You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
#include "likely.h"
|
|
#include <stdlib.h>
|
|
#ifndef _WIN32
|
|
#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 _WIN32
|
|
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 _WIN32
|
|
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];
|
|
}
|