lock0lock.c

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		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 || mode1 == LOCK_AUTO_INC);
	ut_ad(mode2 == LOCK_X || mode2 == LOCK_S || mode2 == LOCK_IX
				|| mode2 == LOCK_IS || mode2 == LOCK_AUTO_INC);

	if (mode1 == LOCK_S && (mode2 == LOCK_IS || mode2 == LOCK_S)) {

		return(TRUE);

	} else if (mode1 == LOCK_X) {

		return(FALSE);

	} else if (mode1 == LOCK_AUTO_INC && (mode2 == LOCK_IS
					  	|| mode2 == LOCK_IX)) {
		return(TRUE);

	} else if (mode1 == LOCK_IS && (mode2 == LOCK_IS
					  	|| mode2 == LOCK_IX
					  	|| mode2 == LOCK_AUTO_INC
					  	|| mode2 == LOCK_S)) {
		return(TRUE);

	} else if (mode1 == LOCK_IX && (mode2 == LOCK_IS
					  	|| mode2 == LOCK_AUTO_INC
					  	|| mode2 == LOCK_IX)) {
		return(TRUE);
	}

	return(FALSE);
}

/*************************************************************************
Checks if a lock request for a new lock has to wait for request lock2. */
UNIV_INLINE
ibool
lock_rec_has_to_wait(
/*=================*/
			/* out: TRUE if new lock has to wait for lock2 to be
			removed */
	trx_t*	trx,	/* in: trx of new lock */
	ulint	type_mode,/* in: precise mode of the new lock to set:
			LOCK_S or LOCK_X, possibly ORed to
			LOCK_GAP or LOCK_REC_NOT_GAP, LOCK_INSERT_INTENTION */
	lock_t*	lock2,	/* in: another record lock; NOTE that it is assumed
			that this has a lock bit set on the same record as
			in the new lock we are setting */
	ibool lock_is_on_supremum)  /* in: TRUE if we are setting the lock
			on the 'supremum' record of an index
			page: we know then that the lock request
			is really for a 'gap' type lock */
{
	ut_ad(trx && lock2);
	ut_ad(lock_get_type(lock2) == LOCK_REC);

	if (trx != lock2->trx
	    && !lock_mode_compatible(LOCK_MODE_MASK & type_mode,
				     		lock_get_mode(lock2))) {

		/* We have somewhat complex rules when gap type record locks
		cause waits */

		if ((lock_is_on_supremum || (type_mode & LOCK_GAP))
		    && !(type_mode & LOCK_INSERT_INTENTION)) {

			/* Gap type locks without LOCK_INSERT_INTENTION flag
			do not need to wait for anything. This is because 
			different users can have conflicting lock types 
			on gaps. */
						  
			return(FALSE);
		}
		
		if (!(type_mode & LOCK_INSERT_INTENTION)
						&& lock_rec_get_gap(lock2)) {

			/* Record lock (LOCK_ORDINARY or LOCK_REC_NOT_GAP
			does not need to wait for a gap type lock */

			return(FALSE);
		}

		if ((type_mode & LOCK_GAP)
					&& lock_rec_get_rec_not_gap(lock2)) {
		
			/* Lock on gap does not need to wait for
			a LOCK_REC_NOT_GAP type lock */

			return(FALSE);
		}

		if (lock_rec_get_insert_intention(lock2)) {

			/* No lock request needs to wait for an insert
			intention lock to be removed. This is ok since our
			rules allow conflicting locks on gaps. This eliminates
			a spurious deadlock caused by a next-key lock waiting
			for an insert intention lock; when the insert
			intention lock was granted, the insert deadlocked on
			the waiting next-key lock.

			Also, insert intention locks do not disturb each
			other. */
				
			return(FALSE);
		}

		return(TRUE);
	}

	return(FALSE);
}

/*************************************************************************
Checks if a lock request lock1 has to wait for request lock2. */
static
ibool
lock_has_to_wait(
/*=============*/
			/* out: TRUE if lock1 has to wait for lock2 to be
			removed */
	lock_t*	lock1,	/* in: waiting 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
			the locks are record locks */
{
	ut_ad(lock1 && lock2);

	if (lock1->trx != lock2->trx
			&& !lock_mode_compatible(lock_get_mode(lock1),
				     		lock_get_mode(lock2))) {
		if (lock_get_type(lock1) == LOCK_REC) {
			ut_ad(lock_get_type(lock2) == LOCK_REC);

			/* If this lock request is for a supremum record
			then the second bit on the lock bitmap is set */
			
			return(lock_rec_has_to_wait(lock1->trx,
					lock1->type_mode, lock2,
					lock_rec_get_nth_bit(lock1,1)));
		}

		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);
}

/**************************************************************************
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;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(lock_get_type(lock) == LOCK_REC);

	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;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */

	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;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	
	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 */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(lock_get_type(lock) == LOCK_REC);

	if (page_rec_is_comp(rec)) {
		do {
			lock = lock_rec_get_next_on_page(lock);
		} while (lock && !lock_rec_get_nth_bit(lock,
					rec_get_heap_no(rec, TRUE)));
	} else {
		do {
			lock = lock_rec_get_next_on_page(lock);
		} while (lock && !lock_rec_get_nth_bit(lock,
					rec_get_heap_no(rec, FALSE)));
	}

	return(lock);
}

/*************************************************************************
Gets the first explicit lock request on a record. */
UNIV_INLINE