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1 | #include "cache.h" | |
2 | #include "prio-queue.h" | |
3 | ||
4 | static inline int compare(struct prio_queue *queue, int i, int j) | |
5 | { | |
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; | |
11 | } | |
12 | ||
13 | static inline void swap(struct prio_queue *queue, int i, int j) | |
14 | { | |
15 | SWAP(queue->array[i], queue->array[j]); | |
16 | } | |
17 | ||
18 | void prio_queue_reverse(struct prio_queue *queue) | |
19 | { | |
20 | int i, j; | |
21 | ||
22 | if (queue->compare != NULL) | |
23 | BUG("prio_queue_reverse() on non-LIFO queue"); | |
24 | for (i = 0; i < (j = (queue->nr - 1) - i); i++) | |
25 | swap(queue, i, j); | |
26 | } | |
27 | ||
28 | void clear_prio_queue(struct prio_queue *queue) | |
29 | { | |
30 | FREE_AND_NULL(queue->array); | |
31 | queue->nr = 0; | |
32 | queue->alloc = 0; | |
33 | queue->insertion_ctr = 0; | |
34 | } | |
35 | ||
36 | void prio_queue_put(struct prio_queue *queue, void *thing) | |
37 | { | |
38 | int ix, parent; | |
39 | ||
40 | /* Append at the end */ | |
41 | ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc); | |
42 | queue->array[queue->nr].ctr = queue->insertion_ctr++; | |
43 | queue->array[queue->nr].data = thing; | |
44 | queue->nr++; | |
45 | if (!queue->compare) | |
46 | return; /* LIFO */ | |
47 | ||
48 | /* Bubble up the new one */ | |
49 | for (ix = queue->nr - 1; ix; ix = parent) { | |
50 | parent = (ix - 1) / 2; | |
51 | if (compare(queue, parent, ix) <= 0) | |
52 | break; | |
53 | ||
54 | swap(queue, parent, ix); | |
55 | } | |
56 | } | |
57 | ||
58 | void *prio_queue_get(struct prio_queue *queue) | |
59 | { | |
60 | void *result; | |
61 | int ix, child; | |
62 | ||
63 | if (!queue->nr) | |
64 | return NULL; | |
65 | if (!queue->compare) | |
66 | return queue->array[--queue->nr].data; /* LIFO */ | |
67 | ||
68 | result = queue->array[0].data; | |
69 | if (!--queue->nr) | |
70 | return result; | |
71 | ||
72 | queue->array[0] = queue->array[queue->nr]; | |
73 | ||
74 | /* Push down the one at the root */ | |
75 | for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) { | |
76 | child = ix * 2 + 1; /* left */ | |
77 | if (child + 1 < queue->nr && | |
78 | compare(queue, child, child + 1) >= 0) | |
79 | child++; /* use right child */ | |
80 | ||
81 | if (compare(queue, ix, child) <= 0) | |
82 | break; | |
83 | ||
84 | swap(queue, child, ix); | |
85 | } | |
86 | return result; | |
87 | } | |
88 | ||
89 | void *prio_queue_peek(struct prio_queue *queue) | |
90 | { | |
91 | if (!queue->nr) | |
92 | return NULL; | |
93 | if (!queue->compare) | |
94 | return queue->array[queue->nr - 1].data; | |
95 | return queue->array[0].data; | |
96 | } |