/******************************************************************//**
Try to free a block. If bpage is a descriptor of a compressed-only
page, the descriptor object will be freed as well.
NOTE: If this function returns TRUE, it will temporarily
release buf_pool->mutex. Furthermore, the page frame will no longer be
accessible via bpage.
The caller must hold buf_pool->mutex and buf_page_get_mutex(bpage) and
release these two mutexes after the call. No other
buf_page_get_mutex() may be held when calling this function.
@return TRUE if freed, FALSE otherwise. */
UNIV_INTERN
ibool
buf_LRU_free_block(
/*===============*/
buf_page_t* bpage, /*!< in: block to be freed */
ibool zip) /*!< in: TRUE if should remove also the
compressed page of an uncompressed page */
{
buf_page_t* b = NULL;
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
mutex_t* block_mutex = buf_page_get_mutex(bpage);
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(mutex_own(block_mutex));
ut_ad(buf_page_in_file(bpage));
ut_ad(bpage->in_LRU_list);
ut_ad(!bpage->in_flush_list == !bpage->oldest_modification);
#if UNIV_WORD_SIZE == 4
/* On 32-bit systems, there is no padding in buf_page_t. On
other systems, Valgrind could complain about uninitialized pad
bytes. */
UNIV_MEM_ASSERT_RW(bpage, sizeof *bpage);
#endif
if (!buf_page_can_relocate(bpage)) {
/* Do not free buffer-fixed or I/O-fixed blocks. */
return(FALSE);
}
#ifdef UNIV_IBUF_COUNT_DEBUG
ut_a(ibuf_count_get(bpage->space, bpage->offset) == );
#endif /* UNIV_IBUF_COUNT_DEBUG */
if (zip || !bpage->zip.data) {
/* This would completely free the block. */
/* Do not completely free dirty blocks. */
if (bpage->oldest_modification) {
return(FALSE);
}
} else if (bpage->oldest_modification) {
/* Do not completely free dirty blocks. */
if (buf_page_get_state(bpage) != BUF_BLOCK_FILE_PAGE) {
ut_ad(buf_page_get_state(bpage)
== BUF_BLOCK_ZIP_DIRTY);
return(FALSE);
}
goto alloc;
} else if (buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE) {
/* Allocate the control block for the compressed page.
If it cannot be allocated (without freeing a block
from the LRU list), refuse to free bpage. */
alloc:
b = buf_page_alloc_descriptor();
ut_a(b);
memcpy(b, bpage, sizeof *b);
}
#ifdef UNIV_DEBUG
if (buf_debug_prints) {
fprintf(stderr, "Putting space %lu page %lu to free list\n",
(ulong) buf_page_get_space(bpage),
(ulong) buf_page_get_page_no(bpage));
}
#endif /* UNIV_DEBUG */
if (buf_LRU_block_remove_hashed_page(bpage, zip)!= BUF_BLOCK_ZIP_FREE) { //这里
ut_a(bpage->buf_fix_count == );
if (b) {
buf_page_t* hash_b;
buf_page_t* prev_b = UT_LIST_GET_PREV(LRU, b);
const ulint fold = buf_page_address_fold(
bpage->space, bpage->offset);
hash_b = buf_page_hash_get_low(
buf_pool, bpage->space, bpage->offset, fold);
ut_a(!hash_b);
b->state = b->oldest_modification
? BUF_BLOCK_ZIP_DIRTY
: BUF_BLOCK_ZIP_PAGE;
UNIV_MEM_DESC(b->zip.data,
page_zip_get_size(&b->zip), b);
/* The fields in_page_hash and in_LRU_list of
the to-be-freed block descriptor should have
been cleared in
buf_LRU_block_remove_hashed_page(), which
invokes buf_LRU_remove_block(). */
ut_ad(!bpage->in_page_hash);
ut_ad(!bpage->in_LRU_list);
/* bpage->state was BUF_BLOCK_FILE_PAGE because
b != NULL. The type cast below is thus valid. */
ut_ad(!((buf_block_t*) bpage)->in_unzip_LRU_list);
