path: root/storage/xtradb/include/log0log.ic

/*****************************************************************************

Copyright (c) 1995, 2010, Innobase Oy. All Rights Reserved.

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 St, Fifth Floor, Boston, MA 02110-1301 USA

*****************************************************************************/

/**************************************************//**
@file include/log0log.ic
Database log

Created 12/9/1995 Heikki Tuuri
*******************************************************/

#include "os0file.h"
#include "mach0data.h"
#include "mtr0mtr.h"

#ifdef UNIV_LOG_DEBUG
/******************************************************//**
Checks by parsing that the catenated log segment for a single mtr is
consistent. */
UNIV_INTERN
ibool
log_check_log_recs(
/*===============*/
	const byte*	buf,		/*!< in: pointer to the start of
					the log segment in the
					log_sys->buf log buffer */
	ulint		len,		/*!< in: segment length in bytes */
	ib_uint64_t	buf_start_lsn);	/*!< in: buffer start lsn */
#endif /* UNIV_LOG_DEBUG */

/************************************************************//**
Gets a log block flush bit.
@return	TRUE if this block was the first to be written in a log flush */
UNIV_INLINE
ibool
log_block_get_flush_bit(
/*====================*/
	const byte*	log_block)	/*!< in: log block */
{
	if (LOG_BLOCK_FLUSH_BIT_MASK
	    & mach_read_from_4(log_block + LOG_BLOCK_HDR_NO)) {

		return(TRUE);
	}

	return(FALSE);
}

/************************************************************//**
Sets the log block flush bit. */
UNIV_INLINE
void
log_block_set_flush_bit(
/*====================*/
	byte*	log_block,	/*!< in/out: log block */
	ibool	val)		/*!< in: value to set */
{
	ulint	field;

	field = mach_read_from_4(log_block + LOG_BLOCK_HDR_NO);

	if (val) {
		field = field | LOG_BLOCK_FLUSH_BIT_MASK;
	} else {
		field = field & ~LOG_BLOCK_FLUSH_BIT_MASK;
	}

	mach_write_to_4(log_block + LOG_BLOCK_HDR_NO, field);
}

/************************************************************//**
Gets a log block number stored in the header.
@return	log block number stored in the block header */
UNIV_INLINE
ulint
log_block_get_hdr_no(
/*=================*/
	const byte*	log_block)	/*!< in: log block */
{
	return(~LOG_BLOCK_FLUSH_BIT_MASK
	       & mach_read_from_4(log_block + LOG_BLOCK_HDR_NO));
}

/************************************************************//**
Sets the log block number stored in the header; NOTE that this must be set
before the flush bit! */
UNIV_INLINE
void
log_block_set_hdr_no(
/*=================*/
	byte*	log_block,	/*!< in/out: log block */
	ulint	n)		/*!< in: log block number: must be > 0 and
				< LOG_BLOCK_FLUSH_BIT_MASK */
{
	ut_ad(n > 0);
	ut_ad(n < LOG_BLOCK_FLUSH_BIT_MASK);

	mach_write_to_4(log_block + LOG_BLOCK_HDR_NO, n);
}

/************************************************************//**
Gets a log block data length.
@return	log block data length measured as a byte offset from the block start */
UNIV_INLINE
ulint
log_block_get_data_len(
/*===================*/
	const byte*	log_block)	/*!< in: log block */
{
	return(mach_read_from_2(log_block + LOG_BLOCK_HDR_DATA_LEN));
}

/************************************************************//**
Sets the log block data length. */
UNIV_INLINE
void
log_block_set_data_len(
/*===================*/
	byte*	log_block,	/*!< in/out: log block */
	ulint	len)		/*!< in: data length */
{
	mach_write_to_2(log_block + LOG_BLOCK_HDR_DATA_LEN, len);
}

/************************************************************//**
Gets a log block first mtr log record group offset.
@return first mtr log record group byte offset from the block start, 0
if none */
UNIV_INLINE
ulint
log_block_get_first_rec_group(
/*==========================*/
	const byte*	log_block)	/*!< in: log block */
{
	return(mach_read_from_2(log_block + LOG_BLOCK_FIRST_REC_GROUP));
}

/************************************************************//**
Sets the log block first mtr log record group offset. */
UNIV_INLINE
void
log_block_set_first_rec_group(
/*==========================*/
	byte*	log_block,	/*!< in/out: log block */
	ulint	offset)		/*!< in: offset, 0 if none */
{
	mach_write_to_2(log_block + LOG_BLOCK_FIRST_REC_GROUP, offset);
}

/************************************************************//**
Gets a log block checkpoint number field (4 lowest bytes).
@return	checkpoint no (4 lowest bytes) */
UNIV_INLINE
ulint
log_block_get_checkpoint_no(
/*========================*/
	const byte*	log_block)	/*!< in: log block */
{
	return(mach_read_from_4(log_block + LOG_BLOCK_CHECKPOINT_NO));
}

