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buf_block_alloc(): Define as an alias in buf0lru.h, which defines the underlying buf_LRU_get_free_block(). buf_block_free(): Define as an alias of the non-inline function buf_pool.free_block(block). Reviewed by: Vladislav Lesin
199 lines
7.7 KiB
C
199 lines
7.7 KiB
C
/*****************************************************************************
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Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2017, 2021, MariaDB Corporation.
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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.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
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*****************************************************************************/
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/**************************************************//**
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@file include/buf0lru.h
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The database buffer pool LRU replacement algorithm
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Created 11/5/1995 Heikki Tuuri
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*******************************************************/
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#pragma once
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#include "buf0types.h"
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#include "hash0hash.h"
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// Forward declaration
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struct trx_t;
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struct fil_space_t;
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/*#######################################################################
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These are low-level functions
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#########################################################################*/
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/** Minimum LRU list length for which the LRU_old pointer is defined */
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#define BUF_LRU_OLD_MIN_LEN 512 /* 8 megabytes of 16k pages */
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/** Try to free a block. If bpage is a descriptor of a compressed-only
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ROW_FORMAT=COMPRESSED page, the buf_page_t object will be freed as well.
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The caller must hold buf_pool.mutex.
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@param bpage block to be freed
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@param zip whether to remove both copies of a ROW_FORMAT=COMPRESSED page
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@retval true if freed and buf_pool.mutex may have been temporarily released
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@retval false if the page was not freed */
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bool buf_LRU_free_page(buf_page_t *bpage, bool zip)
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MY_ATTRIBUTE((nonnull));
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/** Try to free a replaceable block.
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@param limit maximum number of blocks to scan
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@return true if found and freed */
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bool buf_LRU_scan_and_free_block(ulint limit= ULINT_UNDEFINED);
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/** @return a buffer block from the buf_pool.free list
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@retval NULL if the free list is empty */
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buf_block_t* buf_LRU_get_free_only();
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/** Get a block from the buf_pool.free list.
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If the list is empty, blocks will be moved from the end of buf_pool.LRU
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to buf_pool.free.
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This function is called from a user thread when it needs a clean
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block to read in a page. Note that we only ever get a block from
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the free list. Even when we flush a page or find a page in LRU scan
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we put it to free list to be used.
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* iteration 0:
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* get a block from the buf_pool.free list
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* if buf_pool.try_LRU_scan is set
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* scan LRU up to 100 pages to free a clean block
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* success:retry the free list
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* invoke buf_pool.page_cleaner_wakeup(true) and wait its completion
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* subsequent iterations: same as iteration 0 except:
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* scan the entire LRU list
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@param have_mutex whether buf_pool.mutex is already being held
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@return the free control block, in state BUF_BLOCK_MEMORY */
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buf_block_t* buf_LRU_get_free_block(bool have_mutex)
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MY_ATTRIBUTE((malloc,warn_unused_result));
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#define buf_block_alloc() buf_LRU_get_free_block(false)
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/** @return whether the unzip_LRU list should be used for evicting a victim
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instead of the general LRU list */
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bool buf_LRU_evict_from_unzip_LRU();
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/** Free a buffer block which does not contain a file page,
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while holding buf_pool.mutex.
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@param block block to be put to buf_pool.free */
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void buf_LRU_block_free_non_file_page(buf_block_t *block);
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/******************************************************************//**
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Adds a block to the LRU list. Please make sure that the page_size is
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already set when invoking the function, so that we can get correct
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page_size from the buffer page when adding a block into LRU */
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void
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buf_LRU_add_block(
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/*==============*/
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buf_page_t* bpage, /*!< in: control block */
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bool old); /*!< in: true if should be put to the old
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blocks in the LRU list, else put to the
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start; if the LRU list is very short, added to
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the start regardless of this parameter */
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/** Move a block to the start of the buf_pool.LRU list.
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@param bpage buffer pool page */
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void buf_page_make_young(buf_page_t *bpage);
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/** Flag a page accessed in buf_pool and move it to the start of buf_pool.LRU
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if it is too old.
