mariadb/include/buf0buf.ic

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

Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.
Copyright (c) 2008, Google Inc.

Portions of this file contain modifications contributed and copyrighted by
Google, Inc. Those modifications are gratefully acknowledged and are described
briefly in the InnoDB documentation. The contributions by Google are
incorporated with their permission, and subject to the conditions contained in
the file COPYING.Google.

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., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

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

/**************************************************//**
@file include/buf0buf.ic
The database buffer buf_pool

Created 11/5/1995 Heikki Tuuri
*******************************************************/

#include "mtr0mtr.h"
#ifndef UNIV_HOTBACKUP
#include "buf0flu.h"
#include "buf0lru.h"
#include "buf0rea.h"

/********************************************************************//**
Reads the freed_page_clock of a buffer block.
@return	freed_page_clock */
UNIV_INLINE
ulint
buf_page_get_freed_page_clock(
/*==========================*/
	const buf_page_t*	bpage)	/*!< in: block */
{
	/* This is sometimes read without holding buf_pool_mutex. */
	return(bpage->freed_page_clock);
}

/********************************************************************//**
Reads the freed_page_clock of a buffer block.
@return	freed_page_clock */
UNIV_INLINE
ulint
buf_block_get_freed_page_clock(
/*===========================*/
	const buf_block_t*	block)	/*!< in: block */
{
	return(buf_page_get_freed_page_clock(&block->page));
}

/********************************************************************//**
Recommends a move of a block to the start of the LRU list if there is danger
of dropping from the buffer pool. NOTE: does not reserve the buffer pool
mutex.
@return	TRUE if should be made younger */
UNIV_INLINE
ibool
buf_page_peek_if_too_old(
/*=====================*/
	const buf_page_t*	bpage)	/*!< in: block to make younger */
{
	if (UNIV_UNLIKELY(buf_pool->freed_page_clock == 0)) {
		/* If eviction has not started yet, do not update the
		statistics or move blocks in the LRU list.  This is
		either the warm-up phase or an in-memory workload. */
		return(FALSE);
	} else if (buf_LRU_old_threshold_ms && bpage->old) {
		unsigned	access_time = buf_page_is_accessed(bpage);

		if (access_time > 0
		    && (ut_time_ms() - access_time)
		    >= buf_LRU_old_threshold_ms) {
			return(TRUE);
		}

		buf_pool->stat.n_pages_not_made_young++;
		return(FALSE);
	} else {
		/* FIXME: bpage->freed_page_clock is 31 bits */
		return((buf_pool->freed_page_clock & ((1UL << 31) - 1))
		       > ((ulint) bpage->freed_page_clock
			  + (buf_pool->curr_size
			     * (BUF_LRU_OLD_RATIO_DIV - buf_LRU_old_ratio)
			     / (BUF_LRU_OLD_RATIO_DIV * 4))));
	}
}

/*********************************************************************//**
Gets the current size of buffer buf_pool in bytes.
@return	size in bytes */
UNIV_INLINE
ulint
buf_pool_get_curr_size(void)
/*========================*/
{
	return(buf_pool->curr_size * UNIV_PAGE_SIZE);
}

/********************************************************************//**
Gets the smallest oldest_modification lsn for any page in the pool. Returns
zero if all modified pages have been flushed to disk.
@return	oldest modification in pool, zero if none */
UNIV_INLINE
ib_uint64_t
buf_pool_get_oldest_modification(void)
/*==================================*/
{
	buf_page_t*	bpage;
	ib_uint64_t	lsn;

	buf_flush_list_mutex_enter();

	bpage = UT_LIST_GET_LAST(buf_pool->flush_list);

	if (bpage == NULL) {
		lsn = 0;
	} else {
		ut_ad(bpage->in_flush_list);
		lsn = bpage->oldest_modification;
	}

	buf_flush_list_mutex_exit();

