/******************************************************
The database buffer buf_pool

(c) 1995 Innobase Oy

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

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

/************************************************************************
Reads the freed_page_clock of a buffer block. */
UNIV_INLINE
ulint
buf_page_get_freed_page_clock(
/*==========================*/
					/* out: freed_page_clock */
	const buf_page_t*	bpage)	/* in: block */
{
	return(bpage->freed_page_clock);
}

/************************************************************************
Reads the freed_page_clock of a buffer block. */
UNIV_INLINE
ulint
buf_block_get_freed_page_clock(
/*===========================*/
					/* out: 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. */
UNIV_INLINE
ibool
buf_page_peek_if_too_old(
/*=====================*/
					/* out: TRUE if should be made
					younger */
	const buf_page_t*	bpage)	/* in: block to make younger */
{
	return(buf_pool->freed_page_clock
	       >= buf_page_get_freed_page_clock(bpage)
	       + 1 + (buf_pool->curr_size / 4));
}

/*************************************************************************
Gets the current size of buffer buf_pool in bytes. */
UNIV_INLINE
ulint
buf_pool_get_curr_size(void)
/*========================*/
			/* out: size in bytes */
{
	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. */
UNIV_INLINE
ib_uint64_t
buf_pool_get_oldest_modification(void)
/*==================================*/
				/* out: oldest modification in pool,
				zero if none */
{
	buf_page_t*	bpage;
	ib_uint64_t	lsn;

	mutex_enter(&(buf_pool->mutex));

	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;
	}

	mutex_exit(&(buf_pool->mutex));

	return(lsn);
}

/***********************************************************************
Increments the buf_pool clock by one and returns its new value. Remember
that in the 32 bit version the clock wraps around at 4 billion! */
UNIV_INLINE
ulint
buf_pool_clock_tic(void)
/*====================*/
			/* out: new clock value */
{
	ut_ad(mutex_own(&(buf_pool->mutex)));

	buf_pool->ulint_clock++;

	return(buf_pool->ulint_clock);
}

/*************************************************************************
Gets the state of a block. */
UNIV_INLINE
enum buf_page_state
buf_page_get_state(
/*===============*/
					/* out: 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. */
UNIV_INLINE
enum buf_page_state
buf_block_get_state(
/*================*/
					/* out: 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. */
UNIV_INLINE
ibool
buf_page_in_file(
/*=============*/
					/* out: TRUE if mapped */
	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);
}

/*************************************************************************
Determine the approximate LRU list position of a block. */
UNIV_INLINE
ulint
buf_page_get_LRU_position(
/*======================*/
					/* out: LRU list position */
	const buf_page_t*	bpage)	/* in: control block */
{
	ut_ad(buf_page_in_file(bpage));

	return(bpage->LRU_position);
}

/*************************************************************************
Gets the mutex of a block. */
UNIV_INLINE
mutex_t*
buf_page_get_mutex(
/*===============*/
				/* out: pointer to mutex protecting bpage */
	buf_page_t*	bpage)	/* in: pointer to control block */
{
	switch (buf_page_get_state(bpage)) {
	case BUF_BLOCK_ZIP_FREE:
		ut_error;
		break;
	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. */
UNIV_INLINE
enum buf_flush
buf_page_get_flush_type(
/*====================*/
					/* out: 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. */
UNIV_INLINE
enum buf_io_fix
buf_page_get_io_fix(
/*================*/
					/* out: io_fix state */
	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. */
UNIV_INLINE
enum buf_io_fix
buf_block_get_io_fix(
/*================*/
					/* out: io_fix state */
	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);
}

/************************************************************************
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((buf_page_t*) 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. */
UNIV_INLINE
ibool
buf_page_is_old(
/*============*/
					/* out: TRUE if old */
	const buf_page_t*	bpage)	/* in: control block */
{
	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 */
	ibool		old)	/* in: old */
{
	ut_a(buf_page_in_file(bpage));
	ut_ad(mutex_own(&buf_pool->mutex));

	bpage->old = old;
}

/*************************************************************************
Determine if a block has been accessed in the buffer pool. */
UNIV_INLINE
ibool
buf_page_is_accessed(
/*=================*/
					/* out: TRUE if accessed */
	const buf_page_t*	bpage)	/* in: control block */
{
	ut_ad(buf_page_in_file(bpage));

