~drizzle-trunk/drizzle/development

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

Copyright (c) 1995, 2009, 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 mtr/mtr0mtr.c
Mini-transaction buffer

Created 11/26/1995 Heikki Tuuri
*******************************************************/

#include "mtr0mtr.h"

#ifdef UNIV_NONINL
#include "mtr0mtr.ic"
#endif

#include "buf0buf.h"
#include "buf0flu.h"
#include "page0types.h"
#include "mtr0log.h"
#include "log0log.h"

#ifndef UNIV_HOTBACKUP
# include "log0recv.h"
/*****************************************************************//**
Releases the item in the slot given. */
static
void
mtr_memo_slot_release(
/*==================*/
	mtr_t*			mtr,	/*!< in: mtr */
	mtr_memo_slot_t*	slot)	/*!< in: memo slot */
{
	void*	object;
	ulint	type;

	ut_ad(mtr);
	ut_ad(slot);

#ifndef UNIV_DEBUG
	UT_NOT_USED(mtr);
#endif /* UNIV_DEBUG */

	object = slot->object;
	type = slot->type;

	if (UNIV_LIKELY(object != NULL)) {
		if (type <= MTR_MEMO_BUF_FIX) {
			buf_page_release((buf_block_t*)object, type);
		} else if (type == MTR_MEMO_S_LOCK) {
			rw_lock_s_unlock((rw_lock_t*)object);
#ifdef UNIV_DEBUG
		} else if (type != MTR_MEMO_X_LOCK) {
			ut_ad(type == MTR_MEMO_MODIFY);
			ut_ad(mtr_memo_contains(mtr, object,
						MTR_MEMO_PAGE_X_FIX));
#endif /* UNIV_DEBUG */
		} else {
			rw_lock_x_unlock((rw_lock_t*)object);
		}
	}

	slot->object = NULL;
}

/**********************************************************//**
Releases the mlocks and other objects stored in an mtr memo.
They are released in the order opposite to which they were pushed
to the memo. */
static
void
mtr_memo_pop_all(
/*=============*/
	mtr_t*	mtr)	/*!< in: mtr */
{
	mtr_memo_slot_t* slot;
	dyn_array_t*	memo;
	ulint		offset;

	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_COMMITTING); /* Currently only used in
					     commit */
	memo = &(mtr->memo);

	offset = dyn_array_get_data_size(memo);

	while (offset > 0) {
		offset -= sizeof(mtr_memo_slot_t);
		slot = dyn_array_get_element(memo, offset);

		mtr_memo_slot_release(mtr, slot);
	}
}

/*****************************************************************//**
Releases the item in the slot given. */
static
void
mtr_memo_slot_note_modification(
/*============================*/
	mtr_t*			mtr,	/*!< in: mtr */
	mtr_memo_slot_t*	slot)	/*!< in: memo slot */
{
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->modifications);

	if (slot->object != NULL && slot->type == MTR_MEMO_PAGE_X_FIX) {
		buf_block_t*	block = (buf_block_t*) slot->object;

#ifdef UNIV_DEBUG
		ut_ad(log_flush_order_mutex_own());
#endif /* UNIV_DEBUG */
		buf_flush_note_modification(block, mtr);
	}
}

/**********************************************************//**
Add the modified pages to the buffer flush list. They are released
in the order opposite to which they were pushed to the memo. NOTE! It is
essential that the x-rw-lock on a modified buffer page is not released
before buf_page_note_modification is called for that page! Otherwise,
some thread might race to modify it, and the flush list sort order on
lsn would be destroyed. */
static
void
mtr_memo_note_modifications(
/*========================*/
	mtr_t*	mtr)	/*!< in: mtr */
{
	dyn_array_t*	memo;
	ulint		offset;

	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_COMMITTING); /* Currently only used in
					     commit */
	memo = &mtr->memo;

	offset = dyn_array_get_data_size(memo);

	while (offset > 0) {
		mtr_memo_slot_t* slot;

		offset -= sizeof(mtr_memo_slot_t);
		slot = dyn_array_get_element(memo, offset);

		mtr_memo_slot_note_modification(mtr, slot);
	}
}

/************************************************************//**
Writes the contents of a mini-transaction log, if any, to the database log. */
static
void
mtr_log_reserve_and_write(
/*======================*/
	mtr_t*	mtr)	/*!< in: mtr */
{
	dyn_array_t*	mlog;
	dyn_block_t*	block;
	ulint		data_size;
	byte*		first_data;

	ut_ad(mtr);

	mlog = &(mtr->log);

	first_data = dyn_block_get_data(mlog);

	if (mtr->n_log_recs > 1) {
		mlog_catenate_ulint(mtr, MLOG_MULTI_REC_END, MLOG_1BYTE);
	} else {
		*first_data = (byte)((ulint)*first_data
				     | MLOG_SINGLE_REC_FLAG);
	}

	if (mlog->heap == NULL) {
		mtr->end_lsn = log_reserve_and_write_fast(
			first_data, dyn_block_get_used(mlog),
			&mtr->start_lsn);
		if (mtr->end_lsn) {

			/* Success. We have the log mutex.
			Add pages to flush list and exit */
			goto func_exit;
		}
	}

	data_size = dyn_array_get_data_size(mlog);

	/* Open the database log for log_write_low */
	mtr->start_lsn = log_reserve_and_open(data_size);

	if (mtr->log_mode == MTR_LOG_ALL) {

		block = mlog;

		while (block != NULL) {
			log_write_low(dyn_block_get_data(block),
				      dyn_block_get_used(block));
			block = dyn_array_get_next_block(mlog, block);
		}
	} else {
		ut_ad(mtr->log_mode == MTR_LOG_NONE);
		/* Do nothing */
	}

	mtr->end_lsn = log_close();

func_exit:
	log_flush_order_mutex_enter();

