freshlybakedca.ke
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1/*
2 * Copyright 2020 Google LLC
3 *
4 * Use of this source code is governed by a BSD-style
5 * license that can be found in the LICENSE file or at
6 * https://developers.google.com/open-source/licenses/bsd
7 */
8
9#include "pq.h"
10
11#include "reftable-error.h"
12#include "reftable-record.h"
13#include "system.h"
14#include "basics.h"
15
16int pq_less(struct pq_entry *a, struct pq_entry *b)
17{
18 int cmp, err;
19
20 err = reftable_record_cmp(a->rec, b->rec, &cmp);
21 if (err < 0)
22 return err;
23
24 if (cmp == 0)
25 return a->index > b->index;
26 return cmp < 0;
27}
28
29int merged_iter_pqueue_remove(struct merged_iter_pqueue *pq, struct pq_entry *out)
30{
31 size_t i = 0;
32 struct pq_entry e = pq->heap[0];
33 pq->heap[0] = pq->heap[pq->len - 1];
34 pq->len--;
35
36 while (i < pq->len) {
37 size_t min = i;
38 size_t j = 2 * i + 1;
39 size_t k = 2 * i + 2;
40 int cmp;
41
42 if (j < pq->len) {
43 cmp = pq_less(&pq->heap[j], &pq->heap[i]);
44 if (cmp < 0)
45 return -1;
46 else if (cmp)
47 min = j;
48 }
49
50 if (k < pq->len) {
51 cmp = pq_less(&pq->heap[k], &pq->heap[min]);
52 if (cmp < 0)
53 return -1;
54 else if (cmp)
55 min = k;
56 }
57
58 if (min == i)
59 break;
60 REFTABLE_SWAP(pq->heap[i], pq->heap[min]);
61 i = min;
62 }
63
64 if (out)
65 *out = e;
66
67 return 0;
68}
69
70int merged_iter_pqueue_add(struct merged_iter_pqueue *pq, const struct pq_entry *e)
71{
72 size_t i = 0;
73
74 REFTABLE_ALLOC_GROW_OR_NULL(pq->heap, pq->len + 1, pq->cap);
75 if (!pq->heap)
76 return REFTABLE_OUT_OF_MEMORY_ERROR;
77 pq->heap[pq->len++] = *e;
78
79 i = pq->len - 1;
80 while (i > 0) {
81 size_t j = (i - 1) / 2;
82 if (pq_less(&pq->heap[j], &pq->heap[i]))
83 break;
84 REFTABLE_SWAP(pq->heap[j], pq->heap[i]);
85 i = j;
86 }
87
88 return 0;
89}
90
91void merged_iter_pqueue_release(struct merged_iter_pqueue *pq)
92{
93 REFTABLE_FREE_AND_NULL(pq->heap);
94 memset(pq, 0, sizeof(*pq));
95}