/**********************************************************************//**
Deallocate a block. */
UNIV_INTERN
void
buf_buddy_free_low(
/*===============*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
void* buf, /*!< in: block to be freed, must not be
pointed to by the buffer pool */
ulint i) /*!< in: index of buf_pool->zip_free[],
or BUF_BUDDY_SIZES */
{
buf_page_t* bpage;
buf_page_t* buddy;
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(!mutex_own(&buf_pool->zip_mutex));
ut_ad(i <= BUF_BUDDY_SIZES);
ut_ad(i >= buf_buddy_get_slot(PAGE_ZIP_MIN_SIZE));
ut_ad(buf_pool->buddy_stat[i].used > 0);
buf_pool->buddy_stat[i].used--;
recombine:
UNIV_MEM_ASSERT_AND_ALLOC(buf, BUF_BUDDY_LOW << i);
((buf_page_t*) buf)->state = BUF_BLOCK_ZIP_FREE;
if (i == BUF_BUDDY_SIZES) {
buf_buddy_block_free(buf_pool, buf);
return;
}
ut_ad(i < BUF_BUDDY_SIZES);
ut_ad(buf == ut_align_down(buf, BUF_BUDDY_LOW << i));
ut_ad(!buf_pool_contains_zip(buf_pool, buf));
/* Do not recombine blocks if there are few free blocks.
We may waste up to 15360*max_len bytes to free blocks
(1024 + 2048 + 4096 + 8192 = 15360) */
if (UT_LIST_GET_LEN(buf_pool->zip_free[i]) < 16) {
goto func_exit;
}
/* Try to combine adjacent blocks. */
buddy = (buf_page_t*) buf_buddy_get(((byte*) buf), BUF_BUDDY_LOW << i);
#ifndef UNIV_DEBUG_VALGRIND
/* When Valgrind instrumentation is not enabled, we can read
buddy->state to quickly determine that a block is not free.
When the block is not free, buddy->state belongs to a compressed
page frame that may be flagged uninitialized in our Valgrind
instrumentation. */
if (buddy->state != BUF_BLOCK_ZIP_FREE) {
goto buddy_nonfree;
}
#endif /* !UNIV_DEBUG_VALGRIND */
for (bpage = UT_LIST_GET_FIRST(buf_pool->zip_free[i]); bpage; ) {
ut_ad(buf_page_get_state(bpage) == BUF_BLOCK_ZIP_FREE);
if (bpage == buddy) {
/* The buddy is free: recombine */
buf_buddy_remove_from_free(buf_pool, bpage, i);
buddy_is_free:
ut_ad(buf_page_get_state(buddy) == BUF_BLOCK_ZIP_FREE);
ut_ad(!buf_pool_contains_zip(buf_pool, buddy));
i++;
buf = ut_align_down(buf, BUF_BUDDY_LOW << i);
goto recombine;
}
ut_a(bpage != buf);
UNIV_MEM_ASSERT_W(bpage, BUF_BUDDY_LOW << i);
bpage = UT_LIST_GET_NEXT(list, bpage);
}
#ifndef UNIV_DEBUG_VALGRIND
buddy_nonfree:
#endif /* !UNIV_DEBUG_VALGRIND */
ut_d(BUF_BUDDY_LIST_VALIDATE(buf_pool, i));
/* The buddy is not free. Is there a free block of this size? */
bpage = UT_LIST_GET_FIRST(buf_pool->zip_free[i]);
if (bpage) {
/* Remove the block from the free list, because a successful
buf_buddy_relocate() will overwrite bpage->list. */
buf_buddy_remove_from_free(buf_pool, bpage, i);
/* Try to relocate the buddy of buf to the free block. */
if (buf_buddy_relocate(buf_pool, buddy, bpage, i)) {
buddy->state = BUF_BLOCK_ZIP_FREE;
goto buddy_is_free;
}
buf_buddy_add_to_free(buf_pool, bpage, i);
}
func_exit:
/* Free the block to the buddy list. */
bpage = buf;
/* Fill large blocks with a constant pattern. */
ut_d(memset(bpage, i, BUF_BUDDY_LOW << i));
UNIV_MEM_INVALID(bpage, BUF_BUDDY_LOW << i);
bpage->state = BUF_BLOCK_ZIP_FREE;
buf_buddy_add_to_free(buf_pool, bpage, i);
}
void
btr_pcur_store_position(
/*====================*/
btr_pcur_t* cursor, /* in: persistent cursor */
mtr_t* mtr) /* in: mtr */
{
page_cur_t* page_cursor;
rec_t* rec;
dict_tree_t* tree;
page_t* page;
ulint offs;
ut_a(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
ut_ad(cursor->latch_mode != BTR_NO_LATCHES);
tree = btr_cur_get_tree(btr_pcur_get_btr_cur(cursor));
page_cursor = btr_pcur_get_page_cur(cursor);
rec = page_cur_get_rec(page_cursor);
page = ut_align_down(rec, UNIV_PAGE_SIZE);
offs = ut_align_offset(rec, UNIV_PAGE_SIZE);
ut_ad(mtr_memo_contains(mtr, buf_block_align(page),
MTR_MEMO_PAGE_S_FIX)
|| mtr_memo_contains(mtr, buf_block_align(page),
MTR_MEMO_PAGE_X_FIX));
ut_a(cursor->latch_mode != BTR_NO_LATCHES);
if (UNIV_UNLIKELY(page_get_n_recs(page) == 0)) {
/* It must be an empty index tree; NOTE that in this case
we do not store the modify_clock, but always do a search
if we restore the cursor position */
ut_a(btr_page_get_next(page, mtr) == FIL_NULL);
ut_a(btr_page_get_prev(page, mtr) == FIL_NULL);
cursor->old_stored = BTR_PCUR_OLD_STORED;
if (page_rec_is_supremum_low(offs)) {
cursor->rel_pos = BTR_PCUR_AFTER_LAST_IN_TREE;
} else {
cursor->rel_pos = BTR_PCUR_BEFORE_FIRST_IN_TREE;
}
return;
}
if (page_rec_is_supremum_low(offs)) {
rec = page_rec_get_prev(rec);
cursor->rel_pos = BTR_PCUR_AFTER;
} else if (page_rec_is_infimum_low(offs)) {
rec = page_rec_get_next(rec);
cursor->rel_pos = BTR_PCUR_BEFORE;
} else {
cursor->rel_pos = BTR_PCUR_ON;
}
cursor->old_stored = BTR_PCUR_OLD_STORED;
cursor->old_rec = dict_tree_copy_rec_order_prefix(tree, rec,
&cursor->old_n_fields,
&cursor->old_rec_buf,
&cursor->buf_size);
cursor->block_when_stored = buf_block_align(page);
cursor->modify_clock = buf_block_get_modify_clock(
cursor->block_when_stored);
}
