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638c62acac
Starting with GCC 7 and clang 15, single-bit operations such as fetch_or(1) & 1 are translated into 80386 instructions such as LOCK BTS, instead of using the generic translation pattern of emitting a loop around LOCK CMPXCHG. Given that the oldest currently supported GNU/Linux distributions ship GCC 7, and that older versions of GCC are out of support, let us remove some work-arounds that are not strictly necessary. If someone compiles the code using an older compiler, it will work but possibly less efficiently. srw_mutex_impl::HOLDER: Changed from 1U<<31 to 1 in order to work around https://github.com/llvm/llvm-project/issues/37322 which is specific to setting the most significant bit. srw_mutex_impl::WAITER: A multiplier of waiting requests. This used to be 1, which would now collide with HOLDER. fil_space_t::set_stopping(): Remove this unused function. In MSVC we need _interlockedbittestandset() for LOCK BTS.
287 lines
10 KiB
C++
287 lines
10 KiB
C++
/*****************************************************************************
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Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2017, 2022, 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/trx0rseg.h
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Rollback segment
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Created 3/26/1996 Heikki Tuuri
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*******************************************************/
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#pragma once
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#include "trx0types.h"
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#include "fut0lst.h"
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/** Create a rollback segment header.
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@param[in,out] space system, undo, or temporary tablespace
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@param[in] rseg_id rollback segment identifier
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@param[in] max_trx_id new value of TRX_RSEG_MAX_TRX_ID
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@param[in,out] mtr mini-transaction
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@param[out] err error code
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@return the created rollback segment
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@retval nullptr on failure */
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buf_block_t *trx_rseg_header_create(fil_space_t *space, ulint rseg_id,
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trx_id_t max_trx_id, mtr_t *mtr,
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dberr_t *err)
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MY_ATTRIBUTE((nonnull, warn_unused_result));
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/** Initialize or recover the rollback segments at startup. */
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dberr_t trx_rseg_array_init();
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/** Create the temporary rollback segments. */
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dberr_t trx_temp_rseg_create(mtr_t *mtr);
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/* Number of undo log slots in a rollback segment file copy */
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#define TRX_RSEG_N_SLOTS (srv_page_size / 16)
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/* Maximum number of transactions supported by a single rollback segment */
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#define TRX_RSEG_MAX_N_TRXS (TRX_RSEG_N_SLOTS / 2)
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/** The rollback segment memory object */
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struct alignas(CPU_LEVEL1_DCACHE_LINESIZE) trx_rseg_t
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{
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/** tablespace containing the rollback segment; constant after init() */
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fil_space_t *space;
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/** latch protecting everything except page_no, space */
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IF_DBUG(srw_lock_debug,srw_spin_lock) latch;
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/** rollback segment header page number; constant after init() */
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uint32_t page_no;
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/** length of the TRX_RSEG_HISTORY list (number of transactions) */
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uint32_t history_size;
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/** Last known transaction that has not been purged yet,
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or 0 if everything has been purged. */
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trx_id_t needs_purge;
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private:
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/** Reference counter to track is_persistent() transactions,
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with SKIP flag. */
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std::atomic<uint32_t> ref;
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public:
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/** Whether undo tablespace truncation is pending */
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static constexpr uint32_t SKIP= 1;
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/** Transaction reference count multiplier */
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static constexpr uint32_t REF= 2;
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/** @return the reference count and flags */
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uint32_t ref_load() const { return ref.load(std::memory_order_relaxed); }
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private:
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/** Set the SKIP bit */
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void ref_set_skip()
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{
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ref.fetch_or(SKIP, std::memory_order_relaxed);
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}
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/** Clear a bit in ref */
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void ref_reset_skip()
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{
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ref.fetch_and(~SKIP, std::memory_order_relaxed);
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}
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public:
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/** Initialize the fields that are not zero-initialized. */
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void init(fil_space_t *space, uint32_t page);
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/** Reinitialize the fields on undo tablespace truncation. */
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void reinit(uint32_t page);
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/** Clean up. */
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void destroy();
