Bug#16138582 MTR_MEMO_RELEASE AND DYN_ARRAY TOGETHER ARE VERY INEFFICIENT

Get rid of O(n^2) scan in dyn array (mtr->memo) operations, accessing
the dyn array blocks directly.

dyn_array_get_last_block(), dyn_array_get_next_block(),
dyn_array_get_prev_block(): Define as a constness-preserving macro.

Add const qualifiers to many dyn_array functions.

mtr_memo_slot_release_func(): Renamed from mtr_memo_slot_release():
Make mtr_t* a debug-only parameter. Assume that slot->object != NULL.

mtr_memo_pop_all(): Access the dyn_array blocks directly, replacing
O(n^2) operation with O(n).

mtr_memo_release(): Access the dyn_array blocks directly, replacing
O(n^2) operation with O(n). This caused the performance problem.

rb#1540 approved by Jimmy Yang

storage/innobase/dyn/dyn0dyn.c

 /*****************************************************************************
 
-Copyright (c) 1996, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1996, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -11,8 +11,8 @@ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License along with
-this program; if not, write to the Free Software Foundation, Inc., 59 Temple
-Place, Suite 330, Boston, MA 02111-1307 USA
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
 
 *****************************************************************************/
 
@@ -35,7 +35,7 @@ UNIV_INTERN
 dyn_block_t*
 dyn_array_add_block(
 /*================*/
-	dyn_array_t*	arr)	/*!< in: dyn array */
+	dyn_array_t*	arr)	/*!< in/out: dyn array */
 {
 	mem_heap_t*	heap;
 	dyn_block_t*	block;

storage/innobase/include/dyn0dyn.h

 /*****************************************************************************
 
-Copyright (c) 1996, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1996, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -11,8 +11,8 @@ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License along with
-this program; if not, write to the Free Software Foundation, Inc., 59 Temple
-Place, Suite 330, Boston, MA 02111-1307 USA
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
 
