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/*
Copyright 2020 Google LLC
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file or at
https://developers.google.com/open-source/licenses/bsd
*/
#include "pq.h"
#include "reftable-record.h"
#include "system.h"
#include "basics.h"
int pq_less(struct pq_entry *a, struct pq_entry *b)
{
struct strbuf ak = STRBUF_INIT;
struct strbuf bk = STRBUF_INIT;
int cmp = 0;
reftable_record_key(&a->rec, &ak);
reftable_record_key(&b->rec, &bk);
cmp = strbuf_cmp(&ak, &bk);
strbuf_release(&ak);
strbuf_release(&bk);
if (cmp == 0)
return a->index > b->index;
return cmp < 0;
}
struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
{
return pq.heap[0];
}
int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
{
return pq.len == 0;
}
struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
{
int i = 0;
struct pq_entry e = pq->heap[0];
pq->heap[0] = pq->heap[pq->len - 1];
pq->len--;
i = 0;
while (i < pq->len) {
int min = i;
int j = 2 * i + 1;
int k = 2 * i + 2;
if (j < pq->len && pq_less(&pq->heap[j], &pq->heap[i])) {
min = j;
}
if (k < pq->len && pq_less(&pq->heap[k], &pq->heap[min])) {
min = k;
}
if (min == i) {
break;
}
SWAP(pq->heap[i], pq->heap[min]);
i = min;
}
return e;
}
void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, const struct pq_entry *e)
{
int i = 0;
if (pq->len == pq->cap) {
pq->cap = 2 * pq->cap + 1;
pq->heap = reftable_realloc(pq->heap,
pq->cap * sizeof(struct pq_entry));
}
pq->heap[pq->len++] = *e;
i = pq->len - 1;
while (i > 0) {
int j = (i - 1) / 2;
if (pq_less(&pq->heap[j], &pq->heap[i])) {
break;
}
SWAP(pq->heap[j], pq->heap[i]);
i = j;
}
}
void merged_iter_pqueue_release(struct merged_iter_pqueue *pq)
{
int i = 0;
for (i = 0; i < pq->len; i++) {
reftable_record_release(&pq->heap[i].rec);
}
FREE_AND_NULL(pq->heap);
pq->len = pq->cap = 0;
}
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