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mariadb/storage/innobase/buf/buf0flu.cc
Marko Mäkelä 417434f12d MDEV-13039 innodb_fast_shutdown=0 may fail to purge all undo log 
When a slow shutdown is performed soon after spawning some work for
background threads that can create or commit transactions, it is possible
that new transactions are started or committed after the purge has finished.
This is violating the specification of innodb_fast_shutdown=0, namely that
the purge must be completed. (None of the history of the recent transactions
would be purged.)

Also, it is possible that the purge threads would exit in slow shutdown
while there exist active transactions, such as recovered incomplete
transactions that are being rolled back. Thus, the slow shutdown could
fail to purge some undo log that becomes purgeable after the transaction
commit or rollback.

srv_undo_sources: A flag that indicates if undo log can be generated
or the persistent, whether by background threads or by user SQL.
Even when this flag is clear, active transactions that already exist
in the system may be committed or rolled back.

innodb_shutdown(): Renamed from innobase_shutdown_for_mysql().
Do not return an error code; the operation never fails.
Clear the srv_undo_sources flag, and also ensure that the background
DROP TABLE queue is empty.

srv_purge_should_exit(): Do not allow the purge to exit if
srv_undo_sources are active or the background DROP TABLE queue is not
empty, or in slow shutdown, if any active transactions exist
(and are being rolled back).

srv_purge_coordinator_thread(): Remove some previous workarounds
for this bug.

innobase_start_or_create_for_mysql(): Set buf_page_cleaner_is_active
and srv_dict_stats_thread_active directly. Set srv_undo_sources before
starting the purge subsystem, to prevent immediate shutdown of the purge.
Create dict_stats_thread and fts_optimize_thread immediately
after setting srv_undo_sources, so that shutdown can use this flag to
determine if these subsystems were started.

dict_stats_shutdown(): Shut down dict_stats_thread. Backported from 10.2.

srv_shutdown_table_bg_threads(): Remove (unused).
2017-06-09 16:20:42 +03:00

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/*****************************************************************************
Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file buf/buf0flu.cc
The database buffer buf_pool flush algorithm
Created 11/11/1995 Heikki Tuuri
*******************************************************/
#include "buf0flu.h"
#ifdef UNIV_NONINL
#include "buf0flu.ic"
#endif
#include "buf0buf.h"
#include "buf0checksum.h"
#include "srv0start.h"
#include "srv0srv.h"
#include "page0zip.h"
#ifndef UNIV_HOTBACKUP
#include "ut0byte.h"
#include "ut0lst.h"
#include "page0page.h"
#include "fil0fil.h"
#include "buf0lru.h"
#include "buf0rea.h"
#include "ibuf0ibuf.h"
#include "log0log.h"
#include "os0file.h"
#include "trx0sys.h"
#include "srv0mon.h"
#include "mysql/plugin.h"
#include "mysql/service_thd_wait.h"
/** Number of pages flushed through non flush_list flushes. */
static ulint buf_lru_flush_page_count = 0;
/** Flag indicating if the page_cleaner is in active state. This flag
is set to TRUE by the page_cleaner thread when it is spawned and is set
back to FALSE at shutdown by the page_cleaner as well. Therefore no
need to protect it by a mutex. It is only ever read by the thread
doing the shutdown */
UNIV_INTERN bool buf_page_cleaner_is_active;
/** LRU flush batch is further divided into this chunk size to
reduce the wait time for the threads waiting for a clean block */
#define PAGE_CLEANER_LRU_BATCH_CHUNK_SIZE 100
#ifdef UNIV_PFS_THREAD
UNIV_INTERN mysql_pfs_key_t buf_page_cleaner_thread_key;
#endif /* UNIV_PFS_THREAD */
/** If LRU list of a buf_pool is less than this size then LRU eviction
should not happen. This is because when we do LRU flushing we also put
the blocks on free list. If LRU list is very small then we can end up
in thrashing. */
#define BUF_LRU_MIN_LEN 256
/* @} */
/** Handled page counters for a single flush */
struct flush_counters_t {
ulint flushed; /*!< number of dirty pages flushed */
ulint evicted; /*!< number of clean pages evicted, including
evicted uncompressed page images */
ulint unzip_LRU_evicted;/*!< number of uncompressed page images
evicted */
};
/******************************************************************//**
Increases flush_list size in bytes with zip_size for compressed page,
UNIV_PAGE_SIZE for uncompressed page in inline function */
static inline
void
incr_flush_list_size_in_bytes(
/*==========================*/
buf_block_t* block, /*!< in: control block */
buf_pool_t* buf_pool) /*!< in: buffer pool instance */
{
ut_ad(buf_flush_list_mutex_own(buf_pool));
ulint zip_size = page_zip_get_size(&block->page.zip);
buf_pool->stat.flush_list_bytes += zip_size ? zip_size : UNIV_PAGE_SIZE;
ut_ad(buf_pool->stat.flush_list_bytes <= buf_pool->curr_pool_size);
}
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
/******************************************************************//**
Validates the flush list.
@return TRUE if ok */
static
ibool
buf_flush_validate_low(
/*===================*/
buf_pool_t* buf_pool); /*!< in: Buffer pool instance */
/******************************************************************//**
Validates the flush list some of the time.
@return TRUE if ok or the check was skipped */
static
ibool
buf_flush_validate_skip(
/*====================*/
buf_pool_t* buf_pool) /*!< in: Buffer pool instance */
{
/** Try buf_flush_validate_low() every this many times */
# define BUF_FLUSH_VALIDATE_SKIP 23
/** The buf_flush_validate_low() call skip counter.
Use a signed type because of the race condition below. */
static int buf_flush_validate_count = BUF_FLUSH_VALIDATE_SKIP;
/* There is a race condition below, but it does not matter,
because this call is only for heuristic purposes. We want to
reduce the call frequency of the costly buf_flush_validate_low()
check in debug builds. */
if (--buf_flush_validate_count > 0) {
return(TRUE);
}
buf_flush_validate_count = BUF_FLUSH_VALIDATE_SKIP;
return(buf_flush_validate_low(buf_pool));
}
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
/*******************************************************************//**
Sets hazard pointer during flush_list iteration. */
UNIV_INLINE
void
buf_flush_set_hp(
/*=============*/
buf_pool_t* buf_pool,/*!< in/out: buffer pool instance */
const buf_page_t* bpage) /*!< in: buffer control block */
{
ut_ad(buf_flush_list_mutex_own(buf_pool));
ut_ad(buf_pool->flush_list_hp == NULL || bpage == NULL);
ut_ad(!bpage || buf_page_in_file(bpage));
ut_ad(!bpage || bpage->in_flush_list);
ut_ad(!bpage || buf_pool_from_bpage(bpage) == buf_pool);
buf_pool->flush_list_hp = bpage;
}
/*******************************************************************//**
Checks if the given block is a hazard pointer
@return true if bpage is hazard pointer */
UNIV_INLINE
bool
buf_flush_is_hp(
/*============*/
buf_pool_t* buf_pool,/*!< in: buffer pool instance */
const buf_page_t* bpage) /*!< in: buffer control block */
{
ut_ad(buf_flush_list_mutex_own(buf_pool));
return(buf_pool->flush_list_hp == bpage);
}
/*******************************************************************//**
Whenever we move a block in flush_list (either to remove it or to
relocate it) we check the hazard pointer set by some other thread
doing the flush list scan. If the hazard pointer is the same as the
one we are about going to move then we set it to NULL to force a rescan
in the thread doing the batch. */
UNIV_INLINE
void
buf_flush_update_hp(
/*================*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
buf_page_t* bpage) /*!< in: buffer control block */
{
ut_ad(buf_flush_list_mutex_own(buf_pool));
if (buf_flush_is_hp(buf_pool, bpage)) {
buf_flush_set_hp(buf_pool, NULL);
MONITOR_INC(MONITOR_FLUSH_HP_RESCAN);
}
}
/******************************************************************//**
Insert a block in the flush_rbt and returns a pointer to its
predecessor or NULL if no predecessor. The ordering is maintained
on the basis of the <oldest_modification, space, offset> key.
@return pointer to the predecessor or NULL if no predecessor. */
static
buf_page_t*
buf_flush_insert_in_flush_rbt(
/*==========================*/
buf_page_t* bpage) /*!< in: bpage to be inserted. */
{
const ib_rbt_node_t* c_node;
const ib_rbt_node_t* p_node;
buf_page_t* prev = NULL;
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(buf_flush_list_mutex_own(buf_pool));
/* Insert this buffer into the rbt. */
c_node = rbt_insert(buf_pool->flush_rbt, &bpage, &bpage);
ut_a(c_node != NULL);
/* Get the predecessor. */
p_node = rbt_prev(buf_pool->flush_rbt, c_node);
if (p_node != NULL) {
buf_page_t** value;
value = rbt_value(buf_page_t*, p_node);
prev = *value;
ut_a(prev != NULL);
}
return(prev);
}
/*********************************************************//**
Delete a bpage from the flush_rbt. */
static
void
buf_flush_delete_from_flush_rbt(
/*============================*/
buf_page_t* bpage) /*!< in: bpage to be removed. */
{
#ifdef UNIV_DEBUG
ibool ret = FALSE;
#endif /* UNIV_DEBUG */
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(buf_flush_list_mutex_own(buf_pool));
#ifdef UNIV_DEBUG
ret =
#endif /* UNIV_DEBUG */
rbt_delete(buf_pool->flush_rbt, &bpage);
ut_ad(ret);
}
/*****************************************************************//**
Compare two modified blocks in the buffer pool. The key for comparison
is:
key = <oldest_modification, space, offset>
This comparison is used to maintian ordering of blocks in the
buf_pool->flush_rbt.
Note that for the purpose of flush_rbt, we only need to order blocks
on the oldest_modification. The other two fields are used to uniquely
identify the blocks.
