Merge branch 'mh/write-refs-sooner-2.4' into maint
[git.git] / prio-queue.c
blobe4365b00d6c3366e6753fc6da3fe1a165ab1222d
1 #include "cache.h"
2 #include "prio-queue.h"
4 static inline int compare(struct prio_queue *queue, int i, int j)
6 int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
7 queue->cb_data);
8 if (!cmp)
9 cmp = queue->array[i].ctr - queue->array[j].ctr;
10 return cmp;
13 static inline void swap(struct prio_queue *queue, int i, int j)
15 struct prio_queue_entry tmp = queue->array[i];
16 queue->array[i] = queue->array[j];
17 queue->array[j] = tmp;
20 void prio_queue_reverse(struct prio_queue *queue)
22 int i, j;
24 if (queue->compare != NULL)
25 die("BUG: prio_queue_reverse() on non-LIFO queue");
26 for (i = 0; i <= (j = (queue->nr - 1) - i); i++)
27 swap(queue, i, j);
30 void clear_prio_queue(struct prio_queue *queue)
32 free(queue->array);
33 queue->nr = 0;
34 queue->alloc = 0;
35 queue->array = NULL;
36 queue->insertion_ctr = 0;
39 void prio_queue_put(struct prio_queue *queue, void *thing)
41 int ix, parent;
43 /* Append at the end */
44 ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
45 queue->array[queue->nr].ctr = queue->insertion_ctr++;
46 queue->array[queue->nr].data = thing;
47 queue->nr++;
48 if (!queue->compare)
49 return; /* LIFO */
51 /* Bubble up the new one */
52 for (ix = queue->nr - 1; ix; ix = parent) {
53 parent = (ix - 1) / 2;
54 if (compare(queue, parent, ix) <= 0)
55 break;
57 swap(queue, parent, ix);
61 void *prio_queue_get(struct prio_queue *queue)
63 void *result;
64 int ix, child;
66 if (!queue->nr)
67 return NULL;
68 if (!queue->compare)
69 return queue->array[--queue->nr].data; /* LIFO */
71 result = queue->array[0].data;
72 if (!--queue->nr)
73 return result;
75 queue->array[0] = queue->array[queue->nr];
77 /* Push down the one at the root */
78 for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
79 child = ix * 2 + 1; /* left */
80 if (child + 1 < queue->nr &&
81 compare(queue, child, child + 1) >= 0)
82 child++; /* use right child */
84 if (compare(queue, ix, child) <= 0)
85 break;
87 swap(queue, child, ix);
89 return result;