nth_bit(similar_lock, heap_no); return(similar_lock); } return(lock_rec_create(type_mode, rec, index, trx)); } /************************************************************************* 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. */ UNIV_INLINE ibool lock_rec_lock_fast( /*===============*/ /* out: TRUE if locking succeeded */ ibool impl, /* in: if TRUE, no lock is set if no wait is necessary: we assume that the caller will set an implicit lock */ ulint mode, /* in: lock mode */ rec_t* rec, /* in: record */ dict_index_t* index, /* in: index of record */ que_thr_t* thr) /* in: query thread */ { lock_t* lock; ulint heap_no; ut_ad(mutex_own(&kernel_mutex)); ut_ad((mode == LOCK_X) || (mode == LOCK_S)); heap_no = rec_get_heap_no(rec); lock = lock_rec_get_first_on_page(rec); if (lock == NULL) { if (!impl) { lock_rec_create(mode, rec, index, thr_get_trx(thr)); } return(TRUE); } if (lock_rec_get_next_on_page(lock)) { return(FALSE); } if ((lock->trx != thr_get_trx(thr)) || (lock->type_mode != (mode | LOCK_REC)) || (lock_rec_get_n_bits(lock) <= heap_no)) { return(FALSE); } if (!impl) { lock_rec_set_nth_bit(lock, heap_no); } return(TRUE); } /************************************************************************* 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. */ static ulint lock_rec_lock_slow( /*===============*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, or error code */ ibool impl, /* in: if TRUE, no lock is set if no wait is necessary: we assume that the caller will set an implicit lock */ ulint mode, /* in: lock mode */ rec_t* rec, /* in: record */ dict_index_t* index, /* in: index of record */ que_thr_t* thr) /* in: query thread */ { ulint confl_mode; trx_t* trx; ulint err; ut_ad(mutex_own(&kernel_mutex)); ut_ad((mode == LOCK_X) || (mode == LOCK_S)); trx = thr_get_trx(thr); confl_mode = lock_get_confl_mode(mode); ut_ad((mode != LOCK_S) || lock_table_has(trx, index->table, LOCK_IS)); ut_ad((mode != LOCK_X) || lock_table_has(trx, index->table, LOCK_IX)); if (lock_rec_has_expl(mode, rec, trx)) { /* The trx already has a strong enough lock on rec: do nothing */ err = DB_SUCCESS; } else if (lock_rec_other_has_expl_req(confl_mode, 0, LOCK_WAIT, rec, trx)) { /* If another transaction has a non-gap conflicting request in the queue, as this transaction does not have a lock strong enough already granted on the record, we have to wait. */ err = lock_rec_enqueue_waiting(mode, rec, index, thr); } else { if (!impl) { /* Set the requested lock on the record */ lock_rec_add_to_queue(LOCK_REC | mode, rec, index, trx); } err = DB_SUCCESS; } return(err); } /************************************************************************* 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. */ ulint lock_rec_lock( /*==========*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, or error code */ ibool impl, /* in: if TRUE, no lock is set if no wait is necessary: we assume that the caller will set an implicit lock */ ulint mode, /* in: lock mode */ rec_t* rec, /* in: record */ dict_index_t* index, /* in: index of record */ que_thr_t* thr) /* in: query thread */ { ulint err; ut_ad(mutex_own(&kernel_mutex)); ut_ad((mode != LOCK_S) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IS)); ut_ad((mode != LOCK_X) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); if (lock_rec_lock_fast(impl, mode, rec, index, thr)) { /* We try a simplified and faster subroutine for the most common cases */ err = DB_SUCCESS; } else { err = lock_rec_lock_slow(impl, mode, rec, index, thr); } return(err); } /************************************************************************* Checks if a waiting record lock request still has to wait in a queue. NOTE that we, for simplicity, ignore the gap bits in locks, and treat gap type lock requests like non-gap lock requests. */ static ibool lock_rec_has_to_wait_in_queue( /*==========================*/ /* out: TRUE if still has to wait */ lock_t* wait_lock) /* in: waiting record lock */ { lock_t* lock; ulint space; ulint page_no; ulint heap_no; ut_ad(mutex_own(&kernel_mutex)); ut_ad(lock_get_wait(wait_lock)); space = wait_lock->un_member.rec_lock.space; page_no = wait_lock->un_member.rec_lock.page_no; heap_no = lock_rec_find_set_bit(wait_lock); lock = lock_rec_get_first_on_page_addr(space, page_no); while (lock != wait_lock) { if (lock_has_to_wait(wait_lock, lock) && lock_rec_get_nth_bit(lock, heap_no)) { return(TRUE); } lock = lock_rec_get_next_on_page(lock); } return(FALSE); } /***************************************************************** Grants a lock to a waiting lock request and releases the waiting transaction. */ void lock_grant( /*=======*/ lock_t* lock) /* in: waiting lock request */ { ut_ad(mutex_own(&kernel_mutex)); lock_reset_lock_and_trx_wait(lock); if (lock_print_waits) { printf("Lock wait for trx %lu ends\n", ut_dulint_get_low(lock->trx->id)); } trx_end_lock_wait(lock->trx); } /***************************************************************** 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! */ void lock_rec_cancel( /*============*/ lock_t* lock) /* in: waiting record lock request */ { ut_ad(mutex_own(&kernel_mutex)); /* Reset the bit in lock bitmap */ lock_rec_reset_nth_bit(lock, lock_rec_find_set_bit(lock)); /* Reset the wait flag and the back pointer to lock in trx */ lock_reset_lock_and_trx_wait(lock); /* The following function releases the trx from lock wait */ trx_end_lock_wait(lock->trx); } /***************************************************************** 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. */ void lock_rec_dequeue_from_page( /*=======================*/ lock_t* in_lock)/* in: 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 */ { ulint space; ulint page_no; lock_t* lock; trx_t* trx; ut_ad(mutex_own(&kernel_mutex)); ut_ad(lock_get_type(in_lock) == LOCK_REC); trx = in_lock->trx; space = in_lock->un_member.rec_lock.space; page_no = in_lock->un_member.rec_lock.page_no; HASH_DELETE(lock_t, hash, lock_sys->rec_hash, lock_rec_fold(space, page_no), in_lock); UT_LIST_REMOVE(trx_locks, trx->trx_locks, in_lock); /* Check if waiting locks in the queue can now be granted: grant locks if there are no conflicting locks ahead. */ lock = lock_rec_get_first_on_page_addr(space, page_no); while (lock != NULL) { if (lock_get_wait(lock) && !lock_rec_has_to_wait_in_queue(lock)) { /* Grant the lock */ lock_grant(lock); } lock = lock_rec_get_next_on_page(lock); } } /***************************************************************** 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. */ static void lock_rec_free_all_from_discard_page( /*================================*/ page_t* page) /* in: page to be discarded */ { ulint space; ulint page_no; lock_t* lock; lock_t* next_lock; trx_t* trx; ut_ad(mutex_own(&kernel_mutex)); space = buf_frame_get_space_id(page); page_no = buf_frame_get_page_no(page); lock = lock_rec_get_first_on_page_addr(space, page_no); while (lock != NULL) { ut_ad(lock_rec_find_set_bit(lock) == ULINT_UNDEFINED); ut_ad(!lock_get_wait(lock)); next_lock = lock_rec_get_next_on_page(lock); HASH_DELETE(lock_t, hash, lock_sys->rec_hash, lock_rec_fold(space, page_no), lock); trx = lock->trx; UT_LIST_REMOVE(trx_locks, trx->trx_locks, lock); lock = next_lock; } } /*============= RECORD LOCK MOVING AND INHERITING ===================*/ /***************************************************************** Resets the lock bits for a single record. Releases transactions waiting for lock requests here. */ void lock_rec_reset_and_release_wait( /*============================*/ rec_t* rec) /* in: record whose locks bits should be reset */ { lock_t* lock; ulint heap_no; ut_ad(mutex_own(&kernel_mutex)); heap_no = rec_get_heap_no(rec); lock = lock_rec_get_first(rec); while (lock != NULL) { if (lock_get_wait(lock)) { lock_rec_cancel(lock); } else { lock_rec_reset_nth_bit(lock, heap_no); } lock = lock_rec_get_next(rec, lock); } } /***************************************************************** Makes a record to inherit the locks 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. */ void lock_rec_inherit_to_gap( /*====================*/ rec_t* heir, /* in: record which inherits */ rec_t* rec) /* in: record from which inherited; does NOT reset the locks on this record */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); lock = lock_rec_get_first(rec); while (lock != NULL) { lock_rec_add_to_queue((lock->type_mode | LOCK_GAP) & ~LOCK_WAIT, heir, lock->index, lock->trx); lock = lock_rec_get_next(rec, lock); } } /***************************************************************** Moves the locks of a record to another record and resets the lock bits of the donating record. */ static void lock_rec_move( /*==========*/ rec_t* receiver, /* in: record which gets locks; this record must have no lock requests on it! */ rec_t* donator) /* in: record which gives locks */ { lock_t* lock; ulint heap_no; ulint type_mode; ut_ad(mutex_own(&kernel_mutex)); heap_no = rec_get_heap_no(donator); lock = lock_rec_get_first(donator); ut_ad(lock_rec_get_first(receiver) == NULL); while (lock != NULL) { type_mode = lock->type_mode; lock_rec_reset_nth_bit(lock, heap_no); if (lock_get_wait(lock)) { lock_reset_lock_and_trx_wait(lock); } /* Note that we FIRST reset the bit, and then set the lock: the function works also if donator == receiver */ lock_rec_add_to_queue(type_mode, receiver, lock->index, lock->trx); lock = lock_rec_get_next(donator, lock); } ut_ad(lock_rec_get_first(donator) == NULL); } /***************************************************************** 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. */ void lock_move_reorganize_page( /*======================*/ page_t* page, /* in: old index page, now reorganized */ page_t* old_page) /* in: copy of the old, not reorganized page */ { lock_t* lock; lock_t* old_lock; page_cur_t cur1; page_cur_t cur2; ulint old_heap_no; UT_LIST_BASE_NODE_T(lock_t) old_locks; mem_heap_t* heap = NULL; rec_t* sup; lock_mutex_enter_kernel(); lock = lock_rec_get_first_on_page(page); if (lock == NULL) { lock_mutex_exit_kernel(); return; } heap = mem_heap_create(256); /* Copy first all the locks on the page to heap and reset the bitmaps in the original locks; chain the copies of the locks using the trx_locks field in them. */ UT_LIST_INIT(old_locks); while (lock != NULL) { /* Make a copy of the lock */ old_lock = lock_rec_copy(lock, heap); UT_LIST_ADD_LAST(trx_locks, old_locks, old_lock); /* Reset bitmap of lock */ lock_rec_bitmap_reset(lock); if (lock_get_wait(lock)) { lock_reset_lock_and_trx_wait(lock); } lock = lock_rec_get_next_on_page(lock); } sup = page_get_supremum_rec(page); lock = UT_LIST_GET_FIRST(old_locks); while (lock) { /* NOTE: we copy also the locks set on the infimum and supremum 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 */ page_cur_set_before_first(page, &cur1); page_cur_set_before_first(old_page, &cur2); /* Set locks according to old locks */ for (;;) { ut_ad(0 == ut_memcmp(page_cur_get_rec(&cur1), page_cur_get_rec(&cur2), rec_get_data_size( page_cur_get_rec(&cur2)))); old_heap_no = rec_get_heap_no(page_cur_get_rec(&cur2)); if (lock_rec_get_nth_bit(lock, old_heap_no)) { /* NOTE that the old lock bitmap could be too small for the new heap number! */ lock_rec_add_to_queue(lock->type_mode, page_cur_get_rec(&cur1), lock->index, lock->trx); /* if ((page_cur_get_rec(&cur1) == sup) && lock_get_wait(lock)) { printf( "---\n--\n!!!Lock reorg: supr type %lu\n", lock->type_mode); } */ } if (page_cur_get_rec(&cur1) == sup) { break; } page_cur_move_to_next(&cur1); page_cur_move_to_next(&cur2); } /* Remember that we chained old locks on the trx_locks field: */ lock = UT_LIST_GET_NEXT(trx_locks, lock); } lock_mutex_exit_kernel(); mem_heap_free(heap); /* ut_ad(lock_rec_validate_page(buf_frame_get_space_id(page), buf_frame_get_page_no(page))); */ } /***************************************************************** Moves the explicit locks on user records to another page if a record list end is moved to another page. */ void lock_move_rec_list_end( /*===================*/ page_t* new_page, /* in: index page to move to */ page_t* page, /* in: index page */ rec_t* rec) /* in: record on page: this is the first record moved */ { lock_t* lock; page_cur_t cur1; page_cur_t cur2; ulint heap_no; rec_t* sup; ulint type_mode; lock_mutex_enter_kernel(); /* Note: when we move locks from record to record, waiting locks