summaryrefslogtreecommitdiffstats
path: root/src/contrib/libngtcp2/ngtcp2/lib/ngtcp2_pq.c
blob: 96cde8fd5f32d8a713344102b7d64292c932d859 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/*
 * 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.
 */
#include "ngtcp2_pq.h"

#include <assert.h>

#include "ngtcp2_macro.h"

void ngtcp2_pq_init(ngtcp2_pq *pq, ngtcp2_less less, const ngtcp2_mem *mem) {
  pq->mem = mem;
  pq->capacity = 0;
  pq->q = NULL;
  pq->length = 0;
  pq->less = less;
}

void ngtcp2_pq_free(ngtcp2_pq *pq) {
  ngtcp2_mem_free(pq->mem, pq->q);
  pq->q = NULL;
}

static void swap(ngtcp2_pq *pq, size_t i, size_t j) {
  ngtcp2_pq_entry *a = pq->q[i];
  ngtcp2_pq_entry *b = pq->q[j];

  pq->q[i] = b;
  b->index = i;
  pq->q[j] = a;
  a->index = j;
}

static void bubble_up(ngtcp2_pq *pq, size_t index) {
  size_t parent;
  while (index != 0) {
    parent = (index - 1) / 2;
    if (!pq->less(pq->q[index], pq->q[parent])) {
      return;
    }
    swap(pq, parent, index);
    index = parent;
  }
}

int ngtcp2_pq_push(ngtcp2_pq *pq, ngtcp2_pq_entry *item) {
  if (pq->capacity <= pq->length) {
    void *nq;
    size_t ncapacity;

    ncapacity = ngtcp2_max_size(4, pq->capacity * 2);

    nq = ngtcp2_mem_realloc(pq->mem, pq->q,
                            ncapacity * sizeof(ngtcp2_pq_entry *));
    if (nq == NULL) {
      return NGTCP2_ERR_NOMEM;
    }
    pq->capacity = ncapacity;
    pq->q = nq;
  }
  pq->q[pq->length] = item;
  item->index = pq->length;
  ++pq->length;
  bubble_up(pq, pq->length - 1);
  return 0;
}

ngtcp2_pq_entry *ngtcp2_pq_top(ngtcp2_pq *pq) {
  assert(pq->length);
  return pq->q[0];
}

static void bubble_down(ngtcp2_pq *pq, size_t index) {
  size_t i, j, minindex;
  for (;;) {
    j = index * 2 + 1;
    minindex = index;
    for (i = 0; i < 2; ++i, ++j) {
      if (j >= pq->length) {
        break;
      }
      if (pq->less(pq->q[j], pq->q[minindex])) {
        minindex = j;
      }
    }
    if (minindex == index) {
      return;
    }
    swap(pq, index, minindex);
    index = minindex;
  }
}

void ngtcp2_pq_pop(ngtcp2_pq *pq) {
  if (pq->length > 0) {
    pq->q[0] = pq->q[pq->length - 1];
    pq->q[0]->index = 0;
    --pq->length;
    bubble_down(pq, 0);
  }
}

void ngtcp2_pq_remove(ngtcp2_pq *pq, ngtcp2_pq_entry *item) {
  assert(pq->q[item->index] == item);

  if (item->index == 0) {
    ngtcp2_pq_pop(pq);
    return;
  }

  if (item->index == pq->length - 1) {
    --pq->length;
    return;
  }

  pq->q[item->index] = pq->q[pq->length - 1];
  pq->q[item->index]->index = item->index;
  --pq->length;

  if (pq->less(item, pq->q[item->index])) {
    bubble_down(pq, item->index);
  } else {
    bubble_up(pq, item->index);
  }
}

int ngtcp2_pq_empty(ngtcp2_pq *pq) { return pq->length == 0; }

size_t ngtcp2_pq_size(ngtcp2_pq *pq) { return pq->length; }

int ngtcp2_pq_each(ngtcp2_pq *pq, ngtcp2_pq_item_cb fun, void *arg) {
  size_t i;

  if (pq->length == 0) {
    return 0;
  }
  for (i = 0; i < pq->length; ++i) {
    if ((*fun)(pq->q[i], arg)) {
      return 1;
    }
  }
  return 0;
}