 *****************************************************************************/
 
@@ -47,15 +47,17 @@ UNIV_INLINE
 dyn_array_t*
 dyn_array_create(
 /*=============*/
-	dyn_array_t*	arr);	/*!< in: pointer to a memory buffer of
+	dyn_array_t*	arr)	/*!< in/out memory buffer of
 				size sizeof(dyn_array_t) */
+	__attribute__((nonnull));
 /************************************************************//**
 Frees a dynamic array. */
 UNIV_INLINE
 void
 dyn_array_free(
 /*===========*/
-	dyn_array_t*	arr);	/*!< in: dyn array */
+	dyn_array_t*	arr)	/*!< in,own: dyn array */
+	__attribute__((nonnull));
 /*********************************************************************//**
 Makes room on top of a dyn array and returns a pointer to a buffer in it.
 After copying the elements, the caller must close the buffer using
@@ -66,8 +68,9 @@ byte*
 dyn_array_open(
 /*===========*/
 	dyn_array_t*	arr,	/*!< in: dynamic array */
-	ulint		size);	/*!< in: size in bytes of the buffer; MUST be
+	ulint		size)	/*!< in: size in bytes of the buffer; MUST be
 				smaller than DYN_ARRAY_DATA_SIZE! */
+	__attribute__((nonnull, warn_unused_result));
 /*********************************************************************//**
 Closes the buffer returned by dyn_array_open. */
 UNIV_INLINE
@@ -75,7 +78,8 @@ void
 dyn_array_close(
 /*============*/
 	dyn_array_t*	arr,	/*!< in: dynamic array */
-	byte*		ptr);	/*!< in: buffer space from ptr up was not used */
+	const byte*	ptr)	/*!< in: end of used space */
+	__attribute__((nonnull));
 /*********************************************************************//**
 Makes room on top of a dyn array and returns a pointer to
 the added element. The caller must copy the element to
@@ -85,8 +89,9 @@ UNIV_INLINE
 void*
 dyn_array_push(
 /*===========*/
-	dyn_array_t*	arr,	/*!< in: dynamic array */
-	ulint		size);	/*!< in: size in bytes of the element */
+	dyn_array_t*	arr,	/*!< in/out: dynamic array */
+	ulint		size)	/*!< in: size in bytes of the element */
+	__attribute__((nonnull, warn_unused_result));
 /************************************************************//**
 Returns pointer to an element in dyn array.
 @return	pointer to element */
@@ -94,9 +99,10 @@ UNIV_INLINE
 void*
 dyn_array_get_element(
 /*==================*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
-	ulint		pos);	/*!< in: position of element as bytes
-				from array start */
+	const dyn_array_t*	arr,	/*!< in: dyn array */
+	ulint			pos)	/*!< in: position of element
+					in bytes from array start */
+	__attribute__((nonnull, warn_unused_result));
 /************************************************************//**
 Returns the size of stored data in a dyn array.
 @return	data size in bytes */
@@ -104,30 +110,33 @@ UNIV_INLINE
 ulint
 dyn_array_get_data_size(
 /*====================*/
-	dyn_array_t*	arr);	/*!< in: dyn array */
+	const dyn_array_t*	arr)	/*!< in: dyn array */
+	__attribute__((nonnull, warn_unused_result, pure));
 /************************************************************//**
-Gets the first block in a dyn array. */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_first_block(
-/*======================*/
-	dyn_array_t*	arr);	/*!< in: dyn array */
+Gets the first block in a dyn array.
+@param arr	dyn array
+@return		first block */
+#define dyn_array_get_first_block(arr) (arr)
 /************************************************************//**
-Gets the last block in a dyn array. */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_last_block(
-/*=====================*/
-	dyn_array_t*	arr);	/*!< in: dyn array */
+Gets the last block in a dyn array.
+@param arr	dyn array
+@return		last block */
+#define dyn_array_get_last_block(arr)				\
+	((arr)->heap ? UT_LIST_GET_LAST((arr)->base) : (arr))
 /********************************************************************//**
 Gets the next block in a dyn array.
-@return	pointer to next, NULL if end of list */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_next_block(
-/*=====================*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
-	dyn_block_t*	block);	/*!< in: dyn array block */
+@param arr	dyn array
+@param block	dyn array block
+@return		pointer to next, NULL if end of list */
+#define dyn_array_get_next_block(arr, block)			\
+	((arr)->heap ? UT_LIST_GET_NEXT(list, block) : NULL)
+/********************************************************************//**
+Gets the previous block in a dyn array.
+@param arr	dyn array
+@param block	dyn array block
+@return		pointer to previous, NULL if end of list */
+#define dyn_array_get_prev_block(arr, block)			\
+	((arr)->heap ? UT_LIST_GET_PREV(list, block) : NULL)
 /********************************************************************//**
 Gets the number of used bytes in a dyn array block.
 @return	number of bytes used */
@@ -135,7 +144,8 @@ UNIV_INLINE
 ulint
 dyn_block_get_used(
 /*===============*/
-	dyn_block_t*	block);	/*!< in: dyn array block */
+	const dyn_block_t*	block)	/*!< in: dyn array block */
+	__attribute__((nonnull, warn_unused_result, pure));
 /********************************************************************//**
 Gets pointer to the start of data in a dyn array block.
 @return	pointer to data */
@@ -143,16 +153,18 @@ UNIV_INLINE
 byte*
 dyn_block_get_data(
 /*===============*/
-	dyn_block_t*	block);	/*!< in: dyn array block */
+	const dyn_block_t*	block)	/*!< in: dyn array block */
+	__attribute__((nonnull, warn_unused_result, pure));
 /********************************************************//**
 Pushes n bytes to a dyn array. */
 UNIV_INLINE
 void
 dyn_push_string(
 /*============*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
+	dyn_array_t*	arr,	/*!< in/out: dyn array */
 	const byte*	str,	/*!< in: string to write */
-	ulint		len);	/*!< in: string length */
+	ulint		len)	/*!< in: string length */
+	__attribute__((nonnull));
 
 /*#################################################################*/
 

storage/innobase/include/dyn0dyn.ic

 /*****************************************************************************
 
-Copyright (c) 1996, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1996, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -11,8 +11,8 @@ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License along with
-this program; if not, write to the Free Software Foundation, Inc., 59 Temple
-Place, Suite 330, Boston, MA 02111-1307 USA
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
 