@return < 0 if b2 < b1, 0 if b2 == b1, > 0 if b2 > b1 */
static
int
buf_flush_block_cmp(
/*================*/
const void* p1, /*!< in: block1 */
const void* p2) /*!< in: block2 */
{
int ret;
const buf_page_t* b1 = *(const buf_page_t**) p1;
const buf_page_t* b2 = *(const buf_page_t**) p2;
#ifdef UNIV_DEBUG
buf_pool_t* buf_pool = buf_pool_from_bpage(b1);
#endif /* UNIV_DEBUG */
ut_ad(b1 != NULL);
ut_ad(b2 != NULL);
ut_ad(buf_flush_list_mutex_own(buf_pool));
ut_ad(b1->in_flush_list);
ut_ad(b2->in_flush_list);
if (b2->oldest_modification > b1->oldest_modification) {
return(1);
} else if (b2->oldest_modification < b1->oldest_modification) {
return(-1);
}
/* If oldest_modification is same then decide on the space. */
ret = (int)(b2->space - b1->space);
/* Or else decide ordering on the offset field. */
return(ret ? ret : (int)(b2->offset - b1->offset));
}
/********************************************************************//**
Initialize the red-black tree to speed up insertions into the flush_list
during recovery process. Should be called at the start of recovery
process before any page has been read/written. */
UNIV_INTERN
void
buf_flush_init_flush_rbt(void)
/*==========================*/
{
ulint i;
for (i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_array(i);
buf_flush_list_mutex_enter(buf_pool);
/* Create red black tree for speedy insertions in flush list. */
buf_pool->flush_rbt = rbt_create(
sizeof(buf_page_t*), buf_flush_block_cmp);
buf_flush_list_mutex_exit(buf_pool);
}
}
/********************************************************************//**
Frees up the red-black tree. */
UNIV_INTERN
void
buf_flush_free_flush_rbt(void)
/*==========================*/
{
ulint i;
for (i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_array(i);
buf_flush_list_mutex_enter(buf_pool);
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
ut_a(buf_flush_validate_low(buf_pool));
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
rbt_free(buf_pool->flush_rbt);
buf_pool->flush_rbt = NULL;
buf_flush_list_mutex_exit(buf_pool);
}
}
/********************************************************************//**
Inserts a modified block into the flush list. */
UNIV_INTERN
void
buf_flush_insert_into_flush_list(
/*=============================*/
buf_pool_t* buf_pool, /*!< buffer pool instance */
buf_block_t* block, /*!< in/out: block which is modified */
lsn_t lsn) /*!< in: oldest modification */
{
ut_ad(!buf_pool_mutex_own(buf_pool));
ut_ad(log_flush_order_mutex_own());
ut_ad(mutex_own(&block->mutex));
buf_flush_list_mutex_enter(buf_pool);
ut_ad((UT_LIST_GET_FIRST(buf_pool->flush_list) == NULL)
|| (UT_LIST_GET_FIRST(buf_pool->flush_list)->oldest_modification
<= lsn));
/* If we are in the recovery then we need to update the flush
red-black tree as well. */
if (UNIV_LIKELY_NULL(buf_pool->flush_rbt)) {
buf_flush_list_mutex_exit(buf_pool);
buf_flush_insert_sorted_into_flush_list(buf_pool, block, lsn);
return;
}
ut_ad(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
ut_ad(!block->page.in_flush_list);
ut_d(block->page.in_flush_list = TRUE);
block->page.oldest_modification = lsn;
UT_LIST_ADD_FIRST(list, buf_pool->flush_list, &block->page);
incr_flush_list_size_in_bytes(block, buf_pool);
#ifdef UNIV_DEBUG_VALGRIND
{
ulint zip_size = buf_block_get_zip_size(block);
if (zip_size) {
UNIV_MEM_ASSERT_RW(block->page.zip.data, zip_size);
} else {
UNIV_MEM_ASSERT_RW(block->frame, UNIV_PAGE_SIZE);
}
}
#endif /* UNIV_DEBUG_VALGRIND */
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
ut_a(buf_flush_validate_skip(buf_pool));
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
buf_flush_list_mutex_exit(buf_pool);
}
/********************************************************************//**
Inserts a modified block into the flush list in the right sorted position.
This function is used by recovery, because there the modifications do not
necessarily come in the order of lsn's. */
UNIV_INTERN
void
buf_flush_insert_sorted_into_flush_list(
/*====================================*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
buf_block_t* block, /*!< in/out: block which is modified */
lsn_t lsn) /*!< in: oldest modification */
{
buf_page_t* prev_b;
buf_page_t* b;
ut_ad(!buf_pool_mutex_own(buf_pool));
ut_ad(log_flush_order_mutex_own());
ut_ad(mutex_own(&block->mutex));
ut_ad(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
buf_flush_list_mutex_enter(buf_pool);
/* The field in_LRU_list is protected by buf_pool->mutex, which
we are not holding. However, while a block is in the flush
list, it is dirty and cannot be discarded, not from the
page_hash or from the LRU list. At most, the uncompressed
page frame of a compressed block may be discarded or created
(copying the block->page to or from a buf_page_t that is
dynamically allocated from buf_buddy_alloc()). Because those
transitions hold block->mutex and the flush list mutex (via
buf_flush_relocate_on_flush_list()), there is no possibility
of a race condition in the assertions below. */
ut_ad(block->page.in_LRU_list);
ut_ad(block->page.in_page_hash);
/* buf_buddy_block_register() will take a block in the
BUF_BLOCK_MEMORY state, not a file page. */
ut_ad(!block->page.in_zip_hash);
ut_ad(!block->page.in_flush_list);
ut_d(block->page.in_flush_list = TRUE);
block->page.oldest_modification = lsn;
#ifdef UNIV_DEBUG_VALGRIND
{
ulint zip_size = buf_block_get_zip_size(block);
if (zip_size) {
UNIV_MEM_ASSERT_RW(block->page.zip.data, zip_size);
} else {
UNIV_MEM_ASSERT_RW(block->frame, UNIV_PAGE_SIZE);
}
}
#endif /* UNIV_DEBUG_VALGRIND */
prev_b = NULL;
/* For the most part when this function is called the flush_rbt
should not be NULL. In a very rare boundary case it is possible
that the flush_rbt has already been freed by the recovery thread
before the last page was hooked up in the flush_list by the
io-handler thread. In that case we'll just do a simple
linear search in the else block. */
if (buf_pool->flush_rbt) {
prev_b = buf_flush_insert_in_flush_rbt(&block->page);
} else {
b = UT_LIST_GET_FIRST(buf_pool->flush_list);
while (b && b->oldest_modification
> block->page.oldest_modification) {
ut_ad(b->in_flush_list);
prev_b = b;
b = UT_LIST_GET_NEXT(list, b);
}
}
if (prev_b == NULL) {
UT_LIST_ADD_FIRST(list, buf_pool->flush_list, &block->page);
} else {
UT_LIST_INSERT_AFTER(list, buf_pool->flush_list,
prev_b, &block->page);
}
incr_flush_list_size_in_bytes(block, buf_pool);
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
ut_a(buf_flush_validate_low(buf_pool));
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
buf_flush_list_mutex_exit(buf_pool);
}
/********************************************************************//**
Returns TRUE if the file page block is immediately suitable for replacement,
i.e., the transition FILE_PAGE => NOT_USED allowed.
@return TRUE if can replace immediately */
UNIV_INTERN
ibool
buf_flush_ready_for_replace(
/*========================*/
buf_page_t* bpage) /*!< in: buffer control block, must be
buf_page_in_file(bpage) and in the LRU list */
{
#ifdef UNIV_DEBUG
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(buf_pool_mutex_own(buf_pool));
#endif /* UNIV_DEBUG */
ut_ad(mutex_own(buf_page_get_mutex(bpage)));
ut_ad(bpage->in_LRU_list);
if (buf_page_in_file(bpage)) {
return(bpage->oldest_modification == 0
&& bpage->buf_fix_count == 0
&& buf_page_get_io_fix(bpage) == BUF_IO_NONE);
}
ut_print_timestamp(stderr);
fprintf(stderr,
" InnoDB: Error: buffer block state %lu"
" in the LRU list!\n",
(ulong) buf_page_get_state(bpage));
ut_print_buf(stderr, bpage, sizeof(buf_page_t));
putc('\n', stderr);
return(FALSE);
}
/********************************************************************//**
Returns true if the block is modified and ready for flushing.
@return true if can flush immediately */
UNIV_INTERN
bool
buf_flush_ready_for_flush(
/*======================*/
buf_page_t* bpage, /*!< in: buffer control block, must be
buf_page_in_file(bpage) */
buf_flush_t flush_type)/*!< in: type of flush */
{
#ifdef UNIV_DEBUG
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(buf_pool_mutex_own(buf_pool));
#endif /* UNIV_DEBUG */
ut_a(buf_page_in_file(bpage));
ut_ad(mutex_own(buf_page_get_mutex(bpage)));
ut_ad(flush_type < BUF_FLUSH_N_TYPES);
if (bpage->oldest_modification == 0
|| buf_page_get_io_fix(bpage) != BUF_IO_NONE) {
return(false);
}
ut_ad(bpage->in_flush_list);
switch (flush_type) {
case BUF_FLUSH_LIST:
case BUF_FLUSH_LRU:
case BUF_FLUSH_SINGLE_PAGE:
return(true);
case BUF_FLUSH_N_TYPES:
break;
}
ut_error;
return(false);
}
/********************************************************************//**
Remove a block from the flush list of modified blocks. */
UNIV_INTERN
void
buf_flush_remove(
/*=============*/
buf_page_t* bpage) /*!< in: pointer to the block in question */
{
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ulint zip_size;
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(mutex_own(buf_page_get_mutex(bpage)));
ut_ad(bpage->in_flush_list);
buf_flush_list_mutex_enter(buf_pool);
switch (buf_page_get_state(bpage)) {
case BUF_BLOCK_POOL_WATCH:
case BUF_BLOCK_ZIP_PAGE:
/* Clean compressed pages should not be on the flush list */
case BUF_BLOCK_NOT_USED:
case BUF_BLOCK_READY_FOR_USE:
case BUF_BLOCK_MEMORY:
case BUF_BLOCK_REMOVE_HASH:
ut_error;
return;
case BUF_BLOCK_ZIP_DIRTY:
buf_page_set_state(bpage, BUF_BLOCK_ZIP_PAGE);
UT_LIST_REMOVE(list, buf_pool->flush_list, bpage);
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
buf_LRU_insert_zip_clean(bpage);
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
break;
case BUF_BLOCK_FILE_PAGE:
UT_LIST_REMOVE(list, buf_pool->flush_list, bpage);
break;
}
/* If the flush_rbt is active then delete from there as well. */
if (UNIV_LIKELY_NULL(buf_pool->flush_rbt)) {
buf_flush_delete_from_flush_rbt(bpage);
}
/* Must be done after we have removed it from the flush_rbt
because we assert on in_flush_list in comparison function. */
ut_d(bpage->in_flush_list = FALSE);
zip_size = page_zip_get_size(&bpage->zip);
buf_pool->stat.flush_list_bytes -= zip_size ? zip_size : UNIV_PAGE_SIZE;
bpage->oldest_modification = 0;
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
ut_a(buf_flush_validate_skip(buf_pool));
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
buf_flush_update_hp(buf_pool, bpage);
buf_flush_list_mutex_exit(buf_pool);
}
/*******************************************************************//**
Relocates a buffer control block on the flush_list.
