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296 lines
11 KiB
C
296 lines
11 KiB
C
/*****************************************************************************
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Copyright (c) 1995, 2011, Oracle and/or its affiliates. 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.,
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51 Franklin St, 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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#ifndef buf0lru_h
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#define buf0lru_h
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#include "univ.i"
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#include "ut0byte.h"
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#include "buf0types.h"
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/******************************************************************//**
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Tries to remove LRU flushed blocks from the end of the LRU list and put them
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to the free list. This is beneficial for the efficiency of the insert buffer
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operation, as flushed pages from non-unique non-clustered indexes are here
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taken out of the buffer pool, and their inserts redirected to the insert
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buffer. Otherwise, the flushed blocks could get modified again before read
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operations need new buffer blocks, and the i/o work done in flushing would be
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wasted. */
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UNIV_INTERN
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void
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buf_LRU_try_free_flushed_blocks(
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/*============================*/
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buf_pool_t* buf_pool); /*!< in: buffer pool instance */
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/******************************************************************//**
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Returns TRUE if less than 25 % of the buffer pool is available. This can be
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used in heuristics to prevent huge transactions eating up the whole buffer
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pool for their locks.
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@return TRUE if less than 25 % of buffer pool left */
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UNIV_INTERN
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ibool
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buf_LRU_buf_pool_running_out(void);
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/*==============================*/
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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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/** Maximum LRU list search length in buf_flush_LRU_recommendation() */
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#define BUF_LRU_FREE_SEARCH_LEN(b) (5 + 2 * BUF_READ_AHEAD_AREA(b))
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/******************************************************************//**
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Removes all pages belonging to a given tablespace. */
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UNIV_INTERN
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void
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buf_LRU_flush_or_remove_pages(
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/*==========================*/
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ulint id, /*!< in: space id */
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enum buf_remove_t buf_remove);/*!< in: remove or flush
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strategy */
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#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
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/********************************************************************//**
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Insert a compressed block into buf_pool->zip_clean in the LRU order. */
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UNIV_INTERN
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void
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buf_LRU_insert_zip_clean(
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/*=====================*/
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buf_page_t* bpage); /*!< in: pointer to the block in question */
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#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
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/******************************************************************//**
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Try to free a block. If bpage is a descriptor of a compressed-only
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page, the descriptor object will be freed as well.
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NOTE: If this function returns TRUE, it will temporarily
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release buf_pool->mutex. Furthermore, the page frame will no longer be
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accessible via bpage.
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The caller must hold buf_pool->mutex and buf_page_get_mutex(bpage) and
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release these two mutexes after the call. No other
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buf_page_get_mutex() may be held when calling this function.
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@return TRUE if freed, FALSE otherwise. */
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UNIV_INTERN
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ibool
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buf_LRU_free_block(
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/*===============*/
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buf_page_t* bpage, /*!< in: block to be freed */
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ibool zip) /*!< in: TRUE if should remove also the
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compressed page of an uncompressed page */
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__attribute__((nonnull));
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/******************************************************************//**
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Try to free a replaceable block.
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@return TRUE if found and freed */
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UNIV_INTERN
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ibool
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buf_LRU_search_and_free_block(
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/*==========================*/
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buf_pool_t* buf_pool, /*!< in: buffer pool instance */
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ulint n_iterations); /*!< in: how many times this has
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been called repeatedly without
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result: a high value means that
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we should search farther; if
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n_iterations < 10, then we search
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n_iterations / 10 * buf_pool->curr_size
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pages from the end of the LRU list; if
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n_iterations < 5, then we will
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also search n_iterations / 5
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of the unzip_LRU list. */
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/******************************************************************//**
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Returns a free block from the buf_pool. The block is taken off the
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free list. If it is empty, returns NULL.
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@return a free control block, or NULL if the buf_block->free list is empty */
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UNIV_INTERN
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buf_block_t*
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buf_LRU_get_free_only(
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/*==================*/
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buf_pool_t* buf_pool); /*!< buffer pool instance */
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/******************************************************************//**
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Returns a free block from the buf_pool. The block is taken off the
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free list. If it is empty, blocks are moved from the end of the
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LRU list to the free list.
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@return the free control block, in state BUF_BLOCK_READY_FOR_USE */
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UNIV_INTERN
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buf_block_t*
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buf_LRU_get_free_block(
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/*===================*/
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buf_pool_t* buf_pool) /*!< in/out: buffer pool instance */
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__attribute__((nonnull,warn_unused_result));
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/******************************************************************//**
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Puts a block back to the free list. */
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UNIV_INTERN
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void
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buf_LRU_block_free_non_file_page(
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/*=============================*/
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buf_block_t* block); /*!< in: block, must not contain a file page */
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/******************************************************************//**
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Adds a block to the LRU list. Please make sure that the zip_size is
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already set into the page zip when invoking the function, so that we
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can get correct zip_size from the buffer page when adding a block
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into LRU */
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UNIV_INTERN
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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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ibool 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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/******************************************************************//**
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Adds a block to the LRU list of decompressed zip pages. */
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UNIV_INTERN
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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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/******************************************************************//**
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Moves a block to the start of the LRU list. */
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UNIV_INTERN
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void
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buf_LRU_make_block_young(
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/*=====================*/
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buf_page_t* bpage); /*!< in: control block */
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/******************************************************************//**
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Moves a block to the end of the LRU list. */
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UNIV_INTERN
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void
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buf_LRU_make_block_old(
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/*===================*/
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buf_page_t* bpage); /*!< in: control block */
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/**********************************************************************//**
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Updates buf_pool->LRU_old_ratio.
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@return updated old_pct */
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UNIV_INTERN
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ulint
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buf_LRU_old_ratio_update(
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/*=====================*/
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uint old_pct,/*!< in: Reserve this percentage of
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the buffer pool for "old" blocks. */
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ibool adjust);/*!< in: 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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/********************************************************************//**
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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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UNIV_INTERN
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void
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buf_LRU_stat_update(void);
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/*=====================*/
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/******************************************************************//**
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Remove one page from LRU list and put it to free list */
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UNIV_INTERN
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void
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buf_LRU_free_one_page(
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/*==================*/
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buf_page_t* bpage) /*!< in/out: block, must contain a file page and
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be in a state where it can be freed; there
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may or may not be a hash index to the page */
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__attribute__((nonnull));
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#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
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/**********************************************************************//**
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Validates the LRU list.
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@return TRUE */
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UNIV_INTERN
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ibool
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buf_LRU_validate(void);
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/*==================*/
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#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
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#if defined UNIV_DEBUG_PRINT || defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
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/**********************************************************************//**
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Prints the LRU list. */
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UNIV_INTERN
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void
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buf_LRU_print(void);
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/*===============*/
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#endif /* UNIV_DEBUG_PRINT || UNIV_DEBUG || UNIV_BUF_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_struct
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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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/** Statistics for selecting the LRU list for eviction. */
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typedef struct buf_LRU_stat_struct buf_LRU_stat_t;
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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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#ifndef UNIV_NONINL
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#include "buf0lru.ic"
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#endif
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#endif
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