	/* The returned answer may be out of date: the flush_list can
	change after the mutex has been released. */

	return(lsn);
}
#endif /* !UNIV_HOTBACKUP */

/*********************************************************************//**
Gets the state of a block.
@return	state */
UNIV_INLINE
enum buf_page_state
buf_page_get_state(
/*===============*/
	const buf_page_t*	bpage)	/*!< in: pointer to the control block */
{
	enum buf_page_state	state = (enum buf_page_state) bpage->state;

#ifdef UNIV_DEBUG
	switch (state) {
	case BUF_BLOCK_ZIP_FREE:
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
	case BUF_BLOCK_NOT_USED:
	case BUF_BLOCK_READY_FOR_USE:
	case BUF_BLOCK_FILE_PAGE:
	case BUF_BLOCK_MEMORY:
	case BUF_BLOCK_REMOVE_HASH:
		break;
	default:
		ut_error;
	}
#endif /* UNIV_DEBUG */

	return(state);
}
/*********************************************************************//**
Gets the state of a block.
@return	state */
UNIV_INLINE
enum buf_page_state
buf_block_get_state(
/*================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	return(buf_page_get_state(&block->page));
}
/*********************************************************************//**
Sets the state of a block. */
UNIV_INLINE
void
buf_page_set_state(
/*===============*/
	buf_page_t*		bpage,	/*!< in/out: pointer to control block */
	enum buf_page_state	state)	/*!< in: state */
{
#ifdef UNIV_DEBUG
	enum buf_page_state	old_state	= buf_page_get_state(bpage);

	switch (old_state) {
	case BUF_BLOCK_ZIP_FREE:
		ut_error;
		break;
	case BUF_BLOCK_ZIP_PAGE:
		ut_a(state == BUF_BLOCK_ZIP_DIRTY);
		break;
	case BUF_BLOCK_ZIP_DIRTY:
		ut_a(state == BUF_BLOCK_ZIP_PAGE);
		break;
	case BUF_BLOCK_NOT_USED:
		ut_a(state == BUF_BLOCK_READY_FOR_USE);
		break;
	case BUF_BLOCK_READY_FOR_USE:
		ut_a(state == BUF_BLOCK_MEMORY
		     || state == BUF_BLOCK_FILE_PAGE
		     || state == BUF_BLOCK_NOT_USED);
		break;
	case BUF_BLOCK_MEMORY:
		ut_a(state == BUF_BLOCK_NOT_USED);
		break;
	case BUF_BLOCK_FILE_PAGE:
		ut_a(state == BUF_BLOCK_NOT_USED
		     || state == BUF_BLOCK_REMOVE_HASH);
		break;
	case BUF_BLOCK_REMOVE_HASH:
		ut_a(state == BUF_BLOCK_MEMORY);
		break;
	}
#endif /* UNIV_DEBUG */
	bpage->state = state;
	ut_ad(buf_page_get_state(bpage) == state);
}

/*********************************************************************//**
Sets the state of a block. */
UNIV_INLINE
void
buf_block_set_state(
/*================*/
	buf_block_t*		block,	/*!< in/out: pointer to control block */
	enum buf_page_state	state)	/*!< in: state */
{
	buf_page_set_state(&block->page, state);
}

/*********************************************************************//**
Determines if a block is mapped to a tablespace.
@return	TRUE if mapped */
UNIV_INLINE
ibool
buf_page_in_file(
/*=============*/
	const buf_page_t*	bpage)	/*!< in: pointer to control block */
{
	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_ZIP_FREE:
		/* This is a free page in buf_pool->zip_free[].
		Such pages should only be accessed by the buddy allocator. */
		ut_error;
		break;
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
	case BUF_BLOCK_FILE_PAGE:
		return(TRUE);
	case BUF_BLOCK_NOT_USED:
	case BUF_BLOCK_READY_FOR_USE:
	case BUF_BLOCK_MEMORY:
	case BUF_BLOCK_REMOVE_HASH:
		break;
	}

	return(FALSE);
}

#ifndef UNIV_HOTBACKUP
/*********************************************************************//**
Determines if a block should be on unzip_LRU list.
@return	TRUE if block belongs to unzip_LRU */
UNIV_INLINE
ibool
buf_page_belongs_to_unzip_LRU(
/*==========================*/
	const buf_page_t*	bpage)	/*!< in: pointer to control block */
{
	ut_ad(buf_page_in_file(bpage));

	return(bpage->zip.data
	       && buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE);
}

