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/* Copyright (c) 2000, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef QUEUES_INCLUDED
#define QUEUES_INCLUDED
/**
@file storage/myisam/queues.h
Code for handling of priority queues.
Implementation of queues from "Algorithms in C" by Robert Sedgewick.
*/
#include <stddef.h>
#include <sys/types.h>
#include "my_inttypes.h"
#include "mysql/psi/psi_memory.h"
#ifdef __cplusplus
extern "C" {
#endif
struct QUEUE {
uchar **root;
void *first_cmp_arg;
uint elements;
uint max_elements;
uint offset_to_key; /* compare is done on element+offset */
int max_at_top; /* Normally 1, set to -1 if queue_top gives max */
int (*compare)(void *, uchar *, uchar *);
uint auto_extent;
};
void _downheap(QUEUE *queue, uint idx);
void queue_fix(QUEUE *queue);
#define queue_top(queue) ((queue)->root[1])
#define queue_element(queue, index) ((queue)->root[index + 1])
#define queue_end(queue) ((queue)->root[(queue)->elements])
static inline void queue_replaced(QUEUE *queue) { _downheap(queue, 1); }
static inline void queue_set_max_at_top(QUEUE *queue, int set_arg) {
queue->max_at_top = set_arg ? -1 : 1;
}
typedef int (*queue_compare)(void *, uchar *, uchar *);
int init_queue(QUEUE *queue, PSI_memory_key psi_key, uint max_elements,
uint offset_to_key, bool max_at_top, queue_compare compare,
void *first_cmp_arg);
int reinit_queue(QUEUE *queue, PSI_memory_key psi_key, uint max_elements,
uint offset_to_key, bool max_at_top, queue_compare compare,
void *first_cmp_arg);
void delete_queue(QUEUE *queue);
void queue_insert(QUEUE *queue, uchar *element);
uchar *queue_remove(QUEUE *queue, uint idx);
static inline void queue_remove_all(QUEUE *queue) { queue->elements = 0; }
static inline bool queue_is_full(QUEUE *queue) {
return queue->elements == queue->max_elements;
}
static inline bool is_queue_inited(QUEUE *queue) {
return queue->root != nullptr;
}
#ifdef __cplusplus
}
#endif
#endif // QUEUES_INCLUDED
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