1 /* $NetBSD: minheap-internal.h,v 1.4 2021/04/07 03:36:48 christos Exp $ */
2 /*
3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
4 *
5 * Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29 #ifndef MINHEAP_INTERNAL_H_INCLUDED_
30 #define MINHEAP_INTERNAL_H_INCLUDED_
31
32 #include "event2/event-config.h"
33 #include "evconfig-private.h"
34 #include "event2/event.h"
35 #include "event2/event_struct.h"
36 #include "event2/util.h"
37 #include "util-internal.h"
38 #include "mm-internal.h"
39
40 typedef struct min_heap
41 {
42 struct event** p;
43 unsigned n, a;
44 } min_heap_t;
45
46 static inline void min_heap_ctor_(min_heap_t* s);
47 static inline void min_heap_dtor_(min_heap_t* s);
48 static inline void min_heap_elem_init_(struct event* e);
49 static inline int min_heap_elt_is_top_(const struct event *e);
50 static inline int min_heap_empty_(min_heap_t* s);
51 static inline unsigned min_heap_size_(min_heap_t* s);
52 static inline struct event* min_heap_top_(min_heap_t* s);
53 static inline int min_heap_reserve_(min_heap_t* s, unsigned n);
54 static inline int min_heap_push_(min_heap_t* s, struct event* e);
55 static inline struct event* min_heap_pop_(min_heap_t* s);
56 static inline int min_heap_adjust_(min_heap_t *s, struct event* e);
57 static inline int min_heap_erase_(min_heap_t* s, struct event* e);
58 static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e);
59 static inline void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e);
60 static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e);
61
62 #define min_heap_elem_greater(a, b) \
63 (evutil_timercmp(&(a)->ev_timeout, &(b)->ev_timeout, >))
64
min_heap_ctor_(min_heap_t * s)65 void min_heap_ctor_(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; }
min_heap_dtor_(min_heap_t * s)66 void min_heap_dtor_(min_heap_t* s) { if (s->p) mm_free(s->p); }
min_heap_elem_init_(struct event * e)67 void min_heap_elem_init_(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; }
min_heap_empty_(min_heap_t * s)68 int min_heap_empty_(min_heap_t* s) { return 0u == s->n; }
min_heap_size_(min_heap_t * s)69 unsigned min_heap_size_(min_heap_t* s) { return s->n; }
min_heap_top_(min_heap_t * s)70 struct event* min_heap_top_(min_heap_t* s) { return s->n ? *s->p : 0; }
71
min_heap_push_(min_heap_t * s,struct event * e)72 int min_heap_push_(min_heap_t* s, struct event* e)
73 {
74 if (s->n == UINT32_MAX || min_heap_reserve_(s, s->n + 1))
75 return -1;
76 min_heap_shift_up_(s, s->n++, e);
77 return 0;
78 }
79
min_heap_pop_(min_heap_t * s)80 struct event* min_heap_pop_(min_heap_t* s)
81 {
82 if (s->n)
83 {
84 struct event* e = *s->p;
85 min_heap_shift_down_(s, 0u, s->p[--s->n]);
86 e->ev_timeout_pos.min_heap_idx = -1;
87 return e;
88 }
89 return 0;
90 }
91
min_heap_elt_is_top_(const struct event * e)92 int min_heap_elt_is_top_(const struct event *e)
93 {
94 return e->ev_timeout_pos.min_heap_idx == 0;
95 }
96
min_heap_erase_(min_heap_t * s,struct event * e)97 int min_heap_erase_(min_heap_t* s, struct event* e)
98 {
99 if (-1 != e->ev_timeout_pos.min_heap_idx)
100 {
101 struct event *last = s->p[--s->n];
102 unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2;
103 /* we replace e with the last element in the heap. We might need to
104 shift it upward if it is less than its parent, or downward if it is
105 greater than one or both its children. Since the children are known
106 to be less than the parent, it can't need to shift both up and
107 down. */
108 if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last))
109 min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, last);
110 else
111 min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last);
112 e->ev_timeout_pos.min_heap_idx = -1;
113 return 0;
114 }
115 return -1;
116 }
117
min_heap_adjust_(min_heap_t * s,struct event * e)118 int min_heap_adjust_(min_heap_t *s, struct event *e)
119 {
120 if (-1 == e->ev_timeout_pos.min_heap_idx) {
121 return min_heap_push_(s, e);
122 } else {
123 unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2;
124 /* The position of e has changed; we shift it up or down
125 * as needed. We can't need to do both. */
126 if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], e))
127 min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, e);
128 else
129 min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, e);
130 return 0;
131 }
132 }
133
min_heap_reserve_(min_heap_t * s,unsigned n)134 int min_heap_reserve_(min_heap_t* s, unsigned n)
135 {
136 if (s->a < n)
137 {
138 struct event** p;
139 unsigned a = s->a ? s->a * 2 : 8;
140 if (a < n)
141 a = n;
142 #if (SIZE_MAX == UINT32_MAX)
143 if (a > SIZE_MAX / sizeof *p)
144 return -1;
145 #endif
146 if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p)))
147 return -1;
148 s->p = p;
149 s->a = a;
150 }
151 return 0;
152 }
153
min_heap_shift_up_unconditional_(min_heap_t * s,unsigned hole_index,struct event * e)154 void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e)
155 {
156 unsigned parent = (hole_index - 1) / 2;
157 do
158 {
159 (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index;
160 hole_index = parent;
161 parent = (hole_index - 1) / 2;
162 } while (hole_index && min_heap_elem_greater(s->p[parent], e));
163 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
164 }
165
min_heap_shift_up_(min_heap_t * s,unsigned hole_index,struct event * e)166 void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e)
167 {
168 unsigned parent = (hole_index - 1) / 2;
169 while (hole_index && min_heap_elem_greater(s->p[parent], e))
170 {
171 (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index;
172 hole_index = parent;
173 parent = (hole_index - 1) / 2;
174 }
175 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
176 }
177
min_heap_shift_down_(min_heap_t * s,unsigned hole_index,struct event * e)178 static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e)
179 {
180 unsigned min_child = 2 * (hole_index + 1);
181 while (min_child <= s->n)
182 {
183 min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]);
184 if (!(min_heap_elem_greater(e, s->p[min_child])))
185 break;
186 (s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index;
187 hole_index = min_child;
188 min_child = 2 * (hole_index + 1);
189 }
190 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
191 }
192
193 #endif /* MINHEAP_INTERNAL_H_INCLUDED_ */
194