/*********************************************************************//**
Gets the mutex of a block.
@return	pointer to mutex protecting bpage */
UNIV_INLINE
mutex_t*
buf_page_get_mutex(
/*===============*/
	const buf_page_t*	bpage)	/*!< in: pointer to control block */
{
	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_ZIP_FREE:
		ut_error;
		return(NULL);
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
		return(&buf_pool_zip_mutex);
	default:
		return(&((buf_block_t*) bpage)->mutex);
	}
}

/*********************************************************************//**
Get the flush type of a page.
@return	flush type */
UNIV_INLINE
enum buf_flush
buf_page_get_flush_type(
/*====================*/
	const buf_page_t*	bpage)	/*!< in: buffer page */
{
	enum buf_flush	flush_type = (enum buf_flush) bpage->flush_type;

#ifdef UNIV_DEBUG
	switch (flush_type) {
	case BUF_FLUSH_LRU:
	case BUF_FLUSH_SINGLE_PAGE:
	case BUF_FLUSH_LIST:
		return(flush_type);
	case BUF_FLUSH_N_TYPES:
		break;
	}
	ut_error;
#endif /* UNIV_DEBUG */
	return(flush_type);
}
/*********************************************************************//**
Set the flush type of a page. */
UNIV_INLINE
void
buf_page_set_flush_type(
/*====================*/
	buf_page_t*	bpage,		/*!< in: buffer page */
	enum buf_flush	flush_type)	/*!< in: flush type */
{
	bpage->flush_type = flush_type;
	ut_ad(buf_page_get_flush_type(bpage) == flush_type);
}

/*********************************************************************//**
Map a block to a file page. */
UNIV_INLINE
void
buf_block_set_file_page(
/*====================*/
	buf_block_t*		block,	/*!< in/out: pointer to control block */
	ulint			space,	/*!< in: tablespace id */
	ulint			page_no)/*!< in: page number */
{
	buf_block_set_state(block, BUF_BLOCK_FILE_PAGE);
	block->page.space = space;
	block->page.offset = page_no;
}

/*********************************************************************//**
Gets the io_fix state of a block.
@return	io_fix state */
UNIV_INLINE
enum buf_io_fix
buf_page_get_io_fix(
/*================*/
	const buf_page_t*	bpage)	/*!< in: pointer to the control block */
{
	enum buf_io_fix	io_fix = (enum buf_io_fix) bpage->io_fix;
#ifdef UNIV_DEBUG
	switch (io_fix) {
	case BUF_IO_NONE:
	case BUF_IO_READ:
	case BUF_IO_WRITE:
		return(io_fix);
	}
	ut_error;
#endif /* UNIV_DEBUG */
	return(io_fix);
}

/*********************************************************************//**
Gets the io_fix state of a block.
@return	io_fix state */
UNIV_INLINE
enum buf_io_fix
buf_block_get_io_fix(
/*================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	return(buf_page_get_io_fix(&block->page));
}

/*********************************************************************//**
Sets the io_fix state of a block. */
UNIV_INLINE
void
buf_page_set_io_fix(
/*================*/
	buf_page_t*	bpage,	/*!< in/out: control block */
	enum buf_io_fix	io_fix)	/*!< in: io_fix state */
{
	ut_ad(buf_pool_mutex_own());
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));

	bpage->io_fix = io_fix;
	ut_ad(buf_page_get_io_fix(bpage) == io_fix);
}

/*********************************************************************//**
Sets the io_fix state of a block. */
UNIV_INLINE
void
buf_block_set_io_fix(
/*=================*/
	buf_block_t*	block,	/*!< in/out: control block */
	enum buf_io_fix	io_fix)	/*!< in: io_fix state */
{
	buf_page_set_io_fix(&block->page, io_fix);
}