Note that it is assumed that the contents of bpage have already been
copied to dpage.
IMPORTANT: When this function is called bpage and dpage are not
exact copies of each other. For example, they both will have different
::state. Also the ::list pointers in dpage may be stale. We need to
use the current list node (bpage) to do the list manipulation because
the list pointers could have changed between the time that we copied
the contents of bpage to the dpage and the flush list manipulation
below. */
UNIV_INTERN
void
buf_flush_relocate_on_flush_list(
/*=============================*/
buf_page_t* bpage, /*!< in/out: control block being moved */
buf_page_t* dpage) /*!< in/out: destination block */
{
buf_page_t* prev;
buf_page_t* prev_b = NULL;
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(buf_pool_mutex_own(buf_pool));
/* Must reside in the same buffer pool. */
ut_ad(buf_pool == buf_pool_from_bpage(dpage));
ut_ad(mutex_own(buf_page_get_mutex(bpage)));
buf_flush_list_mutex_enter(buf_pool);
/* FIXME: At this point we have both buf_pool and flush_list
mutexes. Theoretically removal of a block from flush list is
only covered by flush_list mutex but currently we do
have buf_pool mutex in buf_flush_remove() therefore this block
is guaranteed to be in the flush list. We need to check if
this will work without the assumption of block removing code
having the buf_pool mutex. */
ut_ad(bpage->in_flush_list);
ut_ad(dpage->in_flush_list);
/* If recovery is active we must swap the control blocks in
the flush_rbt as well. */
if (UNIV_LIKELY_NULL(buf_pool->flush_rbt)) {
buf_flush_delete_from_flush_rbt(bpage);
prev_b = buf_flush_insert_in_flush_rbt(dpage);
}
/* Must be done after we have removed it from the flush_rbt
because we assert on in_flush_list in comparison function. */
ut_d(bpage->in_flush_list = FALSE);
prev = UT_LIST_GET_PREV(list, bpage);
UT_LIST_REMOVE(list, buf_pool->flush_list, bpage);
if (prev) {
ut_ad(prev->in_flush_list);
UT_LIST_INSERT_AFTER(
list,
buf_pool->flush_list,
prev, dpage);
} else {
UT_LIST_ADD_FIRST(
list,
buf_pool->flush_list,
dpage);
}
/* Just an extra check. Previous in flush_list
should be the same control block as in flush_rbt. */
ut_a(!buf_pool->flush_rbt || prev_b == prev);
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
ut_a(buf_flush_validate_low(buf_pool));
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
buf_flush_update_hp(buf_pool, bpage);
buf_flush_list_mutex_exit(buf_pool);
}
/********************************************************************//**
Updates the flush system data structures when a write is completed. */
UNIV_INTERN
void
buf_flush_write_complete(
/*=====================*/
buf_page_t* bpage) /*!< in: pointer to the block in question */
{
buf_flush_t flush_type;
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(bpage);
buf_flush_remove(bpage);
flush_type = buf_page_get_flush_type(bpage);
buf_pool->n_flush[flush_type]--;
ut_ad(buf_pool_mutex_own(buf_pool));
if (buf_pool->n_flush[flush_type] == 0
&& buf_pool->init_flush[flush_type] == FALSE) {
/* The running flush batch has ended */
os_event_set(buf_pool->no_flush[flush_type]);
}
buf_dblwr_update(bpage, flush_type);
}
#endif /* !UNIV_HOTBACKUP */
/********************************************************************//**
Calculate the checksum of a page from compressed table and update the page. */
UNIV_INTERN
void
buf_flush_update_zip_checksum(
/*==========================*/
buf_frame_t* page, /*!< in/out: Page to update */
ulint zip_size, /*!< in: Compressed page size */
lsn_t lsn) /*!< in: Lsn to stamp on the page */
{
ut_a(zip_size > 0);
ib_uint32_t checksum = static_cast<ib_uint32_t>(
page_zip_calc_checksum(
page, zip_size,
static_cast<srv_checksum_algorithm_t>(
srv_checksum_algorithm)));
mach_write_to_8(page + FIL_PAGE_LSN, lsn);
memset(page + FIL_PAGE_FILE_FLUSH_LSN, 0, 8);
mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM, checksum);
}
/********************************************************************//**
Initializes a page for writing to the tablespace. */
UNIV_INTERN
void
buf_flush_init_for_writing(
/*=======================*/
byte* page, /*!< in/out: page */
void* page_zip_, /*!< in/out: compressed page, or NULL */
lsn_t newest_lsn) /*!< in: newest modification lsn
to the page */
{
ib_uint32_t checksum = 0 /* silence bogus gcc warning */;
ut_ad(page);
if (page_zip_) {
page_zip_des_t* page_zip;
ulint zip_size;
page_zip = static_cast<page_zip_des_t*>(page_zip_);
zip_size = page_zip_get_size(page_zip);
ut_ad(zip_size);
ut_ad(ut_is_2pow(zip_size));
ut_ad(zip_size <= UNIV_ZIP_SIZE_MAX);
switch (UNIV_EXPECT(fil_page_get_type(page), FIL_PAGE_INDEX)) {
case FIL_PAGE_TYPE_ALLOCATED:
case FIL_PAGE_INODE:
case FIL_PAGE_IBUF_BITMAP:
case FIL_PAGE_TYPE_FSP_HDR:
case FIL_PAGE_TYPE_XDES:
/* These are essentially uncompressed pages. */
memcpy(page_zip->data, page, zip_size);
/* fall through */
case FIL_PAGE_TYPE_ZBLOB:
case FIL_PAGE_TYPE_ZBLOB2:
case FIL_PAGE_INDEX:
buf_flush_update_zip_checksum(
page_zip->data, zip_size, newest_lsn);
return;
}
ut_print_timestamp(stderr);
fputs(" InnoDB: ERROR: The compressed page to be written"
" seems corrupt:", stderr);
ut_print_buf(stderr, page, zip_size);
fputs("\nInnoDB: Possibly older version of the page:", stderr);
ut_print_buf(stderr, page_zip->data, zip_size);
putc('\n', stderr);
ut_error;
}
/* Write the newest modification lsn to the page header and trailer */
mach_write_to_8(page + FIL_PAGE_LSN, newest_lsn);
mach_write_to_8(page + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN_OLD_CHKSUM,
newest_lsn);
/* Store the new formula checksum */
switch ((srv_checksum_algorithm_t) srv_checksum_algorithm) {
case SRV_CHECKSUM_ALGORITHM_CRC32:
case SRV_CHECKSUM_ALGORITHM_STRICT_CRC32:
checksum = buf_calc_page_crc32(page);
mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM, checksum);
break;
case SRV_CHECKSUM_ALGORITHM_INNODB:
case SRV_CHECKSUM_ALGORITHM_STRICT_INNODB:
checksum = (ib_uint32_t) buf_calc_page_new_checksum(page);
mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM, checksum);
checksum = (ib_uint32_t) buf_calc_page_old_checksum(page);
break;
case SRV_CHECKSUM_ALGORITHM_NONE:
case SRV_CHECKSUM_ALGORITHM_STRICT_NONE:
checksum = BUF_NO_CHECKSUM_MAGIC;
mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM, checksum);
break;
/* no default so the compiler will emit a warning if new enum
is added and not handled here */
}
/* With the InnoDB checksum, we overwrite the first 4 bytes of
the end lsn field to store the old formula checksum. Since it
depends also on the field FIL_PAGE_SPACE_OR_CHKSUM, it has to
be calculated after storing the new formula checksum.
In other cases we write the same value to both fields.
If CRC32 is used then it is faster to use that checksum
(calculated above) instead of calculating another one.
We can afford to store something other than
buf_calc_page_old_checksum() or BUF_NO_CHECKSUM_MAGIC in
this field because the file will not be readable by old
versions of MySQL/InnoDB anyway (older than MySQL 5.6.3) */
mach_write_to_4(page + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN_OLD_CHKSUM,
checksum);
}
#ifndef UNIV_HOTBACKUP
/********************************************************************//**
Does an asynchronous write of a buffer page. NOTE: in simulated aio and
also when the doublewrite buffer is used, we must call
buf_dblwr_flush_buffered_writes after we have posted a batch of
writes! */
static
void
buf_flush_write_block_low(
/*======================*/
buf_page_t* bpage, /*!< in: buffer block to write */
buf_flush_t flush_type, /*!< in: type of flush */
bool sync) /*!< in: true if sync IO request */
{
ulint zip_size = buf_page_get_zip_size(bpage);
page_t* frame = NULL;
#ifdef UNIV_DEBUG
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
ut_ad(!buf_pool_mutex_own(buf_pool));
#endif
#ifdef UNIV_LOG_DEBUG
static ibool univ_log_debug_warned;
#endif /* UNIV_LOG_DEBUG */
ut_ad(buf_page_in_file(bpage));
/* We are not holding buf_pool->mutex or block_mutex here.
