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| -rw-r--r-- | storage/innobase/include/buf0rea.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/storage/innobase/include/buf0rea.h b/storage/innobase/include/buf0rea.h new file mode 100644 index 00000000..3dd085dd --- /dev/null +++ b/storage/innobase/include/buf0rea.h @@ -0,0 +1,120 @@ +/***************************************************************************** + +Copyright (c) 1995, 2015, Oracle and/or its affiliates. All Rights Reserved. +Copyright (c) 2015, 2021, 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, Fifth Floor, Boston, MA 02110-1335 USA + +*****************************************************************************/ + +/**************************************************//** +@file include/buf0rea.h +The database buffer read + +Created 11/5/1995 Heikki Tuuri +*******************************************************/ + +#ifndef buf0rea_h +#define buf0rea_h + +#include "buf0buf.h" + +/** High-level function which reads a page asynchronously from a file to the +buffer buf_pool if it is not already there. Sets the io_fix flag and sets +an exclusive lock on the buffer frame. The flag is cleared and the x-lock +released by the i/o-handler thread. +@param page_id page id +@param zip_size ROW_FORMAT=COMPRESSED page size, or 0 +@retval DB_SUCCESS if the page was read and is not corrupted +@retval DB_SUCCESS_LOCKED_REC if the page was not read +@retval DB_PAGE_CORRUPTED if page based on checksum check is corrupted +@retval DB_DECRYPTION_FAILED if page post encryption checksum matches but +after decryption normal page checksum does not match. +@retval DB_TABLESPACE_DELETED if tablespace .ibd file is missing */ +dberr_t buf_read_page(const page_id_t page_id, ulint zip_size); + +/** High-level function which reads a page asynchronously from a file to the +buffer buf_pool if it is not already there. Sets the io_fix flag and sets +an exclusive lock on the buffer frame. The flag is cleared and the x-lock +released by the i/o-handler thread. +@param[in,out] space tablespace +@param[in] page_id page id +@param[in] zip_size ROW_FORMAT=COMPRESSED page size, or 0 */ +void buf_read_page_background(fil_space_t *space, const page_id_t page_id, + ulint zip_size) + MY_ATTRIBUTE((nonnull)); + +/** Applies a random read-ahead in buf_pool if there are at least a threshold +value of accessed pages from the random read-ahead area. Does not read any +page, not even the one at the position (space, offset), if the read-ahead +mechanism is not activated. NOTE 1: the calling thread may own latches on +pages: to avoid deadlocks this function must be written such that it cannot +end up waiting for these latches! NOTE 2: the calling thread must want +access to the page given: this rule is set to prevent unintended read-aheads +performed by ibuf routines, a situation which could result in a deadlock if +the OS does not support asynchronous i/o. +@param[in] page_id page id of a page which the current thread +wants to access +@param[in] zip_size ROW_FORMAT=COMPRESSED page size, or 0 +@param[in] ibuf whether we are inside ibuf routine +@return number of page read requests issued; NOTE that if we read ibuf +pages, it may happen that the page at the given page number does not +get read even if we return a positive value! */ +ulint +buf_read_ahead_random(const page_id_t page_id, ulint zip_size, bool ibuf); + +/** Applies linear read-ahead if in the buf_pool the page is a border page of +a linear read-ahead area and all the pages in the area have been accessed. +Does not read any page if the read-ahead mechanism is not activated. Note +that the algorithm looks at the 'natural' adjacent successor and +predecessor of the page, which on the leaf level of a B-tree are the next +and previous page in the chain of leaves. To know these, the page specified +in (space, offset) must already be present in the buf_pool. Thus, the +natural way to use this function is to call it when a page in the buf_pool +is accessed the first time, calling this function just after it has been +bufferfixed. +NOTE 1: as this function looks at the natural predecessor and successor +fields on the page, what happens, if these are not initialized to any +sensible value? No problem, before applying read-ahead we check that the +area to read is within the span of the space, if not, read-ahead is not +applied. An uninitialized value may result in a useless read operation, but +only very improbably. +NOTE 2: the calling thread may own latches on pages: to avoid deadlocks this +function must be written such that it cannot end up waiting for these +latches! +NOTE 3: the calling thread must want access to the page given: this rule is +set to prevent unintended read-aheads performed by ibuf routines, a situation +which could result in a deadlock if the OS does not support asynchronous io. +@param[in] page_id page id; see NOTE 3 above +@param[in] zip_size ROW_FORMAT=COMPRESSED page size, or 0 +@param[in] ibuf whether if we are inside ibuf routine +@return number of page read requests issued */ +ulint +buf_read_ahead_linear(const page_id_t page_id, ulint zip_size, bool ibuf); + +/** Schedule a page for recovery. +@param space tablespace +@param page_id page identifier +@param recs log records +@param init page initialization, or nullptr if the page needs to be read */ +void buf_read_recover(fil_space_t *space, const page_id_t page_id, + page_recv_t &recs, recv_init *init); + +/** @name Modes used in read-ahead @{ */ +/** read only pages belonging to the insert buffer tree */ +#define BUF_READ_IBUF_PAGES_ONLY 131 +/** read any page */ +#define BUF_READ_ANY_PAGE 132 +/* @} */ + +#endif |