/******************************************************
Lock queue iterator type and function prototypes.

(c) 2007 Innobase Oy

Created July 16, 2007 Vasil Dimov
*******************************************************/

#ifndef lock0iter_h
#define lock0iter_h

#include "univ.i"
#include "lock0types.h"

typedef struct lock_queue_iterator_struct {
	lock_t*	current_lock;
	/* In case this is a record lock queue (not table lock queue)
	then bit_no is the record number within the heap in which the
	record is stored. */
	ulint	bit_no;
} lock_queue_iterator_t;

/***********************************************************************
Initialize lock queue iterator so that it starts to iterate from
"lock". bit_no specifies the record number within the heap where the
record is stored. It can be undefined (ULINT_UNDEFINED) in two cases:
1. If the lock is a table lock, thus we have a table lock queue;
2. If the lock is a record lock and it is a wait lock. In this case
   bit_no is calculated in this function by using
   lock_rec_find_set_bit(). There is exactly one bit set in the bitmap
   of a wait lock. */

void
lock_queue_iterator_reset(
/*======================*/
	lock_queue_iterator_t*	iter,	/* out: iterator */
	lock_t*			lock,	/* in: lock to start from */
	ulint			bit_no);/* in: record number in the
					heap */

/***********************************************************************
Gets the previous lock in the lock queue, returns NULL if there are no
more locks (i.e. the current lock is the first one). The iterator is
receded (if not-NULL is returned). */

lock_t*
lock_queue_iterator_get_prev(
/*=========================*/
					/* out: previous lock or NULL */
	lock_queue_iterator_t*	iter);	/* in/out: iterator */

#endif /* lock0iter_h */
