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-rw-r--r--src/basic/prioq.c318
1 files changed, 0 insertions, 318 deletions
diff --git a/src/basic/prioq.c b/src/basic/prioq.c
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--- a/src/basic/prioq.c
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@@ -1,318 +0,0 @@
-/***
- This file is part of systemd.
-
- Copyright 2013 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-/*
- * Priority Queue
- * The prioq object implements a priority queue. That is, it orders objects by
- * their priority and allows O(1) access to the object with the highest
- * priority. Insertion and removal are Θ(log n). Optionally, the caller can
- * provide a pointer to an index which will be kept up-to-date by the prioq.
- *
- * The underlying algorithm used in this implementation is a Heap.
- */
-
-#include <errno.h>
-#include <stdlib.h>
-
-#include "alloc-util.h"
-#include "hashmap.h"
-#include "prioq.h"
-
-struct prioq_item {
- void *data;
- unsigned *idx;
-};
-
-struct Prioq {
- compare_func_t compare_func;
- unsigned n_items, n_allocated;
-
- struct prioq_item *items;
-};
-
-Prioq *prioq_new(compare_func_t compare_func) {
- Prioq *q;
-
- q = new0(Prioq, 1);
- if (!q)
- return q;
-
- q->compare_func = compare_func;
- return q;
-}
-
-Prioq* prioq_free(Prioq *q) {
- if (!q)
- return NULL;
-
- free(q->items);
- return mfree(q);
-}
-
-int prioq_ensure_allocated(Prioq **q, compare_func_t compare_func) {
- assert(q);
-
- if (*q)
- return 0;
-
- *q = prioq_new(compare_func);
- if (!*q)
- return -ENOMEM;
-
- return 0;
-}
-
-static void swap(Prioq *q, unsigned j, unsigned k) {
- void *saved_data;
- unsigned *saved_idx;
-
- assert(q);
- assert(j < q->n_items);
- assert(k < q->n_items);
-
- assert(!q->items[j].idx || *(q->items[j].idx) == j);
- assert(!q->items[k].idx || *(q->items[k].idx) == k);
-
- saved_data = q->items[j].data;
- saved_idx = q->items[j].idx;
- q->items[j].data = q->items[k].data;
- q->items[j].idx = q->items[k].idx;
- q->items[k].data = saved_data;
- q->items[k].idx = saved_idx;
-
- if (q->items[j].idx)
- *q->items[j].idx = j;
-
- if (q->items[k].idx)
- *q->items[k].idx = k;
-}
-
-static unsigned shuffle_up(Prioq *q, unsigned idx) {
- assert(q);
-
- while (idx > 0) {
- unsigned k;
-
- k = (idx-1)/2;
-
- if (q->compare_func(q->items[k].data, q->items[idx].data) <= 0)
- break;
-
- swap(q, idx, k);
- idx = k;
- }
-
- return idx;
-}
-
-static unsigned shuffle_down(Prioq *q, unsigned idx) {
- assert(q);
-
- for (;;) {
- unsigned j, k, s;
-
- k = (idx+1)*2; /* right child */
- j = k-1; /* left child */
-
- if (j >= q->n_items)
- break;
-
- if (q->compare_func(q->items[j].data, q->items[idx].data) < 0)
-
- /* So our left child is smaller than we are, let's
- * remember this fact */
- s = j;
- else
- s = idx;
-
- if (k < q->n_items &&
- q->compare_func(q->items[k].data, q->items[s].data) < 0)
-
- /* So our right child is smaller than we are, let's
- * remember this fact */
- s = k;
-
- /* s now points to the smallest of the three items */
-
- if (s == idx)
- /* No swap necessary, we're done */
- break;
-
- swap(q, idx, s);
- idx = s;
- }
-
- return idx;
-}
-
-int prioq_put(Prioq *q, void *data, unsigned *idx) {
- struct prioq_item *i;
- unsigned k;
-
- assert(q);
-
- if (q->n_items >= q->n_allocated) {
- unsigned n;
- struct prioq_item *j;
-
- n = MAX((q->n_items+1) * 2, 16u);
- j = realloc(q->items, sizeof(struct prioq_item) * n);
- if (!j)
- return -ENOMEM;
-
- q->items = j;
- q->n_allocated = n;
- }
-
- k = q->n_items++;
- i = q->items + k;
- i->data = data;
- i->idx = idx;
-
- if (idx)
- *idx = k;
-
- shuffle_up(q, k);
-
- return 0;
-}
-
-static void remove_item(Prioq *q, struct prioq_item *i) {
- struct prioq_item *l;
-
- assert(q);
- assert(i);
-
- l = q->items + q->n_items - 1;
-
- if (i == l)
- /* Last entry, let's just remove it */
- q->n_items--;
- else {
- unsigned k;
-
- /* Not last entry, let's replace the last entry with
- * this one, and reshuffle */
-
- k = i - q->items;
-
- i->data = l->data;
- i->idx = l->idx;
- if (i->idx)
- *i->idx = k;
- q->n_items--;
-
- k = shuffle_down(q, k);
- shuffle_up(q, k);
- }
-}
-
-_pure_ static struct prioq_item* find_item(Prioq *q, void *data, unsigned *idx) {
- struct prioq_item *i;
-
- assert(q);
-
- if (idx) {
- if (*idx == PRIOQ_IDX_NULL ||
- *idx > q->n_items)
- return NULL;
-
- i = q->items + *idx;
- if (i->data != data)
- return NULL;
-
- return i;
- } else {
- for (i = q->items; i < q->items + q->n_items; i++)
- if (i->data == data)
- return i;
- return NULL;
- }
-}
-
-int prioq_remove(Prioq *q, void *data, unsigned *idx) {
- struct prioq_item *i;
-
- if (!q)
- return 0;
-
- i = find_item(q, data, idx);
- if (!i)
- return 0;
-
- remove_item(q, i);
- return 1;
-}
-
-int prioq_reshuffle(Prioq *q, void *data, unsigned *idx) {
- struct prioq_item *i;
- unsigned k;
-
- assert(q);
-
- i = find_item(q, data, idx);
- if (!i)
- return 0;
-
- k = i - q->items;
- k = shuffle_down(q, k);
- shuffle_up(q, k);
- return 1;
-}
-
-void *prioq_peek(Prioq *q) {
-
- if (!q)
- return NULL;
-
- if (q->n_items <= 0)
- return NULL;
-
- return q->items[0].data;
-}
-
-void *prioq_pop(Prioq *q) {
- void *data;
-
- if (!q)
- return NULL;
-
- if (q->n_items <= 0)
- return NULL;
-
- data = q->items[0].data;
- remove_item(q, q->items);
- return data;
-}
-
-unsigned prioq_size(Prioq *q) {
-
- if (!q)
- return 0;
-
- return q->n_items;
-}
-
-bool prioq_isempty(Prioq *q) {
-
- if (!q)
- return true;
-
- return q->n_items <= 0;
-}
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