mariadb/storage/innobase/include/buf0buf.ic

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

Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2008, Google Inc.
Copyright (c) 2014, 2020, MariaDB Corporation.

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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA

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

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

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

#include "mtr0mtr.h"
#include "buf0flu.h"
#include "buf0lru.h"
#include "buf0rea.h"
#include "fsp0types.h"

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

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

/** Determine if a block is still close enough to the MRU end of the LRU list
meaning that it is not in danger of getting evicted and also implying
that it has been accessed recently.
The page must be either buffer-fixed, or its page hash must be locked.
@param[in]	bpage		buffer pool page
@return whether bpage is close to MRU end of LRU */
inline bool buf_page_peek_if_young(const buf_page_t *bpage)
{
	/* FIXME: bpage->freed_page_clock is 31 bits */
	return((buf_pool.freed_page_clock & ((1UL << 31) - 1))
	       < (bpage->freed_page_clock
		  + (buf_pool.curr_size
		     * (BUF_LRU_OLD_RATIO_DIV - buf_pool.LRU_old_ratio)
		     / (BUF_LRU_OLD_RATIO_DIV * 4))));
}

/** Determine if a block should be moved to the start of the LRU list if
there is danger of dropping from the buffer pool.
@param[in]	bpage		buffer pool page
@return true if bpage should be made younger */
inline bool buf_page_peek_if_too_old(const buf_page_t *bpage)
{
	if (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);

		/* It is possible that the below comparison returns an
		unexpected result. 2^32 milliseconds pass in about 50 days,
		so if the difference between ut_time_ms() and access_time
		is e.g. 50 days + 15 ms, then the below will behave as if
		it is 15 ms. This is known and fixing it would require to
		increase buf_page_t::access_time from 32 to 64 bits. */
		if (access_time > 0
		    && ((ib_uint32_t) (ut_time_ms() - access_time))
		    >= buf_LRU_old_threshold_ms) {
			return(TRUE);
		}

		buf_pool.stat.n_pages_not_made_young++;
		return false;
	} else {
		return !buf_page_peek_if_young(bpage);
	}
}

/*********************************************************************//**
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	= bpage->state;

#ifdef UNIV_DEBUG
	switch (state) {
	case BUF_BLOCK_POOL_WATCH:
	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_POOL_WATCH:
		ut_error;
		break;
	case BUF_BLOCK_ZIP_PAGE:
		ut_ad(state == BUF_BLOCK_ZIP_DIRTY);
		break;
	case BUF_BLOCK_ZIP_DIRTY:
		ut_ad(state == BUF_BLOCK_ZIP_PAGE);
		break;
	case BUF_BLOCK_NOT_USED:
		ut_ad(state == BUF_BLOCK_READY_FOR_USE);
		break;
	case BUF_BLOCK_READY_FOR_USE:
		ut_ad(state == BUF_BLOCK_MEMORY
		      || state == BUF_BLOCK_FILE_PAGE
		      || state == BUF_BLOCK_NOT_USED);
		break;
	case BUF_BLOCK_MEMORY:
		ut_ad(state == BUF_BLOCK_NOT_USED);
		break;
	case BUF_BLOCK_FILE_PAGE:
		ut_ad(state == BUF_BLOCK_NOT_USED
	              || state == BUF_BLOCK_REMOVE_HASH
		      || state == BUF_BLOCK_FILE_PAGE);
		if (state == BUF_BLOCK_REMOVE_HASH) {
			ut_ad(!bpage->in_page_hash);
			ut_ad(!bpage->in_zip_hash);
			ut_ad(!bpage->in_LRU_list);
			ut_ad(!bpage->in_free_list);
		}
		break;
	case BUF_BLOCK_REMOVE_HASH:
		ut_ad(state == BUF_BLOCK_MEMORY);
		break;
	}
#endif /* UNIV_DEBUG */
	bpage->state = 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_POOL_WATCH:
		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);
}

/*********************************************************************//**
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
BPageMutex*
buf_page_get_mutex(
/*===============*/
	const buf_page_t*	bpage)	/*!< in: pointer to control block */
{
	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_POOL_WATCH:
		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
buf_flush_t
buf_page_get_flush_type(
/*====================*/
	const buf_page_t*	bpage)	/*!< in: buffer page */
{
	buf_flush_t	flush_type = (buf_flush_t) bpage->flush_type;