and possible granted gap type locks behind them are enqueued in the original order, because new elements are inserted to a hash table to the end of the hash chain, and lock_rec_add_to_queue does not reuse locks if there are waiters in the queue. */ sup = page_get_supremum_rec(page); lock = lock_rec_get_first_on_page(page); while (lock != NULL) { page_cur_position(rec, &cur1); if (page_cur_is_before_first(&cur1)) { page_cur_move_to_next(&cur1); } page_cur_set_before_first(new_page, &cur2); page_cur_move_to_next(&cur2); /* Copy lock requests on user records to new page and reset the lock bits on the old */ while (page_cur_get_rec(&cur1) != sup) { ut_ad(0 == ut_memcmp(page_cur_get_rec(&cur1), page_cur_get_rec(&cur2), rec_get_data_size( page_cur_get_rec(&cur2)))); heap_no = rec_get_heap_no(page_cur_get_rec(&cur1)); if (lock_rec_get_nth_bit(lock, heap_no)) { type_mode = lock->type_mode; lock_rec_reset_nth_bit(lock, heap_no); if (lock_get_wait(lock)) { lock_reset_lock_and_trx_wait(lock); } lock_rec_add_to_queue(type_mode, page_cur_get_rec(&cur2), lock->index, lock->trx); } page_cur_move_to_next(&cur1); page_cur_move_to_next(&cur2); } lock = lock_rec_get_next_on_page(lock); } lock_mutex_exit_kernel(); /* ut_ad(lock_rec_validate_page(buf_frame_get_space_id(page), buf_frame_get_page_no(page))); ut_ad(lock_rec_validate_page(buf_frame_get_space_id(new_page), buf_frame_get_page_no(new_page))); */ } /***************************************************************** Moves the explicit locks on user records to another page if a record list start is moved to another page. */ void lock_move_rec_list_start( /*=====================*/ page_t* new_page, /* in: index page to move to */ page_t* page, /* in: index page */ rec_t* rec, /* in: record on page: this is the first record NOT copied */ rec_t* old_end) /* in: old previous-to-last record on new_page before the records were copied */ { lock_t* lock; page_cur_t cur1; page_cur_t cur2; ulint heap_no; ulint type_mode; ut_ad(new_page); lock_mutex_enter_kernel(); lock = lock_rec_get_first_on_page(page); while (lock != NULL) { page_cur_set_before_first(page, &cur1); page_cur_move_to_next(&cur1); page_cur_position(old_end, &cur2); page_cur_move_to_next(&cur2); /* Copy lock requests on user records to new page and reset the lock bits on the old */ while (page_cur_get_rec(&cur1) != rec) { ut_ad(0 == ut_memcmp(page_cur_get_rec(&cur1), page_cur_get_rec(&cur2), rec_get_data_size( page_cur_get_rec(&cur2)))); heap_no = rec_get_heap_no(page_cur_get_rec(&cur1)); if (lock_rec_get_nth_bit(lock, heap_no)) { type_mode = lock->type_mode; lock_rec_reset_nth_bit(lock, heap_no); if (lock_get_wait(lock)) { lock_reset_lock_and_trx_wait(lock); } lock_rec_add_to_queue(type_mode, page_cur_get_rec(&cur2), lock->index, lock->trx); } page_cur_move_to_next(&cur1); page_cur_move_to_next(&cur2); } lock = lock_rec_get_next_on_page(lock); } lock_mutex_exit_kernel(); /* ut_ad(lock_rec_validate_page(buf_frame_get_space_id(page), buf_frame_get_page_no(page))); ut_ad(lock_rec_validate_page(buf_frame_get_space_id(new_page), buf_frame_get_page_no(new_page))); */ } /***************************************************************** Updates the lock table when a page is split to the right. */ void lock_update_split_right( /*====================*/ page_t* right_page, /* in: right page */ page_t* left_page) /* in: left page */ { lock_mutex_enter_kernel(); /* Move the locks on the supremum of the left page to the supremum of the right page */ lock_rec_move(page_get_supremum_rec(right_page), page_get_supremum_rec(left_page)); /* Inherit the locks to the supremum of left page from the successor of the infimum on right page */ lock_rec_inherit_to_gap(page_get_supremum_rec(left_page), page_rec_get_next(page_get_infimum_rec(right_page))); lock_mutex_exit_kernel(); } /***************************************************************** Updates the lock table when a page is merged to the right. */ void lock_update_merge_right( /*====================*/ rec_t* orig_succ, /* in: original successor of infimum on the right page before merge */ page_t* left_page) /* in: merged index page which will be discarded */ { lock_mutex_enter_kernel(); /* Inherit the locks from the supremum of the left page to the original successor of infimum on the right page, to which the left page was merged */ lock_rec_inherit_to_gap(orig_succ, page_get_supremum_rec(left_page)); /* Reset the locks on the supremum of the left page, releasing waiting transactions */ lock_rec_reset_and_release_wait(page_get_supremum_rec(left_page)); lock_rec_free_all_from_discard_page(left_page); lock_mutex_exit_kernel(); } /***************************************************************** 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. */ void lock_update_root_raise( /*===================*/ page_t* new_page, /* in: index page to which copied */ page_t* root) /* in: root page */ { lock_mutex_enter_kernel(); /* Move the locks on the supremum of the root to the supremum of new_page */ lock_rec_move(page_get_supremum_rec(new_page), page_get_supremum_rec(root)); lock_mutex_exit_kernel(); } /***************************************************************** 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! */ void lock_update_copy_and_discard( /*=========================*/ page_t* new_page, /* in: index page to which copied */ page_t* page) /* in: index page; NOT the root! */ { lock_mutex_enter_kernel(); /* Move the locks on the supremum of the old page to the supremum of new_page */ lock_rec_move(page_get_supremum_rec(new_page), page_get_supremum_rec(page)); lock_rec_free_all_from_discard_page(page); lock_mutex_exit_kernel(); } /***************************************************************** Updates the lock table when a page is split to the left. */ void lock_update_split_left( /*===================*/ page_t* right_page, /* in: right page */ page_t* left_page) /* in: left page */ { lock_mutex_enter_kernel(); /* Inherit the locks to the supremum of the left page from the successor of the infimum on the right page */ lock_rec_inherit_to_gap(page_get_supremum_rec(left_page), page_rec_get_next(page_get_infimum_rec(right_page))); lock_mutex_exit_kernel(); } /***************************************************************** Updates