// check next meta whether free, if free, then do quick merge
// replace_next == 0 means meta will replace next in free link
// return 0 means do quick merge success
int _slab_free_quick_merge(meta_t* meta, int replace_next)
{
meta_t* next, *prev;
page_t* page = META_PAGE(meta);
int shift = META_SHIFT(meta) + META_SIZE + meta->size;
if (shift < getpagesize()) {
next = META(meta, shift);
if (!(next->color & META_COLOR_ALLOC)) {
prev = next->free_prev > 0 ? PAGE_META(page, next->free_prev) : NULL;
// quick merge with next
meta->size += next->size + META_SIZE;
if (replace_next == 0) {
_slab_free_replace(next, meta);
if (META_SHIFT(next) == page->free) {
page->free = META_SHIFT(meta);
}
}
// quick merge with prev
if (prev && META_SHIFT(prev) + META_SIZE + prev->size == META_SHIFT(meta)) {
prev->size += META_SIZE + meta->size;
prev->free_next = meta->free_next;
next = meta->free_next > 0 ? PAGE_META(page, meta->free_next) : NULL;
if (next) {
next->free_prev = META_SHIFT(prev);
}
}
return 0;
}
}
return -1;
}
void* _slab_alloc(page_t* page, list_head_t* head, size_t sz)
{
int16_t shift;
meta_t* meta, *next, *split;
// no free memory
if (page->free <= 0 || page->remain < (int)sz + (int)META_SIZE) {
return NULL;
}
// loop free memory
shift = page->free;
while (shift > 0) {
meta = PAGE_META(page, shift);
shift = meta->free_next;
// not enough, ignore
if (meta->size < (int)sz) {
meta = NULL;
continue;
}
// just fit, erase from free list
else if (meta->size <= (int)(sz + META_SIZE)) {
next = _slab_free_erase(meta);
// erase free-link head
if (META_SHIFT(meta) == page->free) {
page->free = next ? META_SHIFT(next) : -1;
}
meta->color |= META_COLOR_ALLOC;
break;
}
// do split
else {
split = _slab_free_split(meta, sz);
_slab_free_replace(meta, split);
if (META_SHIFT(meta) == page->free) {
page->free = META_SHIFT(split);
}
meta->color |= META_COLOR_ALLOC;
break;
}
}
if (meta) {
page->remain -= (META_SIZE + meta->size);
_slab_page_erase(page, head);
return META_MEM(meta);
}
return NULL;
}
/*
* Called when bufp's page contains a partial key (index should be 1)
*
* All pages in the big key/data pair except bufp are freed. We cannot
* free bufp because the page pointing to it is lost and we can't get rid
* of its pointer.
*
* Returns:
* 0 => OK
*-1 => ERROR
*/
int
__big_delete(HTAB *hashp, BUFHEAD *bufp)
{
BUFHEAD *last_bfp, *rbufp;
uint16_t *bp, pageno;
int key_done, n;
size_t temp;
rbufp = bufp;
last_bfp = NULL;
bp = (uint16_t *)(void *)bufp->page;
pageno = 0;
key_done = 0;
while (!key_done || (bp[2] != FULL_KEY_DATA)) {
if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA)
key_done = 1;
/*
* If there is freespace left on a FULL_KEY_DATA page, then
* the data is short and fits entirely on this page, and this
* is the last page.
*/
if (bp[2] == FULL_KEY_DATA && FREESPACE(bp))
break;
pageno = bp[bp[0] - 1];
rbufp->flags |= BUF_MOD;
rbufp = __get_buf(hashp, (uint32_t)pageno, rbufp, 0);
if (last_bfp)
__free_ovflpage(hashp, last_bfp);
last_bfp = rbufp;
if (!rbufp)
return (-1); /* Error. */
bp = (uint16_t *)(void *)rbufp->page;
}
/*
* If we get here then rbufp points to the last page of the big
* key/data pair. Bufp points to the first one -- it should now be
* empty pointing to the next page after this pair. Can't free it
* because we don't have the page pointing to it.
*/
/* This is information from the last page of the pair. */
n = bp[0];
pageno = bp[n - 1];
/* Now, bp is the first page of the pair. */
bp = (uint16_t *)(void *)bufp->page;
if (n > 2) {
/* There is an overflow page. */
bp[1] = pageno;
bp[2] = OVFLPAGE;
bufp->ovfl = rbufp->ovfl;
} else
/* This is the last page. */
bufp->ovfl = NULL;
n -= 2;
bp[0] = n;
temp = hashp->BSIZE - PAGE_META(n);
_DBFIT(temp, uint16_t);
FREESPACE(bp) = (uint16_t)temp;
OFFSET(bp) = hashp->BSIZE;
bufp->flags |= BUF_MOD;
if (rbufp)
__free_ovflpage(hashp, rbufp);
if (last_bfp && last_bfp != rbufp)
__free_ovflpage(hashp, last_bfp);
hashp->NKEYS--;
return (0);
}
/*
* Big_insert
*
* You need to do an insert and the key/data pair is too big
*
* Returns:
* 0 ==> OK
*-1 ==> ERROR
*/
int
__big_insert(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
{
uint16_t *p, n;
size_t key_size, val_size;
uint16_t space, move_bytes, off;
char *cp, *key_data, *val_data;
size_t temp;
cp = bufp->page; /* Character pointer of p. */
p = (uint16_t *)(void *)cp;
key_data = (char *)key->data;
_DBFIT(key->size, int);
key_size = key->size;
val_data = (char *)val->data;
_DBFIT(val->size, int);
val_size = val->size;
/* First move the Key */
temp = FREESPACE(p) - BIGOVERHEAD;
_DBFIT(temp, uint16_t);
space = (uint16_t)temp;
while (key_size) {
move_bytes = MIN(space, key_size);
off = OFFSET(p) - move_bytes;
memmove(cp + off, key_data, (size_t)move_bytes);
key_size -= move_bytes;
key_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
temp = off - PAGE_META(n);
_DBFIT(temp, uint16_t);
FREESPACE(p) = (uint16_t)temp;
OFFSET(p) = off;
p[n] = PARTIAL_KEY;
bufp = __add_ovflpage(hashp, bufp);
if (!bufp)
return (-1);
n = p[0];
if (!key_size) {
space = FREESPACE(p);
if (space) {
move_bytes = MIN(space, val_size);
/*
* If the data would fit exactly in the
* remaining space, we must overflow it to the
* next page; otherwise the invariant that the
* data must end on a page with FREESPACE
* non-zero would fail.