#ifdef UNIV_DEBUG
	switch (flush_type) {
	case BUF_FLUSH_LRU:
	case BUF_FLUSH_LIST:
	case BUF_FLUSH_SINGLE_PAGE:
		return(flush_type);
	case BUF_FLUSH_N_TYPES:
		ut_error;
	}
	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 */
	buf_flush_t	flush_type)	/*!< in: flush type */
{
	bpage->flush_type = flush_type & 3;
	ut_ad(buf_page_get_flush_type(bpage) == flush_type);
}

/** Map a block to a file page.
@param[in,out]	block	pointer to control block
@param[in]	page_id	page id */
UNIV_INLINE
void
buf_block_set_file_page(
	buf_block_t*		block,
	const page_id_t		page_id)
{
	buf_block_set_state(block, BUF_BLOCK_FILE_PAGE);
	block->page.id = page_id;
}

/*********************************************************************//**
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 */
{
	ut_ad(bpage != NULL);

	enum buf_io_fix	io_fix	= bpage->io_fix;

#ifdef UNIV_DEBUG
	switch (io_fix) {
	case BUF_IO_NONE:
	case BUF_IO_READ:
	case BUF_IO_WRITE:
	case BUF_IO_PIN:
		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(mutex_own(&buf_pool.mutex));
	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);
}

/*********************************************************************//**
Makes a block sticky. A sticky block implies that even after we release
the buf_pool.mutex and the block->mutex:
* it cannot be removed from the flush_list
* the block descriptor cannot be relocated
* it cannot be removed from the LRU list
Note that:
* the block can still change its position in the LRU list
* the next and previous pointers can change. */
UNIV_INLINE
void
buf_page_set_sticky(
/*================*/
	buf_page_t*	bpage)	/*!< in/out: control block */
{
	ut_ad(mutex_own(&buf_pool.mutex));
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));
	ut_ad(buf_page_get_io_fix(bpage) == BUF_IO_NONE);

	bpage->io_fix = BUF_IO_PIN;
}

/*********************************************************************//**
Removes stickiness of a block. */
UNIV_INLINE
void
buf_page_unset_sticky(
/*==================*/
	buf_page_t*	bpage)	/*!< in/out: control block */
{
	ut_ad(mutex_own(&buf_pool.mutex));
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));
	ut_ad(buf_page_get_io_fix(bpage) == BUF_IO_PIN);

	bpage->io_fix = BUF_IO_NONE;
}

/********************************************************************//**
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(mutex_own(&buf_pool.mutex));
	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 */
{
	/* Buffer page mutex is not strictly required here for heuristic
	purposes even if LRU mutex is not being held. Keep the assertion
	for not since all the callers hold it. */
	ut_ad(mutex_own(buf_page_get_mutex(bpage))
	      || mutex_own(&buf_pool.mutex));
	ut_ad(buf_page_in_file(bpage));

	return(bpage->old);
}

/*********************************************************************//**
Flag a block old. */
UNIV_INLINE
void
buf_page_set_old(
/*=============*/
	buf_page_t*	bpage,	/*!< in/out: control block */
	bool		old)	/*!< in: old */
{
	ut_a(buf_page_in_file(bpage));
	ut_ad(mutex_own(&buf_pool.mutex));
	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 */
{
	ut_ad(!mutex_own(&buf_pool.mutex));
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));
	ut_a(buf_page_in_file(bpage));

	if (bpage->access_time == 0) {
		/* Make this the time of the first access. */
		bpage->access_time = static_cast<uint>(ut_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 (bpage != NULL) {
		ut_ad(buf_page_hash_lock_held_s_or_x(bpage)
		      || mutex_own(&buf_pool.mutex));
		ut_ad(buf_page_in_file(bpage));

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

	return(NULL);
}

#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 */
{
	if (!block) {
		return NULL;
	}

	switch (buf_block_get_state(block)) {
	case BUF_BLOCK_POOL_WATCH:
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
	case BUF_BLOCK_NOT_USED:
		ut_error;
		break;
	case BUF_BLOCK_FILE_PAGE:
		ut_a(block->page.buf_fix_count > 0);
		/* 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 */

