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/*
* Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _MIN_HEAP_H_
#define _MIN_HEAP_H_
#include "event2/event.h"
#include "event2/util.h"
typedef struct min_heap
{
struct event** p;
unsigned n, a;
} min_heap_t;
static inline void min_heap_ctor(min_heap_t* s);
static inline void min_heap_dtor(min_heap_t* s);
static inline void min_heap_elem_init(struct event* e);
static inline int min_heap_elem_greater(struct event *a, struct event *b);
static inline int min_heap_empty(min_heap_t* s);
static inline unsigned min_heap_size(min_heap_t* s);
static inline struct event* min_heap_top(min_heap_t* s);
static inline int min_heap_reserve(min_heap_t* s, unsigned n);
static inline int min_heap_push(min_heap_t* s, struct event* e);
static inline struct event* min_heap_pop(min_heap_t* s);
static inline int min_heap_erase(min_heap_t* s, struct event* e);
static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e);
static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e);
int min_heap_elem_greater(struct event *a, struct event *b)
{
return evutil_timercmp(&a->ev_timeout, &b->ev_timeout, >);
}
void min_heap_ctor(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; }
void min_heap_dtor(min_heap_t* s) { free(s->p); }
void min_heap_elem_init(struct event* e) { e->min_heap_idx = -1; }
int min_heap_empty(min_heap_t* s) { return 0u == s->n; }
unsigned min_heap_size(min_heap_t* s) { return s->n; }
struct event* min_heap_top(min_heap_t* s) { return s->n ? *s->p : 0; }
int min_heap_push(min_heap_t* s, struct event* e)
{
if(min_heap_reserve(s, s->n + 1))
return -1;
min_heap_shift_up_(s, s->n++, e);
return 0;
}
struct event* min_heap_pop(min_heap_t* s)
{
if(s->n)
{
struct event* e = *s->p;
e->min_heap_idx = -1;
min_heap_shift_down_(s, 0u, s->p[--s->n]);
return e;
}
return 0;
}
int min_heap_erase(min_heap_t* s, struct event* e)
{
if(((unsigned int)-1) != e->min_heap_idx)
{
min_heap_shift_down_(s, e->min_heap_idx, s->p[--s->n]);
e->min_heap_idx = -1;
return 0;
}
return -1;
}
int min_heap_reserve(min_heap_t* s, unsigned n)
{
if(s->a < n)
{
struct event** p;
unsigned a = s->a ? s->a * 2 : 8;
if(a < n)
a = n;
if(!(p = (struct event**)realloc(s->p, a * sizeof *p)))
return -1;
s->p = p;
s->a = a;
}
return 0;
}
void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e)
{
unsigned parent = (hole_index - 1) / 2;
while(hole_index && min_heap_elem_greater(s->p[parent], e))
{
(s->p[hole_index] = s->p[parent])->min_heap_idx = hole_index;
hole_index = parent;
parent = (hole_index - 1) / 2;
}
(s->p[hole_index] = e)->min_heap_idx = hole_index;
}
void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e)
{
unsigned min_child = 2 * (hole_index + 1);
while(min_child <= s->n)
{
min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]);
if(!(min_heap_elem_greater(e, s->p[min_child])))
break;
(s->p[hole_index] = s->p[min_child])->min_heap_idx = hole_index;
hole_index = min_child;
min_child = 2 * (hole_index + 1);
}
min_heap_shift_up_(s, hole_index, e);
}
#endif /* _MIN_HEAP_H_ */
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