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buf_read_page(): Return a pointer to a buffer-fixed, non-read-fixed page, or nullptr in case of an error. buf_inc_get(): Wrapper for buf_inc_get(ha_handler_stats*), to read the thread-local variable mariadb_stats before updating it. IORequest::read_complete(): Assert that the page is both read-fixed and buffer-fixed. Sample recv_sys.recovery_on only once. Buffer-unfix the page when the asynchronous read completes. buf_page_t::read_complete(): Assert that the page is both read-fixed and buffer-fixed. buf_page_t::read_wait(): Wait for a read-fixed and buffer-fixed page to be only buffer-fixed, by acquiring a shared latch. buf_page_init_for_read(): Return a pointer to a buffer-fixed block descriptor pointer, bitwise-ORed with 1 in case the block already exists in the buffer pool. buf_read_ahead_update(), buf_read_ahead_update_sql(): Common code for updating some statistics counters. buf_read_page_low(): Replace the parameter sync with err, which will return an error code to a synchronous caller. Add a parameter for thread-local mariadb_stats. Return the pointer to the block, or the special values nullptr (read failure) or -1 or -2 for asynchronous reads. Increment the statistics when a synchronous read was requested. In a synchronous read, if the page has already been allocated in the buffer pool but it is read-fixed, wait for the read to complete. buf_page_get_zip(): Get a buffer-fixed page from buf_read_page(), and unfix() it. Our caller is relying solely on a page latch. buf_read_page_background(): Update the statistics if supplied.
96 lines
4.6 KiB
C
96 lines
4.6 KiB
C
/*****************************************************************************
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Copyright (c) 1995, 2015, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2015, 2023, 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/buf0rea.h
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The database buffer read
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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 "buf0buf.h"
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/** Read a page synchronously from a file. buf_page_t::read_complete()
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will be invoked on read completion.
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@param page_id page identifier
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@param chain buf_pool.page_hash cell for page_id
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@param err error code: DB_SUCCESS if the page was successfully read,
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DB_SUCCESS_LOCKED_REC if the page was not read,
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DB_PAGE_CORRUPTED on page checksum mismatch,
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DB_DECRYPTION_FAILED if page post encryption checksum matches but
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after decryption normal page checksum does not match,
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DB_TABLESPACE_DELETED if tablespace .ibd file is missing
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@param unzip whether to decompress ROW_FORMAT=COMPRESSED pages
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@return buffer-fixed block (*err may be set to DB_SUCCESS_LOCKED_REC)
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@retval nullptr if the page is not available (*err will be set) */
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buf_block_t *buf_read_page(const page_id_t page_id, dberr_t *err,
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buf_pool_t::hash_chain &chain, bool unzip= true)
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noexcept;
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/** Read a page asynchronously into buf_pool if it is not already there.
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@param page_id page identifier
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@param space tablespace
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@param stats statistics */
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void buf_read_page_background(const page_id_t page_id, fil_space_t *space,
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ha_handler_stats *stats) noexcept
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MY_ATTRIBUTE((nonnull(2)));
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/** Applies a random read-ahead in buf_pool if there are at least a threshold
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value of accessed pages from the random read-ahead area. Does not read any
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page, not even the one at the position (space, offset), if the read-ahead
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mechanism is not activated. NOTE: the calling thread may own latches on
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pages: to avoid deadlocks this function must be written such that it cannot
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end up waiting for these latches!
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@param[in] page_id page id of a page which the current thread
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wants to access
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@return number of page read requests issued */
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ulint buf_read_ahead_random(const page_id_t page_id) noexcept;
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/** Applies linear read-ahead if in the buf_pool the page is a border page of
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a linear read-ahead area and all the pages in the area have been accessed.
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Does not read any page if the read-ahead mechanism is not activated. Note
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that the algorithm looks at the 'natural' adjacent successor and
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predecessor of the page, which on the leaf level of a B-tree are the next
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and previous page in the chain of leaves. To know these, the page specified
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in (space, offset) must already be present in the buf_pool. Thus, the
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natural way to use this function is to call it when a page in the buf_pool
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is accessed the first time, calling this function just after it has been
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bufferfixed.
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NOTE 1: as this function looks at the natural predecessor and successor
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fields on the page, what happens, if these are not initialized to any
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sensible value? No problem, before applying read-ahead we check that the
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area to read is within the span of the space, if not, read-ahead is not
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applied. An uninitialized value may result in a useless read operation, but
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only very improbably.
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NOTE 2: the calling thread may own latches on pages: to avoid deadlocks this
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function must be written such that it cannot end up waiting for these
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latches!
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@param[in] page_id page id; see NOTE 3 above
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@return number of page read requests issued */
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ulint buf_read_ahead_linear(const page_id_t page_id) noexcept;
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/** Schedule a page for recovery.
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@param space tablespace
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@param page_id page identifier
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@param recs log records
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@param init_lsn page initialization, or 0 if the page needs to be read */
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void buf_read_recover(fil_space_t *space, const page_id_t page_id,
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page_recv_t &recs, lsn_t init_lsn) noexcept;
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