/******************************************************
Mini-transaction buffer

(c) 1995 Innobase Oy

Created 11/26/1995 Heikki Tuuri
*******************************************************/

#include "sync0sync.h"
#include "sync0rw.h"
#include "mach0data.h"

/*******************************************************************
Starts a mini-transaction and creates a mini-transaction handle 
and a buffer in the memory buffer given by the caller. */
UNIV_INLINE
mtr_t*
mtr_start(
/*======*/
			/* out: mtr buffer which also acts as
			the mtr handle */
	mtr_t*	mtr)	/* in: memory buffer for the mtr buffer */
{
	dyn_array_create(&(mtr->memo));
	dyn_array_create(&(mtr->log));

	mtr->log_mode = MTR_LOG_ALL;
	mtr->modifications = FALSE;
	mtr->n_log_recs = 0;

#ifdef UNIV_DEBUG
	mtr->state = MTR_ACTIVE;
	mtr->magic_n = MTR_MAGIC_N;
#endif
	return(mtr);
}		

/*******************************************************
Pushes an object to an mtr memo stack. */
UNIV_INLINE
void
mtr_memo_push(
/*==========*/
	mtr_t*	mtr,	/* in: mtr */
	void*	object,	/* in: object */
	ulint	type)	/* in: object type: MTR_MEMO_S_LOCK, ... */
{
	dyn_array_t*		memo;
	mtr_memo_slot_t*	slot;

	ut_ad(object);
	ut_ad(type >= MTR_MEMO_PAGE_S_FIX);	
	ut_ad(type <= MTR_MEMO_X_LOCK);
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);

	memo = &(mtr->memo);	

	slot = dyn_array_push(memo, sizeof(mtr_memo_slot_t));

	slot->object = object;
	slot->type = type;
}

/**************************************************************
Sets and returns a savepoint in mtr. */
UNIV_INLINE
ulint
mtr_set_savepoint(
/*==============*/
			/* out: savepoint */
	mtr_t*	mtr)	/* in: mtr */
{
	dyn_array_t*	memo;
 
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);

	memo = &(mtr->memo);	

	return(dyn_array_get_data_size(memo));
}

/**************************************************************
Releases the (index tree) s-latch stored in an mtr memo after a
savepoint. */
UNIV_INLINE
void
mtr_release_s_latch_at_savepoint(
/*=============================*/
	mtr_t*		mtr,		/* in: mtr */
	ulint		savepoint,	/* in: savepoint */
	rw_lock_t* 	lock)		/* in: latch to release */
{
	mtr_memo_slot_t* slot;
	dyn_array_t*	memo;
	
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);
	ut_ad(mtr->state == MTR_ACTIVE);

	memo = &(mtr->memo);

	ut_ad(dyn_array_get_data_size(memo) > savepoint);
	
	slot = dyn_array_get_element(memo, savepoint);

	ut_ad(slot->object == lock);
	ut_ad(slot->type == MTR_MEMO_S_LOCK);

	rw_lock_s_unlock(lock);

	slot->object = NULL;
}

/**************************************************************
Checks if memo contains the given item. */
UNIV_INLINE
ibool
mtr_memo_contains(
/*==============*/
			/* out: TRUE if contains */
	mtr_t*	mtr,	/* in: mtr */
	void*	object,	/* in: object to search */
	ulint	type)	/* in: type of object */
{
	mtr_memo_slot_t* slot;
	dyn_array_t*	memo;
	ulint		offset;

	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);

	memo = &(mtr->memo);

	offset = dyn_array_get_data_size(memo);

	while (offset > 0) {
		offset -= sizeof(mtr_memo_slot_t);

		slot = dyn_array_get_element(memo, offset);

		if ((object == slot->object) && (type == slot->type)) {

			return(TRUE);
		}
	}

	return(FALSE);
}

/*******************************************************************
Returns the log object of a mini-transaction buffer. */
UNIV_INLINE
dyn_array_t*
mtr_get_log(
/*========*/
			/* out: log */
	mtr_t*	mtr)	/* in: mini-transaction */
{
	ut_ad(mtr);
	ut_ad(mtr->magic_n == MTR_MAGIC_N);

	return(&(mtr->log));
}

/*******************************************************************
Gets the logging mode of a mini-transaction. */
UNIV_INLINE
ulint
mtr_get_log_mode(
/*=============*/
			/* out: logging mode: MTR_LOG_NONE, ... */
	mtr_t*	mtr)	/* in: mtr */
{
	ut_ad(mtr);
	ut_ad(mtr->log_mode >= MTR_LOG_ALL);
	ut_ad(mtr->log_mode <= MTR_LOG_SHORT_INSERTS);

	return(mtr->log_mode);
}

/*******************************************************************
Changes the logging mode of a mini-transaction. */
UNIV_INLINE
ulint
mtr_set_log_mode(
/*=============*/
			/* out: old mode */
	mtr_t*	mtr,	/* in: mtr */
	ulint	mode)	/* in: logging mode: MTR_LOG_NONE, ... */
{
	ulint	old_mode;

	ut_ad(mtr);
	ut_ad(mode >= MTR_LOG_ALL);
	ut_ad(mode <= MTR_LOG_SHORT_INSERTS);

	old_mode = mtr->log_mode;

	if ((mode == MTR_LOG_SHORT_INSERTS) && (old_mode == MTR_LOG_NONE)) {
		/* Do nothing */
	} else {
		mtr->log_mode = mode;
	}

	ut_ad(old_mode >= MTR_LOG_ALL);
	ut_ad(old_mode <= MTR_LOG_SHORT_INSERTS);

	return(old_mode);
}

/*************************************************************************
Locks a lock in s-mode. */
UNIV_INLINE
void
mtr_s_lock_func(
/*============*/
	rw_lock_t*	lock,	/* in: rw-lock */
	const char*	file,	/* in: file name */
	ulint		line,	/* in: line number */
	mtr_t*		mtr)	/* in: mtr */
{
	ut_ad(mtr);
	ut_ad(lock);

	rw_lock_s_lock_func(lock, 0, file, line);

	mtr_memo_push(mtr, lock, MTR_MEMO_S_LOCK);
}

/*************************************************************************
Locks a lock in x-mode. */
UNIV_INLINE
void
mtr_x_lock_func(
/*============*/
	rw_lock_t*	lock,	/* in: rw-lock */
	const char*	file,	/* in: file name */
	ulint		line,	/* in: line number */
	mtr_t*		mtr)	/* in: mtr */
{
	ut_ad(mtr);
	ut_ad(lock);

	rw_lock_x_lock_func(lock, 0, file, line);

	mtr_memo_push(mtr, lock, MTR_MEMO_X_LOCK);
}