 *****************************************************************************/
 
@@ -35,56 +35,8 @@ UNIV_INTERN
 dyn_block_t*
 dyn_array_add_block(
 /*================*/
-	dyn_array_t*	arr);	/*!< in: dyn array */
-
-
-/************************************************************//**
-Gets the first block in a dyn array. */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_first_block(
-/*======================*/
-	dyn_array_t*	arr)	/*!< in: dyn array */
-{
-	return(arr);
-}
-
-/************************************************************//**
-Gets the last block in a dyn array. */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_last_block(
-/*=====================*/
-	dyn_array_t*	arr)	/*!< in: dyn array */
-{
-	if (arr->heap == NULL) {
-
-		return(arr);
-	}
-
-	return(UT_LIST_GET_LAST(arr->base));
-}
-
-/********************************************************************//**
-Gets the next block in a dyn array.
-@return	pointer to next, NULL if end of list */
-UNIV_INLINE
-dyn_block_t*
-dyn_array_get_next_block(
-/*=====================*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
-	dyn_block_t*	block)	/*!< in: dyn array block */
-{
-	ut_ad(arr && block);
-
-	if (arr->heap == NULL) {
-		ut_ad(arr == block);
-
-		return(NULL);
-	}
-
-	return(UT_LIST_GET_NEXT(list, block));
-}
+	dyn_array_t*	arr)	/*!< in/out: dyn array */
+	__attribute__((nonnull, warn_unused_result));
 
 /********************************************************************//**
 Gets the number of used bytes in a dyn array block.
@@ -93,7 +45,7 @@ UNIV_INLINE
 ulint
 dyn_block_get_used(
 /*===============*/
-	dyn_block_t*	block)	/*!< in: dyn array block */
+	const dyn_block_t*	block)	/*!< in: dyn array block */
 {
 	ut_ad(block);
 
@@ -107,11 +59,11 @@ UNIV_INLINE
 byte*
 dyn_block_get_data(
 /*===============*/
-	dyn_block_t*	block)	/*!< in: dyn array block */
+	const dyn_block_t*	block)	/*!< in: dyn array block */
 {
 	ut_ad(block);
 
-	return(block->data);
+	return((byte*) block->data);
 }
 
 /*********************************************************************//**
@@ -121,7 +73,7 @@ UNIV_INLINE
 dyn_array_t*
 dyn_array_create(
 /*=============*/
-	dyn_array_t*	arr)	/*!< in: pointer to a memory buffer of
+	dyn_array_t*	arr)	/*!< in/out: memory buffer of
 				size sizeof(dyn_array_t) */
 {
 	ut_ad(arr);
@@ -132,10 +84,9 @@ dyn_array_create(
 	arr->heap = NULL;
 	arr->used = 0;
 
-#ifdef UNIV_DEBUG
-	arr->buf_end = 0;
-	arr->magic_n = DYN_BLOCK_MAGIC_N;
-#endif
+	ut_d(arr->buf_end = 0);
+	ut_d(arr->magic_n = DYN_BLOCK_MAGIC_N);
+
 	return(arr);
 }
 
@@ -151,9 +102,7 @@ dyn_array_free(
 		mem_heap_free(arr->heap);
 	}
 
-#ifdef UNIV_DEBUG
-	arr->magic_n = 0;
-#endif
+	ut_d(arr->magic_n = 0);
 }
 
 /*********************************************************************//**
@@ -164,7 +113,7 @@ UNIV_INLINE
 void*
 dyn_array_push(
 /*===========*/
-	dyn_array_t*	arr,	/*!< in: dynamic array */
+	dyn_array_t*	arr,	/*!< in/out: dynamic array */
 	ulint		size)	/*!< in: size in bytes of the element */
 {
 	dyn_block_t*	block;
@@ -176,24 +125,23 @@ dyn_array_push(
 	ut_ad(size);
 
 	block = arr;
-	used = block->used;
 
-	if (used + size > DYN_ARRAY_DATA_SIZE) {
+	if (block->used + size > DYN_ARRAY_DATA_SIZE) {
 		/* Get the last array block */
 
 		block = dyn_array_get_last_block(arr);
-		used = block->used;
 
-		if (used + size > DYN_ARRAY_DATA_SIZE) {
+		if (block->used + size > DYN_ARRAY_DATA_SIZE) {
 			block = dyn_array_add_block(arr);
-			used = block->used;
 		}
 	}
 
+	used = block->used;
+
 	block->used = used + size;
 	ut_ad(block->used <= DYN_ARRAY_DATA_SIZE);
 
