/******************************************************
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"

#ifdef UNIV_DEBUG
extern ulint		buf_dbg_counter; /* This is used to insert validation
					operations in execution in the
					debug version */
#endif /* UNIV_DEBUG */
/************************************************************************
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_block_peek_if_too_old(
/*======================*/
				/* out: TRUE if should be made younger */
	buf_block_t*	block)	/* in: block to make younger */
{
	return(buf_pool->freed_page_clock >= block->freed_page_clock
	       + 1 + (buf_pool->curr_size / 4));
}

/*************************************************************************
Gets the current size of buffer buf_pool in bytes. In the case of AWE, the
size of AWE window (= the frames). */
UNIV_INLINE
ulint
buf_pool_get_curr_size(void)
/*========================*/
			/* out: size in bytes */
{
	return((buf_pool->n_frames) * UNIV_PAGE_SIZE);
}

/*************************************************************************
Gets the maximum size of buffer buf_pool in bytes. In the case of AWE, the
size of AWE window (= the frames). */
UNIV_INLINE
ulint
buf_pool_get_max_size(void)
/*=======================*/
			/* out: size in bytes */
{
	return((buf_pool->n_frames) * UNIV_PAGE_SIZE);
}

/***********************************************************************
Accessor function for block array. */
UNIV_INLINE
buf_block_t*
buf_pool_get_nth_block(
/*===================*/
				/* out: pointer to block */
	buf_pool_t*	buf_pool,/* in: buf_pool */
	ulint		i)	/* in: index of the block */
{
	ut_ad(buf_pool);
	ut_ad(i < buf_pool->max_size);

	return(i + buf_pool->blocks);
}

/***********************************************************************
Checks if a pointer points to the block array of the buffer pool (blocks, not
the frames). */
UNIV_INLINE
ibool
buf_pool_is_block(
/*==============*/
			/* out: TRUE if pointer to block */
	void*	ptr)	/* in: pointer to memory */
{
	if ((buf_pool->blocks <= (buf_block_t*)ptr)
	    && ((buf_block_t*)ptr < buf_pool->blocks
		+ buf_pool->max_size)) {

		return(TRUE);
	}

	return(FALSE);
}

/************************************************************************
Gets the smallest oldest_modification lsn for any page in the pool. Returns
ut_dulint_zero if all modified pages have been flushed to disk. */
UNIV_INLINE
dulint
buf_pool_get_oldest_modification(void)
/*==================================*/
				/* out: oldest modification in pool,
				ut_dulint_zero if none */
{
	buf_block_t*	block;
	dulint		lsn;

	mutex_enter(&(buf_pool->mutex));

	block = UT_LIST_GET_LAST(buf_pool->flush_list);

	if (block == NULL) {
		lsn = ut_dulint_zero;
	} else {
		lsn = block->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 a pointer to the memory frame of a block. */
UNIV_INLINE
buf_frame_t*
buf_block_get_frame(
/*================*/
				/* out: pointer to the frame */
	buf_block_t*	block)	/* in: pointer to the control block */
{
	ut_ad(block);
	ut_ad(block >= buf_pool->blocks);
	ut_ad(block < buf_pool->blocks + buf_pool->max_size);
	ut_ad(block->state != BUF_BLOCK_NOT_USED);
	ut_ad((block->state != BUF_BLOCK_FILE_PAGE)
	      || (block->buf_fix_count > 0));

	return(block->frame);
}

/*************************************************************************
Gets the space id of a block. */
UNIV_INLINE
ulint
buf_block_get_space(
/*================*/
				/* out: space id */
	buf_block_t*	block)	/* in: pointer to the control block */
{
	ut_ad(block);
	ut_ad(block >= buf_pool->blocks);
	ut_ad(block < buf_pool->blocks + buf_pool->max_size);
	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
	ut_ad(block->buf_fix_count > 0);

	return(block->space);
}

/*************************************************************************
Gets the page number of a block. */
UNIV_INLINE
ulint
buf_block_get_page_no(
/*==================*/
				/* out: page number */
	buf_block_t*	block)	/* in: pointer to the control block */
{
	ut_ad(block);
	ut_ad(block >= buf_pool->blocks);
	ut_ad(block < buf_pool->blocks + buf_pool->max_size);
	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
	ut_ad(block->buf_fix_count > 0);

	return(block->offset);
}

/***********************************************************************
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;
	buf_frame_t*	frame_zero;

	ut_ad(ptr);

