lock0iter.h

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/** @file include/lock0iter.h
 Lock queue iterator type and function prototypes.
 
 Created July 16, 2007 Vasil Dimov
 *******************************************************/
 
#ifndef lock0iter_h
#define lock0iter_h
 
#include "lock0types.h"
#include "univ.i"
 
struct lock_queue_iterator_t {
  const 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;
};
 
/** 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 */
    const 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).
 @return previous lock or NULL */
const lock_t *lock_queue_iterator_get_prev(
    lock_queue_iterator_t *iter); /*!< in/out: iterator */
 
#endif /* lock0iter_h */