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/** Note that undo tablespace truncation was started. */
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void set_skip_allocation() { ut_ad(is_persistent()); ref_set_skip(); }
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/** Note that undo tablespace truncation was completed. */
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void clear_skip_allocation()
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{
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ut_ad(is_persistent());
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#if defined DBUG_OFF
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ref_reset_skip();
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#else
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ut_d(auto r=) ref.fetch_and(~SKIP, std::memory_order_relaxed);
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ut_ad(r == SKIP);
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#endif
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}
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/** @return whether the segment is marked for undo truncation */
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bool skip_allocation() const
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{ return ref.load(std::memory_order_acquire) & SKIP; }
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/** Increment the reference count */
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void acquire()
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{ ut_d(auto r=) ref.fetch_add(REF); ut_ad(!(r & SKIP)); }
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/** Increment the reference count if possible
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@retval true if the reference count was incremented
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@retval false if skip_allocation() holds */
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bool acquire_if_available()
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{
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uint32_t r= 0;
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while (!ref.compare_exchange_weak(r, r + REF,
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std::memory_order_relaxed,
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std::memory_order_relaxed))
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if (r & SKIP)
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return false;
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return true;
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}
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/** Decrement the reference count */
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void release()
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{
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ut_d(const auto r=)
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ref.fetch_sub(REF, std::memory_order_relaxed);
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ut_ad(r >= REF);
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}
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/** @return whether references exist */
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bool is_referenced() const { return ref_load() >= REF; }
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/** current size in pages */
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uint32_t curr_size;
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/** List of undo logs (transactions) */
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UT_LIST_BASE_NODE_T(trx_undo_t) undo_list;
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/** List of undo log segments cached for fast reuse */
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UT_LIST_BASE_NODE_T(trx_undo_t) undo_cached;
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/** Last not yet purged undo log header; FIL_NULL if all purged */
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uint32_t last_page_no;
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/** trx_t::no << 16 | last_offset */
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uint64_t last_commit_and_offset;
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/** @return the commit ID of the last committed transaction */
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trx_id_t last_trx_no() const
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{ return last_commit_and_offset >> 16; }
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/** @return header offset of the last committed transaction */
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uint16_t last_offset() const
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{
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return static_cast<uint16_t>(last_commit_and_offset);
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}
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void set_last_commit(uint16_t last_offset, trx_id_t trx_no)
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{
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last_commit_and_offset= trx_no << 16 | static_cast<uint64_t>(last_offset);
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}
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/** @return the page identifier */
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page_id_t page_id() const { return page_id_t{space->id, page_no}; }
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/** @return the rollback segment header page, exclusively latched */
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buf_block_t *get(mtr_t *mtr, dberr_t *err) const;
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/** @return whether the rollback segment is persistent */
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bool is_persistent() const
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{
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ut_ad(space == fil_system.temp_space || space == fil_system.sys_space ||
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(srv_undo_space_id_start > 0 &&
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space->id >= srv_undo_space_id_start &&
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space->id <= srv_undo_space_id_start + TRX_SYS_MAX_UNDO_SPACES));
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ut_ad(space == fil_system.temp_space || space == fil_system.sys_space ||
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!srv_was_started ||
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(srv_undo_space_id_start > 0 &&
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space->id >= srv_undo_space_id_start
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&& space->id <= srv_undo_space_id_start +
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srv_undo_tablespaces_open));
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return space->id != SRV_TMP_SPACE_ID;
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}
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};
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/* Undo log segment slot in a rollback segment header */
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/*-------------------------------------------------------------*/
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#define TRX_RSEG_SLOT_PAGE_NO 0 /* Page number of the header page of