the lock table when a page is merged to the left. */ void lock_update_merge_left( /*===================*/ page_t* left_page, /* in: left page to which merged */ rec_t* orig_pred, /* in: original predecessor of supremum on the left page before merge */ page_t* right_page) /* in: merged index page which will be discarded */ { lock_mutex_enter_kernel(); if (page_rec_get_next(orig_pred) != page_get_supremum_rec(left_page)) { /* Inherit the locks on the supremum of the left page to the first record which was moved from the right page */ lock_rec_inherit_to_gap(page_rec_get_next(orig_pred), page_get_supremum_rec(left_page)); /* Reset the locks on the supremum of the left page, releasing waiting transactions */ lock_rec_reset_and_release_wait(page_get_supremum_rec( left_page)); } /* Move the locks from the supremum of right page to the supremum of the left page */ lock_rec_move(page_get_supremum_rec(left_page), page_get_supremum_rec(right_page)); lock_rec_free_all_from_discard_page(right_page); lock_mutex_exit_kernel(); } /***************************************************************** Resets the original locks on heir and replaces them with gap type locks inherited from rec. */ void lock_rec_reset_and_inherit_gap_locks( /*=================================*/ rec_t* heir, /* in: heir record */ rec_t* rec) /* in: record */ { mutex_enter(&kernel_mutex); lock_rec_reset_and_release_wait(heir); lock_rec_inherit_to_gap(heir, rec); mutex_exit(&kernel_mutex); } /***************************************************************** Updates the lock table when a page is discarded. */ void lock_update_discard( /*================*/ rec_t* heir, /* in: record which will inherit the locks */ page_t* page) /* in: index page which will be discarded */ { rec_t* rec; lock_mutex_enter_kernel(); if (NULL == lock_rec_get_first_on_page(page)) { /* No locks exist on page, nothing to do */ lock_mutex_exit_kernel(); return; } /* Inherit all the locks on the page to the record and reset all the locks on the page */ rec = page_get_infimum_rec(page); for (;;) { lock_rec_inherit_to_gap(heir, rec); /* Reset the locks on rec, releasing waiting transactions */ lock_rec_reset_and_release_wait(rec); if (rec == page_get_supremum_rec(page)) { break; } rec = page_rec_get_next(rec); } lock_rec_free_all_from_discard_page(page); lock_mutex_exit_kernel(); } /***************************************************************** Updates the lock table when a new user record is inserted. */ void lock_update_insert( /*===============*/ rec_t* rec) /* in: the inserted record */ { lock_mutex_enter_kernel(); /* Inherit the locks for rec, in gap mode, from the next record */ lock_rec_inherit_to_gap(rec, page_rec_get_next(rec)); lock_mutex_exit_kernel(); } /***************************************************************** Updates the lock table when a record is removed. */ void lock_update_delete( /*===============*/ rec_t* rec) /* in: the record to be removed */ { lock_mutex_enter_kernel(); /* Let the next record inherit the locks from rec, in gap mode */ lock_rec_inherit_to_gap(page_rec_get_next(rec), rec); /* Reset the lock bits on rec and release waiting transactions */ lock_rec_reset_and_release_wait(rec); lock_mutex_exit_kernel(); } /************************************************************************* 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. */ void lock_rec_store_on_page_infimum( /*===========================*/ rec_t* rec) /* in: record whose lock state is stored on the infimum record of the same page; lock bits are reset on the record */ { page_t* page; page = buf_frame_align(rec); lock_mutex_enter_kernel(); lock_rec_move(page_get_infimum_rec(page), rec); lock_mutex_exit_kernel(); } /************************************************************************* Restores the state of explicit lock requests on a single record, where the state was stored on the infimum of the page. */ void lock_rec_restore_from_page_infimum( /*===============================*/ rec_t* rec, /* in: record whose lock state is restored */ page_t* page) /* in: page (rec is not necessarily on this page) whose infimum stored the lock state; lock bits are reset on the infimum */ { lock_mutex_enter_kernel(); lock_rec_move(rec, page_get_infimum_rec(page)); lock_mutex_exit_kernel(); } /*=========== DEADLOCK CHECKING ======================================*/ /************************************************************************ Checks if a lock request results in a deadlock. */ static ibool lock_deadlock_occurs( /*=================*/ /* out: TRUE if a deadlock was detected */ lock_t* lock, /* in: lock the transaction is requesting */ trx_t* trx) /* in: transaction */ { dict_table_t* table; dict_index_t* index; ibool ret; ut_ad(trx && lock); ut_ad(mutex_own(&kernel_mutex)); ret = lock_deadlock_recursive(trx, trx, lock); if (ret) { if (lock_get_type(lock) == LOCK_TABLE) { table = lock->un_member.tab_lock.table; index = NULL; } else { index = lock->index; table = index->table; } /* sess_raise_error_low(trx, DB_DEADLOCK, lock->type_mode, table, index, NULL, NULL, NULL); */ } return(ret); } /************************************************************************ Looks recursively for a deadlock. */ static ibool lock_deadlock_recursive( /*====================*/ /* out: TRUE if a deadlock was detected */ trx_t* start, /* in: recursion starting point */ trx_t* trx, /* in: a transaction waiting for a lock */ lock_t* wait_lock) /* in: the lock trx is waiting to be granted */ { lock_t* lock; ulint bit_no; trx_t* lock_trx; ut_a(trx && start && wait_lock); ut_ad(mutex_own(&kernel_mutex)); lock = wait_lock; if (lock_get_type(wait_lock) == LOCK_REC) { bit_no = lock_rec_find_set_bit(wait_lock); ut_a(bit_no != ULINT_UNDEFINED); } /* Look at the locks ahead of wait_lock in the lock queue */ for (;;) { if (lock_get_type(lock) == LOCK_TABLE) { lock = UT_LIST_GET_PREV(un_member.tab_lock.locks, lock); } else { ut_ad(lock_get_type(lock) == LOCK_REC); lock = lock_rec_get_prev(lock, bit_no); } if (lock == NULL) { return(FALSE); } if (lock_has_to_wait(wait_lock, lock)) { lock_trx = lock->trx; if (lock_trx == start) { if (lock_print_waits) { printf("Deadlock detected\n"); } return(TRUE); } if (lock_trx->que_state == TRX_QUE_LOCK_WAIT) { /* Another trx ahead has requested lock in an incompatible mode, and is itself waiting for a lock */ if (lock_deadlock_recursive(start, lock_trx, lock_trx->wait_lock)) { return(TRUE); } } } }/* end of the 'for (;;)'-loop */ } /*========================= TABLE LOCKS ==============================*/ /************************************************************************* 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. */ UNIV_INLINE lock_t* lock_table_create( /*==============*/ /* out, own: new lock object, or NULL if out of memory */ dict_table_t* table, /* in: database table in dictionary cache */ ulint type_mode,/* in: lock mode possibly ORed with LOCK_WAIT */ trx_t* trx) /* in: trx */ { lock_t* lock; ut_ad(table && trx); ut_ad(mutex_own(&kernel_mutex)); lock = mem_heap_alloc(trx->lock_heap, sizeof(lock_t)); if (lock == NULL) { return(NULL); } UT_LIST_ADD_LAST(trx_locks, trx->trx_locks, lock); lock->type_mode = type_mode | LOCK_TABLE; lock->trx = trx; lock->un_member.tab_lock.table = table; UT_LIST_ADD_LAST(un_member.tab_lock.locks, table->locks, lock); if (type_mode & LOCK_WAIT) { lock_set_lock_and_trx_wait(lock, trx); } return(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. */ UNIV_INLINE void lock_table_remove_low( /*==================*/ lock_t* lock) /* in: table lock */ { dict_table_t* table; trx_t* trx; ut_ad(mutex_own(&kernel_mutex)); table = lock->un_member.tab_lock.table; trx = lock->trx; UT_LIST_REMOVE(trx_locks, trx->trx_locks, lock); UT_LIST_REMOVE(un_member.tab_lock.locks, table->locks, lock); } /************************************************************************* Enqueues a waiting request for a table lock which cannot be granted immediately. Checks for deadlocks. */ ulint lock_table_enqueue_waiting( /*=======================*/ /* out: DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint mode, /* in: lock mode this transaction is requesting */ dict_table_t* table, /* in: table */ que_thr_t* thr) /* in: query thread */ { lock_t* lock; trx_t* trx; ut_ad(mutex_own(&kernel_mutex)); /* Test if there already is some other reason to suspend thread: we do not enqueue a lock request if the query thread should be stopped anyway */ if (que_thr_stop(thr)) { return(DB_QUE_THR_SUSPENDED); } trx = thr_get_trx(thr); /* Enqueue the lock request that will wait to be granted */ lock = lock_table_create(table, mode | LOCK_WAIT, trx); /* Check if a deadlock occurs: if yes, remove the lock request and return an error code */ if (lock_deadlock_occurs(lock, trx)) { lock_reset_lock_and_trx_wait(lock); lock_table_remove_low(lock); return(DB_DEADLOCK); } trx->que_state = TRX_QUE_LOCK_WAIT; ut_a(que_thr_stop(thr)); return(DB_LOCK_WAIT); } /************************************************************************* Checks if other transactions have an incompatible mode lock request in the lock queue. */ UNIV_INLINE ibool lock_table_other_has_incompatible( /*==============================*/ trx_t* trx, /* in: transaction, or NULL if all transactions should be included */ ulint wait, /* in: LOCK_WAIT if also waiting locks are taken into account, or 0 if not */ dict_table_t* table, /* in: table */ ulint mode) /* in: lock mode */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); lock = UT_LIST_GET_LAST(table->locks); while (lock != NULL) { if ((lock->trx != trx) && (!lock_mode_compatible(lock_get_mode(lock), mode)) && (wait || !(lock_get_wait(lock)))) { return(TRUE); } lock = UT_LIST_GET_PREV(un_member.tab_lock.locks, lock); } return(FALSE); } /************************************************************************* Locks the specified database table in the mode given. If the lock cannot be granted immediately, the query thread is put to wait. */ ulint lock_table( /*=======*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ dict_table_t* table, /* in: database table in dictionary cache */ ulint mode, /* in: lock mode */ que_thr_t* thr) /* in: query thread */ { trx_t* trx; ulint err; ut_ad(table && thr); if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } trx = thr_get_trx(thr); lock_mutex_enter_kernel(); /* Look for stronger locks the same trx already has on the table */ if (lock_table_has(trx, table, mode)) { lock_mutex_exit_kernel(); return(DB_SUCCESS); } /* We have to check if the new lock is compatible with any locks other transactions have in the table lock queue. */ if (lock_table_other_has_incompatible(trx, LOCK_WAIT, table, mode)) { /* Another trx has request on the table in an incompatible mode: this trx must wait */ err = lock_table_enqueue_waiting(mode, table, thr); lock_mutex_exit_kernel(); return(err); } lock_table_create(table, mode, trx); lock_mutex_exit_kernel(); return(DB_SUCCESS); } /************************************************************************* Checks if there are any locks set on the table. */ ibool lock_is_on_table( /*=============*/ /* out: TRUE if there are lock(s) */ dict_table_t* table) /* in: database table in dictionary cache */ { ibool ret; ut_ad(table); lock_mutex_enter_kernel(); if (UT_LIST_GET_LAST(table->locks)) { ret = TRUE; } else { ret = FALSE; } lock_mutex_exit_kernel(); return(ret); } /************************************************************************* Checks if a waiting table lock request still has to wait in a queue. */ static ibool lock_table_has_to_wait_in_queue( /*============================*/ /* out: TRUE if still has to wait */ lock_t* wait_lock) /* in: waiting table lock */ { dict_table_t* table; lock_t* lock; ut_ad(lock_get_wait(wait_lock)); table = wait_lock->un_member.tab_lock.table; lock = UT_LIST_GET_FIRST(table->locks); while (lock != wait_lock) { if (lock_has_to_wait(wait_lock, lock)) { return(TRUE); } lock = UT_LIST_GET_NEXT(un_member.tab_lock.locks, lock); } return(FALSE); } /***************************************************************** 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. */ void lock_table_dequeue( /*===============*/ lock_t* in_lock)/* in: table lock object; transactions waiting behind will get their lock requests granted, if they are now qualified