Nevertheless, it is safe to access bpage, because it is
io_fixed and oldest_modification != 0. Thus, it cannot be
relocated in the buffer pool or removed from flush_list or
LRU_list. */
ut_ad(!buf_pool_mutex_own(buf_pool));
ut_ad(!buf_flush_list_mutex_own(buf_pool));
ut_ad(!mutex_own(buf_page_get_mutex(bpage)));
ut_ad(buf_page_get_io_fix(bpage) == BUF_IO_WRITE);
ut_ad(bpage->oldest_modification != 0);
#ifdef UNIV_IBUF_COUNT_DEBUG
ut_a(ibuf_count_get(bpage->space, bpage->offset) == 0);
#endif
ut_ad(bpage->newest_modification != 0);
#ifdef UNIV_LOG_DEBUG
if (!univ_log_debug_warned) {
univ_log_debug_warned = TRUE;
fputs("Warning: cannot force log to disk if"
" UNIV_LOG_DEBUG is defined!\n"
"Crash recovery will not work!\n",
stderr);
}
#else
/* Force the log to the disk before writing the modified block */
log_write_up_to(bpage->newest_modification, LOG_WAIT_ALL_GROUPS, TRUE);
#endif
switch (buf_page_get_state(bpage)) {
case BUF_BLOCK_POOL_WATCH:
case BUF_BLOCK_ZIP_PAGE: /* The page should be dirty. */
case BUF_BLOCK_NOT_USED:
case BUF_BLOCK_READY_FOR_USE:
case BUF_BLOCK_MEMORY:
case BUF_BLOCK_REMOVE_HASH:
ut_error;
break;
case BUF_BLOCK_ZIP_DIRTY:
frame = bpage->zip.data;
mach_write_to_8(frame + FIL_PAGE_LSN,
bpage->newest_modification);
ut_a(page_zip_verify_checksum(frame, zip_size));
memset(frame + FIL_PAGE_FILE_FLUSH_LSN, 0, 8);
break;
case BUF_BLOCK_FILE_PAGE:
frame = bpage->zip.data;
if (!frame) {
frame = ((buf_block_t*) bpage)->frame;
}
buf_flush_init_for_writing(((buf_block_t*) bpage)->frame,
bpage->zip.data
? &bpage->zip : NULL,
bpage->newest_modification);
break;
}
if (!srv_use_doublewrite_buf || !buf_dblwr) {
fil_io(OS_FILE_WRITE | OS_AIO_SIMULATED_WAKE_LATER,
sync, buf_page_get_space(bpage), zip_size,
buf_page_get_page_no(bpage), 0,
zip_size ? zip_size : UNIV_PAGE_SIZE,
frame, bpage);
} else if (flush_type == BUF_FLUSH_SINGLE_PAGE) {
buf_dblwr_write_single_page(bpage, sync);
} else {
ut_ad(!sync);
buf_dblwr_add_to_batch(bpage);
}
/* When doing single page flushing the IO is done synchronously
and we flush the changes to disk only for the tablespace we
are working on. */
if (sync) {
ut_ad(flush_type == BUF_FLUSH_SINGLE_PAGE);
fil_flush(buf_page_get_space(bpage));
buf_page_io_complete(bpage);
}
/* Increment the counter of I/O operations used
for selecting LRU policy. */
buf_LRU_stat_inc_io();
}
/********************************************************************//**
Writes a flushable page asynchronously from the buffer pool to a file.
NOTE: in simulated aio we must call
os_aio_simulated_wake_handler_threads after we have posted a batch of
writes! NOTE: buf_pool->mutex and buf_page_get_mutex(bpage) must be
held upon entering this function, and they will be released by this
function if it returns true.
@return TRUE if the page was flushed */
UNIV_INTERN
bool
buf_flush_page(
/*===========*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
buf_page_t* bpage, /*!< in: buffer control block */
buf_flush_t flush_type, /*!< in: type of flush */
bool sync) /*!< in: true if sync IO request */
{
ut_ad(flush_type < BUF_FLUSH_N_TYPES);
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(buf_page_in_file(bpage));
ut_ad(!sync || flush_type == BUF_FLUSH_SINGLE_PAGE);
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
ut_ad(mutex_own(block_mutex));
ut_ad(buf_flush_ready_for_flush(bpage, flush_type));
bool is_uncompressed;
is_uncompressed = (buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE);
ut_ad(is_uncompressed == (block_mutex != &buf_pool->zip_mutex));
ibool flush;
rw_lock_t* rw_lock;
bool no_fix_count = bpage->buf_fix_count == 0;
if (!is_uncompressed) {
flush = TRUE;
rw_lock = NULL;
} else if (!(no_fix_count || flush_type == BUF_FLUSH_LIST)) {
/* This is a heuristic, to avoid expensive S attempts. */
flush = FALSE;
} else {
rw_lock = &reinterpret_cast<buf_block_t*>(bpage)->lock;
if (flush_type != BUF_FLUSH_LIST) {
flush = rw_lock_s_lock_gen_nowait(
rw_lock, BUF_IO_WRITE);
} else {
/* Will S lock later */
flush = TRUE;
}
}
if (flush) {
/* We are committed to flushing by the time we get here */
buf_page_set_io_fix(bpage, BUF_IO_WRITE);
buf_page_set_flush_type(bpage, flush_type);
if (buf_pool->n_flush[flush_type] == 0) {
os_event_reset(buf_pool->no_flush[flush_type]);
}
++buf_pool->n_flush[flush_type];
mutex_exit(block_mutex);
buf_pool_mutex_exit(buf_pool);
if (flush_type == BUF_FLUSH_LIST
&& is_uncompressed
&& !rw_lock_s_lock_gen_nowait(rw_lock, BUF_IO_WRITE)) {
/* avoiding deadlock possibility involves doublewrite
buffer, should flush it, because it might hold the
another block->lock. */
buf_dblwr_flush_buffered_writes();
rw_lock_s_lock_gen(rw_lock, BUF_IO_WRITE);
}
/* Even though bpage is not protected by any mutex at this
point, it is safe to access bpage, because it is io_fixed and
oldest_modification != 0. Thus, it cannot be relocated in the
buffer pool or removed from flush_list or LRU_list. */
buf_flush_write_block_low(bpage, flush_type, sync);
}
return(flush);
}
# if defined UNIV_DEBUG || defined UNIV_IBUF_DEBUG
/********************************************************************//**
Writes a flushable page asynchronously from the buffer pool to a file.
NOTE: buf_pool->mutex and block->mutex must be held upon entering this
function, and they will be released by this function after flushing.
This is loosely based on buf_flush_batch() and buf_flush_page().
@return TRUE if the page was flushed and the mutexes released */
UNIV_INTERN
ibool
buf_flush_page_try(
/*===============*/
buf_pool_t* buf_pool, /*!< in/out: buffer pool instance */
buf_block_t* block) /*!< in/out: buffer control block */
{
ut_ad(buf_pool_mutex_own(buf_pool));
ut_ad(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
ut_ad(mutex_own(&block->mutex));
if (!buf_flush_ready_for_flush(&block->page, BUF_FLUSH_SINGLE_PAGE)) {
return(FALSE);
}
/* The following call will release the buffer pool and
block mutex. */
return(buf_flush_page(
buf_pool, &block->page, BUF_FLUSH_SINGLE_PAGE, true));
}
# endif /* UNIV_DEBUG || UNIV_IBUF_DEBUG */
/***********************************************************//**
Check the page is in buffer pool and can be flushed.
@return true if the page can be flushed. */
static
bool
buf_flush_check_neighbor(
/*=====================*/
ulint space, /*!< in: space id */
ulint offset, /*!< in: page offset */
buf_flush_t flush_type) /*!< in: BUF_FLUSH_LRU or
BUF_FLUSH_LIST */
{
buf_page_t* bpage;
buf_pool_t* buf_pool = buf_pool_get(space, offset);
bool ret;
ut_ad(flush_type == BUF_FLUSH_LRU
|| flush_type == BUF_FLUSH_LIST);
buf_pool_mutex_enter(buf_pool);
/* We only want to flush pages from this buffer pool. */
bpage = buf_page_hash_get(buf_pool, space, offset);
if (!bpage) {
buf_pool_mutex_exit(buf_pool);
return(false);
}
ut_a(buf_page_in_file(bpage));
/* We avoid flushing 'non-old' blocks in an LRU flush,
because the flushed blocks are soon freed */
ret = false;
if (flush_type != BUF_FLUSH_LRU || buf_page_is_old(bpage)) {
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
mutex_enter(block_mutex);
if (buf_flush_ready_for_flush(bpage, flush_type)) {
ret = true;
}
mutex_exit(block_mutex);
}
buf_pool_mutex_exit(buf_pool);
return(ret);
}
/***********************************************************//**
Flushes to disk all flushable pages within the flush area.
@return number of pages flushed */
static
ulint
buf_flush_try_neighbors(
/*====================*/
ulint space, /*!< in: space id */
ulint offset, /*!< in: page offset */
buf_flush_t flush_type, /*!< in: BUF_FLUSH_LRU or
BUF_FLUSH_LIST */
ulint n_flushed, /*!< in: number of pages
flushed so far in this batch */
ulint n_to_flush) /*!< in: maximum number of pages
we are allowed to flush */
{
ulint i;
ulint low;
ulint high;
buf_pool_t* buf_pool = buf_pool_get(space, offset);
ut_ad(flush_type == BUF_FLUSH_LRU || flush_type == BUF_FLUSH_LIST);
if (UT_LIST_GET_LEN(buf_pool->LRU) < BUF_LRU_OLD_MIN_LEN
|| srv_flush_neighbors == 0) {
/* If there is little space or neighbor flushing is
not enabled then just flush the victim. */
low = offset;
high = offset + 1;
} else {
/* When flushed, dirty blocks are searched in
neighborhoods of this size, and flushed along with the
original page. */
ulint buf_flush_area;
buf_flush_area = ut_min(
BUF_READ_AHEAD_AREA(buf_pool),
buf_pool->curr_size / 16);
low = (offset / buf_flush_area) * buf_flush_area;
high = (offset / buf_flush_area + 1) * buf_flush_area;
if (srv_flush_neighbors == 1) {
/* adjust 'low' and 'high' to limit
for contiguous dirty area */
if (offset > low) {
for (i = offset - 1;
i >= low
&& buf_flush_check_neighbor(
space, i, flush_type);
i--) {
/* do nothing */
}
low = i + 1;
}
for (i = offset + 1;
i < high
&& buf_flush_check_neighbor(
space, i, flush_type);
i++) {
/* do nothing */
}
high = i;
}
}
/* fprintf(stderr, "Flush area: low %lu high %lu\n", low, high); */
if (high > fil_space_get_size(space)) {
high = fil_space_get_size(space);
}
ulint count = 0;
for (i = low; i < high; i++) {
if ((count + n_flushed) >= n_to_flush) {
/* We have already flushed enough pages and
should call it a day. There is, however, one
exception. If the page whose neighbors we
are flushing has not been flushed yet then
we'll try to flush the victim that we
selected originally. */
if (i <= offset) {
i = offset;
} else {
break;
}
}
buf_pool = buf_pool_get(space, i);
buf_pool_mutex_enter(buf_pool);
/* We only want to flush pages from this buffer pool. */
buf_page_t* bpage = buf_page_hash_get(buf_pool, space, i);
if (bpage == NULL) {
buf_pool_mutex_exit(buf_pool);
continue;
}
ut_a(buf_page_in_file(bpage));
/* We avoid flushing 'non-old' blocks in an LRU flush,
because the flushed blocks are soon freed */
if (flush_type != BUF_FLUSH_LRU
|| i == offset
|| buf_page_is_old(bpage)) {
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
mutex_enter(block_mutex);
if (buf_flush_ready_for_flush(bpage, flush_type)
&& (i == offset || bpage->buf_fix_count == 0)
&& buf_flush_page(
buf_pool, bpage, flush_type, false)) {
++count;
continue;
}
mutex_exit(block_mutex);
}
buf_pool_mutex_exit(buf_pool);
}
if (count > 0) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_FLUSH_NEIGHBOR_TOTAL_PAGE,
MONITOR_FLUSH_NEIGHBOR_COUNT,
MONITOR_FLUSH_NEIGHBOR_PAGES,
(count - 1));
}
return(count);
}
/********************************************************************//**
Check if the block is modified and ready for flushing. If the the block
is ready to flush then flush the page and try o flush its neighbors.