/********************************************************************//**
Determine if a buffer block can be relocated in memory.  The block
can be dirty, but it must not be I/O-fixed or bufferfixed. */
UNIV_INLINE
ibool
buf_page_can_relocate(
/*==================*/
	const buf_page_t*	bpage)	/*!< control block being relocated */
{
	ut_ad(buf_pool_mutex_own());
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));
	ut_ad(buf_page_in_file(bpage));
	ut_ad(bpage->in_LRU_list);

	return(buf_page_get_io_fix(bpage) == BUF_IO_NONE
	       && bpage->buf_fix_count == 0);
}

/*********************************************************************//**
Determine if a block has been flagged old.
@return	TRUE if old */
UNIV_INLINE
ibool
buf_page_is_old(
/*============*/
	const buf_page_t*	bpage)	/*!< in: control block */
{
	ut_ad(buf_page_in_file(bpage));
	ut_ad(buf_pool_mutex_own());

	return(bpage->old);
}

/*********************************************************************//**
Flag a block old. */
UNIV_INLINE
void
buf_page_set_old(
/*=============*/
	buf_page_t*	bpage,	/*!< in/out: control block */
	ibool		old)	/*!< in: old */
{
	ut_a(buf_page_in_file(bpage));
	ut_ad(buf_pool_mutex_own());
	ut_ad(bpage->in_LRU_list);

#ifdef UNIV_LRU_DEBUG
	ut_a((buf_pool->LRU_old_len == 0) == (buf_pool->LRU_old == NULL));
	/* If a block is flagged "old", the LRU_old list must exist. */
	ut_a(!old || buf_pool->LRU_old);

	if (UT_LIST_GET_PREV(LRU, bpage) && UT_LIST_GET_NEXT(LRU, bpage)) {
		const buf_page_t*	prev = UT_LIST_GET_PREV(LRU, bpage);
		const buf_page_t*	next = UT_LIST_GET_NEXT(LRU, bpage);
		if (prev->old == next->old) {
			ut_a(prev->old == old);
		} else {
			ut_a(!prev->old);
			ut_a(buf_pool->LRU_old == (old ? bpage : next));
		}
	}
#endif /* UNIV_LRU_DEBUG */

	bpage->old = old;
}

/*********************************************************************//**
Determine the time of first access of a block in the buffer pool.
@return	ut_time_ms() at the time of first access, 0 if not accessed */
UNIV_INLINE
unsigned
buf_page_is_accessed(
/*=================*/
	const buf_page_t*	bpage)	/*!< in: control block */
{
	ut_ad(buf_page_in_file(bpage));

	return(bpage->access_time);
}

/*********************************************************************//**
Flag a block accessed. */
UNIV_INLINE
void
buf_page_set_accessed(
/*==================*/
	buf_page_t*	bpage,		/*!< in/out: control block */
	ulint		time_ms)	/*!< in: ut_time_ms() */
{
	ut_a(buf_page_in_file(bpage));
	ut_ad(buf_pool_mutex_own());

	if (!bpage->access_time) {
		/* Make this the time of the first access. */
		bpage->access_time = time_ms;
	}
}

/*********************************************************************//**
Gets the buf_block_t handle of a buffered file block if an uncompressed
page frame exists, or NULL.
@return	control block, or NULL */
UNIV_INLINE
buf_block_t*
buf_page_get_block(
/*===============*/
	buf_page_t*	bpage)	/*!< in: control block, or NULL */
{
	if (UNIV_LIKELY(bpage != NULL)) {
		ut_ad(buf_page_in_file(bpage));

		if (buf_page_get_state(bpage) == BUF_BLOCK_FILE_PAGE) {
			return((buf_block_t*) bpage);
		}
	}

	return(NULL);
}
#endif /* !UNIV_HOTBACKUP */

#ifdef UNIV_DEBUG
/*********************************************************************//**
Gets a pointer to the memory frame of a block.
@return	pointer to the frame */
UNIV_INLINE
buf_frame_t*
buf_block_get_frame(
/*================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	ut_ad(block);