	return(bpage->accessed);
}

/*************************************************************************
Flag a block accessed. */
UNIV_INLINE
void
buf_page_set_accessed(
/*==================*/
	buf_page_t*	bpage,		/* in/out: control block */
	ibool		accessed)	/* in: accessed */
{
	ut_a(buf_page_in_file(bpage));
	ut_ad(mutex_own(buf_page_get_mutex(bpage)));

	bpage->accessed = accessed;
}

/*************************************************************************
Gets the buf_block_t handle of a buffered file block if an uncompressed
page frame exists, or NULL. */
UNIV_INLINE
const buf_block_t*
buf_page_get_block(
/*===============*/
					/* out: control block, or NULL */
	const buf_page_t*	bpage)	/* in: control block */
{
	ut_ad(buf_page_in_file(bpage));
	ut_ad(mutex_own(buf_page_get_mutex((buf_page_t*) bpage)));

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

	return(NULL);
}

#ifdef UNIV_DEBUG
/*************************************************************************
Gets a pointer to the memory frame of a block. */
UNIV_INLINE
buf_frame_t*
buf_block_get_frame(
/*================*/
					/* out: pointer to the 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:
		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 */

/*************************************************************************
Gets the space id of a block. */
UNIV_INLINE
ulint
buf_page_get_space(
/*===============*/
					/* out: space id */
	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. */
UNIV_INLINE
ulint
buf_block_get_space(
/*================*/
					/* out: space id */
	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. */
UNIV_INLINE
ulint
buf_page_get_page_no(
/*=================*/
					/* out: page number */
	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. */
UNIV_INLINE
ulint
buf_block_get_page_no(
/*==================*/
					/* out: page number */
	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. */
UNIV_INLINE
ulint
buf_page_get_zip_size(
/*==================*/
					/* out: compressed page size, or 0 */
	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. */
UNIV_INLINE
ulint
buf_block_get_zip_size(
/*===================*/
					/* out: compressed page size, or 0 */
	const buf_block_t*	block)	/* in: pointer to the control block */
{
	return(block->page.zip.ssize ? 512 << block->page.zip.ssize : 0);
}

/*************************************************************************
Gets the compressed page descriptor corresponding to an uncompressed page
if applicable. */
UNIV_INLINE
page_zip_des_t*
buf_block_get_page_zip(
/*===================*/
				/* out: compressed page descriptor, or NULL */
	buf_block_t*	block)	/* in: pointer to the control block */
{
	if (UNIV_LIKELY_NULL(block->page.zip.data)) {
		return(&block->page.zip);
	}

	return(NULL);
}

#if defined UNIV_DEBUG || defined UNIV_ZIP_DEBUG
/***********************************************************************
Gets the block to whose frame the pointer is pointing to. */
UNIV_INLINE
buf_block_t*
buf_block_align(
/*============*/
			/* out: pointer to block */
	byte*	ptr)	/* in: pointer to a frame */
{
	buf_block_t*	block;
	ulint		space_id, page_no;

	ptr = ut_align_down(ptr, UNIV_PAGE_SIZE);
	page_no = mach_read_from_4(ptr + FIL_PAGE_OFFSET);
	space_id = mach_read_from_4(ptr + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID);

	block = (buf_block_t*) buf_page_hash_get(space_id, page_no);
	ut_ad(block);
	ut_ad(buf_block_get_state(block) == BUF_BLOCK_FILE_PAGE);
	ut_ad(block->frame == ptr);
	return(block);
}

/*************************************************************************
Gets the compressed page descriptor corresponding to an uncompressed page
if applicable. */
UNIV_INLINE
page_zip_des_t*
buf_frame_get_page_zip(
/*===================*/
			/* out: compressed page descriptor, or NULL */
	byte*	ptr)	/* in: pointer to the page */
{
	page_zip_des_t*	page_zip;
	mutex_enter(&buf_pool->mutex);
	page_zip = buf_block_get_page_zip(buf_block_align(ptr));
	mutex_exit(&buf_pool->mutex);
	return(page_zip);
}
#endif /* UNIV_DEBUG || UNIV_ZIP_DEBUG */

/**************************************************************************
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((void*) 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);
}

/**************************************************************************
Gets the hash value of the page the pointer is pointing to. This can be used
in searches in the lock hash table. */
UNIV_INLINE
ulint
buf_block_get_lock_hash_val(
/*========================*/
					/* out: lock hash value */
	const buf_block_t*	block)	/* in: block */
{
	return(block->lock_hash_val);
}

