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/*
** pool.c - memory pool
**
** See Copyright Notice in mruby.h
*/
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <mruby.h>
/* configuration section */
/* allocated memory address should be multiple of POOL_ALIGNMENT */
/* or undef it if alignment does not matter */
#ifndef POOL_ALIGNMENT
#if INTPTR_MAX == INT64_MAX
#define POOL_ALIGNMENT 8
#else
#define POOL_ALIGNMENT 4
#endif
#endif
/* page size of memory pool */
#ifndef POOL_PAGE_SIZE
#define POOL_PAGE_SIZE 16000
#endif
/* end of configuration section */
struct mrb_pool_page {
struct mrb_pool_page *next;
size_t offset;
size_t len;
void *last;
char page[];
};
struct mrb_pool {
mrb_state *mrb;
struct mrb_pool_page *pages;
};
#undef TEST_POOL
#ifdef TEST_POOL
#define mrb_malloc_simple(m,s) malloc(s)
#define mrb_free(m,p) free(p)
#endif
#ifdef POOL_ALIGNMENT
# define ALIGN_PADDING(x) ((SIZE_MAX - (x) + 1) & (POOL_ALIGNMENT - 1))
#else
# define ALIGN_PADDING(x) (0)
#endif
MRB_API mrb_pool*
mrb_pool_open(mrb_state *mrb)
{
mrb_pool *pool = (mrb_pool *)mrb_malloc_simple(mrb, sizeof(mrb_pool));
if (pool) {
pool->mrb = mrb;
pool->pages = NULL;
}
return pool;
}
MRB_API void
mrb_pool_close(mrb_pool *pool)
{
struct mrb_pool_page *page, *tmp;
if (!pool) return;
page = pool->pages;
while (page) {
tmp = page;
page = page->next;
mrb_free(pool->mrb, tmp);
}
mrb_free(pool->mrb, pool);
}
static struct mrb_pool_page*
page_alloc(mrb_pool *pool, size_t len)
{
struct mrb_pool_page *page;
if (len < POOL_PAGE_SIZE)
len = POOL_PAGE_SIZE;
page = (struct mrb_pool_page *)mrb_malloc_simple(pool->mrb, sizeof(struct mrb_pool_page)+len);
if (page) {
page->offset = 0;
page->len = len;
}
return page;
}
MRB_API void*
mrb_pool_alloc(mrb_pool *pool, size_t len)
{
struct mrb_pool_page *page;
size_t n;
if (!pool) return NULL;
len += ALIGN_PADDING(len);
page = pool->pages;
while (page) {
if (page->offset + len <= page->len) {
n = page->offset;
page->offset += len;
page->last = (char*)page->page+n;
return page->last;
}
page = page->next;
}
page = page_alloc(pool, len);
if (!page) return NULL;
page->offset = len;
page->next = pool->pages;
pool->pages = page;
page->last = (void*)page->page;
return page->last;
}
MRB_API mrb_bool
mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
{
struct mrb_pool_page *page;
if (!pool) return FALSE;
len += ALIGN_PADDING(len);
page = pool->pages;
while (page) {
if (page->last == p) {
size_t beg;
beg = (char*)p - page->page;
if (beg + len > page->len) return FALSE;
return TRUE;
}
page = page->next;
}
return FALSE;
}
MRB_API void*
mrb_pool_realloc(mrb_pool *pool, void *p, size_t oldlen, size_t newlen)
{
struct mrb_pool_page *page;
void *np;
if (!pool) return NULL;
oldlen += ALIGN_PADDING(oldlen);
newlen += ALIGN_PADDING(newlen);
page = pool->pages;
while (page) {
if (page->last == p) {
size_t beg;
beg = (char*)p - page->page;
if (beg + oldlen != page->offset) break;
if (beg + newlen > page->len) {
page->offset = beg;
break;
}
page->offset = beg + newlen;
return p;
}
page = page->next;
}
np = mrb_pool_alloc(pool, newlen);
if (np == NULL) {
return NULL;
}
memcpy(np, p, oldlen);
return np;
}
#ifdef TEST_POOL
int
main(void)
{
int i, len = 250;
mrb_pool *pool;
void *p;
pool = mrb_pool_open(NULL);
p = mrb_pool_alloc(pool, len);
for (i=1; i<20; i++) {
printf("%p (len=%d) %ud\n", p, len, mrb_pool_can_realloc(pool, p, len*2));
p = mrb_pool_realloc(pool, p, len, len*2);
len *= 2;
}
mrb_pool_close(pool);
return 0;
}
#endif
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