Mirror of :pserver:cvs@cvs.fefe.de:/cvs libowfat https://www.fefe.de/libowfat/
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

64 lines
1.7 KiB

#include "likely.h"
#include <stdlib.h>
#ifndef __MINGW32__
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#endif
#include "iarray.h"
#ifdef __dietlibc__
#include <sys/atomic.h>
#else
#define __CAS(ptr,oldval,newval) __sync_val_compare_and_swap(ptr,oldval,newval)
#endif
static iarray_page* new_page(size_t pagesize) {
#ifdef __MINGW32__
void* x=malloc(pagesize);
if (x==0) return 0;
#else
void* x=mmap(0,pagesize,PROT_READ|PROT_WRITE,MAP_ANONYMOUS|MAP_PRIVATE,-1,0);
if (x==MAP_FAILED) return 0;
#endif
return (iarray_page*)x;
}
void* iarray_allocate(iarray* ia,size_t pos) {
size_t index,prevlen=ia->len;
/* first, find the linked list of pages */
iarray_page** p=&ia->pages[pos%(sizeof(ia->pages)/sizeof(ia->pages[0]))];
/* this is here so we don't munmap and then re-mmap pages when a
* certain path makes it necessary to mmap several pages into the
* linked list and we are competing with another thread that does the
* same thing */
iarray_page* newpage=0;
/* since we have a fan-out of 16, on page 0 the elements are 0, 16, 32, ...
* so we divide pos by the fan-out here */
size_t realpos=pos;
pos /= sizeof(ia->pages)/sizeof(ia->pages[0]);
/* now walk the linked list of pages until we reach the one we want */
for (index=0; ; index+=ia->elemperpage) {
if (!*p) {
if (!newpage)
if (!(newpage=new_page(ia->bytesperpage))) return 0;
if (__CAS(p,0,newpage)==0)
newpage=0;
}
if (index+ia->elemperpage>pos)
break;
p=&(*p)->next;
}
if (newpage)
#ifdef __MINGW32__
free(newpage);
#else
munmap(newpage,ia->bytesperpage);
#endif
{
size_t l;
do {
l=__CAS(&ia->len,prevlen,realpos);
} while (l<realpos);
}
return &(*p)->data[(pos-index)*ia->elemsize];
}