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/*****************************************************************************
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Copyright (C) 1995, 2010, Innobase Oy. All Rights Reserved.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
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St, Fifth Floor, Boston, MA 02110-1301 USA
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*****************************************************************************/
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/**************************************************//**
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@file include/buf0flu.h
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The database buffer pool flush algorithm
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Created 11/5/1995 Heikki Tuuri
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*******************************************************/
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#ifndef UNIV_HOTBACKUP
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#include "mtr0types.h"
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#include "buf0types.h"
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/********************************************************************//**
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Remove a block from the flush list of modified blocks. */
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buf_page_t* bpage); /*!< in: pointer to the block in question */
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/*******************************************************************//**
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Relocates a buffer control block on the flush_list.
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Note that it is assumed that the contents of bpage has already been
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buf_flush_relocate_on_flush_list(
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/*=============================*/
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buf_page_t* bpage, /*!< in/out: control block being moved */
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buf_page_t* dpage); /*!< in/out: destination block */
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/********************************************************************//**
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Updates the flush system data structures when a write is completed. */
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buf_flush_write_complete(
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/*=====================*/
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buf_page_t* bpage); /*!< in: pointer to the block in question */
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/*********************************************************************//**
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Flushes pages from the end of the LRU list if there is too small
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a margin of replaceable pages there. If buffer pool is NULL it
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means flush free margin on all buffer pool instances. */
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buf_flush_free_margin(
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/*==================*/
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buf_pool_t* buf_pool);
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/*********************************************************************//**
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Flushes pages from the end of all the LRU lists. */
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buf_flush_free_margins(void);
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/*=========================*/
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#endif /* !UNIV_HOTBACKUP */
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/********************************************************************//**
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Initializes a page for writing to the tablespace. */
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buf_flush_init_for_writing(
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/*=======================*/
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byte* page, /*!< in/out: page */
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void* page_zip_, /*!< in/out: compressed page, or NULL */
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ib_uint64_t newest_lsn); /*!< in: newest modification lsn
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#ifndef UNIV_HOTBACKUP
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# if defined UNIV_DEBUG || defined UNIV_IBUF_DEBUG
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/********************************************************************//**
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Writes a flushable page asynchronously from the buffer pool to a file.
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NOTE: buf_pool->mutex and block->mutex must be held upon entering this
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function, and they will be released by this function after flushing.
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This is loosely based on buf_flush_batch() and buf_flush_page().
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@return TRUE if the page was flushed and the mutexes released */
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buf_pool_t* buf_pool, /*!< in/out: buffer pool instance */
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buf_block_t* block) /*!< in/out: buffer control block */
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__attribute__((nonnull, warn_unused_result));
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# endif /* UNIV_DEBUG || UNIV_IBUF_DEBUG */
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/*******************************************************************//**
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This utility flushes dirty blocks from the end of the LRU list.
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NOTE: The calling thread may own latches to pages: to avoid deadlocks,
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this function must be written so that it cannot end up waiting for these
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@return number of blocks for which the write request was queued;
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ULINT_UNDEFINED if there was a flush of the same type already running */
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buf_pool_t* buf_pool, /*!< in: buffer pool instance */
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ulint min_n); /*!< in: wished minimum mumber of blocks
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flushed (it is not guaranteed that the
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actual number is that big, though) */
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/*******************************************************************//**
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This utility flushes dirty blocks from the end of the flush_list of
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all buffer pool instances.
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NOTE: The calling thread is not allowed to own any latches on pages!