/************************************************************************
Allocates a buffer block. */
UNIV_INLINE
buf_block_t*
buf_block_alloc(
/*============*/
				/* out, own: the allocated block,
				in state BUF_BLOCK_MEMORY */
	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 */
{
	mutex_enter(&(buf_pool->mutex));

	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);

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

/*************************************************************************
Copies contents of a buffer frame to a given buffer. */
UNIV_INLINE
byte*
buf_frame_copy(
/*===========*/
					/* out: buf */
	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);
}

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

/************************************************************************
This function is used to get info if there is an io operation
going on on a buffer page. */
UNIV_INLINE
ibool
buf_page_io_query(
/*==============*/
				/* out: TRUE if io going on */
	buf_page_t*	bpage)	/* in: buf_pool block, must be bufferfixed */
{
	ibool	io_fixed;

	mutex_enter(&(buf_pool->mutex));

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

	io_fixed = buf_page_get_io_fix(bpage) != BUF_IO_NONE;
	mutex_exit(&(buf_pool->mutex));

	return(io_fixed);
}

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

	mutex_enter(&(buf_pool->mutex));

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

	mutex_exit(&(buf_pool->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((mutex_own(&(buf_pool->mutex))
	       && (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. */
UNIV_INLINE
ib_uint64_t
buf_block_get_modify_clock(
/*=======================*/
				/* out: value */
	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: block to bufferfix */
{
#ifdef UNIV_SYNC_DEBUG
	ibool	ret;

	ret = rw_lock_s_lock_func_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
# define buf_block_buf_fix_inc(b,f,l) buf_block_buf_fix_inc_func(f,l,b)
#else /* UNIV_SYNC_DEBUG */
# 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: 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. */
UNIV_INLINE
buf_page_t*
buf_page_hash_get(
/*==============*/
			/* out: block, NULL if not found */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: offset of the page within space */
{
	buf_page_t*	bpage;
	ulint		fold;

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

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

	fold = buf_page_address_fold(space, offset);

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

	return(bpage);
}

/************************************************************************
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. */
UNIV_INLINE
ibool
buf_page_peek(
/*==========*/
			/* out: TRUE if found from page hash table,
			NOTE that the page is not necessarily yet read
			from disk! */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: page number */
{
	const buf_page_t*	bpage;

	mutex_enter(&buf_pool->mutex);

	bpage = buf_page_hash_get(space, offset);

	mutex_exit(&buf_pool->mutex);

	return(bpage != NULL);
}

/************************************************************************
Tries to get the page, but if file io is required, releases all latches
in mtr down to the given savepoint. If io is required, this function
retrieves the page to buffer buf_pool, but does not bufferfix it or latch
it. */
UNIV_INLINE
buf_block_t*
buf_page_get_release_on_io(
/*=======================*/
				/* out: pointer to the block, or NULL
				if not in buffer buf_pool */
	ulint	space,		/* in: space id */
	ulint	zip_size,	/* in: compressed page size in bytes
				or 0 for uncompressed pages */
	ulint	offset,		/* in: offset of the page within space
				in units of a page */
	buf_block_t* guess,	/* in: guessed block or NULL */
	ulint	rw_latch,	/* in: RW_X_LATCH, RW_S_LATCH,
				or RW_NO_LATCH */
	ulint	savepoint,	/* in: mtr savepoint */
	mtr_t*	mtr)		/* in: mtr */
{
	buf_block_t*	block;

	block = buf_page_get_gen(space, zip_size, offset, rw_latch, guess,
				 BUF_GET_IF_IN_POOL,
				 __FILE__, __LINE__,
				 mtr);
	if (block != NULL) {

		return(block);
	}

	/* The page was not in the buffer buf_pool: release the latches
	down to the savepoint */

	mtr_rollback_to_savepoint(mtr, savepoint);

	buf_page_get(space, zip_size, offset, RW_S_LATCH, mtr);

	/* When we get here, the page is in buffer, but we release
	the latches again down to the savepoint, before returning */

	mtr_rollback_to_savepoint(mtr, savepoint);

	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 */
{
	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 */
	mtr_t*		mtr)		/* in: mtr */
{
	ut_ad(block);

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

	if (rw_latch == RW_X_LATCH && mtr->modifications) {
		mutex_enter(&buf_pool->mutex);
		buf_flush_note_modification(block, mtr);
		mutex_exit(&buf_pool->mutex);
	}

	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 */