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@param bpage buffer pool page
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@return whether this is not the first access */
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bool buf_page_make_young_if_needed(buf_page_t *bpage);
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/******************************************************************//**
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Adds a block to the LRU list of decompressed zip pages. */
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void
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buf_unzip_LRU_add_block(
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/*====================*/
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buf_block_t* block, /*!< in: control block */
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ibool old); /*!< in: TRUE if should be put to the end
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of the list, else put to the start */
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/** Update buf_pool.LRU_old_ratio.
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@param[in] old_pct Reserve this percentage of
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the buffer pool for "old" blocks
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@param[in] adjust true=adjust the LRU list;
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false=just assign buf_pool.LRU_old_ratio
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during the initialization of InnoDB
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@return updated old_pct */
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uint buf_LRU_old_ratio_update(uint old_pct, bool adjust);
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/********************************************************************//**
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Update the historical stats that we are collecting for LRU eviction
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policy at the end of each interval. */
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void
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buf_LRU_stat_update();
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#ifdef UNIV_DEBUG
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/** Validate the LRU list. */
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void buf_LRU_validate();
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#endif /* UNIV_DEBUG */
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#if defined UNIV_DEBUG_PRINT || defined UNIV_DEBUG
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/** Dump the LRU list to stderr. */
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void buf_LRU_print();
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#endif /* UNIV_DEBUG_PRINT || UNIV_DEBUG */
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/** @name Heuristics for detecting index scan @{ */
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/** The denominator of buf_pool.LRU_old_ratio. */
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#define BUF_LRU_OLD_RATIO_DIV 1024
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/** Maximum value of buf_pool.LRU_old_ratio.
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@see buf_LRU_old_adjust_len
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@see buf_pool.LRU_old_ratio_update */
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#define BUF_LRU_OLD_RATIO_MAX BUF_LRU_OLD_RATIO_DIV
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/** Minimum value of buf_pool.LRU_old_ratio.
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@see buf_LRU_old_adjust_len
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@see buf_pool.LRU_old_ratio_update
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The minimum must exceed
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(BUF_LRU_OLD_TOLERANCE + 5) * BUF_LRU_OLD_RATIO_DIV / BUF_LRU_OLD_MIN_LEN. */
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#define BUF_LRU_OLD_RATIO_MIN 51
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#if BUF_LRU_OLD_RATIO_MIN >= BUF_LRU_OLD_RATIO_MAX
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# error "BUF_LRU_OLD_RATIO_MIN >= BUF_LRU_OLD_RATIO_MAX"
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#endif
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#if BUF_LRU_OLD_RATIO_MAX > BUF_LRU_OLD_RATIO_DIV
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# error "BUF_LRU_OLD_RATIO_MAX > BUF_LRU_OLD_RATIO_DIV"
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#endif
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/** Move blocks to "new" LRU list only if the first access was at
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least this many milliseconds ago. Not protected by any mutex or latch. */
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extern uint buf_LRU_old_threshold_ms;
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/* @} */
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/** @brief Statistics for selecting the LRU list for eviction.
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These statistics are not 'of' LRU but 'for' LRU. We keep count of I/O
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and page_zip_decompress() operations. Based on the statistics we decide
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if we want to evict from buf_pool.unzip_LRU or buf_pool.LRU. */
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struct buf_LRU_stat_t
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{
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ulint io; /**< Counter of buffer pool I/O operations. */
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ulint unzip; /**< Counter of page_zip_decompress operations. */
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};
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/** Current operation counters. Not protected by any mutex.
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Cleared by buf_LRU_stat_update(). */
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extern buf_LRU_stat_t buf_LRU_stat_cur;
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/** Running sum of past values of buf_LRU_stat_cur.
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Updated by buf_LRU_stat_update(). Protected by buf_pool.mutex. */
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extern buf_LRU_stat_t buf_LRU_stat_sum;
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/********************************************************************//**
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Increments the I/O counter in buf_LRU_stat_cur. */
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#define buf_LRU_stat_inc_io() buf_LRU_stat_cur.io++
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/********************************************************************//**
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Increments the page_zip_decompress() counter in buf_LRU_stat_cur. */
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#define buf_LRU_stat_inc_unzip() buf_LRU_stat_cur.unzip++
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