/******************************************************
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;

	buf_pool_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_pool_mutex_exit();

	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(buf_pool_mutex_own());

	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);
}

/*************************************************************************
Determines if a block should be on unzip_LRU list. */
UNIV_INLINE
ibool
buf_page_belongs_to_unzip_LRU(
/*==========================*/
					/* out: TRUE if block 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);
}

/*************************************************************************
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 */
	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. */
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(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. */
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(buf_pool_mutex_own());
	ut_ad(bpage->in_LRU_list);

#ifdef UNIV_LRU_DEBUG
	if (UT_LIST_GET_PREV(LRU, bpage) && UT_LIST_GET_NEXT(LRU, bpage)
	    && UT_LIST_GET_PREV(LRU, bpage)->old
	    == UT_LIST_GET_NEXT(LRU, bpage)->old) {
		ut_a(UT_LIST_GET_PREV(LRU, bpage)->old == old);
	}
#endif /* UNIV_LRU_DEBUG */

	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
buf_block_t*
buf_page_get_block(
/*===============*/
				/* out: control block, or NULL */
	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);
}

#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);
}

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

	ptr = (const byte*) 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 = (const 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
const page_zip_des_t*
buf_frame_get_page_zip(
/*===================*/
				/* out: compressed page descriptor, or NULL */
	const byte*	ptr)	/* in: pointer to the page */
{
	const page_zip_des_t*	page_zip;
	buf_pool_mutex_enter();
	page_zip = buf_block_get_page_zip(buf_block_align(ptr));
	buf_pool_mutex_exit();
	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(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 */
{
	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();
}

/*************************************************************************
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;

	buf_pool_mutex_enter();

	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;
	buf_pool_mutex_exit();

	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;

	buf_pool_mutex_enter();

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

	buf_pool_mutex_exit();

	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. */
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(buf_pool_mutex_own());

	/* 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);
	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
or an uncompressed page frame does not exist. */
UNIV_INLINE
buf_block_t*
buf_block_hash_get(
/*===============*/
			/* out: block, NULL if not found */
	ulint	space,	/* in: space id */
	ulint	offset)	/* in: offset of the page within space */
{
	return(buf_page_get_block(buf_page_hash_get(space, offset)));
}

/************************************************************************
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;

	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 */
	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) {
		buf_pool_mutex_enter();
		buf_flush_note_modification(block, mtr);
		buf_pool_mutex_exit();
	}

	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 */