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@return number of blocks for which the write request was queued;
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ULINT_UNDEFINED if there was a flush of the same type already running */
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ulint min_n, /*!< in: wished minimum mumber of blocks
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flushed (it is not guaranteed that the
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actual number is that big, though) */
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ib_uint64_t lsn_limit); /*!< in the case BUF_FLUSH_LIST all
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blocks whose oldest_modification is
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smaller than this should be flushed
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(if their number does not exceed
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min_n), otherwise ignored */
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/******************************************************************//**
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Waits until a flush batch of the given type ends */
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buf_flush_wait_batch_end(
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/*=====================*/
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buf_pool_t* buf_pool, /*!< buffer pool instance */
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enum buf_flush type); /*!< in: BUF_FLUSH_LRU
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/********************************************************************//**
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This function should be called at a mini-transaction commit, if a page was
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modified in it. Puts the block to the list of modified blocks, if it not
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buf_flush_note_modification(
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/*========================*/
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buf_block_t* block, /*!< in: block which is modified */
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mtr_t* mtr); /*!< in: mtr */
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/********************************************************************//**
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This function should be called when recovery has modified a buffer page. */
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buf_flush_recv_note_modification(
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/*=============================*/
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buf_block_t* block, /*!< in: block which is modified */
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ib_uint64_t start_lsn, /*!< in: start lsn of the first mtr in a
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ib_uint64_t end_lsn); /*!< in: end lsn of the last mtr in the
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/********************************************************************//**
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Returns TRUE if the file page block is immediately suitable for replacement,
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i.e., transition FILE_PAGE => NOT_USED allowed.
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@return TRUE if can replace immediately */
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buf_flush_ready_for_replace(
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/*========================*/
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buf_page_t* bpage); /*!< in: buffer control block, must be
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buf_page_in_file(bpage) and in the LRU list */
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/** @brief Statistics for selecting flush rate based on redo log
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These statistics are generated for heuristics used in estimating the
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rate at which we should flush the dirty blocks to avoid bursty IO
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activity. Note that the rate of flushing not only depends on how many
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dirty pages we have in the buffer pool but it is also a fucntion of
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how much redo the workload is generating and at what rate. */
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struct buf_flush_stat_struct
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ib_uint64_t redo; /**< amount of redo generated. */
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ulint n_flushed; /**< number of pages flushed. */
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/** Statistics for selecting flush rate of dirty pages. */
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typedef struct buf_flush_stat_struct buf_flush_stat_t;
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/*********************************************************************
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Update the historical stats that we are collecting for flush rate
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heuristics at the end of each interval. */
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buf_flush_stat_update(void);
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/*=======================*/
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/*********************************************************************
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Determines the fraction of dirty pages that need to be flushed based
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on the speed at which we generate redo log. Note that if redo log
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is generated at significant rate without a corresponding increase
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in the number of dirty pages (for example, an in-memory workload)
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it can cause IO bursts of flushing. This function implements heuristics
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to avoid this burstiness.
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@return number of dirty pages to be flushed / second */
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buf_flush_get_desired_flush_rate(void);
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/*==================================*/
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#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
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/******************************************************************//**
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Validates the flush list.
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@return TRUE if ok */
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buf_pool_t* buf_pool);
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#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
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/********************************************************************//**
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Initialize the red-black tree to speed up insertions into the flush_list
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during recovery process. Should be called at the start of recovery
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process before any page has been read/written. */
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buf_flush_init_flush_rbt(void);
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/*==========================*/
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/********************************************************************//**
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Frees up the red-black tree. */
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buf_flush_free_flush_rbt(void);
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/*==========================*/
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/** When buf_flush_free_margin is called, it tries to make this many blocks
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available to replacement in the free list and at the end of the LRU list (to
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make sure that a read-ahead batch can be read efficiently in a single
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#define BUF_FLUSH_FREE_BLOCK_MARGIN(b) (5 + BUF_READ_AHEAD_AREA(b))
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/** Extra margin to apply above BUF_FLUSH_FREE_BLOCK_MARGIN */
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#define BUF_FLUSH_EXTRA_MARGIN(b) ((BUF_FLUSH_FREE_BLOCK_MARGIN(b) / 4 \
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+ 100) / srv_buf_pool_instances)
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#endif /* !UNIV_HOTBACKUP */
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#include "buf0flu.ic"