*/
if (space == val_size && val_size == val->size)
goto toolarge;
off = OFFSET(p) - move_bytes;
memmove(cp + off, val_data, (size_t)move_bytes);
val_data += move_bytes;
val_size -= move_bytes;
p[n] = off;
p[n - 2] = FULL_KEY_DATA;
FREESPACE(p) = FREESPACE(p) - move_bytes;
OFFSET(p) = off;
} else {
toolarge:
p[n - 2] = FULL_KEY;
}
}
p = (uint16_t *)(void *)bufp->page;
cp = bufp->page;
bufp->flags |= BUF_MOD;
temp = FREESPACE(p) - BIGOVERHEAD;
_DBFIT(temp, uint16_t);
space = (uint16_t)temp;
}
/* Now move the data */
temp = FREESPACE(p) - BIGOVERHEAD;
_DBFIT(temp, uint16_t);
space = (uint16_t)temp;
while (val_size) {
move_bytes = MIN(space, val_size);
/*
* Here's the hack to make sure that if the data ends on the
* same page as the key ends, FREESPACE is at least one.
*/
if (space == val_size && val_size == val->size)
move_bytes--;
off = OFFSET(p) - move_bytes;
memmove(cp + off, val_data, (size_t)move_bytes);
val_size -= move_bytes;
val_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
temp = off - PAGE_META(n);
_DBFIT(temp, uint16_t);
FREESPACE(p) = (uint16_t)temp;
OFFSET(p) = off;
if (val_size) {
p[n] = FULL_KEY;
bufp = __add_ovflpage(hashp, bufp);
if (!bufp)
return (-1);
cp = bufp->page;
p = (uint16_t *)(void *)cp;
} else
p[n] = FULL_KEY_DATA;
bufp->flags |= BUF_MOD;
temp = FREESPACE(p) - BIGOVERHEAD;
_DBFIT(temp, uint16_t);
space = (uint16_t)temp;
}
return (0);
}
/*
* Big_insert
*
* You need to do an insert and the key/data pair is too big
*
* Returns:
* 0 ==> OK
*-1 ==> ERROR
*/
extern int
dbm_big_insert(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
{
register uint16 *p;
uint key_size, n, val_size;
uint16 space, move_bytes, off;
char *cp, *key_data, *val_data;
cp = bufp->page; /* Character pointer of p. */
p = (uint16 *)cp;
key_data = (char *)key->data;
key_size = key->size;
val_data = (char *)val->data;
val_size = val->size;
/* First move the Key */
for (space = FREESPACE(p) - BIGOVERHEAD; key_size;
space = FREESPACE(p) - BIGOVERHEAD) {
move_bytes = PR_MIN(space, key_size);
off = OFFSET(p) - move_bytes;
memmove(cp + off, key_data, move_bytes);
key_size -= move_bytes;
key_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
FREESPACE(p) = off - PAGE_META(n);
OFFSET(p) = off;
p[n] = PARTIAL_KEY;
bufp = dbm_add_ovflpage(hashp, bufp);
if (!bufp)
return (-1);
n = p[0];
if (!key_size) {
if (FREESPACE(p)) {
move_bytes = PR_MIN(FREESPACE(p), val_size);
off = OFFSET(p) - move_bytes;
p[n] = off;
memmove(cp + off, val_data, move_bytes);
val_data += move_bytes;
val_size -= move_bytes;
p[n - 2] = FULL_KEY_DATA;
FREESPACE(p) = FREESPACE(p) - move_bytes;
OFFSET(p) = off;
} else
p[n - 2] = FULL_KEY;
}
p = (uint16 *)bufp->page;
cp = bufp->page;
bufp->flags |= BUF_MOD;
}
/* Now move the data */
for (space = FREESPACE(p) - BIGOVERHEAD; val_size;
space = FREESPACE(p) - BIGOVERHEAD) {
move_bytes = PR_MIN(space, val_size);
/*
* Here's the hack to make sure that if the data ends on the
* same page as the key ends, FREESPACE is at least one.
*/
if (space == val_size && val_size == val->size)
move_bytes--;
off = OFFSET(p) - move_bytes;
memmove(cp + off, val_data, move_bytes);
val_size -= move_bytes;
val_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
FREESPACE(p) = off - PAGE_META(n);
OFFSET(p) = off;
if (val_size) {
p[n] = FULL_KEY;
bufp = dbm_add_ovflpage(hashp, bufp);
if (!bufp)
return (-1);
cp = bufp->page;
p = (uint16 *)cp;
} else
p[n] = FULL_KEY_DATA;
bufp->flags |= BUF_MOD;
}
return (0);
}
