189 lines
6.8 KiB
C
189 lines
6.8 KiB
C
/*
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* Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
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*
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* Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef MINHEAP_INTERNAL_H_INCLUDED_
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#define MINHEAP_INTERNAL_H_INCLUDED_
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#include "event2/event-config.h"
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#include "evconfig-private.h"
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#include "event2/event.h"
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#include "event2/event_struct.h"
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#include "event2/util.h"
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#include "util-internal.h"
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#include "mm-internal.h"
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typedef struct min_heap
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{
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struct event** p;
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unsigned n, a;
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} min_heap_t;
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static inline void min_heap_ctor_(min_heap_t* s);
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static inline void min_heap_dtor_(min_heap_t* s);
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static inline void min_heap_elem_init_(struct event* e);
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static inline int min_heap_elt_is_top_(const struct event *e);
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static inline int min_heap_empty_(min_heap_t* s);
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static inline unsigned min_heap_size_(min_heap_t* s);
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static inline struct event* min_heap_top_(min_heap_t* s);
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static inline int min_heap_reserve_(min_heap_t* s, unsigned n);
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static inline int min_heap_push_(min_heap_t* s, struct event* e);
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static inline struct event* min_heap_pop_(min_heap_t* s);
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static inline int min_heap_adjust_(min_heap_t *s, struct event* e);
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static inline int min_heap_erase_(min_heap_t* s, struct event* e);
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static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e);
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static inline void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e);
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static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e);
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#define min_heap_elem_greater(a, b) \
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(evutil_timercmp(&(a)->ev_timeout, &(b)->ev_timeout, >))
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void min_heap_ctor_(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; }
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void min_heap_dtor_(min_heap_t* s) { if (s->p) mm_free(s->p); }
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void min_heap_elem_init_(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; }
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int min_heap_empty_(min_heap_t* s) { return 0u == s->n; }
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unsigned min_heap_size_(min_heap_t* s) { return s->n; }
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struct event* min_heap_top_(min_heap_t* s) { return s->n ? *s->p : 0; }
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int min_heap_push_(min_heap_t* s, struct event* e)
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{
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if (min_heap_reserve_(s, s->n + 1))
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return -1;
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min_heap_shift_up_(s, s->n++, e);
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return 0;
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}
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struct event* min_heap_pop_(min_heap_t* s)
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{
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if (s->n)
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{
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struct event* e = *s->p;
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min_heap_shift_down_(s, 0u, s->p[--s->n]);
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e->ev_timeout_pos.min_heap_idx = -1;
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return e;
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}
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return 0;
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}
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int min_heap_elt_is_top_(const struct event *e)
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{
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return e->ev_timeout_pos.min_heap_idx == 0;
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}
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int min_heap_erase_(min_heap_t* s, struct event* e)
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{
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if (-1 != e->ev_timeout_pos.min_heap_idx)
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{
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struct event *last = s->p[--s->n];
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unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2;
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/* we replace e with the last element in the heap. We might need to
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shift it upward if it is less than its parent, or downward if it is
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greater than one or both its children. Since the children are known
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to be less than the parent, it can't need to shift both up and
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down. */
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if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last))
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min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, last);
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else
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min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last);
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e->ev_timeout_pos.min_heap_idx = -1;
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return 0;
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}
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return -1;
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}
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int min_heap_adjust_(min_heap_t *s, struct event *e)
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{
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if (-1 == e->ev_timeout_pos.min_heap_idx) {
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return min_heap_push_(s, e);
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} else {
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unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2;
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/* The position of e has changed; we shift it up or down
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* as needed. We can't need to do both. */
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if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], e))
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min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, e);
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else
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min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, e);
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return 0;
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}
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}
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int min_heap_reserve_(min_heap_t* s, unsigned n)
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{
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if (s->a < n)
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{
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struct event** p;
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unsigned a = s->a ? s->a * 2 : 8;
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if (a < n)
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a = n;
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if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p)))
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return -1;
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s->p = p;
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s->a = a;
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}
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return 0;
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}
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void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e)
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{
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unsigned parent = (hole_index - 1) / 2;
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do
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{
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(s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index;
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hole_index = parent;
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parent = (hole_index - 1) / 2;
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} while (hole_index && min_heap_elem_greater(s->p[parent], e));
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(s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
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}
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void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e)
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{
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unsigned parent = (hole_index - 1) / 2;
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while (hole_index && min_heap_elem_greater(s->p[parent], e))
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{
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(s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index;
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hole_index = parent;
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parent = (hole_index - 1) / 2;
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}
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(s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
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}
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void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e)
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{
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unsigned min_child = 2 * (hole_index + 1);
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while (min_child <= s->n)
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{
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min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]);
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if (!(min_heap_elem_greater(e, s->p[min_child])))
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break;
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(s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index;
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hole_index = min_child;
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min_child = 2 * (hole_index + 1);
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}
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(s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
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}
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#endif /* MINHEAP_INTERNAL_H_INCLUDED_ */
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