	switch (buf_block_get_state(block)) {
	case BUF_BLOCK_ZIP_FREE:
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
	case BUF_BLOCK_NOT_USED:
		ut_error;
		break;
	case BUF_BLOCK_FILE_PAGE:
# ifndef UNIV_HOTBACKUP
		ut_a(block->page.buf_fix_count > 0);
# endif /* !UNIV_HOTBACKUP */
		/* fall through */
	case BUF_BLOCK_READY_FOR_USE:
	case BUF_BLOCK_MEMORY:
	case BUF_BLOCK_REMOVE_HASH:
		goto ok;
	}
	ut_error;
ok:
	return((buf_frame_t*) block->frame);
}
#endif /* UNIV_DEBUG */

/*********************************************************************//**
Gets the space id of a block.
@return	space id */
UNIV_INLINE
ulint
buf_page_get_space(
/*===============*/
	const buf_page_t*	bpage)	/*!< in: pointer to the control block */
{
	ut_ad(bpage);
	ut_a(buf_page_in_file(bpage));

	return(bpage->space);
}

/*********************************************************************//**
Gets the space id of a block.
@return	space id */
UNIV_INLINE
ulint
buf_block_get_space(
/*================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	ut_ad(block);
	ut_a(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);

	return(block->page.space);
}

/*********************************************************************//**
Gets the page number of a block.
@return	page number */
UNIV_INLINE
ulint
buf_page_get_page_no(
/*=================*/
	const buf_page_t*	bpage)	/*!< in: pointer to the control block */
{
	ut_ad(bpage);
	ut_a(buf_page_in_file(bpage));

	return(bpage->offset);
}

/*********************************************************************//**
Gets the page number of a block.
@return	page number */
UNIV_INLINE
ulint
buf_block_get_page_no(
/*==================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	ut_ad(block);
	ut_a(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);

	return(block->page.offset);
}

/*********************************************************************//**
Gets the compressed page size of a block.
@return	compressed page size, or 0 */
UNIV_INLINE
ulint
buf_page_get_zip_size(
/*==================*/
	const buf_page_t*	bpage)	/*!< in: pointer to the control block */
{
	return(bpage->zip.ssize ? 512 << bpage->zip.ssize : 0);
}

/*********************************************************************//**
Gets the compressed page size of a block.
@return	compressed page size, or 0 */
UNIV_INLINE
ulint
buf_block_get_zip_size(
/*===================*/
	const buf_block_t*	block)	/*!< in: pointer to the control block */
{
	return(block->page.zip.ssize ? 512 << block->page.zip.ssize : 0);
}

#ifndef UNIV_HOTBACKUP
#if defined UNIV_DEBUG || defined UNIV_ZIP_DEBUG
/*********************************************************************//**
Gets the compressed page descriptor corresponding to an uncompressed page
if applicable.
@return	compressed page descriptor, or NULL */
UNIV_INLINE
const page_zip_des_t*
buf_frame_get_page_zip(
/*===================*/
	const byte*	ptr)	/*!< in: pointer to the page */
{
	return(buf_block_get_page_zip(buf_block_align(ptr)));
}
#endif /* UNIV_DEBUG || UNIV_ZIP_DEBUG */
#endif /* !UNIV_HOTBACKUP */

/**********************************************************************//**
Gets the space id, page offset, and byte offset within page of a
pointer pointing to a buffer frame containing a file page. */
UNIV_INLINE
void
buf_ptr_get_fsp_addr(
/*=================*/
	const void*	ptr,	/*!< in: pointer to a buffer frame */
	ulint*		space,	/*!< out: space id */
	fil_addr_t*	addr)	/*!< out: page offset and byte offset */
{
	const page_t*	page = (const page_t*) ut_align_down(ptr,
							     UNIV_PAGE_SIZE);

