#include "buf0flu.h"
#include "buf0buf.h"
#include "buf0checksum.h"
#include "srv0start.h"
#include "srv0srv.h"
#include "page0zip.h"
#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"

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Macros
#define	PAGE_CLEANER_LRU_BATCH_CHUNK_SIZE 100
#define	BUF_LRU_MIN_LEN 256

Functions
UNIV_INLINE void	buf_flush_set_hp (buf_pool_t buf_pool, const buf_page_t bpage)
UNIV_INLINE bool	buf_flush_is_hp (buf_pool_t buf_pool, const buf_page_t bpage)
UNIV_INLINE void	buf_flush_update_hp (buf_pool_t buf_pool, buf_page_t bpage)
UNIV_INTERN void	buf_flush_init_flush_rbt (void)
UNIV_INTERN void	buf_flush_free_flush_rbt (void)
UNIV_INTERN void	buf_flush_insert_into_flush_list (buf_pool_t buf_pool, buf_block_t block, lsn_t lsn)
UNIV_INTERN void	buf_flush_insert_sorted_into_flush_list (buf_pool_t buf_pool, buf_block_t block, lsn_t lsn)
UNIV_INTERN ibool	buf_flush_ready_for_replace (buf_page_t *bpage)
UNIV_INTERN bool	buf_flush_ready_for_flush (buf_page_t *bpage, buf_flush_t flush_type)
UNIV_INTERN void	buf_flush_remove (buf_page_t *bpage)
UNIV_INTERN void	buf_flush_relocate_on_flush_list (buf_page_t bpage, buf_page_t dpage)
UNIV_INTERN void	buf_flush_write_complete (buf_page_t *bpage)
UNIV_INTERN void	buf_flush_update_zip_checksum (buf_frame_t *page, ulint zip_size, lsn_t lsn)
UNIV_INTERN void	buf_flush_init_for_writing (byte page, void page_zip_, lsn_t newest_lsn)
UNIV_INTERN void	buf_flush_page (buf_pool_t buf_pool, buf_page_t bpage, buf_flush_t flush_type, bool sync)
UNIV_INTERN void	buf_flush_wait_batch_end (buf_pool_t *buf_pool, buf_flush_t type)
UNIV_INTERN bool	buf_flush_list (ulint min_n, lsn_t lsn_limit, ulint *n_processed)
UNIV_INTERN ibool	buf_flush_single_page_from_LRU (buf_pool_t *buf_pool)
UNIV_INTERN ulint	buf_flush_LRU_tail (void)
UNIV_INTERN void	buf_flush_wait_LRU_batch_end (void)
UNIV_INTERN os_thread_ret_t DECLARE_THREAD()	buf_flush_page_cleaner_thread (void *arg __attribute__((unused)))

Variables
UNIV_INTERN ibool	buf_page_cleaner_is_active = FALSE

Detailed Description

The database buffer buf_pool flush algorithm

Created 11/11/1995 Heikki Tuuri

Definition in file buf0flu.cc.

Macro Definition Documentation

#define BUF_LRU_MIN_LEN 256

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.

Definition at line 74 of file buf0flu.cc.

#define PAGE_CLEANER_LRU_BATCH_CHUNK_SIZE 100

LRU flush batch is further divided into this chunk size to

reduce the wait time for the threads waiting for a clean block

Definition at line 64 of file buf0flu.cc.

Function Documentation

UNIV_INTERN void buf_flush_free_flush_rbt ( void )

Frees up the red-black tree.

Definition at line 320 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_init_flush_rbt ( void )

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.

Definition at line 296 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_init_for_writing	(	byte *	page,
		void *	page_zip_,
		lsn_t	newest_lsn
	)

Initializes a page for writing to the tablespace.

Parameters

page	in/out: page
page_zip_	in/out: compressed page, or NULL
newest_lsn	in: newest modification lsn to the page

Definition at line 773 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_insert_into_flush_list	(	buf_pool_t *	buf_pool,
		buf_block_t *	block,
		lsn_t	lsn
	)

Inserts a modified block into the flush list.

Parameters

buf_pool	buffer pool instance
block	in/out: block which is modified
lsn	in: oldest modification

Definition at line 347 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_insert_sorted_into_flush_list	(	buf_pool_t *	buf_pool,
		buf_block_t *	block,
		lsn_t	lsn
	)

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.

Parameters

buf_pool	in: buffer pool instance
block	in/out: block which is modified
lsn	in: oldest modification

Definition at line 403 of file buf0flu.cc.

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UNIV_INLINE bool buf_flush_is_hp	(	buf_pool_t *	buf_pool,
		const buf_page_t *	bpage
	)

Checks if the given block is a hazard pointer

Returns: true if bpage is hazard pointer

Parameters

buf_pool	in: buffer pool instance
bpage	in: buffer control block

Definition at line 156 of file buf0flu.cc.