@return TRUE if buf_pool mutex was released during this function.
This does not guarantee that some pages were written as well.
Number of pages written are incremented to the count. */
static
ibool
buf_flush_page_and_try_neighbors(
/*=============================*/
buf_page_t* bpage, /*!< in: buffer control block,
must be
buf_page_in_file(bpage) */
buf_flush_t flush_type, /*!< in: BUF_FLUSH_LRU
or BUF_FLUSH_LIST */
ulint n_to_flush, /*!< in: number of pages to
flush */
ulint* count) /*!< in/out: number of pages
flushed */
{
ibool flushed;
ib_mutex_t* block_mutex;
#ifdef UNIV_DEBUG
buf_pool_t* buf_pool = buf_pool_from_bpage(bpage);
#endif /* UNIV_DEBUG */
ut_ad(buf_pool_mutex_own(buf_pool));
block_mutex = buf_page_get_mutex(bpage);
mutex_enter(block_mutex);
ut_a(buf_page_in_file(bpage));
if (buf_flush_ready_for_flush(bpage, flush_type)) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_bpage(bpage);
buf_pool_mutex_exit(buf_pool);
/* These fields are protected by both the
buffer pool mutex and block mutex. */
ulint space = buf_page_get_space(bpage);
ulint offset = buf_page_get_page_no(bpage);
mutex_exit(block_mutex);
/* Try to flush also all the neighbors */
*count += buf_flush_try_neighbors(
space, offset, flush_type, *count, n_to_flush);
buf_pool_mutex_enter(buf_pool);
flushed = TRUE;
} else {
mutex_exit(block_mutex);
flushed = FALSE;
}
ut_ad(buf_pool_mutex_own(buf_pool));
return(flushed);
}
/*******************************************************************//**
This utility moves the uncompressed frames of pages to the free list.
Note that this function does not actually flush any data to disk. It
just detaches the uncompressed frames from the compressed pages at the
tail of the unzip_LRU and puts those freed frames in the free list.
Note that it is a best effort attempt and it is not guaranteed that
after a call to this function there will be 'max' blocks in the free
list.
@return number of blocks moved to the free list. */
static
ulint
buf_free_from_unzip_LRU_list_batch(
/*===============================*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
ulint max) /*!< in: desired number of
blocks in the free_list */
{
buf_block_t* block;
ulint scanned = 0;
ulint count = 0;
ulint free_len = UT_LIST_GET_LEN(buf_pool->free);
ulint lru_len = UT_LIST_GET_LEN(buf_pool->unzip_LRU);
ut_ad(buf_pool_mutex_own(buf_pool));
block = UT_LIST_GET_LAST(buf_pool->unzip_LRU);
while (block != NULL && count < max
&& free_len < srv_LRU_scan_depth
&& lru_len > UT_LIST_GET_LEN(buf_pool->LRU) / 10) {
++scanned;
if (buf_LRU_free_page(&block->page, false)) {
/* Block was freed. buf_pool->mutex potentially
released and reacquired */
++count;
block = UT_LIST_GET_LAST(buf_pool->unzip_LRU);
} else {
block = UT_LIST_GET_PREV(unzip_LRU, block);
}
free_len = UT_LIST_GET_LEN(buf_pool->free);
lru_len = UT_LIST_GET_LEN(buf_pool->unzip_LRU);
}
ut_ad(buf_pool_mutex_own(buf_pool));
if (scanned) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_BATCH_SCANNED,
MONITOR_LRU_BATCH_SCANNED_NUM_CALL,
MONITOR_LRU_BATCH_SCANNED_PER_CALL,
scanned);
}
return(count);
}
/*******************************************************************//**
This utility flushes dirty blocks from the end of the LRU list.
The calling thread is not allowed to own any latches on pages!
It attempts to make 'max' blocks available in the free list. Note that
it is a best effort attempt and it is not guaranteed that after a call
to this function there will be 'max' blocks in the free list.
@return number of blocks for which the write request was queued. */
static
void
buf_flush_LRU_list_batch(
/*=====================*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
ulint max, /*!< in: desired number of
blocks in the free_list */
flush_counters_t* n) /*!< out: flushed/evicted page
counts */
{
buf_page_t* bpage;
ulint count = 0;
ulint scanned = 0;
ulint free_len = UT_LIST_GET_LEN(buf_pool->free);
ulint lru_len = UT_LIST_GET_LEN(buf_pool->LRU);
ut_ad(buf_pool_mutex_own(buf_pool));
n->flushed = 0;
n->evicted = 0;
n->unzip_LRU_evicted = 0;
bpage = UT_LIST_GET_LAST(buf_pool->LRU);
while (bpage != NULL && count < max
&& (n->flushed + n->evicted) < max
&& free_len < srv_LRU_scan_depth
&& lru_len > BUF_LRU_MIN_LEN) {
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
ibool evict;
mutex_enter(block_mutex);
evict = buf_flush_ready_for_replace(bpage);
mutex_exit(block_mutex);
++scanned;
/* If the block is ready to be replaced we try to
free it i.e.: put it on the free list.
Otherwise we try to flush the block and its
neighbors. In this case we'll put it on the
free list in the next pass. We do this extra work
of putting blocks to the free list instead of
just flushing them because after every flush
we have to restart the scan from the tail of
the LRU list and if we don't clear the tail
of the flushed pages then the scan becomes
O(n*n). */
if (evict) {
if (buf_LRU_free_page(bpage, true)) {
/* buf_pool->mutex was potentially
released and reacquired. */
n->evicted++;
bpage = UT_LIST_GET_LAST(buf_pool->LRU);
} else {
bpage = UT_LIST_GET_PREV(LRU, bpage);
}
} else {
ulint space;
ulint offset;
buf_page_t* prev_bpage;
prev_bpage = UT_LIST_GET_PREV(LRU, bpage);
/* Save the previous bpage */
if (prev_bpage != NULL) {
space = prev_bpage->space;
offset = prev_bpage->offset;
} else {
space = ULINT_UNDEFINED;
offset = ULINT_UNDEFINED;
}
if (!buf_flush_page_and_try_neighbors(
bpage, BUF_FLUSH_LRU, max, &n->flushed)) {
bpage = prev_bpage;
} else {
/* buf_pool->mutex was released.
reposition the iterator. Note: the
prev block could have been repositioned
too but that should be rare. */
if (prev_bpage != NULL) {
ut_ad(space != ULINT_UNDEFINED);
ut_ad(offset != ULINT_UNDEFINED);
prev_bpage = buf_page_hash_get(
buf_pool, space, offset);
}
bpage = prev_bpage;
}
}
free_len = UT_LIST_GET_LEN(buf_pool->free);
lru_len = UT_LIST_GET_LEN(buf_pool->LRU);
}
/* We keep track of all flushes happening as part of LRU
flush. When estimating the desired rate at which flush_list
should be flushed, we factor in this value. */
buf_lru_flush_page_count += n->flushed;
ut_ad(buf_pool_mutex_own(buf_pool));
if (scanned) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_BATCH_SCANNED,
MONITOR_LRU_BATCH_SCANNED_NUM_CALL,
MONITOR_LRU_BATCH_SCANNED_PER_CALL,
scanned);
}
}
/*******************************************************************//**
Flush and move pages from LRU or unzip_LRU list to the free list.
Whether LRU or unzip_LRU is used depends on the state of the system.
@return number of blocks for which either the write request was queued
or in case of unzip_LRU the number of blocks actually moved to the
free list */
static
void
buf_do_LRU_batch(
/*=============*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
ulint max, /*!< in: desired number of
blocks in the free_list */
flush_counters_t* n) /*!< out: flushed/evicted page
counts */
{
if (buf_LRU_evict_from_unzip_LRU(buf_pool)) {
n->unzip_LRU_evicted = buf_free_from_unzip_LRU_list_batch(buf_pool, max);
} else {
n->unzip_LRU_evicted = 0;
}
if (max > n->unzip_LRU_evicted) {
buf_flush_LRU_list_batch(buf_pool, max - n->unzip_LRU_evicted, n);
} else {
n->evicted = 0;
n->flushed = 0;
}
}
/*******************************************************************//**
This utility flushes dirty blocks from the end of the flush_list.
the calling thread is not allowed to own any latches on pages!
@return number of blocks for which the write request was queued;
ULINT_UNDEFINED if there was a flush of the same type already
running */
static
ulint
buf_do_flush_list_batch(
/*====================*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
ulint min_n, /*!< in: wished minimum mumber
of blocks flushed (it is not
guaranteed that the actual
number is that big, though) */
lsn_t lsn_limit) /*!< all blocks whose
oldest_modification is smaller
than this should be flushed (if
their number does not exceed
min_n) */
{
ulint count = 0;
ulint scanned = 0;
ut_ad(buf_pool_mutex_own(buf_pool));
/* Start from the end of the list looking for a suitable
block to be flushed. */
buf_flush_list_mutex_enter(buf_pool);
ulint len = UT_LIST_GET_LEN(buf_pool->flush_list);
/* In order not to degenerate this scan to O(n*n) we attempt
to preserve pointer of previous block in the flush list. To do
so we declare it a hazard pointer. Any thread working on the
flush list must check the hazard pointer and if it is removing
the same block then it must reset it. */
for (buf_page_t* bpage = UT_LIST_GET_LAST(buf_pool->flush_list);
count < min_n && bpage != NULL && len > 0
&& bpage->oldest_modification < lsn_limit;
++scanned) {
buf_page_t* prev;
ut_a(bpage->oldest_modification > 0);
ut_ad(bpage->in_flush_list);
prev = UT_LIST_GET_PREV(list, bpage);
buf_flush_set_hp(buf_pool, prev);
buf_flush_list_mutex_exit(buf_pool);
#ifdef UNIV_DEBUG
bool flushed =
#endif /* UNIV_DEBUG */
buf_flush_page_and_try_neighbors(
bpage, BUF_FLUSH_LIST, min_n, &count);
buf_flush_list_mutex_enter(buf_pool);
ut_ad(flushed || buf_flush_is_hp(buf_pool, prev));
if (!buf_flush_is_hp(buf_pool, prev)) {
/* The hazard pointer was reset by some other
thread. Restart the scan. */
ut_ad(buf_flush_is_hp(buf_pool, NULL));
bpage = UT_LIST_GET_LAST(buf_pool->flush_list);
len = UT_LIST_GET_LEN(buf_pool->flush_list);
} else {
bpage = prev;
--len;
buf_flush_set_hp(buf_pool, NULL);
}
ut_ad(!bpage || bpage->in_flush_list);
}
buf_flush_list_mutex_exit(buf_pool);
MONITOR_INC_VALUE_CUMULATIVE(MONITOR_FLUSH_BATCH_SCANNED,
MONITOR_FLUSH_BATCH_SCANNED_NUM_CALL,
MONITOR_FLUSH_BATCH_SCANNED_PER_CALL,
scanned);
ut_ad(buf_pool_mutex_own(buf_pool));
return(count);
}
/*******************************************************************//**
This utility flushes dirty blocks from the end of the LRU list or flush_list.