	*space = mach_read_from_4(page + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID);
	addr->page = mach_read_from_4(page + FIL_PAGE_OFFSET);
	addr->boffset = ut_align_offset(ptr, UNIV_PAGE_SIZE);
}

#ifndef UNIV_HOTBACKUP
/**********************************************************************//**
Gets the hash value of the page the pointer is pointing to. This can be used
in searches in the lock hash table.
@return	lock hash value */
UNIV_INLINE
ulint
buf_block_get_lock_hash_val(
/*========================*/
	const buf_block_t*	block)	/*!< in: block */
{
	ut_ad(block);
	ut_ad(buf_page_in_file(&block->page));
#ifdef UNIV_SYNC_DEBUG
	ut_ad(rw_lock_own(&(((buf_block_t*) block)->lock), RW_LOCK_EXCLUSIVE)
	      || rw_lock_own(&(((buf_block_t*) block)->lock), RW_LOCK_SHARED));
#endif /* UNIV_SYNC_DEBUG */
	return(block->lock_hash_val);
}

/********************************************************************//**
Allocates a buffer block.
@return	own: the allocated block, in state BUF_BLOCK_MEMORY */
UNIV_INLINE
buf_block_t*
buf_block_alloc(
/*============*/
	ulint	zip_size)	/*!< in: compressed page size in bytes,
				or 0 if uncompressed tablespace */
{
	buf_block_t*	block;

	block = buf_LRU_get_free_block(zip_size);

	buf_block_set_state(block, BUF_BLOCK_MEMORY);

	return(block);
}

/********************************************************************//**
Frees a buffer block which does not contain a file page. */
UNIV_INLINE
void
buf_block_free(
/*===========*/
	buf_block_t*	block)	/*!< in, own: block to be freed */
{
	buf_pool_mutex_enter();

	mutex_enter(&block->mutex);

	ut_a(buf_block_get_state(block) != BUF_BLOCK_FILE_PAGE);

	buf_LRU_block_free_non_file_page(block);

	mutex_exit(&block->mutex);

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

/*********************************************************************//**
Copies contents of a buffer frame to a given buffer.
@return	buf */
UNIV_INLINE
byte*
buf_frame_copy(
/*===========*/
	byte*			buf,	/*!< in: buffer to copy to */
	const buf_frame_t*	frame)	/*!< in: buffer frame */
{
	ut_ad(buf && frame);

	ut_memcpy(buf, frame, UNIV_PAGE_SIZE);

	return(buf);
}

#ifndef UNIV_HOTBACKUP
/********************************************************************//**
Calculates a folded value of a file page address to use in the page hash
table.
@return	the folded value */
UNIV_INLINE
ulint
buf_page_address_fold(
/*==================*/
	ulint	space,	/*!< in: space id */
	ulint	offset)	/*!< in: offset of the page within space */
{
	return((space << 20) + space + offset);
}

/********************************************************************//**
Gets the youngest modification log sequence number for a frame.
Returns zero if not file page or no modification occurred yet.
@return	newest modification to page */
UNIV_INLINE
ib_uint64_t
buf_page_get_newest_modification(
/*=============================*/
	const buf_page_t*	bpage)	/*!< in: block containing the
					page frame */
{
	ib_uint64_t	lsn;
	mutex_t*	block_mutex = buf_page_get_mutex(bpage);

	mutex_enter(block_mutex);

	if (buf_page_in_file(bpage)) {
		lsn = bpage->newest_modification;
	} else {
		lsn = 0;
	}

	mutex_exit(block_mutex);

	return(lsn);
}

/********************************************************************//**
Increments the modify clock of a frame by 1. The caller must (1) own the
buf_pool mutex and block bufferfix count has to be zero, (2) or own an x-lock
on the block. */
UNIV_INLINE
void
buf_block_modify_clock_inc(
/*=======================*/
	buf_block_t*	block)	/*!< in: block */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad((buf_pool_mutex_own()
	       && (block->page.buf_fix_count == 0))
	      || rw_lock_own(&(block->lock), RW_LOCK_EXCLUSIVE));
#endif /* UNIV_SYNC_DEBUG */

	block->modify_clock++;
}

/********************************************************************//**
Returns the value of the modify clock. The caller must have an s-lock
or x-lock on the block.
@return	value */
UNIV_INLINE
ib_uint64_t
buf_block_get_modify_clock(
/*=======================*/
	buf_block_t*	block)	/*!< in: block */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(rw_lock_own(&(block->lock), RW_LOCK_SHARED)
	      || rw_lock_own(&(block->lock), RW_LOCK_EXCLUSIVE));
#endif /* UNIV_SYNC_DEBUG */

	return(block->modify_clock);
}

/*******************************************************************//**
Increments the bufferfix count. */
UNIV_INLINE
void
buf_block_buf_fix_inc_func(
/*=======================*/
#ifdef UNIV_SYNC_DEBUG
	const char*	file,	/*!< in: file name */
	ulint		line,	/*!< in: line */
#endif /* UNIV_SYNC_DEBUG */
	buf_block_t*	block)	/*!< in/out: block to bufferfix */
{
#ifdef UNIV_SYNC_DEBUG
	ibool	ret;

	ret = rw_lock_s_lock_nowait(&(block->debug_latch), file, line);
	ut_a(ret);
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(mutex_own(&block->mutex));

	block->page.buf_fix_count++;
}
#ifdef UNIV_SYNC_DEBUG
/** Increments the bufferfix count.
@param b	in/out: block to bufferfix
@param f	in: file name where requested
@param l	in: line number where requested */
# define buf_block_buf_fix_inc(b,f,l) buf_block_buf_fix_inc_func(f,l,b)
#else /* UNIV_SYNC_DEBUG */
/** Increments the bufferfix count.
@param b	in/out: block to bufferfix
@param f	in: file name where requested
@param l	in: line number where requested */
# define buf_block_buf_fix_inc(b,f,l) buf_block_buf_fix_inc_func(b)
#endif /* UNIV_SYNC_DEBUG */

/*******************************************************************//**
Decrements the bufferfix count. */
UNIV_INLINE
void
buf_block_buf_fix_dec(
/*==================*/
	buf_block_t*	block)	/*!< in/out: block to bufferunfix */
{
	ut_ad(mutex_own(&block->mutex));

	block->page.buf_fix_count--;
#ifdef UNIV_SYNC_DEBUG
	rw_lock_s_unlock(&block->debug_latch);
#endif
}

/******************************************************************//**
Returns the control block of a file page, NULL if not found.
@return	block, NULL if not found */
UNIV_INLINE
buf_page_t*
buf_page_hash_get_low(
/*==================*/
	ulint	space,	/*!< in: space id */
	ulint	offset,	/*!< in: offset of the page within space */
	ulint	fold)	/*!< in: buf_page_address_fold(space, offset) */
{
	buf_page_t*	bpage;

	ut_ad(buf_pool);
	ut_ad(buf_pool_mutex_own());
	ut_ad(fold == buf_page_address_fold(space, offset));

	/* Look for the page in the hash table */

	HASH_SEARCH(hash, buf_pool->page_hash, fold, buf_page_t*, bpage,
		    ut_ad(bpage->in_page_hash && !bpage->in_zip_hash
			  && buf_page_in_file(bpage)),
		    bpage->space == space && bpage->offset == offset);
	if (bpage) {
		ut_a(buf_page_in_file(bpage));
		ut_ad(bpage->in_page_hash);
		ut_ad(!bpage->in_zip_hash);
		UNIV_MEM_ASSERT_RW(bpage, sizeof *bpage);
	}

	return(bpage);
}

/******************************************************************//**
Returns the control block of a file page, NULL if not found.
@return	block, NULL if not found or not a real control block */
UNIV_INLINE
buf_page_t*
buf_page_hash_get(
/*==============*/
	ulint	space,	/*!< in: space id */
	ulint	offset)	/*!< in: offset of the page within space */
{
	ulint		fold	= buf_page_address_fold(space, offset);
	buf_page_t*	bpage	= buf_page_hash_get_low(space, offset, fold);

	if (bpage && UNIV_UNLIKELY(buf_pool_watch_is(bpage))) {
		bpage = NULL;
	}

	return(bpage);
}

/******************************************************************//**
Returns the control block of a file page, NULL if not found
or an uncompressed page frame does not exist.
@return	block, NULL if not found */
UNIV_INLINE
buf_block_t*
buf_block_hash_get(
/*===============*/
	ulint	space,	/*!< in: space id */
	ulint	offset)	/*!< in: offset of the page within space */
{
	buf_block_t*	block;

	block = buf_page_get_block(buf_page_hash_get(space, offset));

	return(block);
}

/********************************************************************//**
Returns TRUE if the page can be found in the buffer pool hash table.

NOTE that it is possible that the page is not yet read from disk,
though.

@return	TRUE if found in the page hash table */
UNIV_INLINE
ibool
buf_page_peek(
/*==========*/
	ulint	space,	/*!< in: space id */
	ulint	offset)	/*!< in: page number */
{
	const buf_page_t*	bpage;

	buf_pool_mutex_enter();

	bpage = buf_page_hash_get(space, offset);

	buf_pool_mutex_exit();

	return(bpage != NULL);
}

/********************************************************************//**
Releases a compressed-only page acquired with buf_page_get_zip(). */
UNIV_INLINE
void
buf_page_release_zip(
/*=================*/
	buf_page_t*	bpage)		/*!< in: buffer block */
{
	buf_block_t*	block;

	ut_ad(bpage);
	ut_a(bpage->buf_fix_count > 0);

	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
		mutex_enter(&buf_pool_zip_mutex);
		bpage->buf_fix_count--;
		mutex_exit(&buf_pool_zip_mutex);
		return;
	case BUF_BLOCK_FILE_PAGE:
		block = (buf_block_t*) bpage;
		mutex_enter(&block->mutex);
#ifdef UNIV_SYNC_DEBUG
		rw_lock_s_unlock(&block->debug_latch);
#endif
		bpage->buf_fix_count--;
		mutex_exit(&block->mutex);
		return;
	case BUF_BLOCK_ZIP_FREE:
	case BUF_BLOCK_NOT_USED:
	case BUF_BLOCK_READY_FOR_USE:
	case BUF_BLOCK_MEMORY:
	case BUF_BLOCK_REMOVE_HASH:
		break;
	}

	ut_error;
}

/********************************************************************//**
Decrements the bufferfix count of a buffer control block and releases
a latch, if specified. */
UNIV_INLINE
void
buf_page_release(
/*=============*/
	buf_block_t*	block,		/*!< in: buffer block */
	ulint		rw_latch)	/*!< in: RW_S_LATCH, RW_X_LATCH,
					RW_NO_LATCH */
{
	ut_ad(block);

	ut_a(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
	ut_a(block->page.buf_fix_count > 0);

	mutex_enter(&block->mutex);

#ifdef UNIV_SYNC_DEBUG
	rw_lock_s_unlock(&(block->debug_latch));
#endif
	block->page.buf_fix_count--;

	mutex_exit(&block->mutex);

	if (rw_latch == RW_S_LATCH) {
		rw_lock_s_unlock(&(block->lock));
	} else if (rw_latch == RW_X_LATCH) {
		rw_lock_x_unlock(&(block->lock));
	}
}

#ifdef UNIV_SYNC_DEBUG
/*********************************************************************//**
Adds latch level info for the rw-lock protecting the buffer frame. This
should be called in the debug version after a successful latching of a
page if we know the latching order level of the acquired latch. */
UNIV_INLINE
void
buf_block_dbg_add_level(
/*====================*/
	buf_block_t*	block,	/*!< in: buffer page
				where we have acquired latch */
	ulint		level)	/*!< in: latching order level */
{
	sync_thread_add_level(&block->lock, level);
}
#endif /* UNIV_SYNC_DEBUG */
#endif /* !UNIV_HOTBACKUP */