/***********************************************************************
FIXME_FTS Gets the frame the pointer is pointing to. */
UNIV_INLINE
buf_frame_t*
buf_frame_align(
/*============*/
                        /* out: pointer to frame */
        byte*   ptr)    /* in: pointer to a frame */
{
        buf_frame_t*    frame;

        ut_ad(ptr);

        frame = (buf_frame_t*) ut_align_down(ptr, srv_page_size);

        return(frame);
}

/**********************************************************************//**
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
unsigned
buf_block_get_lock_hash_val(
/*========================*/
	const buf_block_t*	block)	/*!< in: block */
{
	ut_ad(block);
	ut_ad(buf_page_in_file(&block->page));
	ut_ad(rw_lock_own(&(((buf_block_t*) block)->lock), RW_LOCK_X)
	      || rw_lock_own(&(((buf_block_t*) block)->lock), RW_LOCK_S));

	return(block->lock_hash_val);
}

/********************************************************************//**
Allocates a buf_page_t descriptor. This function must succeed. In case
of failure we assert in this function.
@return: the allocated descriptor. */
UNIV_INLINE
buf_page_t*
buf_page_alloc_descriptor(void)
/*===========================*/
{
	buf_page_t*	bpage;

	bpage = (buf_page_t*) ut_zalloc_nokey(sizeof *bpage);
	ut_ad(bpage);
	UNIV_MEM_ALLOC(bpage, sizeof *bpage);

	return(bpage);
}

/********************************************************************//**
Free a buf_page_t descriptor. */
UNIV_INLINE
void
buf_page_free_descriptor(
/*=====================*/
	buf_page_t*	bpage)	/*!< in: bpage descriptor to free. */
{
	ut_free(bpage);
}

/********************************************************************//**
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 */
{
	mutex_enter(&buf_pool.mutex);

	buf_page_mutex_enter(block);

	ut_a(buf_block_get_state(block) != BUF_BLOCK_FILE_PAGE);

	buf_LRU_block_free_non_file_page(block);

	buf_page_mutex_exit(block);

	mutex_exit(&buf_pool.mutex);
}

/********************************************************************//**
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 */
{
	/* No latch is acquired for the shared temporary tablespace. */
	ut_ad(fsp_is_system_temporary(block->page.id.space())
	      || (mutex_own(&buf_pool.mutex)
		  && block->page.buf_fix_count == 0)
	      || rw_lock_own_flagged(&block->lock,
				     RW_LOCK_FLAG_X | RW_LOCK_FLAG_SX));
	assert_block_ahi_valid(block);

	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_DEBUG
	/* No latch is acquired for the shared temporary tablespace. */
	if (!fsp_is_system_temporary(block->page.id.space())) {
		ut_ad(rw_lock_own(&(block->lock), RW_LOCK_S)
		      || rw_lock_own(&(block->lock), RW_LOCK_X)
		      || rw_lock_own(&(block->lock), RW_LOCK_SX));
	}
#endif /* UNIV_DEBUG */

	return(block->modify_clock);
}

/*******************************************************************//**
Increments the bufferfix count. */
UNIV_INLINE
void
buf_block_buf_fix_inc_func(
/*=======================*/
#ifdef UNIV_DEBUG
	const char*	file,	/*!< in: file name */
	unsigned	line,	/*!< in: line */
#endif /* UNIV_DEBUG */
	buf_block_t*	block)	/*!< in/out: block to bufferfix */
{
#ifdef UNIV_DEBUG
	/* No debug latch is acquired if block belongs to system temporary.
	Debug latch is not of much help if access to block is single
	threaded. */
	if (!fsp_is_system_temporary(block->page.id.space())) {
		ibool   ret;
		ret = rw_lock_s_lock_nowait(block->debug_latch, file, line);
		ut_a(ret);
	}
#endif /* UNIV_DEBUG */

	block->fix();
}

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

#ifdef UNIV_DEBUG
	/* No debug latch is acquired if block belongs to system temporary.
	Debug latch is not of much help if access to block is single
	threaded. */
	if (!fsp_is_system_temporary(block->page.id.space())) {
		rw_lock_s_unlock(block->debug_latch);
	}
#endif /* UNIV_DEBUG */
}

/** Returns the control block of a file page, NULL if not found.
@param[in]	page_id		page id
@return block, NULL if not found */
inline buf_page_t *buf_page_hash_get_low(page_id_t page_id)
{
	buf_page_t*	bpage;

#ifdef UNIV_DEBUG
	rw_lock_t*	hash_lock;

	hash_lock = hash_get_lock(buf_pool.page_hash, page_id.fold());
	ut_ad(rw_lock_own(hash_lock, RW_LOCK_X)
	      || rw_lock_own(hash_lock, RW_LOCK_S));
#endif /* UNIV_DEBUG */

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

	HASH_SEARCH(hash, buf_pool.page_hash, page_id.fold(), buf_page_t*,
		    bpage,
		    ut_ad(bpage->in_page_hash && !bpage->in_zip_hash
			  && buf_page_in_file(bpage)),
		    page_id == bpage->id);
	if (bpage) {
		ut_a(buf_page_in_file(bpage));
		ut_ad(bpage->in_page_hash);
		ut_ad(!bpage->in_zip_hash);
	}

	return(bpage);
}

/** Returns the control block of a file page, NULL if not found.
If the block is found and lock is not NULL then the appropriate
page_hash lock is acquired in the specified lock mode. Otherwise,
mode value is ignored. It is up to the caller to release the
lock. If the block is found and the lock is NULL then the page_hash
lock is released by this function.
@param[in]	page_id		page id
@param[in,out]	lock		lock of the page hash acquired if bpage is
found, NULL otherwise. If NULL is passed then the hash_lock is released by
this function.
@param[in]	lock_mode	RW_LOCK_X or RW_LOCK_S. Ignored if
lock == NULL
@param[in]	watch		if true, return watch sentinel also.
@return pointer to the bpage or NULL; if NULL, lock is also NULL or
a watch sentinel. */
UNIV_INLINE
buf_page_t*
buf_page_hash_get_locked(
	const page_id_t		page_id,
	rw_lock_t**		lock,
	ulint			lock_mode,
	bool			watch)
{
	buf_page_t*	bpage = NULL;
	rw_lock_t*	hash_lock;
	ulint		mode = RW_LOCK_S;

	if (lock != NULL) {
		*lock = NULL;
		ut_ad(lock_mode == RW_LOCK_X
		      || lock_mode == RW_LOCK_S);
		mode = lock_mode;
	}

	hash_lock = hash_get_lock(buf_pool.page_hash, page_id.fold());

	ut_ad(!rw_lock_own(hash_lock, RW_LOCK_X)
	      && !rw_lock_own(hash_lock, RW_LOCK_S));

	if (mode == RW_LOCK_S) {
		rw_lock_s_lock(hash_lock);

		/* If not own buf_pool_mutex, page_hash can be changed. */
		hash_lock = hash_lock_s_confirm(
			hash_lock, buf_pool.page_hash, page_id.fold());
	} else {
		rw_lock_x_lock(hash_lock);
		/* If not own buf_pool_mutex, page_hash can be changed. */
		hash_lock = hash_lock_x_confirm(
			hash_lock, buf_pool.page_hash, page_id.fold());
	}

	bpage = buf_page_hash_get_low(page_id);

	if (!bpage || buf_pool_watch_is_sentinel(bpage)) {
		if (!watch) {
			bpage = NULL;
		}
		goto unlock_and_exit;
	}

	ut_ad(buf_page_in_file(bpage));
	ut_ad(page_id == bpage->id);

	if (lock == NULL) {
		/* The caller wants us to release the page_hash lock */
		goto unlock_and_exit;
	} else {
		/* To be released by the caller */
		*lock = hash_lock;
		goto exit;
	}

unlock_and_exit:
	if (mode == RW_LOCK_S) {
		rw_lock_s_unlock(hash_lock);
	} else {
		rw_lock_x_unlock(hash_lock);
	}
exit:
	return(bpage);
}

