~drizzle-trunk/drizzle/development : contents of storage/innobase/mem/mem0pool.c at revision 36

~drizzle-trunk/drizzle/development : (revision 36)

/************************************************************************
The lowest-level memory management

(c) 1997 Innobase Oy

Created 5/12/1997 Heikki Tuuri
*************************************************************************/

#include "mem0pool.h"
#ifdef UNIV_NONINL
#include "mem0pool.ic"
#endif

#include "sync0sync.h"
#include "ut0mem.h"
#include "ut0lst.h"
#include "ut0byte.h"
#include "mem0mem.h"

/* We would like to use also the buffer frames to allocate memory. This
would be desirable, because then the memory consumption of the database
would be fixed, and we might even lock the buffer pool to the main memory.
The problem here is that the buffer management routines can themselves call
memory allocation, while the buffer pool mutex is reserved.

The main components of the memory consumption are:

1. buffer pool,
2. parsed and optimized SQL statements,
3. data dictionary cache,
4. log buffer,
5. locks for each transaction,
6. hash table for the adaptive index,
7. state and buffers for each SQL query currently being executed,
8. session for each user, and
9. stack for each OS thread.

Items 1 and 2 are managed by an LRU algorithm. Items 5 and 6 can potentially
consume very much memory. Items 7 and 8 should consume quite little memory,
and the OS should take care of item 9, which too should consume little memory.

A solution to the memory management:

1. the buffer pool size is set separately;
2. log buffer size is set separately;
3. the common pool size for all the other entries, except 8, is set separately.

Problems: we may waste memory if the common pool is set too big. Another
problem is the locks, which may take very much space in big transactions.
Then the shared pool size should be set very big. We can allow locks to take
space from the buffer pool, but the SQL optimizer is then unaware of the
usable size of the buffer pool. We could also combine the objects in the
common pool and the buffers in the buffer pool into a single LRU list and
manage it uniformly, but this approach does not take into account the parsing
and other costs unique to SQL statements.

The locks for a transaction can be seen as a part of the state of the
transaction. Hence, they should be stored in the common pool. We still
have the problem of a very big update transaction, for example, which
will set very many x-locks on rows, and the locks will consume a lot
of memory, say, half of the buffer pool size.

Another problem is what to do if we are not able to malloc a requested
block of memory from the common pool. Then we can request memory from
the operating system. If it does not help, a system error results.

Because 5 and 6 may potentially consume very much memory, we let them grow
into the buffer pool. We may let the locks of a transaction take frames
from the buffer pool, when the corresponding memory heap block has grown to
the size of a buffer frame. Similarly for the hash node cells of the locks,
and for the adaptive index. Thus, for each individual transaction, its locks
can occupy at most about the size of the buffer frame of memory in the common
pool, and after that its locks will grow into the buffer pool. */

/* Mask used to extract the free bit from area->size */
#define MEM_AREA_FREE	1

/* The smallest memory area total size */
#define MEM_AREA_MIN_SIZE	(2 * MEM_AREA_EXTRA_SIZE)


/* Data structure for a memory pool. The space is allocated using the buddy
algorithm, where free list i contains areas of size 2 to power i. */
struct mem_pool_struct{
	byte*		buf;		/* memory pool */
	ulint		size;		/* memory common pool size */
	ulint		reserved;	/* amount of currently allocated
					memory */
	mutex_t		mutex;		/* mutex protecting this struct */
	UT_LIST_BASE_NODE_T(mem_area_t)
			free_list[64];	/* lists of free memory areas: an
					area is put to the list whose number
					is the 2-logarithm of the area size */
};

/* The common memory pool */
mem_pool_t*	mem_comm_pool	= NULL;

/* We use this counter to check that the mem pool mutex does not leak;
this is to track a strange assertion failure reported at
mysql@lists.mysql.com */

ulint		mem_n_threads_inside		= 0;

/************************************************************************
Reserves the mem pool mutex. */

void
mem_pool_mutex_enter(void)
/*======================*/
{
	mutex_enter(&(mem_comm_pool->mutex));
}

/************************************************************************
Releases the mem pool mutex. */

void
mem_pool_mutex_exit(void)
/*=====================*/
{
	mutex_exit(&(mem_comm_pool->mutex));
}

/************************************************************************
Returns memory area size. */
UNIV_INLINE
ulint
mem_area_get_size(
/*==============*/
				/* out: size */
	mem_area_t*	area)	/* in: area */
{
	return(area->size_and_free & ~MEM_AREA_FREE);
}

/************************************************************************
Sets memory area size. */
UNIV_INLINE
void
mem_area_set_size(
/*==============*/
	mem_area_t*	area,	/* in: area */
	ulint		size)	/* in: size */
{
	area->size_and_free = (area->size_and_free & MEM_AREA_FREE)
		| size;
}

/************************************************************************
Returns memory area free bit. */
UNIV_INLINE
ibool
mem_area_get_free(
/*==============*/
				/* out: TRUE if free */
	mem_area_t*	area)	/* in: area */
{
#if TRUE != MEM_AREA_FREE
# error "TRUE != MEM_AREA_FREE"
#endif
	return(area->size_and_free & MEM_AREA_FREE);
}

