blob: 2b5b7d1c0e28666becae6fea86e72788b99e7997 [file] [log] [blame]
/*
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)
{
int cmp = reftable_record_cmp(a->rec, b->rec);
if (cmp == 0)
return a->index > b->index;
return cmp < 0;
}
struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
{
size_t i = 0;
struct pq_entry e = pq->heap[0];
pq->heap[0] = pq->heap[pq->len - 1];
pq->len--;
while (i < pq->len) {
size_t min = i;
size_t j = 2 * i + 1;
size_t 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)
{
size_t i = 0;
REFTABLE_ALLOC_GROW(pq->heap, pq->len + 1, pq->cap);
pq->heap[pq->len++] = *e;
i = pq->len - 1;
while (i > 0) {
size_t 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)
{
FREE_AND_NULL(pq->heap);
memset(pq, 0, sizeof(*pq));
}