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aaef2e1d8c
buf_page_t::frame: Moved from buf_block_t::frame.
All 'thin' buf_page_t describing compressed-only ROW_FORMAT=COMPRESSED
pages will have frame=nullptr, while all 'fat' buf_block_t
will have a non-null frame pointing to aligned innodb_page_size bytes.
This eliminates the need for separate states for
BUF_BLOCK_FILE_PAGE and BUF_BLOCK_ZIP_PAGE.
buf_page_t:🔒 Moved from buf_block_t::lock. That is, all block
descriptors will have a page latch. The IO_PIN state that was used
for discarding or creating the uncompressed page frame of a
ROW_FORMAT=COMPRESSED block is replaced by a combination of read-fix
and page X-latch.
page_zip_des_t::fix: Replaces state_, buf_fix_count_, io_fix_, status
of buf_page_t with a single std::atomic<uint32_t>. All modifications
will use store(), fetch_add(), fetch_sub(). This space was previously
wasted to alignment on 64-bit systems. We will use the following encoding
that combines a state (partly read-fix or write-fix) and a buffer-fix
count:
buf_page_t::NOT_USED=0 (previously BUF_BLOCK_NOT_USED)
buf_page_t::MEMORY=1 (previously BUF_BLOCK_MEMORY)
buf_page_t::REMOVE_HASH=2 (previously BUF_BLOCK_REMOVE_HASH)
buf_page_t::FREED=3 + fix: pages marked as freed in the file
buf_page_t::UNFIXED=1U<<29 + fix: normal pages
buf_page_t::IBUF_EXIST=2U<<29 + fix: normal pages; may need ibuf merge
buf_page_t::REINIT=3U<<29 + fix: reinitialized pages (skip doublewrite)
buf_page_t::READ_FIX=4U<<29 + fix: read-fixed pages (also X-latched)
buf_page_t::WRITE_FIX=5U<<29 + fix: write-fixed pages (also U-latched)
buf_page_t::WRITE_FIX_IBUF=6U<<29 + fix: write-fixed; may have ibuf
buf_page_t::WRITE_FIX_REINIT=7U<<29 + fix: write-fixed (no doublewrite)
buf_page_t::write_complete(): Change WRITE_FIX or WRITE_FIX_REINIT to
UNFIXED, and WRITE_FIX_IBUF to IBUF_EXIST, before releasing the U-latch.
buf_page_t::read_complete(): Renamed from buf_page_read_complete().
Change READ_FIX to UNFIXED or IBUF_EXIST, before releasing the X-latch.
buf_page_t::can_relocate(): If the page latch is being held or waited for,
or the block is buffer-fixed or io-fixed, return false. (The condition
on the page latch is new.)
Outside buf_page_get_gen(), buf_page_get_low() and buf_page_free(), we
will acquire the page latch before fix(), and unfix() before unlocking.
buf_page_t::flush(): Replaces buf_flush_page(). Optimize the
handling of FREED pages.
buf_pool_t::release_freed_page(): Assume that buf_pool.mutex is held
by the caller.
buf_page_t::is_read_fixed(), buf_page_t::is_write_fixed(): New predicates.
buf_page_get_low(): Ignore guesses that are read-fixed because they
may not yet be registered in buf_pool.page_hash and buf_pool.LRU.
buf_page_optimistic_get(): Acquire latch before buffer-fixing.
buf_page_make_young(): Leave read-fixed blocks alone, because they
might not be registered in buf_pool.LRU yet.
recv_sys_t::recover_deferred(), recv_sys_t::recover_low():
Possibly fix MDEV-26326, by holding a page X-latch instead of
only buffer-fixing the page.
76 lines
2.8 KiB
C++
76 lines
2.8 KiB
C++
/*****************************************************************************
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Copyright (c) 2020, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2020, 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, version 2.0, as published by the
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Free Software Foundation.
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This program is also distributed with certain software (including but not
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limited to OpenSSL) that is licensed under separate terms, as designated in a
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particular file or component or in included license documentation. The authors
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of MySQL hereby grant you an additional permission to link the program and
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your derivative works with the separately licensed software that they have
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included with MySQL.
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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, version 2.0,
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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 02110-1301 USA
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*****************************************************************************/
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#pragma once
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#include "buf0buf.h"
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namespace buf {
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class Block_hint {
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public:
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/** Stores the pointer to the block, which is currently buffer-fixed.
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@param block a pointer to a buffer-fixed block to be stored */
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inline void store(buf_block_t *block)
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{
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ut_ad(block->page.buf_fix_count());
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m_block= block;
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m_page_id= block->page.id();
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}
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/** Clears currently stored pointer. */
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inline void clear() { m_block= nullptr; }
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/** Invoke f on m_block(which may be null)
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@param f The function to be executed. It will be passed the pointer.
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If you wish to use the block pointer subsequently,
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you need to ensure you buffer-fix it before returning from f.
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@return the return value of f
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*/
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template <typename F>
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bool run_with_hint(const F &f)
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{
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buffer_fix_block_if_still_valid();
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/* m_block could be changed during f() call, so we use local
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variable to remember which block we need to unfix */
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buf_block_t *block= m_block;
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bool res= f(block);
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if (block)
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block->page.unfix();
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return res;
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}
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buf_block_t *block() const { return m_block; }
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private:
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/** The block pointer stored by store(). */
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buf_block_t *m_block= nullptr;
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/** If m_block is non-null, the m_block->page.id at time it was stored. */
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page_id_t m_page_id{0, 0};
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/** A helper function which checks if m_block is not a dangling pointer and
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still points to block with page with m_page_id and if so, buffer-fixes it,
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otherwise clear()s it */
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void buffer_fix_block_if_still_valid();
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};
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} // namespace buf
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