/************************************************************//**
Sets a log block checkpoint number field (4 lowest bytes). */
UNIV_INLINE
void
log_block_set_checkpoint_no(
/*========================*/
	byte*		log_block,	/*!< in/out: log block */
	ib_uint64_t	no)		/*!< in: checkpoint no */
{
	mach_write_to_4(log_block + LOG_BLOCK_CHECKPOINT_NO, (ulint) no);
}

/************************************************************//**
Converts a lsn to a log block number.
@return	log block number, it is > 0 and <= 1G */
UNIV_INLINE
ulint
log_block_convert_lsn_to_no(
/*========================*/
	ib_uint64_t	lsn)	/*!< in: lsn of a byte within the block */
{
	return(((ulint) (lsn / OS_FILE_LOG_BLOCK_SIZE) & 0x3FFFFFFFUL) + 1);
}

/************************************************************//**
Calculates the checksum for a log block.
@return	checksum */
UNIV_INLINE
ulint
log_block_calc_checksum(
/*====================*/
	const byte*	block)	/*!< in: log block */
{
	ulint	sum;
	ulint	sh;
	ulint	i;

	sum = 1;
	sh = 0;

	for (i = 0; i < OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE; i++) {
		ulint	b = (ulint) block[i];
		sum &= 0x7FFFFFFFUL;
		sum += b;
		sum += b << sh;
		sh++;
		if (sh > 24) {
			sh = 0;
		}
	}

	return(sum);
}

/************************************************************//**
Gets a log block checksum field value.
@return	checksum */
UNIV_INLINE
ulint
log_block_get_checksum(
/*===================*/
	const byte*	log_block)	/*!< in: log block */
{
	return(mach_read_from_4(log_block + OS_FILE_LOG_BLOCK_SIZE
				- LOG_BLOCK_CHECKSUM));
}

/************************************************************//**
Sets a log block checksum field value. */
UNIV_INLINE
void
log_block_set_checksum(
/*===================*/
	byte*	log_block,	/*!< in/out: log block */
	ulint	checksum)	/*!< in: checksum */
{
	mach_write_to_4(log_block + OS_FILE_LOG_BLOCK_SIZE
			- LOG_BLOCK_CHECKSUM,
			checksum);
}

/************************************************************//**
Initializes a log block in the log buffer. */
UNIV_INLINE
void
log_block_init(
/*===========*/
	byte*		log_block,	/*!< in: pointer to the log buffer */
	ib_uint64_t	lsn)		/*!< in: lsn within the log block */
{
	ulint	no;

	ut_ad(mutex_own(&(log_sys->mutex)));

	no = log_block_convert_lsn_to_no(lsn);

	log_block_set_hdr_no(log_block, no);

	log_block_set_data_len(log_block, LOG_BLOCK_HDR_SIZE);
	log_block_set_first_rec_group(log_block, 0);
}

/************************************************************//**
Initializes a log block in the log buffer in the old format, where there
was no checksum yet. */
UNIV_INLINE
void
log_block_init_in_old_format(
/*=========================*/
	byte*		log_block,	/*!< in: pointer to the log buffer */
	ib_uint64_t	lsn)		/*!< in: lsn within the log block */
{
	ulint	no;

	ut_ad(mutex_own(&(log_sys->mutex)));

	no = log_block_convert_lsn_to_no(lsn);

	log_block_set_hdr_no(log_block, no);
	mach_write_to_4(log_block + OS_FILE_LOG_BLOCK_SIZE
			- LOG_BLOCK_CHECKSUM, no);
	log_block_set_data_len(log_block, LOG_BLOCK_HDR_SIZE);
	log_block_set_first_rec_group(log_block, 0);
}

#ifndef UNIV_HOTBACKUP
/************************************************************//**
Writes to the log the string given. The log must be released with
log_release.
@return	end lsn of the log record, zero if did not succeed */
UNIV_INLINE
ib_uint64_t
log_reserve_and_write_fast(
/*=======================*/
	const void*	str,	/*!< in: string */
	ulint		len,	/*!< in: string length */
	ib_uint64_t*	start_lsn)/*!< out: start lsn of the log record */
{
	ulint		data_len;
#ifdef UNIV_LOG_LSN_DEBUG
	/* length of the LSN pseudo-record */
	ulint		lsn_len;
#endif /* UNIV_LOG_LSN_DEBUG */

	mutex_enter(&log_sys->mutex);
#ifdef UNIV_LOG_LSN_DEBUG
	lsn_len = 1
		+ mach_get_compressed_size(log_sys->lsn >> 32)
		+ mach_get_compressed_size(log_sys->lsn & 0xFFFFFFFFUL);
#endif /* UNIV_LOG_LSN_DEBUG */

	data_len = len
#ifdef UNIV_LOG_LSN_DEBUG
		+ lsn_len
#endif /* UNIV_LOG_LSN_DEBUG */
		+ log_sys->buf_free % OS_FILE_LOG_BLOCK_SIZE;

	if (data_len >= OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE) {

		/* The string does not fit within the current log block or the
		log block would become full. Do not release the log mutex,
		because it has to be reacquired immediately for the "slow" write
		procedure via log_write_low(). */

		return(0);
	}

	*start_lsn = log_sys->lsn;

