nghttp2/lib/spdylay_pq.c

123 lines
2.8 KiB
C

/*
* Spdylay - SPDY Library
*
* Copyright (c) 2012 Tatsuhiro Tsujikawa
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "spdylay_pq.h"
int spdylay_pq_init(spdylay_pq *pq, spdylay_compar compar)
{
pq->capacity = 4096;
pq->q = malloc(pq->capacity);
if(pq->q == NULL) {
return SPDYLAY_ERR_NOMEM;
}
pq->length = 0;
pq->compar = compar;
return 0;
}
void spdylay_pq_free(spdylay_pq *pq)
{
free(pq->q);
pq->q = NULL;
}
static void swap(spdylay_pq *pq, size_t i, size_t j)
{
void *t = pq->q[i];
pq->q[i] = pq->q[j];
pq->q[j] = t;
}
static void bubble_up(spdylay_pq *pq, size_t index)
{
if(index == 0) {
return;
} else {
size_t parent = (index-1)/2;
if(pq->compar(pq->q[parent], pq->q[index]) > 0) {
swap(pq, parent, index);
bubble_up(pq, parent);
}
}
}
int spdylay_pq_push(spdylay_pq *pq, void *item)
{
if(pq->capacity <= pq->length) {
void *nq = realloc(pq->q, pq->capacity*2);
if(nq == NULL) {
return SPDYLAY_ERR_NOMEM;
}
pq->capacity *= 2;
pq->q = nq;
}
pq->q[pq->length] = item;
++pq->length;
bubble_up(pq, pq->length-1);
return 0;
}
void* spdylay_pq_top(spdylay_pq *pq)
{
if(pq->length == 0) {
return NULL;
} else {
return pq->q[0];
}
}
static void bubble_down(spdylay_pq *pq, size_t index)
{
size_t lchild = index*2+1;
size_t minindex = index;
int i, j;
for(i = 0; i < 2; ++i) {
j = lchild+i;
if(j >= pq->length) {
break;
}
if(pq->compar(pq->q[minindex], pq->q[j]) > 0) {
minindex = j;
}
}
if(minindex != index) {
swap(pq, index, minindex);
bubble_down(pq, minindex);
}
}
void spdylay_pq_pop(spdylay_pq *pq)
{
if(pq->length > 0) {
pq->q[0] = pq->q[pq->length-1];
--pq->length;
bubble_down(pq, 0);
}
}
int spdylay_pq_empty(spdylay_pq *pq)
{
return pq->length == 0;
}