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an undo log segment */
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/*-------------------------------------------------------------*/
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/* Slot size */
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#define TRX_RSEG_SLOT_SIZE 4
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/* The offset of the rollback segment header on its page */
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#define TRX_RSEG FSEG_PAGE_DATA
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/* Transaction rollback segment header */
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/*-------------------------------------------------------------*/
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/** 0xfffffffe = pre-MariaDB 10.3.5 format; 0=MariaDB 10.3.5 or later */
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#define TRX_RSEG_FORMAT 0
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/** Number of pages in the TRX_RSEG_HISTORY list */
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#define TRX_RSEG_HISTORY_SIZE 4
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/** Committed transaction logs that have not been purged yet */
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#define TRX_RSEG_HISTORY 8
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#define TRX_RSEG_FSEG_HEADER (8 + FLST_BASE_NODE_SIZE)
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/* Header for the file segment where
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this page is placed */
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#define TRX_RSEG_UNDO_SLOTS (8 + FLST_BASE_NODE_SIZE + FSEG_HEADER_SIZE)
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/* Undo log segment slots */
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/** Maximum transaction ID (valid only if TRX_RSEG_FORMAT is 0) */
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#define TRX_RSEG_MAX_TRX_ID (TRX_RSEG_UNDO_SLOTS + TRX_RSEG_N_SLOTS \
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* TRX_RSEG_SLOT_SIZE)
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/** 8 bytes offset within the binlog file */
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#define TRX_RSEG_BINLOG_OFFSET TRX_RSEG_MAX_TRX_ID + 8
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/** MySQL log file name, 512 bytes, including terminating NUL
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(valid only if TRX_RSEG_FORMAT is 0).
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If no binlog information is present, the first byte is NUL. */
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#define TRX_RSEG_BINLOG_NAME TRX_RSEG_MAX_TRX_ID + 16
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/** Maximum length of binlog file name, including terminating NUL, in bytes */
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#define TRX_RSEG_BINLOG_NAME_LEN 512
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#ifdef WITH_WSREP
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# include "trx0xa.h"
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/** Update the WSREP XID information in rollback segment header.
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@param[in,out] rseg_header rollback segment header
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@param[in] xid WSREP XID
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@param[in,out] mtr mini-transaction */
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void
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trx_rseg_update_wsrep_checkpoint(
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buf_block_t* rseg_header,
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const XID* xid,
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mtr_t* mtr);
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/** Update WSREP checkpoint XID in first rollback segment header
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as part of wsrep_set_SE_checkpoint() when it is guaranteed that there
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are no wsrep transactions committing.
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If the UUID part of the WSREP XID does not match to the UUIDs of XIDs already
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stored into rollback segments, the WSREP XID in all the remaining rollback
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segments will be reset.
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@param[in] xid WSREP XID */
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void trx_rseg_update_wsrep_checkpoint(const XID* xid);
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/** Recover the latest WSREP checkpoint XID.
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@param[out] xid WSREP XID
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@return whether the WSREP XID was found */
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bool trx_rseg_read_wsrep_checkpoint(XID& xid);
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#endif /* WITH_WSREP */
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/** Read the page number of an undo log slot.
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@param[in] rseg_header rollback segment header
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@param[in] n slot number */
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inline uint32_t trx_rsegf_get_nth_undo(const buf_block_t *rseg_header, ulint n)
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{
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ut_ad(n < TRX_RSEG_N_SLOTS);
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return mach_read_from_4(TRX_RSEG + TRX_RSEG_UNDO_SLOTS +
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n * TRX_RSEG_SLOT_SIZE + rseg_header->page.frame);
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}
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/** Upgrade a rollback segment header page to MariaDB 10.3 format.
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@param[in,out] rseg_header rollback segment header page
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@param[in,out] mtr mini-transaction */
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void trx_rseg_format_upgrade(buf_block_t *rseg_header, mtr_t *mtr);
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/** Update the offset information about the end of the binlog entry
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which corresponds to the transaction just being committed.
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In a replication slave, this updates the master binlog position
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up to which replication has proceeded.
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@param[in,out] rseg_header rollback segment header
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@param[in] trx committing transaction
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@param[in,out] mtr mini-transaction */
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void trx_rseg_update_binlog_offset(buf_block_t *rseg_header, const trx_t *trx,
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mtr_t *mtr);
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