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UNIV_INTERN bool buf_flush_list	(	ulint	min_n,
		lsn_t	lsn_limit,
		ulint *	n_processed
	)

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!

Returns: 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

Parameters

min_n	in: wished minimum mumber of blocks flushed (it is not guaranteed that the actual number is that big, though)
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
n_processed	out: the number of pages which were processed is passed back to caller. Ignored if NULL

Definition at line 1895 of file buf0flu.cc.

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UNIV_INTERN ulint buf_flush_LRU_tail ( void )

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.

Returns: total pages flushed

Definition at line 2073 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_page	(	buf_pool_t *	buf_pool,
		buf_page_t *	bpage,
		buf_flush_t	flush_type,
		bool	sync
	)

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.

Parameters

buf_pool	in: buffer pool instance
bpage	in: buffer control block
flush_type	in: type of flush
sync	in: true if sync IO request

Definition at line 997 of file buf0flu.cc.

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UNIV_INTERN os_thread_ret_t DECLARE_THREAD() buf_flush_page_cleaner_thread ( void *arg __attribute__(unused) )

page_cleaner thread tasked with flushing dirty pages from the buffer pools. As of now we'll have only one instance of this thread.

Returns: a dummy parameter

Parameters

__attribute__ in: a dummy parameter required by os_thread_create

Definition at line 2389 of file buf0flu.cc.

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UNIV_INTERN bool buf_flush_ready_for_flush	(	buf_page_t *	bpage,
		buf_flush_t	flush_type
	)

Returns true if the block is modified and ready for flushing.

Returns: true if can flush immediately

Parameters

bpage	in: buffer control block, must be buf_page_in_file(bpage)
flush_type	in: type of flush

Definition at line 532 of file buf0flu.cc.

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UNIV_INTERN ibool buf_flush_ready_for_replace ( buf_page_t * bpage )

Returns TRUE if the file page block is immediately suitable for replacement, i.e., the transition FILE_PAGE => NOT_USED allowed.

Returns: TRUE if can replace immediately

Parameters

bpage in: buffer control block, must be buf_page_in_file(bpage) and in the LRU list

Definition at line 497 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_relocate_on_flush_list	(	buf_page_t *	bpage,
		buf_page_t *	dpage
	)

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.

Parameters

bpage	in/out: control block being moved
dpage	in/out: destination block

Definition at line 649 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_remove ( buf_page_t * bpage )

Remove a block from the flush list of modified blocks.

Parameters

bpage in: pointer to the block in question

Definition at line 579 of file buf0flu.cc.

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UNIV_INLINE void buf_flush_set_hp	(	buf_pool_t *	buf_pool,
		const buf_page_t *	bpage
	)

Sets hazard pointer during flush_list iteration.

Parameters

buf_pool	in/out: buffer pool instance
bpage	in: buffer control block

Definition at line 137 of file buf0flu.cc.

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UNIV_INTERN ibool buf_flush_single_page_from_LRU ( buf_pool_t * buf_pool )

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.

Returns: TRUE if success.

Parameters

buf_pool in/out: buffer pool instance

Definition at line 1982 of file buf0flu.cc.

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UNIV_INLINE void buf_flush_update_hp	(	buf_pool_t *	buf_pool,
		buf_page_t *	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.

Parameters

buf_pool	in: buffer pool instance
bpage	in: buffer control block

Definition at line 174 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_update_zip_checksum	(	buf_frame_t *	page,
		ulint	zip_size,
		lsn_t	lsn
	)

Calculate the checksum of a page from compressed table and update the page.

Parameters

page	in/out: Page to update
zip_size	in: Compressed page size
lsn	in: Lsn to stamp on the page

Definition at line 752 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_wait_batch_end	(	buf_pool_t *	buf_pool,
		buf_flush_t	type
	)

Waits until a flush batch of the given type ends

Parameters

buf_pool	buffer pool instance
type	in: BUF_FLUSH_LRU or BUF_FLUSH_LIST

Definition at line 1817 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_wait_LRU_batch_end ( void )

Wait for any possible LRU flushes that are in progress to end.

Definition at line 2138 of file buf0flu.cc.

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UNIV_INTERN void buf_flush_write_complete ( buf_page_t * bpage )

Updates the flush system data structures when a write is completed.

Parameters

bpage in: pointer to the block in question

Definition at line 719 of file buf0flu.cc.

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Variable Documentation

UNIV_INTERN ibool buf_page_cleaner_is_active = FALSE

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

Definition at line 60 of file buf0flu.cc.

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation