Permalink
35d803b Jan 30, 2017
@peff @gitster @rscharfe
89 lines (72 sloc) 1.85 KB
#include "cache.h"
#include "prio-queue.h"
static inline int compare(struct prio_queue *queue, int i, int j)
{
int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
queue->cb_data);
if (!cmp)
cmp = queue->array[i].ctr - queue->array[j].ctr;
return cmp;
}
static inline void swap(struct prio_queue *queue, int i, int j)
{
SWAP(queue->array[i], queue->array[j]);
}
void prio_queue_reverse(struct prio_queue *queue)
{
int i, j;
if (queue->compare != NULL)
die("BUG: prio_queue_reverse() on non-LIFO queue");
for (i = 0; i <= (j = (queue->nr - 1) - i); i++)
swap(queue, i, j);
}
void clear_prio_queue(struct prio_queue *queue)
{
free(queue->array);
queue->nr = 0;
queue->alloc = 0;
queue->array = NULL;
queue->insertion_ctr = 0;
}
void prio_queue_put(struct prio_queue *queue, void *thing)
{
int ix, parent;
/* Append at the end */
ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
queue->array[queue->nr].ctr = queue->insertion_ctr++;
queue->array[queue->nr].data = thing;
queue->nr++;
if (!queue->compare)
return; /* LIFO */
/* Bubble up the new one */
for (ix = queue->nr - 1; ix; ix = parent) {
parent = (ix - 1) / 2;
if (compare(queue, parent, ix) <= 0)
break;
swap(queue, parent, ix);
}
}
void *prio_queue_get(struct prio_queue *queue)
{
void *result;
int ix, child;
if (!queue->nr)
return NULL;
if (!queue->compare)
return queue->array[--queue->nr].data; /* LIFO */
result = queue->array[0].data;
if (!--queue->nr)
return result;
queue->array[0] = queue->array[queue->nr];
/* Push down the one at the root */
for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
child = ix * 2 + 1; /* left */
if (child + 1 < queue->nr &&
compare(queue, child, child + 1) >= 0)
child++; /* use right child */
if (compare(queue, ix, child) <= 0)
break;
swap(queue, child, ix);
}
return result;
}