buf0buf.ic

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buf_frame_get_lock_mutex(
/*=====================*/
			/* out: mutex */
	byte*	ptr)	/* in: pointer to within a buffer frame */
{
	buf_block_t*	block;

	block = buf_block_align(ptr);

	return(block->lock_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 */
	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_block_t*	block)	/* in: buf_pool block, must be bufferfixed */
{
	mutex_enter(&(buf_pool->mutex));

	ut_ad(block->state == BUF_BLOCK_FILE_PAGE);
	ut_ad(block->buf_fix_count > 0);

	if (block->io_fix != 0) {
		mutex_exit(&(buf_pool->mutex));

		return(TRUE);
	}

	mutex_exit(&(buf_pool->mutex));

	return(FALSE);
}

/************************************************************************
Gets the youngest modification log sequence number for a frame. Returns zero
if not a file page or no modification occurred yet. */
UNIV_INLINE
dulint
buf_frame_get_newest_modification(
/*==============================*/
				/* out: newest modification to the page */
	buf_frame_t*	frame)	/* in: pointer to a frame */
{
	buf_block_t*	block;
	dulint		lsn;
	
	ut_ad(frame);

	block = buf_block_align(frame);

	mutex_enter(&(buf_pool->mutex));

	if (block->state == BUF_BLOCK_FILE_PAGE) {
		lsn = block->newest_modification;
	} else {
		lsn = ut_dulint_zero;
	}

	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
dulint
buf_frame_modify_clock_inc(
/*=======================*/
				/* out: new value */
	buf_frame_t*	frame)	/* in: pointer to a frame */
{
	buf_block_t*	block;

	ut_ad(frame);

	block = buf_block_align(frame);

#ifdef UNIV_SYNC_DEBUG
	ut_ad((mutex_own(&(buf_pool->mutex)) && (block->buf_fix_count == 0))
	      || rw_lock_own(&(block->lock), RW_LOCK_EXCLUSIVE));
#endif /*UNIV_SYNC_DEBUG */

	UT_DULINT_INC(block->modify_clock);

	return(block->modify_clock);
}

/************************************************************************
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
dulint
buf_block_modify_clock_inc(
/*=======================*/
				/* out: new value */
	buf_block_t*	block)	/* in: block */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad((mutex_own(&(buf_pool->mutex)) && (block->buf_fix_count == 0))
	      || rw_lock_own(&(block->lock), RW_LOCK_EXCLUSIVE));
#endif /* UNIV_SYNC_DEBUG */

	UT_DULINT_INC(block->modify_clock);

	return(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
dulint
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);
}

#ifdef UNIV_SYNC_DEBUG
/***********************************************************************
Increments the bufferfix count. */
UNIV_INLINE
void
buf_block_buf_fix_inc_debug(
/*========================*/
	buf_block_t*	block,	/* in: block to bufferfix */
	const char*	file __attribute__ ((unused)),	/* in: file name */
	ulint		line __attribute__ ((unused)))	/* in: line */
{
#ifdef UNIV_SYNC_DEBUG	
	ibool	ret;

	ret = rw_lock_s_lock_func_nowait(&(block->debug_latch), file, line);

	ut_ad(ret == TRUE);
#endif
	block->buf_fix_count++;
}
#else /* UNIV_SYNC_DEBUG */
/***********************************************************************
Increments the bufferfix count. */
UNIV_INLINE
void
buf_block_buf_fix_inc(
/*==================*/
	buf_block_t*	block)	/* in: block to bufferfix */
{
	block->buf_fix_count++;
}
#endif /* UNIV_SYNC_DEBUG */
/**********************************************************************
Returns the control block of a file page, NULL if not found. */
UNIV_INLINE
buf_block_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_block_t*	block;
	ulint		fold;
	
	ut_ad(buf_pool);
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(buf_pool->mutex)));
#endif /* UNIV_SYNC_DEBUG */

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

	fold = buf_page_address_fold(space, offset);

	HASH_SEARCH(hash, buf_pool->page_hash, fold, block,
			(block->space == space) && (block->offset == offset));
	ut_a(block == NULL || block->state == BUF_BLOCK_FILE_PAGE);
	
	return(block);
}

/************************************************************************
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_frame_t*
buf_page_get_release_on_io(
/*=======================*/
				/* out: pointer to the frame, or NULL
				if not in buffer buf_pool */
	ulint	space,		/* in: space id */
	ulint	offset,		/* in: offset of the page within space
				in units of a page */
	buf_frame_t* guess,	/* in: guessed frame 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_frame_t*	frame;

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

		return(frame);
	}

	/* 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, 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);
}

/************************************************************************
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 */
{
	ulint	buf_fix_count;
	
	ut_ad(block);

	mutex_enter_fast(&(buf_pool->mutex));

	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
	ut_a(block->buf_fix_count > 0);

	if (rw_latch == RW_X_LATCH && mtr->modifications) {

		buf_flush_note_modification(block, mtr);
	}

#ifdef UNIV_SYNC_DEBUG
	rw_lock_s_unlock(&(block->debug_latch));
#endif
	buf_fix_count = block->buf_fix_count;
	block->buf_fix_count = buf_fix_count - 1;

	mutex_exit(&(buf_pool->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. If
UNIV_SYNC_DEBUG is not defined, compiles to an empty function. */
UNIV_INLINE
void
buf_page_dbg_add_level(
/*===================*/
	buf_frame_t*	frame __attribute__((unused)), /* in: buffer page
                                where we have acquired latch */
	ulint		level __attribute__((unused))) /* in: latching order
                                level */
{
	sync_thread_add_level(&(buf_block_align(frame)->lock), level);
}
#endif /* UNIV_SYNC_DEBUG */