-	return((block->data) + used);
+	return(block->data + used);
 }
 
 /*********************************************************************//**
@@ -210,7 +158,6 @@ dyn_array_open(
 				smaller than DYN_ARRAY_DATA_SIZE! */
 {
 	dyn_block_t*	block;
-	ulint		used;
 
 	ut_ad(arr);
 	ut_ad(arr->magic_n == DYN_BLOCK_MAGIC_N);
@@ -218,28 +165,23 @@ dyn_array_open(
 	ut_ad(size);
 
 	block = arr;
-	used = block->used;
 
-	if (used + size > DYN_ARRAY_DATA_SIZE) {
+	if (block->used + size > DYN_ARRAY_DATA_SIZE) {
 		/* Get the last array block */
 
 		block = dyn_array_get_last_block(arr);
-		used = block->used;
 
-		if (used + size > DYN_ARRAY_DATA_SIZE) {
+		if (block->used + size > DYN_ARRAY_DATA_SIZE) {
 			block = dyn_array_add_block(arr);
-			used = block->used;
 			ut_a(size <= DYN_ARRAY_DATA_SIZE);
 		}
 	}
 
 	ut_ad(block->used <= DYN_ARRAY_DATA_SIZE);
-#ifdef UNIV_DEBUG
 	ut_ad(arr->buf_end == 0);
+	ut_d(arr->buf_end = block->used + size);
 
-	arr->buf_end = used + size;
-#endif
-	return((block->data) + used);
+	return(block->data + block->used);
 }
 
 /*********************************************************************//**
@@ -248,8 +190,8 @@ UNIV_INLINE
 void
 dyn_array_close(
 /*============*/
-	dyn_array_t*	arr,	/*!< in: dynamic array */
-	byte*		ptr)	/*!< in: buffer space from ptr up was not used */
+	dyn_array_t*	arr,	/*!< in/out: dynamic array */
+	const byte*	ptr)	/*!< in: end of used space */
 {
 	dyn_block_t*	block;
 
@@ -264,9 +206,7 @@ dyn_array_close(
 
 	ut_ad(block->used <= DYN_ARRAY_DATA_SIZE);
 
-#ifdef UNIV_DEBUG
-	arr->buf_end = 0;
-#endif
+	ut_d(arr->buf_end = 0);
 }
 
 /************************************************************//**
@@ -276,12 +216,11 @@ UNIV_INLINE
 void*
 dyn_array_get_element(
 /*==================*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
-	ulint		pos)	/*!< in: position of element as bytes
-				from array start */
+	const dyn_array_t*	arr,	/*!< in: dyn array */
+	ulint			pos)	/*!< in: position of element
+					in bytes from array start */
 {
-	dyn_block_t*	block;
-	ulint		used;
+	const dyn_block_t*	block;
 
 	ut_ad(arr);
 	ut_ad(arr->magic_n == DYN_BLOCK_MAGIC_N);
@@ -290,21 +229,23 @@ dyn_array_get_element(
 	block = dyn_array_get_first_block(arr);
 
 	if (arr->heap != NULL) {
-		used = dyn_block_get_used(block);
+		for (;;) {
+			ulint	used = dyn_block_get_used(block);
+
+			if (pos < used) {
+				break;
+			}
 
-		while (pos >= used) {
 			pos -= used;
 			block = UT_LIST_GET_NEXT(list, block);
 			ut_ad(block);
-
-			used = dyn_block_get_used(block);
 		}
 	}
 
 	ut_ad(block);
 	ut_ad(dyn_block_get_used(block) >= pos);
 
-	return(block->data + pos);
+	return((byte*) block->data + pos);
 }
 
 /************************************************************//**
@@ -314,10 +255,10 @@ UNIV_INLINE
 ulint
 dyn_array_get_data_size(
 /*====================*/
-	dyn_array_t*	arr)	/*!< in: dyn array */
+	const dyn_array_t*	arr)	/*!< in: dyn array */
 {
-	dyn_block_t*	block;
-	ulint		sum	= 0;
+	const dyn_block_t*	block;
+	ulint			sum	= 0;
 
 	ut_ad(arr);
 	ut_ad(arr->magic_n == DYN_BLOCK_MAGIC_N);
@@ -344,7 +285,7 @@ UNIV_INLINE
 void
 dyn_push_string(
 /*============*/
-	dyn_array_t*	arr,	/*!< in: dyn array */
+	dyn_array_t*	arr,	/*!< in/out: dyn array */
 	const byte*	str,	/*!< in: string to write */
 	ulint		len)	/*!< in: string length */
 {