	frame_zero = buf_pool->frame_zero;

	if (UNIV_UNLIKELY((ulint)ptr < (ulint)frame_zero)
	    || UNIV_UNLIKELY((ulint)ptr > (ulint)(buf_pool->high_end))) {

		ut_print_timestamp(stderr);
		fprintf(stderr,
			"InnoDB: Error: trying to access a stray pointer %p\n"
			"InnoDB: buf pool start is at %p, end at %p\n"
			"InnoDB: Probable reason is database corruption"
			" or memory\n"
			"InnoDB: corruption. If this happens in an"
			" InnoDB database recovery, see\n"
			"InnoDB: http://dev.mysql.com/doc/refman/5.1/en/"
			"forcing-innodb-recovery.html\n"
			"InnoDB: how to force recovery.\n",
			ptr, frame_zero,
			buf_pool->high_end);
		ut_error;
	}

	block = *(buf_pool->blocks_of_frames + (((ulint)(ptr - frame_zero))
						>> UNIV_PAGE_SIZE_SHIFT));
	return(block);
}

/***********************************************************************
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 = ut_align_down(ptr, UNIV_PAGE_SIZE);

	if (UNIV_UNLIKELY((ulint)frame < (ulint)(buf_pool->frame_zero))
	    || UNIV_UNLIKELY((ulint)frame >= (ulint)(buf_pool->high_end))) {

		ut_print_timestamp(stderr);
		fprintf(stderr,
			"InnoDB: Error: trying to access a stray pointer %p\n"
			"InnoDB: buf pool start is at %p, end at %p\n"
			"InnoDB: Probable reason is database corruption"
			" or memory\n"
			"InnoDB: corruption. If this happens in an"
			" InnoDB database recovery, see\n"
			"InnoDB: http://dev.mysql.com/doc/refman/5.1/en/"
			"forcing-innodb-recovery.html\n"
			"InnoDB: how to force recovery.\n",
			ptr, buf_pool->frame_zero,
			buf_pool->high_end);
		ut_error;
	}

	return(frame);
}

/**************************************************************************
Gets the page number of a pointer pointing within a buffer frame containing
a file page. */
UNIV_INLINE
ulint
buf_frame_get_page_no(
/*==================*/
			/* out: page number */
	byte*	ptr)	/* in: pointer to within a buffer frame */
{
	return(buf_block_get_page_no(buf_block_align(ptr)));
}

/**************************************************************************
Gets the space id of a pointer pointing within a buffer frame containing a
file page. */
UNIV_INLINE
ulint
buf_frame_get_space_id(
/*===================*/
			/* out: space id */
	byte*	ptr)	/* in: pointer to within a buffer frame */
{
	return(buf_block_get_space(buf_block_align(ptr)));
}

/**************************************************************************
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(
/*=================*/
	byte*		ptr,	/* in: pointer to a buffer frame */
	ulint*		space,	/* out: space id */
	fil_addr_t*	addr)	/* out: page offset and byte offset */
{
	buf_block_t*	block;

	block = buf_block_align(ptr);

	*space = buf_block_get_space(block);
	addr->page = buf_block_get_page_no(block);
	addr->boffset = ptr - buf_frame_align(ptr);
}

/**************************************************************************
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_frame_get_lock_hash_val(
/*========================*/
			/* out: lock hash value */
	byte*	ptr)	/* in: pointer to within a buffer frame */
{
	buf_block_t*	block;

	block = buf_block_align(ptr);

	return(block->lock_hash_val);
}

/**************************************************************************
Gets the mutex number protecting the page record lock hash chain in the lock
table. */
UNIV_INLINE
mutex_t*
buf_frame_get_mutex(
/*================*/
			/* out: mutex */
	byte*	ptr)	/* in: pointer to within a buffer frame */
{
	buf_block_t*	block;

	block = buf_block_align(ptr);

	return(&block->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 */
{
	ibool	ret;

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

	ut_ad(ret == TRUE);
	ut_ad(mutex_own(&block->mutex));
	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 */
{
	ut_ad(mutex_own(&block->mutex));

	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);
	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, block,
		    (block->space == space) && (block->offset == offset));
	ut_a(block == NULL || block->state == BUF_BLOCK_FILE_PAGE);

	return(block);
}

/************************************************************************
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(block->state == BUF_BLOCK_FILE_PAGE);
	ut_a(block->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->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. 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, FALSE);
}
#endif /* UNIV_SYNC_DEBUG */