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92 lines
3.3 KiB
C
92 lines
3.3 KiB
C
/* Copyright (C) 2006,2007 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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/*
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WL#3071 Maria checkpoint
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First version written by Guilhem Bichot on 2006-04-27.
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Does not compile yet.
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*/
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/* This is the interface of this module. */
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typedef enum enum_ma_checkpoint_level {
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CHECKPOINT_NONE= 0,
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/* just write dirty_pages, transactions table and sync files */
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CHECKPOINT_INDIRECT,
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/* also flush all dirty pages which were already dirty at prev checkpoint */
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CHECKPOINT_MEDIUM,
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/* also flush all dirty pages */
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CHECKPOINT_FULL
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} CHECKPOINT_LEVEL;
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C_MODE_START
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int ma_checkpoint_init(ulong interval);
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void ma_checkpoint_end(void);
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int ma_checkpoint_execute(CHECKPOINT_LEVEL level, my_bool no_wait);
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C_MODE_END
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/**
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@brief reads some LSNs with special trickery
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If a 64-bit variable transitions between both halves being zero to both
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halves being non-zero, and back, this function can be used to do a read of
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it (without mutex, without atomic load) which always produces a correct
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(though maybe slightly old) value (even on 32-bit CPUs). The value is at
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least as new as the latest mutex unlock done by the calling thread.
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The assumption is that the system sets both 4-byte halves either at the
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same time, or one after the other (in any order), but NOT some bytes of the
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first half then some bytes of the second half then the rest of bytes of the
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first half. With this assumption, the function can detect when it is
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seeing an inconsistent value.
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@param LSN pointer to the LSN variable to read
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@return LSN part (most significant byte always 0)
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*/
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#if ( SIZEOF_CHARP >= 8 )
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/* 64-bit CPU, 64-bit reads are atomic */
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#define lsn_read_non_atomic LSN_WITH_FLAGS_TO_LSN
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#else
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static inline LSN lsn_read_non_atomic_32(const volatile LSN *x)
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{
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/*
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32-bit CPU, 64-bit reads may give a mixed of old half and new half (old
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low bits and new high bits, or the contrary).
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*/
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for (;;) /* loop until no atomicity problems */
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{
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/*
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Remove most significant byte in case this is a LSN_WITH_FLAGS object.
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Those flags in TRN::first_undo_lsn break the condition on transitions so
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they must be removed below.
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*/
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LSN y= LSN_WITH_FLAGS_TO_LSN(*x);
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if (likely((y == LSN_IMPOSSIBLE) || LSN_VALID(y)))
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return y;
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}
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}
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#define lsn_read_non_atomic(x) lsn_read_non_atomic_32(&x)
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#endif
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/**
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prints a message from a task not connected to any user (checkpoint
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and recovery for example).
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@param level 0 if error, ME_WARNING if warning,
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ME_NOTE if info
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@param sentence text to write
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*/
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#define ma_message_no_user(level, sentence) \
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my_printf_error(HA_ERR_GENERIC, "Aria engine: %s", MYF(level), sentence)
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