storage/innobase/include/mtr0mtr.h

 /*****************************************************************************
 
-Copyright (c) 1995, 2012, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1995, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -295,9 +295,10 @@ UNIV_INTERN
 void
 mtr_memo_release(
 /*=============*/
-	mtr_t*	mtr,	/*!< in: mtr */
+	mtr_t*	mtr,	/*!< in/out: mini-transaction */
 	void*	object,	/*!< in: object */
-	ulint	type);	/*!< in: object type: MTR_MEMO_S_LOCK, ... */
+	ulint	type)	/*!< in: object type: MTR_MEMO_S_LOCK, ... */
+	__attribute__((nonnull));
 #ifdef UNIV_DEBUG
 # ifndef UNIV_HOTBACKUP
 /**********************************************************//**
@@ -309,7 +310,8 @@ mtr_memo_contains(
 /*==============*/
 	mtr_t*		mtr,	/*!< in: mtr */
 	const void*	object,	/*!< in: object to search */
-	ulint		type);	/*!< in: type of object */
+	ulint		type)	/*!< in: type of object */
+	__attribute__((warn_unused_result, nonnull));
 
 /**********************************************************//**
 Checks if memo contains the given page.

storage/innobase/mtr/mtr0mtr.c

 /*****************************************************************************
 
-Copyright (c) 1995, 2012, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1995, 2013, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -39,72 +39,81 @@ Created 11/26/1995 Heikki Tuuri
 # include "log0recv.h"
 /*****************************************************************//**
 Releases the item in the slot given. */
-static
+static __attribute__((nonnull))
 void
-mtr_memo_slot_release(
-/*==================*/
-	mtr_t*			mtr,	/*!< in: mtr */
+mtr_memo_slot_release_func(
+/*=======================*/
+#ifdef UNIV_DEBUG
+ 	mtr_t*			mtr,	/*!< in/out: mini-transaction */
+#endif /* UNIV_DEBUG */
 	mtr_memo_slot_t*	slot)	/*!< in: memo slot */
 {
-	void*	object;
-	ulint	type;
-
-	ut_ad(mtr);
-	ut_ad(slot);
-
-#ifndef UNIV_DEBUG
-	UT_NOT_USED(mtr);
-#endif /* UNIV_DEBUG */
-
-	object = slot->object;
-	type = slot->type;
+	void*	object = slot->object;
+	slot->object = NULL;
 
-	if (UNIV_LIKELY(object != NULL)) {
-		if (type <= MTR_MEMO_BUF_FIX) {
-			buf_page_release((buf_block_t*)object, type);
-		} else if (type == MTR_MEMO_S_LOCK) {
-			rw_lock_s_unlock((rw_lock_t*)object);
+	/* slot release is a local operation for the current mtr.
+	We must not be holding the flush_order mutex while
+	doing this. */
+	ut_ad(!log_flush_order_mutex_own());
+
+	switch (slot->type) {
+	case MTR_MEMO_PAGE_S_FIX:
+	case MTR_MEMO_PAGE_X_FIX:
+	case MTR_MEMO_BUF_FIX:
+		buf_page_release((buf_block_t*) object, slot->type);
+		break;
+	case MTR_MEMO_S_LOCK:
+		rw_lock_s_unlock((rw_lock_t*) object);
+		break;
+	case MTR_MEMO_X_LOCK:
+		rw_lock_x_unlock((rw_lock_t*) object);
+		break;
 #ifdef UNIV_DEBUG
-		} else if (type != MTR_MEMO_X_LOCK) {
-			ut_ad(type == MTR_MEMO_MODIFY);
-			ut_ad(mtr_memo_contains(mtr, object,
-						MTR_MEMO_PAGE_X_FIX));
+	default:
+		ut_ad(slot->type == MTR_MEMO_MODIFY);
+		ut_ad(mtr_memo_contains(mtr, object, MTR_MEMO_PAGE_X_FIX));
 #endif /* UNIV_DEBUG */
-		} else {
-			rw_lock_x_unlock((rw_lock_t*)object);
-		}
 	}
-
-	slot->object = NULL;
 }
 