	/* It is now safe to release the log mutex because the
	flush_order mutex will ensure that we are the first one
	to insert into the flush list. */
	log_release();

	if (mtr->modifications) {
		mtr_memo_note_modifications(mtr);
	}

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

/***************************************************************//**
Commits a mini-transaction. */
UNIV_INTERN
void
mtr_commit(
/*=======*/
	mtr_t*	mtr)	/*!< in: mini-transaction */
{
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_ACTIVE);
	ut_d(mtr->state = MTR_COMMITTING);

#ifndef UNIV_HOTBACKUP
	/* This is a dirty read, for debugging. */
	ut_ad(!recv_no_log_write);

	if (mtr->modifications && mtr->n_log_recs) {
		mtr_log_reserve_and_write(mtr);
	}

	mtr_memo_pop_all(mtr);
#endif /* !UNIV_HOTBACKUP */

	ut_d(mtr->state = MTR_COMMITTED);
	dyn_array_free(&(mtr->memo));
	dyn_array_free(&(mtr->log));
}

#ifndef UNIV_HOTBACKUP
/**********************************************************//**
Releases the latches stored in an mtr memo down to a savepoint.
NOTE! The mtr must not have made changes to buffer pages after the
savepoint, as these can be handled only by mtr_commit. */
UNIV_INTERN
void
mtr_rollback_to_savepoint(
/*======================*/
	mtr_t*	mtr,		/*!< in: mtr */
	ulint	savepoint)	/*!< in: savepoint */
{
	mtr_memo_slot_t* slot;
	dyn_array_t*	memo;
	ulint		offset;

	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_ACTIVE);

	memo = &(mtr->memo);

	offset = dyn_array_get_data_size(memo);
	ut_ad(offset >= savepoint);

	while (offset > savepoint) {
		offset -= sizeof(mtr_memo_slot_t);

		slot = dyn_array_get_element(memo, offset);

		ut_ad(slot->type != MTR_MEMO_MODIFY);

		/* We do not call mtr_memo_slot_note_modification()
		because there MUST be no changes made to the buffer
		pages after the savepoint */
		mtr_memo_slot_release(mtr, slot);
	}
}

/***************************************************//**
Releases an object in the memo stack. */
UNIV_INTERN
void
mtr_memo_release(
/*=============*/
	mtr_t*	mtr,	/*!< in: mtr */
	void*	object,	/*!< in: object */
	ulint	type)	/*!< in: object type: MTR_MEMO_S_LOCK, ... */
{
	mtr_memo_slot_t* slot;
	dyn_array_t*	memo;
	ulint		offset;

	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_ACTIVE);

	memo = &(mtr->memo);

	offset = dyn_array_get_data_size(memo);

	log_flush_order_mutex_enter();
	while (offset > 0) {
		offset -= sizeof(mtr_memo_slot_t);

		slot = dyn_array_get_element(memo, offset);

		if (object == slot->object && type == slot->type) {

			/* We cannot release a page that has been written
			to in the middle of a mini-transaction. */

			ut_ad(!(mtr->modifications
			       	&& slot->type == MTR_MEMO_PAGE_X_FIX));

			mtr_memo_slot_release(mtr, slot);

			break;
		}
	}
	log_flush_order_mutex_exit();
}
#endif /* !UNIV_HOTBACKUP */

/********************************************************//**
Reads 1 - 4 bytes from a file page buffered in the buffer pool.
@return	value read */
UNIV_INTERN
ulint
mtr_read_ulint(
/*===========*/
	const byte*	ptr,	/*!< in: pointer from where to read */
	ulint		type,	/*!< in: MLOG_1BYTE, MLOG_2BYTES, MLOG_4BYTES */
	mtr_t*		mtr __attribute__((unused)))
				/*!< in: mini-transaction handle */
{
	ut_ad(mtr->state == MTR_ACTIVE);
	ut_ad(mtr_memo_contains_page(mtr, ptr, MTR_MEMO_PAGE_S_FIX)
	      || mtr_memo_contains_page(mtr, ptr, MTR_MEMO_PAGE_X_FIX));
	if (type == MLOG_1BYTE) {
		return(mach_read_from_1(ptr));
	} else if (type == MLOG_2BYTES) {
		return(mach_read_from_2(ptr));
	} else {
		ut_ad(type == MLOG_4BYTES);
		return(mach_read_from_4(ptr));
	}
}

#ifdef UNIV_DEBUG
# ifndef UNIV_HOTBACKUP
/**********************************************************//**
Checks if memo contains the given page.
@return	TRUE if contains */
UNIV_INTERN
ibool
mtr_memo_contains_page(
/*===================*/
	mtr_t*		mtr,	/*!< in: mtr */
	const byte*	ptr,	/*!< in: pointer to buffer frame */
	ulint		type)	/*!< in: type of object */
{
	return(mtr_memo_contains(mtr, buf_block_align(ptr), type));
}

/*********************************************************//**
Prints info of an mtr handle. */
UNIV_INTERN
void
mtr_print(
/*======*/
	mtr_t*	mtr)	/*!< in: mtr */
{
	fprintf(stderr,
		"Mini-transaction handle: memo size %lu bytes"
		" log size %lu bytes\n",
		(ulong) dyn_array_get_data_size(&(mtr->memo)),
		(ulong) dyn_array_get_data_size(&(mtr->log)));
}
# endif /* !UNIV_HOTBACKUP */
#endif /* UNIV_DEBUG */