NOTE 1: in the case of an LRU flush the calling thread may own latches to
pages: to avoid deadlocks, this function must be written so that it cannot
end up waiting for these latches! NOTE 2: in the case of a flush list flush,
the calling thread is not allowed to own any latches on pages!
@return number of blocks for which the write request was queued */
static
void
buf_flush_batch(
/*============*/
buf_pool_t* buf_pool, /*!< in: buffer pool instance */
buf_flush_t flush_type, /*!< in: BUF_FLUSH_LRU or
BUF_FLUSH_LIST; if BUF_FLUSH_LIST,
then the caller must not own any
latches on pages */
ulint min_n, /*!< in: wished minimum mumber of blocks
flushed (it is not guaranteed that the
actual number is that big, though) */
lsn_t lsn_limit, /*!< in: in the case of BUF_FLUSH_LIST
all blocks whose oldest_modification is
smaller than this should be flushed
(if their number does not exceed
min_n), otherwise ignored */
flush_counters_t* n) /*!< out: flushed/evicted page
counts */
{
ut_ad(flush_type == BUF_FLUSH_LRU || flush_type == BUF_FLUSH_LIST);
#ifdef UNIV_SYNC_DEBUG
ut_ad((flush_type != BUF_FLUSH_LIST)
|| sync_thread_levels_empty_except_dict());
#endif /* UNIV_SYNC_DEBUG */
buf_pool_mutex_enter(buf_pool);
/* Note: The buffer pool mutex is released and reacquired within
the flush functions. */
switch (flush_type) {
case BUF_FLUSH_LRU:
buf_do_LRU_batch(buf_pool, min_n, n);
break;
case BUF_FLUSH_LIST:
n->flushed = buf_do_flush_list_batch(buf_pool, min_n, lsn_limit);
n->evicted = 0;
break;
default:
ut_error;
}
buf_pool_mutex_exit(buf_pool);
#ifdef UNIV_DEBUG
if (buf_debug_prints && n->flushed > 0) {
fprintf(stderr, flush_type == BUF_FLUSH_LRU
? "Flushed %lu pages in LRU flush\n"
: "Flushed %lu pages in flush list flush\n",
(ulong) n->flushed);
}
#endif /* UNIV_DEBUG */
}
/******************************************************************//**
Gather the aggregated stats for both flush list and LRU list flushing */
static
void
buf_flush_common(
/*=============*/
buf_flush_t flush_type, /*!< in: type of flush */
ulint page_count) /*!< in: number of pages flushed */
{
buf_dblwr_flush_buffered_writes();
ut_a(flush_type == BUF_FLUSH_LRU || flush_type == BUF_FLUSH_LIST);
#ifdef UNIV_DEBUG
if (buf_debug_prints && page_count > 0) {
fprintf(stderr, flush_type == BUF_FLUSH_LRU
? "Flushed %lu pages in LRU flush\n"
: "Flushed %lu pages in flush list flush\n",
(ulong) page_count);
}
#endif /* UNIV_DEBUG */
srv_stats.buf_pool_flushed.add(page_count);
}
/******************************************************************//**
Start a buffer flush batch for LRU or flush list */
static
ibool
buf_flush_start(
/*============*/
buf_pool_t* buf_pool, /*!< buffer pool instance */
buf_flush_t flush_type) /*!< in: BUF_FLUSH_LRU
or BUF_FLUSH_LIST */
{
buf_pool_mutex_enter(buf_pool);
if (buf_pool->n_flush[flush_type] > 0
|| buf_pool->init_flush[flush_type] == TRUE) {
/* There is already a flush batch of the same type running */
buf_pool_mutex_exit(buf_pool);
return(FALSE);
}
buf_pool->init_flush[flush_type] = TRUE;
buf_pool_mutex_exit(buf_pool);
return(TRUE);
}
/******************************************************************//**
End a buffer flush batch for LRU or flush list */
static
void
buf_flush_end(
/*==========*/
buf_pool_t* buf_pool, /*!< buffer pool instance */
buf_flush_t flush_type) /*!< in: BUF_FLUSH_LRU
or BUF_FLUSH_LIST */
{
buf_pool_mutex_enter(buf_pool);
buf_pool->init_flush[flush_type] = FALSE;
buf_pool->try_LRU_scan = TRUE;
if (buf_pool->n_flush[flush_type] == 0) {
/* The running flush batch has ended */
os_event_set(buf_pool->no_flush[flush_type]);
}
buf_pool_mutex_exit(buf_pool);
}
/******************************************************************//**
Waits until a flush batch of the given type ends */
UNIV_INTERN
void
buf_flush_wait_batch_end(
/*=====================*/
buf_pool_t* buf_pool, /*!< buffer pool instance */
buf_flush_t type) /*!< in: BUF_FLUSH_LRU
or BUF_FLUSH_LIST */
{
ut_ad(type == BUF_FLUSH_LRU || type == BUF_FLUSH_LIST);
if (buf_pool == NULL) {
ulint i;
for (i = 0; i < srv_buf_pool_instances; ++i) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_array(i);
thd_wait_begin(NULL, THD_WAIT_DISKIO);
os_event_wait(buf_pool->no_flush[type]);
thd_wait_end(NULL);
}
} else {
thd_wait_begin(NULL, THD_WAIT_DISKIO);
os_event_wait(buf_pool->no_flush[type]);
thd_wait_end(NULL);
}
}
/*******************************************************************//**
This utility flushes dirty blocks from the end of the LRU list and also
puts replaceable clean pages from the end of the LRU list to the free
list.
NOTE: The calling thread is not allowed to own any latches on pages!
@return true if a batch was queued successfully. false if another batch
of same type was already running. */
static
bool
buf_flush_LRU(
/*==========*/
buf_pool_t* buf_pool, /*!< in/out: buffer pool instance */
ulint min_n, /*!< in: wished minimum mumber of blocks
flushed (it is not guaranteed that the
actual number is that big, though) */
flush_counters_t *n) /*!< out: flushed/evicted page
counts */
{
if (!buf_flush_start(buf_pool, BUF_FLUSH_LRU)) {
n->flushed = 0;
n->evicted = 0;
n->unzip_LRU_evicted = 0;
return(false);
}
buf_flush_batch(buf_pool, BUF_FLUSH_LRU, min_n, 0, n);
buf_flush_end(buf_pool, BUF_FLUSH_LRU);
buf_flush_common(BUF_FLUSH_LRU, n->flushed);
return(true);
}
/*******************************************************************//**
This utility flushes dirty blocks from the end of the flush list of
all buffer pool instances.
NOTE: The calling thread is not allowed to own any latches on pages!
@return true if a batch was queued successfully for each buffer pool
instance. false if another batch of same type was already running in
at least one of the buffer pool instance */
UNIV_INTERN
bool
buf_flush_list(
/*===========*/
ulint min_n, /*!< in: wished minimum mumber of blocks
flushed (it is not guaranteed that the
actual number is that big, though) */
lsn_t lsn_limit, /*!< in the case BUF_FLUSH_LIST all
blocks whose oldest_modification is
smaller than this should be flushed
(if their number does not exceed
min_n), otherwise ignored */
ulint* n_processed) /*!< out: the number of pages
which were processed is passed
back to caller. Ignored if NULL */
{
ulint i;
bool success = true;
if (n_processed) {
*n_processed = 0;
}
if (min_n != ULINT_MAX) {
/* Ensure that flushing is spread evenly amongst the
buffer pool instances. When min_n is ULINT_MAX
we need to flush everything up to the lsn limit
so no limit here. */
min_n = (min_n + srv_buf_pool_instances - 1)
/ srv_buf_pool_instances;
}
/* Flush to lsn_limit in all buffer pool instances */
for (i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool;
flush_counters_t n;
buf_pool = buf_pool_from_array(i);
if (!buf_flush_start(buf_pool, BUF_FLUSH_LIST)) {
/* We have two choices here. If lsn_limit was
specified then skipping an instance of buffer
pool means we cannot guarantee that all pages
up to lsn_limit has been flushed. We can
return right now with failure or we can try
to flush remaining buffer pools up to the
lsn_limit. We attempt to flush other buffer
pools based on the assumption that it will
help in the retry which will follow the
failure. */
success = false;
continue;
}
buf_flush_batch(
buf_pool, BUF_FLUSH_LIST, min_n, lsn_limit, &n);
buf_flush_end(buf_pool, BUF_FLUSH_LIST);
buf_flush_common(BUF_FLUSH_LIST, n.flushed);
if (n_processed) {
*n_processed += n.flushed;
}
if (n.flushed) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_FLUSH_BATCH_TOTAL_PAGE,
MONITOR_FLUSH_BATCH_COUNT,
MONITOR_FLUSH_BATCH_PAGES,
n.flushed);
}
}
return(success);
}
/******************************************************************//**
This function picks up a single dirty page from the tail of the LRU
list, flushes it, removes it from page_hash and LRU list and puts
it on the free list. It is called from user threads when they are
unable to find a replaceable page at the tail of the LRU list i.e.:
when the background LRU flushing in the page_cleaner thread is not
fast enough to keep pace with the workload.