to it */ { lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); ut_ad(lock_get_type(in_lock) == LOCK_TABLE); lock = UT_LIST_GET_NEXT(un_member.tab_lock.locks, in_lock); lock_table_remove_low(in_lock); /* Check if waiting locks in the queue can now be granted: grant locks if there are no conflicting locks ahead. */ while (lock != NULL) { if (lock_get_wait(lock) && !lock_table_has_to_wait_in_queue(lock)) { /* Grant the lock */ lock_grant(lock); } lock = UT_LIST_GET_NEXT(un_member.tab_lock.locks, lock); } } /*=========================== LOCK RELEASE ==============================*/ /************************************************************************* Releases transaction locks, and releases possible other transactions waiting because of these locks. */ void lock_release_off_kernel( /*====================*/ trx_t* trx) /* in: transaction */ { ulint count; lock_t* lock; ut_ad(mutex_own(&kernel_mutex)); lock = UT_LIST_GET_LAST(trx->trx_locks); count = 0; while (lock != NULL) { count++; if (lock_get_type(lock) == LOCK_REC) { lock_rec_dequeue_from_page(lock); } else { ut_ad(lock_get_type(lock) == LOCK_TABLE); lock_table_dequeue(lock); } if (count == LOCK_RELEASE_KERNEL_INTERVAL) { /* Release the kernel mutex for a while, so that we do not monopolize it */ lock_mutex_exit_kernel(); lock_mutex_enter_kernel(); count = 0; } lock = UT_LIST_GET_LAST(trx->trx_locks); } mem_heap_empty(trx->lock_heap); } /*===================== VALIDATION AND DEBUGGING ====================*/ /************************************************************************* Prints info of a table lock. */ void lock_table_print( /*=============*/ lock_t* lock) /* in: table type lock */ { ut_ad(mutex_own(&kernel_mutex)); ut_a(lock_get_type(lock) == LOCK_TABLE); printf("\nTABLE LOCK table %s trx id %lu %lu", lock->un_member.tab_lock.table->name, (lock->trx)->id.high, (lock->trx)->id.low); if (lock_get_mode(lock) == LOCK_S) { printf(" lock mode S"); } else if (lock_get_mode(lock) == LOCK_X) { printf(" lock_mode X"); } else if (lock_get_mode(lock) == LOCK_IS) { printf(" lock_mode IS"); } else if (lock_get_mode(lock) == LOCK_IX) { printf(" lock_mode IX"); } else { ut_error; } if (lock_get_wait(lock)) { printf(" waiting"); } printf("\n"); } /************************************************************************* Prints info of a record lock. */ void lock_rec_print( /*===========*/ lock_t* lock) /* in: record type lock */ { page_t* page; ulint space; ulint page_no; ulint i; mtr_t mtr; ut_ad(mutex_own(&kernel_mutex)); ut_a(lock_get_type(lock) == LOCK_REC); space = lock->un_member.rec_lock.space; page_no = lock->un_member.rec_lock.page_no; printf("\nRECORD LOCKS space id %lu page no %lu n bits %lu", space, page_no, lock_rec_get_n_bits(lock)); printf(" index %s trx id %lu %lu", (lock->index)->name, (lock->trx)->id.high, (lock->trx)->id.low); if (lock_get_mode(lock) == LOCK_S) { printf(" lock mode S"); } else if (lock_get_mode(lock) == LOCK_X) { printf(" lock_mode X"); } else { ut_error; } if (lock_rec_get_gap(lock)) { printf(" gap type lock"); } if (lock_get_wait(lock)) { printf(" waiting"); } printf("\n"); mtr_start(&mtr); /* If the page is not in the buffer pool, we cannot load it because we have the kernel mutex and ibuf operations would break the latching order */ page = buf_page_get_gen(space, page_no, RW_NO_LATCH, NULL, BUF_GET_IF_IN_POOL, #ifdef UNIV_SYNC_DEBUG __FILE__, __LINE__, #endif &mtr); if (page) { page = buf_page_get_nowait(space, page_no, RW_S_LATCH, &mtr); } if (page) { buf_page_dbg_add_level(page, SYNC_NO_ORDER_CHECK); } for (i = 0; i < lock_rec_get_n_bits(lock); i++) { if (lock_rec_get_nth_bit(lock, i)) { printf("Record lock, heap no %lu ", i); if (page) { rec_print(page_find_rec_with_heap_no(page, i)); } printf("\n"); } } mtr_commit(&mtr); } /************************************************************************* Calculates the number of record lock structs in the record lock hash table. */ static ulint lock_get_n_rec_locks(void) /*======================*/ { lock_t* lock; ulint n_locks = 0; ulint i; ut_ad(mutex_own(&kernel_mutex)); for (i = 0; i < hash_get_n_cells(lock_sys->rec_hash); i++) { lock = HASH_GET_FIRST(lock_sys->rec_hash, i); while (lock) { n_locks++; lock = HASH_GET_NEXT(hash, lock); } } return(n_locks); } /************************************************************************* Prints info of locks for all transactions. */ void lock_print_info(void) /*=================*/ { lock_t* lock; trx_t* trx; ulint space; ulint page_no; page_t* page; ibool load_page_first = TRUE; ulint nth_trx = 0; ulint nth_lock = 0; ulint i; mtr_t mtr; lock_mutex_enter_kernel(); printf("------------------------------------\n"); printf("LOCK INFO:\n"); printf("Number of locks in the record hash table %lu\n", lock_get_n_rec_locks()); loop: trx = UT_LIST_GET_FIRST(trx_sys->trx_list); i = 0; while (trx && (i < nth_trx)) { trx = UT_LIST_GET_NEXT(trx_list, trx); i++; } if (trx == NULL) { lock_mutex_exit_kernel(); lock_validate(); return; } if (nth_lock == 0) { printf("\nLOCKS FOR TRANSACTION ID %lu %lu\n", trx->id.high, trx->id.low); } i = 0; lock = UT_LIST_GET_FIRST(trx->trx_locks); while (lock && (i < nth_lock)) { lock = UT_LIST_GET_NEXT(trx_locks, lock); i++; } if (lock == NULL) { nth_trx++; nth_lock = 0; goto loop; } if (lock_get_type(lock) == LOCK_REC) { space = lock->un_member.rec_lock.space; page_no = lock->un_member.rec_lock.page_no; if (load_page_first) { lock_mutex_exit_kernel(); mtr_start(&mtr); page = buf_page_get_with_no_latch(space, page_no, &mtr); mtr_commit(&mtr); load_page_first = FALSE; lock_mutex_enter_kernel(); goto loop; } lock_rec_print(lock); } else { ut_ad(lock_get_type(lock) == LOCK_TABLE); lock_table_print(lock); } load_page_first = TRUE; nth_lock++; goto loop; } /************************************************************************* Validates the lock queue on a table. */ ibool lock_table_queue_validate( /*======================*/ /* out: TRUE if ok */ dict_table_t* table) /* in: table */ { lock_t* lock; ibool is_waiting; ut_ad(mutex_own(&kernel_mutex)); is_waiting = FALSE; lock = UT_LIST_GET_FIRST(table->locks); while (lock) { ut_a(((lock->trx)->conc_state == TRX_ACTIVE) || ((lock->trx)->conc_state == TRX_COMMITTED_IN_MEMORY)); if (!lock_get_wait(lock)) { ut_a(!is_waiting); ut_a(!lock_table_other_has_incompatible(lock->trx, 0, table, lock_get_mode(lock))); } else { is_waiting = TRUE; ut_a(lock_table_has_to_wait_in_queue(lock)); } lock = UT_LIST_GET_NEXT(un_member.tab_lock.locks, lock); } return(TRUE); } /************************************************************************* Validates the lock queue on a single record. */ ibool lock_rec_queue_validate( /*====================*/ /* out: TRUE if ok */ rec_t* rec, /* in: record to look at */ dict_index_t* index) /* in: index, or NULL if not known */ { trx_t* impl_trx; lock_t* lock; ibool is_waiting; ut_a(rec); lock_mutex_enter_kernel(); if (page_rec_is_supremum(rec) || page_rec_is_infimum(rec)) { lock = lock_rec_get_first(rec); while (lock) { ut_a(lock->trx->conc_state == TRX_ACTIVE || lock->trx->conc_state == TRX_COMMITTED_IN_MEMORY); ut_a(trx_in_trx_list(lock->trx)); if (lock_get_wait(lock)) { ut_a(lock_rec_has_to_wait_in_queue(lock)); } if (index) { ut_a(lock->index == index); } lock = lock_rec_get_next(rec, lock); } lock_mutex_exit_kernel(); return(TRUE); } if (index && index->type & DICT_CLUSTERED) { impl_trx = lock_clust_rec_some_has_impl(rec, index); if (impl_trx && lock_rec_other_has_expl_req(LOCK_S, 0, LOCK_WAIT, rec, impl_trx)) { ut_a(lock_rec_has_expl(LOCK_X, rec, impl_trx)); } } if (index && !(index->type & DICT_CLUSTERED)) { /* The kernel mutex may get released temporarily in the next function call: we have to release lock table mutex to obey the latching order */ impl_trx = lock_sec_rec_some_has_impl_off_kernel(rec, index); if (impl_trx && lock_rec_other_has_expl_req(LOCK_S, 0, LOCK_WAIT, rec, impl_trx)) { ut_a(lock_rec_has_expl(LOCK_X, rec, impl_trx)); } } is_waiting = FALSE; lock = lock_rec_get_first(rec); while (lock) { ut_a(lock->trx->conc_state == TRX_ACTIVE || lock->trx->conc_state == TRX_COMMITTED_IN_MEMORY); ut_a(trx_in_trx_list(lock->trx)); if (index) { ut_a(lock->index == index); } if (!lock_rec_get_gap(lock) && !lock_get_wait(lock)) { ut_a(!is_waiting); if (lock_get_mode(lock) == LOCK_S) { ut_a(!lock_rec_other_has_expl_req(LOCK_X, 0, 0, rec, lock->trx)); } else { ut_a(!lock_rec_other_has_expl_req(LOCK_S, 0, 0, rec, lock->trx)); } } else if (lock_get_wait(lock) && !lock_rec_get_gap(lock)) { is_waiting = TRUE; ut_a(lock_rec_has_to_wait_in_queue(lock)); } lock = lock_rec_get_next(rec, lock); } lock_mutex_exit_kernel(); return(TRUE); } /************************************************************************* Validates the record lock queues on a page. */ ibool lock_rec_validate_page( /*===================*/ /* out: TRUE if ok */ ulint space, /* in: space id */ ulint page_no)/* in: page number */ { dict_index_t* index; page_t* page; lock_t* lock; rec_t* rec; ulint nth_lock = 0; ulint nth_bit = 0; ulint i; mtr_t mtr; ut_ad(!mutex_own(&kernel_mutex)); mtr_start(&mtr); page = buf_page_get(space, page_no, RW_X_LATCH, &mtr); buf_page_dbg_add_level(page, SYNC_NO_ORDER_CHECK); lock_mutex_enter_kernel(); loop: lock = lock_rec_get_first_on_page_addr(space, page_no); if (!lock) { goto function_exit; } for (i = 0; i < nth_lock; i++) { lock = lock_rec_get_next_on_page(lock); if (!lock) { goto function_exit; } } ut_a(trx_in_trx_list(lock->trx)); ut_a(((lock->trx)->conc_state == TRX_ACTIVE) || ((lock->trx)->conc_state == TRX_COMMITTED_IN_MEMORY)); for (i = nth_bit; i < lock_rec_get_n_bits(lock); i++) { if ((i == 1) || lock_rec_get_nth_bit(lock, i)) { index = lock->index; rec = page_find_rec_with_heap_no(page, i); printf("Validating %lu %lu\n", space, page_no); lock_mutex_exit_kernel(); lock_rec_queue_validate(rec, index); lock_mutex_enter_kernel(); nth_bit = i + 1; goto loop; } } nth_bit = 0; nth_lock++; goto loop; function_exit: lock_mutex_exit_kernel(); mtr_commit(&mtr); return(TRUE); } /************************************************************************* Validates the lock system. */ ibool lock_validate(void) /*===============*/ /* out: TRUE if ok */ { lock_t* lock; trx_t* trx; dulint limit; ulint space; ulint page_no; ulint i; lock_mutex_enter_kernel(); trx = UT_LIST_GET_FIRST(trx_sys->trx_list); while (trx) { lock = UT_LIST_GET_FIRST(trx->trx_locks); while (lock) { if (lock_get_type(lock) == LOCK_TABLE) { lock_table_queue_validate( lock->un_member.tab_lock.table); } lock = UT_LIST_GET_NEXT(trx_locks, lock); } trx = UT_LIST_GET_NEXT(trx_list, trx); } for (i = 0; i < hash_get_n_cells(lock_sys->rec_hash); i++) { limit = ut_dulint_zero; for (;;) { lock = HASH_GET_FIRST(lock_sys->rec_hash, i); while (lock) { ut_a(trx_in_trx_list(lock->trx)); space = lock->un_member.rec_lock.space; page_no = lock->un_member.rec_lock.page_no; if (ut_dulint_cmp( ut_dulint_create(space, page_no), limit) >= 0) { break; } lock = HASH_GET_NEXT(hash, lock); } if (!lock) { break; } lock_mutex_exit_kernel(); lock_rec_validate_page(space, page_no); lock_mutex_enter_kernel(); limit = ut_dulint_create(space, page_no + 1); } } lock_mutex_exit_kernel(); return(TRUE); } /*============ RECORD LOCK CHECKS FOR ROW OPERATIONS ====================*/ /************************************************************************* 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. */ ulint lock_rec_insert_check_and_lock( /*===========================*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ rec_t* rec, /* in: record after which to insert */ dict_index_t* index, /* in: index */ que_thr_t* thr, /* in: query thread */ ibool* inherit)/* out: set to TRUE if the new inserted record maybe should inherit LOCK_GAP type locks from the successor record */ { rec_t* next_rec; trx_t* trx; lock_t* lock; ulint err; if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } ut_ad(rec); trx = thr_get_trx(thr); next_rec = page_rec_get_next(rec); *inherit = FALSE; lock_mutex_enter_kernel(); ut_ad(lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); lock = lock_rec_get_first(next_rec); if (lock == NULL) { /* We optimize CPU time usage in the simplest case */ lock_mutex_exit_kernel(); if (!