+#ifdef UNIV_DEBUG
+# define mtr_memo_slot_release(mtr, slot) mtr_memo_slot_release_func(mtr, slot)
+#else /* UNIV_DEBUG */
+# define mtr_memo_slot_release(mtr, slot) mtr_memo_slot_release_func(slot)
+#endif /* UNIV_DEBUG */
+
 /**********************************************************//**
 Releases the mlocks and other objects stored in an mtr memo.
 They are released in the order opposite to which they were pushed
 to the memo. */
-static
+static __attribute__((nonnull))
 void
 mtr_memo_pop_all(
 /*=============*/
-	mtr_t*	mtr)	/*!< in: mtr */
+	mtr_t*	mtr)	/*!< in/out: mini-transaction */
 {
-	mtr_memo_slot_t* slot;
-	dyn_array_t*	memo;
-	ulint		offset;
+	const dyn_block_t*	block;
 
-	ut_ad(mtr);
 	ut_ad(mtr->magic_n == MTR_MAGIC_N);
 	ut_ad(mtr->state == MTR_COMMITTING); /* Currently only used in
 					     commit */
-	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);
-
-		mtr_memo_slot_release(mtr, slot);
+	for (block = dyn_array_get_last_block(&mtr->memo);
+	     block;
+	     block = dyn_array_get_prev_block(&mtr->memo, block)) {
+		const mtr_memo_slot_t*	start
+			= (mtr_memo_slot_t*) dyn_block_get_data(block);
+		mtr_memo_slot_t*	slot
+			= (mtr_memo_slot_t*) (dyn_block_get_data(block)
+					      + dyn_block_get_used(block));
+
+		ut_ad(!(dyn_block_get_used(block) % sizeof(mtr_memo_slot_t)));
+
+		while (slot-- != start) {
+			if (slot->object != NULL) {
+				mtr_memo_slot_release(mtr, slot);
+			}
+		}
 	}
 }
 
@@ -288,42 +297,36 @@ UNIV_INTERN
 void
 mtr_memo_release(
 /*=============*/
-	mtr_t*	mtr,	/*!< in: mtr */
+	mtr_t*	mtr,	/*!< in/out: mini-transaction */
 	void*	object,	/*!< in: object */
 	ulint	type)	/*!< in: object type: MTR_MEMO_S_LOCK, ... */
 {
-	mtr_memo_slot_t* slot;
-	dyn_array_t*	memo;
-	ulint		offset;
+	const dyn_block_t*	block;
 
-	ut_ad(mtr);
 	ut_ad(mtr->magic_n == MTR_MAGIC_N);
 	ut_ad(mtr->state == MTR_ACTIVE);
-
-	memo = &(mtr->memo);
-
-	offset = dyn_array_get_data_size(memo);
-
-	log_flush_order_mutex_enter();
-	while (offset > 0) {
-		offset -= sizeof(mtr_memo_slot_t);
-
-		slot = dyn_array_get_element(memo, offset);
-
-		if (object == slot->object && type == slot->type) {
-
-			/* We cannot release a page that has been written
-			to in the middle of a mini-transaction. */
-
-			ut_ad(!(mtr->modifications
-			       	&& slot->type == MTR_MEMO_PAGE_X_FIX));
-
-			mtr_memo_slot_release(mtr, slot);
-
-			break;
+	/* We cannot release a page that has been written to in the
+	middle of a mini-transaction. */
+	ut_ad(!mtr->modifications || type != MTR_MEMO_PAGE_X_FIX);
+
+	for (block = dyn_array_get_last_block(&mtr->memo);
+	     block;
+	     block = dyn_array_get_prev_block(&mtr->memo, block)) {
+		const mtr_memo_slot_t*	start
+			= (mtr_memo_slot_t*) dyn_block_get_data(block);
+		mtr_memo_slot_t*	slot
+			= (mtr_memo_slot_t*) (dyn_block_get_data(block)
+					      + dyn_block_get_used(block));
+
+		ut_ad(!(dyn_block_get_used(block) % sizeof(mtr_memo_slot_t)));
+
+		while (slot-- != start) {
+			if (object == slot->object && type == slot->type) {
+				mtr_memo_slot_release(mtr, slot);
+				return;
+			}
 		}
 	}
-	log_flush_order_mutex_exit();
 }
 #endif /* !UNIV_HOTBACKUP */