@return TRUE if success. */
UNIV_INTERN
ibool
buf_flush_single_page_from_LRU(
/*===========================*/
buf_pool_t* buf_pool) /*!< in/out: buffer pool instance */
{
ulint scanned;
buf_page_t* bpage;
buf_pool_mutex_enter(buf_pool);
for (bpage = UT_LIST_GET_LAST(buf_pool->LRU), scanned = 1;
bpage != NULL;
bpage = UT_LIST_GET_PREV(LRU, bpage), ++scanned) {
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
mutex_enter(block_mutex);
if (buf_flush_ready_for_flush(bpage, BUF_FLUSH_SINGLE_PAGE)) {
/* The following call will release the buffer pool
and block mutex. */
ibool flushed = buf_flush_page(
buf_pool, bpage, BUF_FLUSH_SINGLE_PAGE, true);
if (flushed) {
/* buf_flush_page() will release the
block mutex */
break;
}
}
mutex_exit(block_mutex);
}
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_SINGLE_FLUSH_SCANNED,
MONITOR_LRU_SINGLE_FLUSH_SCANNED_NUM_CALL,
MONITOR_LRU_SINGLE_FLUSH_SCANNED_PER_CALL,
scanned);
if (bpage == NULL) {
/* Can't find a single flushable page. */
buf_pool_mutex_exit(buf_pool);
return(FALSE);
}
ibool freed = FALSE;
/* At this point the page has been written to the disk.
As we are not holding buffer pool or block mutex therefore
we cannot use the bpage safely. It may have been plucked out
of the LRU list by some other thread or it may even have
relocated in case of a compressed page. We need to start
the scan of LRU list again to remove the block from the LRU
list and put it on the free list. */
buf_pool_mutex_enter(buf_pool);
for (bpage = UT_LIST_GET_LAST(buf_pool->LRU);
bpage != NULL;
bpage = UT_LIST_GET_PREV(LRU, bpage)) {
ib_mutex_t* block_mutex = buf_page_get_mutex(bpage);
mutex_enter(block_mutex);
ibool ready = buf_flush_ready_for_replace(bpage);
mutex_exit(block_mutex);
if (ready) {
bool evict_zip;
evict_zip = !buf_LRU_evict_from_unzip_LRU(buf_pool);;
freed = buf_LRU_free_page(bpage, evict_zip);
break;
}
}
buf_pool_mutex_exit(buf_pool);
return(freed);
}
/*********************************************************************//**
Clears up tail of the LRU lists:
* Put replaceable pages at the tail of LRU to the free list
* Flush dirty pages at the tail of LRU to the disk
The depth to which we scan each buffer pool is controlled by dynamic
config parameter innodb_LRU_scan_depth.
@return total pages flushed */
UNIV_INTERN
ulint
buf_flush_LRU_tail(void)
/*====================*/
{
ulint total_flushed = 0;
for (ulint i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool = buf_pool_from_array(i);
ulint scan_depth;
/* srv_LRU_scan_depth can be arbitrarily large value.
We cap it with current LRU size. */
buf_pool_mutex_enter(buf_pool);
scan_depth = UT_LIST_GET_LEN(buf_pool->LRU);
buf_pool_mutex_exit(buf_pool);
scan_depth = ut_min(srv_LRU_scan_depth, scan_depth);
/* We divide LRU flush into smaller chunks because
there may be user threads waiting for the flush to
end in buf_LRU_get_free_block(). */
for (ulint j = 0;
j < scan_depth;
j += PAGE_CLEANER_LRU_BATCH_CHUNK_SIZE) {
flush_counters_t n;
/* Currently page_cleaner is the only thread
that can trigger an LRU flush. It is possible
that a batch triggered during last iteration is
still running, */
if (buf_flush_LRU(buf_pool,
PAGE_CLEANER_LRU_BATCH_CHUNK_SIZE,
&n)) {
/* Allowed only one batch per
buffer pool instance. */
buf_flush_wait_batch_end(
buf_pool, BUF_FLUSH_LRU);
}
if (n.flushed) {
total_flushed += n.flushed;
} else {
/* Nothing to flush */
break;
}
}
}
if (total_flushed) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_BATCH_TOTAL_PAGE,
MONITOR_LRU_BATCH_COUNT,
MONITOR_LRU_BATCH_PAGES,
total_flushed);
}
return(total_flushed);
}
/*********************************************************************//**
Wait for any possible LRU flushes that are in progress to end. */
UNIV_INTERN
void
buf_flush_wait_LRU_batch_end(void)
/*==============================*/
{
for (ulint i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_array(i);
buf_pool_mutex_enter(buf_pool);
if (buf_pool->n_flush[BUF_FLUSH_LRU] > 0
|| buf_pool->init_flush[BUF_FLUSH_LRU]) {
buf_pool_mutex_exit(buf_pool);
buf_flush_wait_batch_end(buf_pool, BUF_FLUSH_LRU);
} else {
buf_pool_mutex_exit(buf_pool);
}
}
}
/*********************************************************************//**
Flush a batch of dirty pages from the flush list
@return number of pages flushed, 0 if no page is flushed or if another
flush_list type batch is running */
static
ulint
page_cleaner_do_flush_batch(
/*========================*/
ulint n_to_flush, /*!< in: number of pages that
we should attempt to flush. */
lsn_t lsn_limit) /*!< in: LSN up to which flushing
must happen */
{
ulint n_flushed;
buf_flush_list(n_to_flush, lsn_limit, &n_flushed);
return(n_flushed);
}
/*********************************************************************//**
Calculates if flushing is required based on number of dirty pages in
the buffer pool.
@return percent of io_capacity to flush to manage dirty page ratio */
static
ulint
af_get_pct_for_dirty()
/*==================*/
{
ulint dirty_pct = buf_get_modified_ratio_pct();
if (dirty_pct > 0 && srv_max_buf_pool_modified_pct == 0) {
return(100);
}
ut_a(srv_max_dirty_pages_pct_lwm
<= srv_max_buf_pool_modified_pct);
if (srv_max_dirty_pages_pct_lwm == 0) {
/* The user has not set the option to preflush dirty
pages as we approach the high water mark. */
if (dirty_pct > srv_max_buf_pool_modified_pct) {
/* We have crossed the high water mark of dirty
pages In this case we start flushing at 100% of
innodb_io_capacity. */
return(100);
}
} else if (dirty_pct > srv_max_dirty_pages_pct_lwm) {
/* We should start flushing pages gradually. */
return((dirty_pct * 100)
/ (srv_max_buf_pool_modified_pct + 1));
}
return(0);
}
/*********************************************************************//**
Calculates if flushing is required based on redo generation rate.
@return percent of io_capacity to flush to manage redo space */
static
ulint
af_get_pct_for_lsn(
/*===============*/
lsn_t age) /*!< in: current age of LSN. */
{
lsn_t max_async_age;
lsn_t lsn_age_factor;
lsn_t af_lwm = (srv_adaptive_flushing_lwm
* log_get_capacity()) / 100;
if (age < af_lwm) {
/* No adaptive flushing. */
return(0);
}
max_async_age = log_get_max_modified_age_async();
if (age < max_async_age && !srv_adaptive_flushing) {
/* We have still not reached the max_async point and
the user has disabled adaptive flushing. */
return(0);
}
/* If we are here then we know that either:
1) User has enabled adaptive flushing
2) User may have disabled adaptive flushing but we have reached
max_async_age. */
lsn_age_factor = (age * 100) / max_async_age;
ut_ad(srv_max_io_capacity >= srv_io_capacity);
return(static_cast<ulint>(
((srv_max_io_capacity / srv_io_capacity)
* (lsn_age_factor * sqrt((double)lsn_age_factor)))
/ 7.5));
}
/*********************************************************************//**
This function is called approximately once every second by the
page_cleaner thread. Based on various factors it decides if there is a
need to do flushing. If flushing is needed it is performed and the
number of pages flushed is returned.
@return number of pages flushed */
static
ulint
page_cleaner_flush_pages_if_needed(void)
/*====================================*/
{
static lsn_t lsn_avg_rate = 0;
static lsn_t prev_lsn = 0;
static lsn_t last_lsn = 0;
static ulint sum_pages = 0;
static ulint last_pages = 0;
static ulint prev_pages = 0;
static ulint avg_page_rate = 0;
static ulint n_iterations = 0;
lsn_t oldest_lsn;
lsn_t cur_lsn;
lsn_t age;
lsn_t lsn_rate;
ulint n_pages = 0;
ulint pct_for_dirty = 0;
ulint pct_for_lsn = 0;
ulint pct_total = 0;
int age_factor = 0;
cur_lsn = log_get_lsn_nowait();
/* log_get_lsn_nowait tries to get log_sys->mutex with
mutex_enter_nowait, if this does not succeed function
returns 0, do not use that value to update stats. */
if (cur_lsn == 0) {
return(0);
}
if (prev_lsn == 0) {
/* First time around. */
prev_lsn = cur_lsn;
return(0);
}
if (prev_lsn == cur_lsn) {
return(0);
}
/* We update our variables every srv_flushing_avg_loops
iterations to smooth out transition in workload. */
if (++n_iterations >= srv_flushing_avg_loops) {
avg_page_rate = ((sum_pages / srv_flushing_avg_loops)
+ avg_page_rate) / 2;
/* How much LSN we have generated since last call. */
lsn_rate = (cur_lsn - prev_lsn) / srv_flushing_avg_loops;
lsn_avg_rate = (lsn_avg_rate + lsn_rate) / 2;
prev_lsn = cur_lsn;
n_iterations = 0;
sum_pages = 0;
}
oldest_lsn = buf_pool_get_oldest_modification();
ut_ad(oldest_lsn <= log_get_lsn());
age = cur_lsn > oldest_lsn ? cur_lsn - oldest_lsn : 0;
pct_for_dirty = af_get_pct_for_dirty();
pct_for_lsn = af_get_pct_for_lsn(age);
pct_total = ut_max(pct_for_dirty, pct_for_lsn);
/* Cap the maximum IO capacity that we are going to use by
max_io_capacity. */
n_pages = (PCT_IO(pct_total) + avg_page_rate) / 2;
if (n_pages > srv_max_io_capacity) {
n_pages = srv_max_io_capacity;
}
if (last_pages && cur_lsn - last_lsn > lsn_avg_rate / 2) {
age_factor = static_cast<int>(prev_pages / last_pages);
}
MONITOR_SET(MONITOR_FLUSH_N_TO_FLUSH_REQUESTED, n_pages);
prev_pages = n_pages;
n_pages = page_cleaner_do_flush_batch(
n_pages, oldest_lsn + lsn_avg_rate * (age_factor + 1));
last_lsn= cur_lsn;
last_pages= n_pages + 1;
MONITOR_SET(MONITOR_FLUSH_AVG_PAGE_RATE, avg_page_rate);
MONITOR_SET(MONITOR_FLUSH_LSN_AVG_RATE, lsn_avg_rate);
MONITOR_SET(MONITOR_FLUSH_PCT_FOR_DIRTY, pct_for_dirty);
MONITOR_SET(MONITOR_FLUSH_PCT_FOR_LSN, pct_for_lsn);
if (n_pages) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_FLUSH_ADAPTIVE_TOTAL_PAGE,
MONITOR_FLUSH_ADAPTIVE_COUNT,
MONITOR_FLUSH_ADAPTIVE_PAGES,
n_pages);
sum_pages += n_pages;
}
return(n_pages);
}
/*********************************************************************//**
Puts the page_cleaner thread to sleep if it has finished work in less
than a second */
static
void
page_cleaner_sleep_if_needed(
/*=========================*/
ulint next_loop_time) /*!< in: time when next loop iteration
should start */
{
ulint cur_time = ut_time_ms();
if (next_loop_time > cur_time) {
/* Get sleep interval in micro seconds. We use
ut_min() to avoid long sleep in case of
wrap around. */
os_thread_sleep(ut_min(1000000,
(next_loop_time - cur_time)
* 1000));
}
}
/******************************************************************//**
page_cleaner thread tasked with flushing dirty pages from the buffer
pools. As of now we'll have only one instance of this thread.
