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/*-
* Copyright 2016 Vsevolod Stakhov
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "config.h"
#include "libutil/heap.h"
struct rspamd_min_heap {
GPtrArray *ar;
};
#define __SWAP(a, b) do { \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
a = _b; \
b = _a; \
} while (0)
#define heap_swap(h,e1,e2) do { \
__SWAP((h)->ar->pdata[(e1)->idx - 1], (h)->ar->pdata[(e2)->idx - 1]); \
__SWAP((e1)->idx, (e2)->idx); \
} while (0)
#define min_elt(e1, e2) ((e1)->pri <= (e2)->pri ? (e1) : (e2))
/*
* Swims element added (or changed) to preserve heap's invariant
*/
static void
rspamd_min_heap_swim (struct rspamd_min_heap *heap,
struct rspamd_min_heap_elt *elt)
{
struct rspamd_min_heap_elt *parent;
while (elt->idx > 1) {
parent = g_ptr_array_index (heap->ar, elt->idx / 2 - 1);
if (parent->pri > elt->pri) {
heap_swap (heap, elt, parent);
}
else {
break;
}
}
}
/*
* Sinks the element popped (or changed) to preserve heap's invariant
*/
static void
rspamd_min_heap_sink (struct rspamd_min_heap *heap,
struct rspamd_min_heap_elt *elt)
{
struct rspamd_min_heap_elt *c1, *c2, *m;
while (elt->idx * 2 < heap->ar->len) {
c1 = g_ptr_array_index (heap->ar, elt->idx * 2 - 1);
c2 = g_ptr_array_index (heap->ar, elt->idx * 2);
m = min_elt (c1, c2);
if (elt->pri > m->pri) {
heap_swap (heap, elt, m);
}
else {
break;
}
}
if (elt->idx * 2 - 1 < heap->ar->len) {
m = g_ptr_array_index (heap->ar, elt->idx * 2 - 1);
if (elt->pri > m->pri) {
heap_swap (heap, elt, m);
}
}
}
struct rspamd_min_heap *
rspamd_min_heap_create (gsize reserved_size)
{
struct rspamd_min_heap *heap;
heap = g_slice_alloc (sizeof (*heap));
heap->ar = g_ptr_array_sized_new (reserved_size);
return heap;
}
void
rspamd_min_heap_push (struct rspamd_min_heap *heap,
struct rspamd_min_heap_elt *elt)
{
g_assert (heap != NULL);
g_assert (elt != NULL);
/* Add to the end */
elt->idx = heap->ar->len + 1;
g_ptr_array_add (heap->ar, elt);
/* Now swim it up */
rspamd_min_heap_swim (heap, elt);
}
struct rspamd_min_heap_elt*
rspamd_min_heap_pop (struct rspamd_min_heap *heap)
{
struct rspamd_min_heap_elt *elt, *last;
g_assert (heap != NULL);
if (heap->ar->len == 0) {
return NULL;
}
elt = g_ptr_array_index (heap->ar, 0);
last = g_ptr_array_index (heap->ar, heap->ar->len - 1);
if (elt != last) {
/* Now replace elt with the last element and sink it if needed */
heap_swap (heap, elt, last);
g_ptr_array_remove_index_fast (heap->ar, heap->ar->len - 1);
rspamd_min_heap_sink (heap, last);
}
else {
g_ptr_array_remove_index_fast (heap->ar, heap->ar->len - 1);
}
return elt;
}
void
rspamd_min_heap_update_elt (struct rspamd_min_heap *heap,
struct rspamd_min_heap_elt *elt, guint npri)
{
guint oldpri;
g_assert (heap != NULL);
g_assert (elt->idx > 0 && elt->idx <= heap->ar->len);
oldpri = elt->pri;
elt->pri = npri;
if (npri > oldpri) {
/* We might need to sink */
rspamd_min_heap_sink (heap, elt);
}
else if (npri < oldpri) {
/* We might need to swim */
rspamd_min_heap_swim (heap, elt);
}
}
void
rspamd_min_heap_remove_elt (struct rspamd_min_heap *heap,
struct rspamd_min_heap_elt *elt)
{
struct rspamd_min_heap_elt *first;
g_assert (heap != NULL);
g_assert (elt->idx > 0 && elt->idx <= heap->ar->len);
first = g_ptr_array_index (heap->ar, 0);
if (elt != first) {
elt->pri = first->pri - 1;
rspamd_min_heap_swim (heap, elt);
}
/* Now the desired element is on the top of queue */
(void)rspamd_min_heap_pop (heap);
}
void
rspamd_min_heap_destroy (struct rspamd_min_heap *heap)
{
if (heap) {
g_ptr_array_free (heap->ar, TRUE);
g_slice_free1 (sizeof (*heap), heap);
}
}
struct rspamd_min_heap_elt*
rspamd_min_heap_index (struct rspamd_min_heap *heap, guint idx)
{
g_assert (heap != NULL);
g_assert (idx < heap->ar->len);
return g_ptr_array_index (heap->ar, idx);
}
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