#ifdef UNIV_LOG_LSN_DEBUG
	{
		/* Write the LSN pseudo-record. */
		byte* b = &log_sys->buf[log_sys->buf_free];
		*b++ = MLOG_LSN | (MLOG_SINGLE_REC_FLAG & *(const byte*) str);
		/* Write the LSN in two parts,
		as a pseudo page number and space id. */
		b += mach_write_compressed(b, log_sys->lsn >> 32);
		b += mach_write_compressed(b, log_sys->lsn & 0xFFFFFFFFUL);
		ut_a(b - lsn_len == &log_sys->buf[log_sys->buf_free]);

		memcpy(b, str, len);
		len += lsn_len;
	}
#else /* UNIV_LOG_LSN_DEBUG */
	memcpy(log_sys->buf + log_sys->buf_free, str, len);
#endif /* UNIV_LOG_LSN_DEBUG */

	log_block_set_data_len((byte*) ut_align_down(log_sys->buf
						     + log_sys->buf_free,
						     OS_FILE_LOG_BLOCK_SIZE),
			       data_len);
#ifdef UNIV_LOG_DEBUG
	log_sys->old_buf_free = log_sys->buf_free;
	log_sys->old_lsn = log_sys->lsn;
#endif
	log_sys->buf_free += len;

	ut_ad(log_sys->buf_free <= log_sys->buf_size);

	log_sys->lsn += len;

#ifdef UNIV_LOG_DEBUG
	log_check_log_recs(log_sys->buf + log_sys->old_buf_free,
			   log_sys->buf_free - log_sys->old_buf_free,
			   log_sys->old_lsn);
#endif
	return(log_sys->lsn);
}

/**************************************************************************//**
Locks the log mutex and opens the log for log_write_low. The log must be closed
with log_close and released with log_release.
@return start lsn of the log record */
UNIV_INLINE
ib_uint64_t
log_reserve_and_open(
/*=================*/
	ulint	len)	/*!< in: length of data to be catenated */
{
	mutex_enter(&(log_sys->mutex));

	return log_open(len);
}

/***********************************************************************//**
Releases the log mutex. */
UNIV_INLINE
void
log_release(void)
/*=============*/
{
	mutex_exit(&(log_sys->mutex));
}

/************************************************************//**
Gets the current lsn.
@return	current lsn */
UNIV_INLINE
ib_uint64_t
log_get_lsn(void)
/*=============*/
{
	ib_uint64_t	lsn;

	mutex_enter(&(log_sys->mutex));

	lsn = log_sys->lsn;

	mutex_exit(&(log_sys->mutex));

	return(lsn);
}

/************************************************************//**
Gets the current lsn with a trylock
@return	current lsn or 0 if false*/
UNIV_INLINE
lsn_t
log_get_lsn_nowait(void)
/*=============*/
{
	lsn_t	lsn=0;

	if (!mutex_enter_nowait(&(log_sys->mutex))) {

		lsn = log_sys->lsn;

		mutex_exit(&(log_sys->mutex));
	}

	return(lsn);
}

/****************************************************************
Gets the log group capacity. It is OK to read the value without
holding log_sys->mutex because it is constant.
@return	log group capacity */
UNIV_INLINE
ulint
log_get_capacity(void)
/*==================*/
{
	return(log_sys->log_group_capacity);
}

/***********************************************************************//**
Checks if there is need for a log buffer flush or a new checkpoint, and does
this if yes. Any database operation should call this when it has modified
more than about 4 pages. NOTE that this function may only be called when the
OS thread owns no synchronization objects except the dictionary mutex. */
UNIV_INLINE
void
log_free_check(void)
/*================*/
{

#ifdef UNIV_SYNC_DEBUG
	ut_ad(sync_thread_levels_empty_except_dict());
#endif /* UNIV_SYNC_DEBUG */

	if (log_sys->check_flush_or_checkpoint) {

		log_check_margins();
	}
}
#endif /* !UNIV_HOTBACKUP */

/****************************************************************//**
Safely reads the log_sys->tracked_lsn value.  Uses atomic operations
if available, otherwise this field is protected with the log system
mutex.  The writer counterpart function is log_set_tracked_lsn() in
log0online.c.

@return log_sys->tracked_lsn value. */
UNIV_INLINE
ib_uint64_t
log_get_tracked_lsn(void)
/*=====================*/
{
#ifdef HAVE_ATOMIC_BUILTINS_64
	return os_atomic_increment_uint64(&log_sys->tracked_lsn, 0);
#else
	ut_ad(mutex_own(&(log_sys->mutex)));
	return log_sys->tracked_lsn;
#endif
}