(index->type & DICT_CLUSTERED)) { /* Update the page max trx id field */ page_update_max_trx_id(buf_frame_align(rec), thr_get_trx(thr)->id); } return(DB_SUCCESS); } *inherit = TRUE; /* If another transaction has an explicit lock request, gap or not, waiting or granted, on the successor, the insert has to wait */ if (lock_rec_other_has_expl_req(LOCK_S, LOCK_GAP, LOCK_WAIT, next_rec, trx)) { err = lock_rec_enqueue_waiting(LOCK_X | LOCK_GAP, next_rec, index, thr); } else { err = DB_SUCCESS; } lock_mutex_exit_kernel(); if (!(index->type & DICT_CLUSTERED) && (err == DB_SUCCESS)) { /* Update the page max trx id field */ page_update_max_trx_id(buf_frame_align(rec), thr_get_trx(thr)->id); } ut_ad(lock_rec_queue_validate(next_rec, index)); return(err); } /************************************************************************* If a transaction has an implicit x-lock on a record, but no explicit x-lock set on the record, sets one for it. NOTE that in the case of a secondary index, the kernel mutex may get temporarily released. */ static void lock_rec_convert_impl_to_expl( /*==========================*/ rec_t* rec, /* in: user record on page */ dict_index_t* index) /* in: index of record */ { trx_t* impl_trx; ut_ad(mutex_own(&kernel_mutex)); ut_ad(page_rec_is_user_rec(rec)); if (index->type & DICT_CLUSTERED) { impl_trx = lock_clust_rec_some_has_impl(rec, index); } else { impl_trx = lock_sec_rec_some_has_impl_off_kernel(rec, index); } if (impl_trx) { /* If the transaction has no explicit x-lock set on the record, set one for it */ if (!lock_rec_has_expl(LOCK_X, rec, impl_trx)) { lock_rec_add_to_queue(LOCK_REC | LOCK_X, rec, index, impl_trx); } } } /************************************************************************* 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. */ ulint lock_clust_rec_modify_check_and_lock( /*=================================*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ rec_t* rec, /* in: record which should be modified */ dict_index_t* index, /* in: clustered index */ que_thr_t* thr) /* in: query thread */ { trx_t* trx; ulint err; if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } ut_ad(index->type & DICT_CLUSTERED); trx = thr_get_trx(thr); lock_mutex_enter_kernel(); ut_ad(lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); /* If a transaction has no explicit x-lock set on the record, set one for it */ lock_rec_convert_impl_to_expl(rec, index); err = lock_rec_lock(TRUE, LOCK_X, rec, index, thr); lock_mutex_exit_kernel(); ut_ad(lock_rec_queue_validate(rec, index)); return(err); } /************************************************************************* Checks if locks of other transactions prevent an immediate modify (delete mark or delete unmark) of a secondary index record. */ ulint lock_sec_rec_modify_check_and_lock( /*===============================*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ rec_t* 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 */ dict_index_t* index, /* in: secondary index */ que_thr_t* thr) /* in: query thread */ { ulint err; if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } ut_ad(!(index->type & DICT_CLUSTERED)); /* Another transaction cannot have an implicit lock on the record, because when we come here, we already have modified the clustered index record, and this would not have been possible if another active transaction had modified this secondary index record. */ lock_mutex_enter_kernel(); ut_ad(lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); err = lock_rec_lock(TRUE, LOCK_X, rec, index, thr); lock_mutex_exit_kernel(); ut_ad(lock_rec_queue_validate(rec, index)); if (err == DB_SUCCESS) { /* Update the page max trx id field */ page_update_max_trx_id(buf_frame_align(rec), thr_get_trx(thr)->id); } return(err); } /************************************************************************* Like the counterpart for a clustered index below, but now we read a secondary index record. */ ulint lock_sec_rec_read_check_and_lock( /*=============================*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ rec_t* rec, /* in: user record or page supremum record which should be read or passed over by a read cursor */ dict_index_t* index, /* in: secondary index */ ulint 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 */ que_thr_t* thr) /* in: query thread */ { ulint err; ut_ad(!(index->type & DICT_CLUSTERED)); ut_ad(page_rec_is_user_rec(rec) || page_rec_is_supremum(rec)); if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } lock_mutex_enter_kernel(); ut_ad((mode != LOCK_X) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); ut_ad((mode != LOCK_S) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IS)); /* Some transaction may have an implicit x-lock on the record only if the max trx id for the page >= min trx id for the trx list or a database recovery is running. */ if (((ut_dulint_cmp(page_get_max_trx_id(buf_frame_align(rec)), trx_list_get_min_trx_id()) >= 0) || recv_recovery_is_on()) && !page_rec_is_supremum(rec)) { lock_rec_convert_impl_to_expl(rec, index); } err = lock_rec_lock(FALSE, mode, rec, index, thr); lock_mutex_exit_kernel(); ut_ad(lock_rec_queue_validate(rec, index)); return(err); } /************************************************************************* 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. */ ulint lock_clust_rec_read_check_and_lock( /*===============================*/ /* out: DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */ ulint flags, /* in: if BTR_NO_LOCKING_FLAG bit is set, does nothing */ rec_t* rec, /* in: user record or page supremum record which should be read or passed over by a read cursor */ dict_index_t* index, /* in: clustered index */ ulint 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 */ que_thr_t* thr) /* in: query thread */ { ulint err; ut_ad(index->type & DICT_CLUSTERED); ut_ad(page_rec_is_user_rec(rec) || page_rec_is_supremum(rec)); if (flags & BTR_NO_LOCKING_FLAG) { return(DB_SUCCESS); } lock_mutex_enter_kernel(); ut_ad((mode != LOCK_X) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IX)); ut_ad((mode != LOCK_S) || lock_table_has(thr_get_trx(thr), index->table, LOCK_IS)); if (!page_rec_is_supremum(rec)) { lock_rec_convert_impl_to_expl(rec, index); } err = lock_rec_lock(FALSE, mode, rec, index, thr); lock_mutex_exit_kernel(); ut_ad(lock_rec_queue_validate(rec, index)); return(err); }