/*******************************************************************//**
Checks if the cache can safely be updated.
@return TRUE if can be updated */
static
ibool
can_cache_be_updated(
/*=================*/
trx_i_s_cache_t* cache) /*!< in: cache */
{
ullint now;
/* Here we read cache->last_read without acquiring its mutex
because last_read is only updated when a shared rw lock on the
whole cache is being held (see trx_i_s_cache_end_read()) and
we are currently holding an exclusive rw lock on the cache.
So it is not possible for last_read to be updated while we are
reading it. */
#ifdef UNIV_SYNC_DEBUG
ut_a(rw_lock_own(&cache->rw_lock, RW_LOCK_EX));
#endif
now = ut_time_us(NULL);
if (now - cache->last_read > CACHE_MIN_IDLE_TIME_US) {
return(TRUE);
}
return(FALSE);
}
/*******************************************************************//**
Release a shared/read lock on the tables cache. */
UNIV_INTERN
void
trx_i_s_cache_end_read(
/*===================*/
trx_i_s_cache_t* cache) /*!< in: cache */
{
ullint now;
#ifdef UNIV_SYNC_DEBUG
ut_a(rw_lock_own(&cache->rw_lock, RW_LOCK_SHARED));
#endif
/* update cache last read time */
now = ut_time_us(NULL);
mutex_enter(&cache->last_read_mutex);
cache->last_read = now;
mutex_exit(&cache->last_read_mutex);
rw_lock_s_unlock(&cache->rw_lock);
}
/**********************************************************************//**
Try to relocate a block.
@return TRUE if relocated */
static
ibool
buf_buddy_relocate(
/*===============*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
void* src, /*!< in: block to relocate */
void* dst, /*!< in: free block to relocate to */
ulint i) /*!< in: index of
buf_pool->zip_free[] */
{
buf_page_t* bpage;
const ulint size = BUF_BUDDY_LOW << i;
ullint usec = ut_time_us(NULL);
mutex_t* mutex;
ulint space;
ulint page_no;
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(!mutex_own(&buf_pool->zip_mutex));
ut_ad(!ut_align_offset(src, size));
ut_ad(!ut_align_offset(dst, size));
ut_ad(i >= buf_buddy_get_slot(PAGE_ZIP_MIN_SIZE));
UNIV_MEM_ASSERT_W(dst, size);
/* We assume that all memory from buf_buddy_alloc()
is used for compressed page frames. */
/* We look inside the allocated objects returned by
buf_buddy_alloc() and assume that each block is a compressed
page that contains a valid space_id and page_no in the page
header. Should the fields be invalid, we will be unable to
relocate the block. */
/* The src block may be split into smaller blocks,
some of which may be free. Thus, the
mach_read_from_4() calls below may attempt to read
from free memory. The memory is "owned" by the buddy
allocator (and it has been allocated from the buffer
pool), so there is nothing wrong about this. The
mach_read_from_4() calls here will only trigger bogus
Valgrind memcheck warnings in UNIV_DEBUG_VALGRIND builds. */
space = mach_read_from_4((const byte *) src
+ FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID);
page_no = mach_read_from_4((const byte *) src
+ FIL_PAGE_OFFSET);
/* Suppress Valgrind warnings about conditional jump
on uninitialized value. */
UNIV_MEM_VALID(&space, sizeof space);
UNIV_MEM_VALID(&page_no, sizeof page_no);
bpage = buf_page_hash_get(buf_pool, space, page_no);
if (!bpage || bpage->zip.data != src) {
/* The block has probably been freshly
allocated by buf_LRU_get_free_block() but not
added to buf_pool->page_hash yet. Obviously,
it cannot be relocated. */
return(FALSE);
}
if (page_zip_get_size(&bpage->zip) != size) {
/* The block is of different size. We would
have to relocate all blocks covered by src.
For the sake of simplicity, give up. */
ut_ad(page_zip_get_size(&bpage->zip) < size);
return(FALSE);
}
/* The block must have been allocated, but it may
contain uninitialized data. */
UNIV_MEM_ASSERT_W(src, size);
mutex = buf_page_get_mutex(bpage);
mutex_enter(mutex);
if (buf_page_can_relocate(bpage)) {
/* Relocate the compressed page. */
ut_a(bpage->zip.data == src);
memcpy(dst, src, size);
bpage->zip.data = dst;
mutex_exit(mutex);
UNIV_MEM_INVALID(src, size);
{
buf_buddy_stat_t* buddy_stat
= &buf_pool->buddy_stat[i];
buddy_stat->relocated++;
buddy_stat->relocated_usec
+= ut_time_us(NULL) - usec;
}
return(TRUE);
}
mutex_exit(mutex);
return(FALSE);
}
