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/*
* ngtcp2
*
* Copyright (c) 2017 ngtcp2 contributors
* Copyright (c) 2012 nghttp2 contributors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef NGTCP2_PQ_H
#define NGTCP2_PQ_H
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <ngtcp2/ngtcp2.h>
#include "ngtcp2_mem.h"
/* Implementation of priority queue */
/* NGTCP2_PQ_BAD_INDEX is the priority queue index which indicates
that an entry is not queued. Assigning this value to
ngtcp2_pq_entry.index can check that the entry is queued or not. */
#define NGTCP2_PQ_BAD_INDEX SIZE_MAX
typedef struct ngtcp2_pq_entry {
size_t index;
} ngtcp2_pq_entry;
/* ngtcp2_pq_less is a "less" function, that returns nonzero if |lhs|
is considered to be less than |rhs|. */
typedef int (*ngtcp2_pq_less)(const ngtcp2_pq_entry *lhs,
const ngtcp2_pq_entry *rhs);
typedef struct ngtcp2_pq {
/* q is a pointer to an array that stores the items. */
ngtcp2_pq_entry **q;
/* mem is a memory allocator. */
const ngtcp2_mem *mem;
/* length is the number of items stored. */
size_t length;
/* capacity is the maximum number of items this queue can store.
This is automatically extended when length is reached to this
limit. */
size_t capacity;
/* less is the less function to compare items. */
ngtcp2_pq_less less;
} ngtcp2_pq;
/*
* ngtcp2_pq_init initializes |pq| with compare function |cmp|.
*/
void ngtcp2_pq_init(ngtcp2_pq *pq, ngtcp2_pq_less less, const ngtcp2_mem *mem);
/*
* ngtcp2_pq_free deallocates any resources allocated for |pq|. The
* stored items are not freed by this function.
*/
void ngtcp2_pq_free(ngtcp2_pq *pq);
/*
* ngtcp2_pq_push adds |item| to |pq|.
*
* This function returns 0 if it succeeds, or one of the following
* negative error codes:
*
* NGTCP2_ERR_NOMEM
* Out of memory.
*/
int ngtcp2_pq_push(ngtcp2_pq *pq, ngtcp2_pq_entry *item);
/*
* ngtcp2_pq_top returns item at the top of |pq|. It is undefined if
* |pq| is empty.
*/
ngtcp2_pq_entry *ngtcp2_pq_top(const ngtcp2_pq *pq);
/*
* ngtcp2_pq_pop pops item at the top of |pq|. The popped item is not
* freed by this function. It is undefined if |pq| is empty.
*/
void ngtcp2_pq_pop(ngtcp2_pq *pq);
/*
* ngtcp2_pq_empty returns nonzero if |pq| is empty.
*/
int ngtcp2_pq_empty(const ngtcp2_pq *pq);
/*
* ngtcp2_pq_size returns the number of items |pq| contains.
*/
size_t ngtcp2_pq_size(const ngtcp2_pq *pq);
typedef int (*ngtcp2_pq_item_cb)(ngtcp2_pq_entry *item, void *arg);
/*
* ngtcp2_pq_each applies |fun| to each item in |pq|. The |arg| is
* passed as arg parameter to callback function. This function must
* not change the ordering key. If the return value from callback is
* nonzero, this function returns 1 immediately without iterating
* remaining items. Otherwise this function returns 0.
*/
int ngtcp2_pq_each(const ngtcp2_pq *pq, ngtcp2_pq_item_cb fun, void *arg);
/*
* ngtcp2_pq_remove removes |item| from |pq|. |pq| must contain
* |item| otherwise the behavior is undefined.
*/
void ngtcp2_pq_remove(ngtcp2_pq *pq, ngtcp2_pq_entry *item);
#endif /* NGTCP2_PQ_H */
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