/* The fields of bpage were copied to b before
buf_LRU_block_remove_hashed_page() was invoked. */
ut_ad(!b->in_zip_hash);
ut_ad(b->in_page_hash);
ut_ad(b->in_LRU_list);
HASH_INSERT(buf_page_t, hash,
buf_pool->page_hash, fold, b);
/* Insert b where bpage was in the LRU list. */
if (UNIV_LIKELY(prev_b != NULL)) {
ulint lru_len;
ut_ad(prev_b->in_LRU_list);
ut_ad(buf_page_in_file(prev_b));
#if UNIV_WORD_SIZE == 4
/* On 32-bit systems, there is no
padding in buf_page_t. On other
systems, Valgrind could complain about
uninitialized pad bytes. */
UNIV_MEM_ASSERT_RW(prev_b, sizeof *prev_b);
#endif
UT_LIST_INSERT_AFTER(LRU, buf_pool->LRU,
prev_b, b);
incr_LRU_size_in_bytes(b, buf_pool);
if (buf_page_is_old(b)) {
buf_pool->LRU_old_len++;
if (UNIV_UNLIKELY
(buf_pool->LRU_old
== UT_LIST_GET_NEXT(LRU, b))) {
buf_pool->LRU_old = b;
}
}
lru_len = UT_LIST_GET_LEN(buf_pool->LRU);
if (lru_len > BUF_LRU_OLD_MIN_LEN) {
ut_ad(buf_pool->LRU_old);
/* Adjust the length of the
old block list if necessary */
buf_LRU_old_adjust_len(buf_pool);
} else if (lru_len == BUF_LRU_OLD_MIN_LEN) {
/* The LRU list is now long
enough for LRU_old to become
defined: init it */
buf_LRU_old_init(buf_pool);
}
#ifdef UNIV_LRU_DEBUG
/* Check that the "old" flag is consistent
in the block and its neighbours. */
buf_page_set_old(b, buf_page_is_old(b));
#endif /* UNIV_LRU_DEBUG */
} else {
ut_d(b->in_LRU_list = FALSE);
buf_LRU_add_block_low(b, buf_page_is_old(b));
}
if (b->state == BUF_BLOCK_ZIP_PAGE) {
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
buf_LRU_insert_zip_clean(b);
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
} else {
/* Relocate on buf_pool->flush_list. */
buf_flush_relocate_on_flush_list(bpage, b);
}
bpage->zip.data = NULL;
page_zip_set_size(&bpage->zip, );
/* Prevent buf_page_get_gen() from
decompressing the block while we release
buf_pool->mutex and block_mutex. */
mutex_enter(&buf_pool->zip_mutex);
buf_page_set_sticky(b);
mutex_exit(&buf_pool->zip_mutex);
}
buf_pool_mutex_exit(buf_pool);
mutex_exit(block_mutex);
/* Remove possible adaptive hash index on the page.
The page was declared uninitialized by
buf_LRU_block_remove_hashed_page(). We need to flag
the contents of the page valid (which it still is) in
order to avoid bogus Valgrind warnings.*/
UNIV_MEM_VALID(((buf_block_t*) bpage)->frame,
UNIV_PAGE_SIZE);
btr_search_drop_page_hash_index((buf_block_t*) bpage);
UNIV_MEM_INVALID(((buf_block_t*) bpage)->frame,
UNIV_PAGE_SIZE);
if (b) {
/* Compute and stamp the compressed page
checksum while not holding any mutex. The
block is already half-freed
(BUF_BLOCK_REMOVE_HASH) and removed from
buf_pool->page_hash, thus inaccessible by any
other thread. */
mach_write_to_4(
b->zip.data + FIL_PAGE_SPACE_OR_CHKSUM,
UNIV_LIKELY(srv_use_checksums)
? page_zip_calc_checksum(
b->zip.data,
page_zip_get_size(&b->zip))
: BUF_NO_CHECKSUM_MAGIC);
}
buf_pool_mutex_enter(buf_pool);
mutex_enter(block_mutex);
if (b) {
mutex_enter(&buf_pool->zip_mutex);
buf_page_unset_sticky(b);
mutex_exit(&buf_pool->zip_mutex);
}
buf_LRU_block_free_hashed_page((buf_block_t*) bpage);
} else {
/* The block_mutex should have been released by
buf_LRU_block_remove_hashed_page() when it returns
BUF_BLOCK_ZIP_FREE. */
ut_ad(block_mutex == &buf_pool->zip_mutex);
mutex_enter(block_mutex);
}
return(TRUE);
}