/** Returns the control block of a file page, NULL if not found.
If the block is found and lock is not NULL then the appropriate
page_hash lock is acquired in the specified lock mode. Otherwise,
mode value is ignored. It is up to the caller to release the
lock. If the block is found and the lock is NULL then the page_hash
lock is released by this function.
@param[in]	page_id		page id
@param[in,out]	lock		lock of the page hash acquired if bpage is
found, NULL otherwise. If NULL is passed then the hash_lock is released by
this function.
@param[in]	lock_mode	RW_LOCK_X or RW_LOCK_S. Ignored if
lock == NULL
@return pointer to the block or NULL; if NULL, lock is also NULL. */
UNIV_INLINE
buf_block_t*
buf_block_hash_get_locked(
	const page_id_t		page_id,
	rw_lock_t**		lock,
	ulint			lock_mode)
{
	buf_page_t*	bpage = buf_page_hash_get_locked(page_id, lock,
							 lock_mode);
	buf_block_t*	block = buf_page_get_block(bpage);

	if (block != NULL) {

		ut_ad(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
		ut_ad(!lock || rw_lock_own(*lock, lock_mode));

		return(block);
	} else if (bpage) {
		/* It is not a block. Just a bpage */
		ut_ad(buf_page_in_file(bpage));

		if (lock) {
			if (lock_mode == RW_LOCK_S) {
				rw_lock_s_unlock(*lock);
			} else {
				rw_lock_x_unlock(*lock);
			}
		}
		*lock = NULL;
		return(NULL);
	}

	ut_ad(!bpage);
	ut_ad(lock == NULL ||*lock == NULL);
	return(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 */
{
	ut_ad(bpage);
	ut_a(bpage->buf_fix_count > 0);

	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_FILE_PAGE:
#ifdef UNIV_DEBUG
	{
		/* No debug latch is acquired if block belongs to system
		temporary. Debug latch is not of much help if access to block
		is single threaded. */
		buf_block_t*	block = reinterpret_cast<buf_block_t*>(bpage);
		if (!fsp_is_system_temporary(block->page.id.space())) {
			rw_lock_s_unlock(block->debug_latch);
		}
	}
#endif /* UNIV_DEBUG */
		/* Fall through */
	case BUF_BLOCK_ZIP_PAGE:
	case BUF_BLOCK_ZIP_DIRTY:
		reinterpret_cast<buf_block_t*>(bpage)->unfix();
		return;

	case BUF_BLOCK_POOL_WATCH:
	case BUF_BLOCK_NOT_USED:
	case BUF_BLOCK_READY_FOR_USE:
	case BUF_BLOCK_MEMORY:
	case BUF_BLOCK_REMOVE_HASH:
		break;
	}

	ut_error;
}

/********************************************************************//**
Releases a latch, if specified. */
UNIV_INLINE
void
buf_page_release_latch(
/*===================*/
	buf_block_t*	block,		/*!< in: buffer block */
	ulint		rw_latch)	/*!< in: RW_S_LATCH, RW_X_LATCH,
					RW_NO_LATCH */
{
#ifdef UNIV_DEBUG
	/* No debug latch is acquired if block belongs to system
	temporary. Debug latch is not of much help if access to block
	is single threaded. */
	if (!fsp_is_system_temporary(block->page.id.space())) {
		rw_lock_s_unlock(block->debug_latch);
	}
#endif /* UNIV_DEBUG */

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

#ifdef UNIV_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 */
	latch_level_t	level)	/*!< in: latching order level */
{
	sync_check_lock(&block->lock, level);
}
#endif /* UNIV_DEBUG */

/********************************************************************//**
Get buf frame. */
UNIV_INLINE
void *
buf_page_get_frame(
/*===============*/
	const buf_page_t*	bpage) /*!< in: buffer pool page */
{
	/* In encryption/compression buffer pool page may contain extra
	buffer where result is stored. */
	if (bpage->slot && bpage->slot->out_buf) {
		return bpage->slot->out_buf;
	} else if (bpage->zip.data) {
		return bpage->zip.data;
	} else {
		return ((buf_block_t*) bpage)->frame;
	}
}

/** Calculate aligned buffer pool size based on srv_buf_pool_chunk_unit,
if needed.
@param[in]	size	size in bytes
@return	aligned size */
UNIV_INLINE
ulint
buf_pool_size_align(
	ulint	size)
{
	const ulong	m = srv_buf_pool_chunk_unit;
	size = ut_max(size, srv_buf_pool_min_size);

	if (size % m == 0) {
		return(size);
	} else {
		return (ulint)((size / m + 1) * m);
	}
}