@return a dummy parameter */
extern "C" UNIV_INTERN
os_thread_ret_t
DECLARE_THREAD(buf_flush_page_cleaner_thread)(
/*==========================================*/
void* arg MY_ATTRIBUTE((unused)))
/*!< in: a dummy parameter required by
os_thread_create */
{
my_thread_init();
ulint next_loop_time = ut_time_ms() + 1000;
ulint n_flushed = 0;
ulint last_activity = srv_get_activity_count();
ut_ad(!srv_read_only_mode);
#ifdef UNIV_PFS_THREAD
pfs_register_thread(buf_page_cleaner_thread_key);
#endif /* UNIV_PFS_THREAD */
#ifdef UNIV_DEBUG_THREAD_CREATION
fprintf(stderr, "InnoDB: page_cleaner thread running, id %lu\n",
os_thread_pf(os_thread_get_curr_id()));
#endif /* UNIV_DEBUG_THREAD_CREATION */
while (srv_shutdown_state == SRV_SHUTDOWN_NONE) {
page_cleaner_sleep_if_needed(next_loop_time);
next_loop_time = ut_time_ms() + 1000;
if (srv_check_activity(last_activity)) {
last_activity = srv_get_activity_count();
/* Flush pages from flush_list if required */
page_cleaner_flush_pages_if_needed();
n_flushed = 0;
} else {
n_flushed = page_cleaner_do_flush_batch(
PCT_IO(100),
LSN_MAX);
if (n_flushed) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_FLUSH_BACKGROUND_TOTAL_PAGE,
MONITOR_FLUSH_BACKGROUND_COUNT,
MONITOR_FLUSH_BACKGROUND_PAGES,
n_flushed);
}
}
/* Flush pages from end of LRU if required */
n_flushed = buf_flush_LRU_tail();
}
ut_ad(srv_shutdown_state > 0);
if (srv_fast_shutdown == 2) {
/* In very fast shutdown we simulate a crash of
buffer pool. We are not required to do any flushing */
goto thread_exit;
}
/* In case of normal and slow shutdown the page_cleaner thread
must wait for all other activity in the server to die down.
Note that we can start flushing the buffer pool as soon as the
server enters shutdown phase but we must stay alive long enough
to ensure that any work done by the master or purge threads is
also flushed.
During shutdown we pass through two stages. In the first stage,
when SRV_SHUTDOWN_CLEANUP is set other threads like the master
and the purge threads may be working as well. We start flushing
the buffer pool but can't be sure that no new pages are being
dirtied until we enter SRV_SHUTDOWN_FLUSH_PHASE phase. */
do {
n_flushed = page_cleaner_do_flush_batch(PCT_IO(100), LSN_MAX);
/* We sleep only if there are no pages to flush */
if (n_flushed == 0) {
os_thread_sleep(100000);
}
} while (srv_shutdown_state == SRV_SHUTDOWN_CLEANUP);
/* At this point all threads including the master and the purge
thread must have been suspended. */
ut_a(srv_get_active_thread_type() == SRV_NONE);
ut_a(srv_shutdown_state == SRV_SHUTDOWN_FLUSH_PHASE);
/* We can now make a final sweep on flushing the buffer pool
and exit after we have cleaned the whole buffer pool.
It is important that we wait for any running batch that has
been triggered by us to finish. Otherwise we can end up
considering end of that batch as a finish of our final
sweep and we'll come out of the loop leaving behind dirty pages
in the flush_list */
buf_flush_wait_batch_end(NULL, BUF_FLUSH_LIST);
buf_flush_wait_LRU_batch_end();
bool success;
do {
success = buf_flush_list(PCT_IO(100), LSN_MAX, &n_flushed);
buf_flush_wait_batch_end(NULL, BUF_FLUSH_LIST);
} while (!success || n_flushed > 0);
/* Some sanity checks */
ut_a(srv_get_active_thread_type() == SRV_NONE);
ut_a(srv_shutdown_state == SRV_SHUTDOWN_FLUSH_PHASE);
for (ulint i = 0; i < srv_buf_pool_instances; i++) {
buf_pool_t* buf_pool = buf_pool_from_array(i);
ut_a(UT_LIST_GET_LEN(buf_pool->flush_list) == 0);
}
/* We have lived our life. Time to die. */
thread_exit:
buf_page_cleaner_is_active = false;
my_thread_end();
/* We count the number of threads in os_thread_exit(). A created
thread should always use that to exit and not use return() to exit. */
os_thread_exit(NULL);
OS_THREAD_DUMMY_RETURN;
}
#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
/** Functor to validate the flush list. */
struct Check {
void operator()(const buf_page_t* elem)
{
ut_a(elem->in_flush_list);
}
};
/******************************************************************//**
Validates the flush list.
@return TRUE if ok */
static
ibool
buf_flush_validate_low(
/*===================*/
buf_pool_t* buf_pool) /*!< in: Buffer pool instance */
{
buf_page_t* bpage;
const ib_rbt_node_t* rnode = NULL;
ut_ad(buf_flush_list_mutex_own(buf_pool));
UT_LIST_VALIDATE(list, buf_page_t, buf_pool->flush_list, Check());
bpage = UT_LIST_GET_FIRST(buf_pool->flush_list);
/* If we are in recovery mode i.e.: flush_rbt != NULL
then each block in the flush_list must also be present
in the flush_rbt. */
if (UNIV_LIKELY_NULL(buf_pool->flush_rbt)) {
rnode = rbt_first(buf_pool->flush_rbt);
}
while (bpage != NULL) {
const lsn_t om = bpage->oldest_modification;
ut_ad(buf_pool_from_bpage(bpage) == buf_pool);
ut_ad(bpage->in_flush_list);
/* A page in buf_pool->flush_list can be in
BUF_BLOCK_REMOVE_HASH state. This happens when a page
is in the middle of being relocated. In that case the
original descriptor can have this state and still be
in the flush list waiting to acquire the
buf_pool->flush_list_mutex to complete the relocation. */
ut_a(buf_page_in_file(bpage)
|| buf_page_get_state(bpage) == BUF_BLOCK_REMOVE_HASH);
ut_a(om > 0);
if (UNIV_LIKELY_NULL(buf_pool->flush_rbt)) {
buf_page_t** prpage;
ut_a(rnode);
prpage = rbt_value(buf_page_t*, rnode);
ut_a(*prpage);
ut_a(*prpage == bpage);
rnode = rbt_next(buf_pool->flush_rbt, rnode);
}
bpage = UT_LIST_GET_NEXT(list, bpage);
ut_a(!bpage || om >= bpage->oldest_modification);
}
/* By this time we must have exhausted the traversal of
flush_rbt (if active) as well. */
ut_a(rnode == NULL);
return(TRUE);
}
/******************************************************************//**
Validates the flush list.
@return TRUE if ok */
UNIV_INTERN
ibool
buf_flush_validate(
/*===============*/
buf_pool_t* buf_pool) /*!< buffer pool instance */
{
ibool ret;
buf_flush_list_mutex_enter(buf_pool);
ret = buf_flush_validate_low(buf_pool);
buf_flush_list_mutex_exit(buf_pool);
return(ret);
}
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
#endif /* !UNIV_HOTBACKUP */
#ifdef UNIV_DEBUG
/******************************************************************//**
Check if there are any dirty pages that belong to a space id in the flush
list in a particular buffer pool.
@return number of dirty pages present in a single buffer pool */
UNIV_INTERN
ulint
buf_pool_get_dirty_pages_count(
/*===========================*/
buf_pool_t* buf_pool, /*!< in: buffer pool */
ulint id) /*!< in: space id to check */
{
ulint count = 0;
buf_pool_mutex_enter(buf_pool);
buf_flush_list_mutex_enter(buf_pool);
buf_page_t* bpage;
for (bpage = UT_LIST_GET_FIRST(buf_pool->flush_list);
bpage != 0;
bpage = UT_LIST_GET_NEXT(list, bpage)) {
ut_ad(buf_page_in_file(bpage));
ut_ad(bpage->in_flush_list);
ut_ad(bpage->oldest_modification > 0);
if (buf_page_get_space(bpage) == id) {
++count;
}
}
buf_flush_list_mutex_exit(buf_pool);
buf_pool_mutex_exit(buf_pool);
return(count);
}
/******************************************************************//**
Check if there are any dirty pages that belong to a space id in the flush list.
@return number of dirty pages present in all the buffer pools */
UNIV_INTERN
ulint
buf_flush_get_dirty_pages_count(
/*============================*/
ulint id) /*!< in: space id to check */
{
ulint count = 0;
for (ulint i = 0; i < srv_buf_pool_instances; ++i) {
buf_pool_t* buf_pool;
buf_pool = buf_pool_from_array(i);
count += buf_pool_get_dirty_pages_count(buf_pool, id);
}
return(count);
}
#endif /* UNIV_DEBUG */
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