/************************************************************************
Sets memory area free bit. */
UNIV_INLINE
void
mem_area_set_free(
/*==============*/
	mem_area_t*	area,	/* in: area */
	ibool		free)	/* in: free bit value */
{
#if TRUE != MEM_AREA_FREE
# error "TRUE != MEM_AREA_FREE"
#endif
	area->size_and_free = (area->size_and_free & ~MEM_AREA_FREE)
		| free;
}

/************************************************************************
Creates a memory pool. */

mem_pool_t*
mem_pool_create(
/*============*/
			/* out: memory pool */
	ulint	size)	/* in: pool size in bytes */
{
	mem_pool_t*	pool;
	mem_area_t*	area;
	ulint		i;
	ulint		used;

	ut_a(size > 10000);

	pool = ut_malloc(sizeof(mem_pool_t));

	/* We do not set the memory to zero (FALSE) in the pool,
	but only when allocated at a higher level in mem0mem.c.
	This is to avoid masking useful Purify warnings. */

	pool->buf = ut_malloc_low(size, FALSE, TRUE);
	pool->size = size;

	mutex_create(&pool->mutex, SYNC_MEM_POOL);

	/* Initialize the free lists */

	for (i = 0; i < 64; i++) {

		UT_LIST_INIT(pool->free_list[i]);
	}

	used = 0;

	while (size - used >= MEM_AREA_MIN_SIZE) {

		i = ut_2_log(size - used);

		if (ut_2_exp(i) > size - used) {

			/* ut_2_log rounds upward */

			i--;
		}

		area = (mem_area_t*)(pool->buf + used);

		mem_area_set_size(area, ut_2_exp(i));
		mem_area_set_free(area, TRUE);
		UNIV_MEM_FREE(MEM_AREA_EXTRA_SIZE + (byte*) area,
			      ut_2_exp(i) - MEM_AREA_EXTRA_SIZE);

		UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area);

		used = used + ut_2_exp(i);
	}

	ut_ad(size >= used);

	pool->reserved = 0;

	return(pool);
}

/************************************************************************
Fills the specified free list. */
static
ibool
mem_pool_fill_free_list(
/*====================*/
				/* out: TRUE if we were able to insert a
				block to the free list */
	ulint		i,	/* in: free list index */
	mem_pool_t*	pool)	/* in: memory pool */
{
	mem_area_t*	area;
	mem_area_t*	area2;
	ibool		ret;

	ut_ad(mutex_own(&(pool->mutex)));

	if (i >= 63) {
		/* We come here when we have run out of space in the
		memory pool: */

		return(FALSE);
	}

	area = UT_LIST_GET_FIRST(pool->free_list[i + 1]);

	if (area == NULL) {
		if (UT_LIST_GET_LEN(pool->free_list[i + 1]) > 0) {
			ut_print_timestamp(stderr);

			fprintf(stderr,
				"  InnoDB: Error: mem pool free list %lu"
				" length is %lu\n"
				"InnoDB: though the list is empty!\n",
				(ulong) i + 1,
				(ulong)
				UT_LIST_GET_LEN(pool->free_list[i + 1]));
		}

		ret = mem_pool_fill_free_list(i + 1, pool);

		if (ret == FALSE) {

			return(FALSE);
		}

		area = UT_LIST_GET_FIRST(pool->free_list[i + 1]);
	}

	if (UT_LIST_GET_LEN(pool->free_list[i + 1]) == 0) {
		mem_analyze_corruption(area);

		ut_error;
	}

	UT_LIST_REMOVE(free_list, pool->free_list[i + 1], area);

	area2 = (mem_area_t*)(((byte*)area) + ut_2_exp(i));
	UNIV_MEM_ALLOC(area2, MEM_AREA_EXTRA_SIZE);

	mem_area_set_size(area2, ut_2_exp(i));
	mem_area_set_free(area2, TRUE);

	UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area2);

	mem_area_set_size(area, ut_2_exp(i));

	UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area);

	return(TRUE);
}

/************************************************************************
Allocates memory from a pool. NOTE: This low-level function should only be
used in mem0mem.*! */

void*
mem_area_alloc(
/*===========*/
				/* out, own: allocated memory buffer */
	ulint		size,	/* in: allocated size in bytes; for optimum
				space usage, the size should be a power of 2
				minus MEM_AREA_EXTRA_SIZE */
	mem_pool_t*	pool)	/* in: memory pool */
{
	mem_area_t*	area;
	ulint		n;
	ibool		ret;

	n = ut_2_log(ut_max(size + MEM_AREA_EXTRA_SIZE, MEM_AREA_MIN_SIZE));

	mutex_enter(&(pool->mutex));
	mem_n_threads_inside++;

	ut_a(mem_n_threads_inside == 1);

	area = UT_LIST_GET_FIRST(pool->free_list[n]);

	if (area == NULL) {
		ret = mem_pool_fill_free_list(n, pool);

		if (ret == FALSE) {
			/* Out of memory in memory pool: we try to allocate
			from the operating system with the regular malloc: */

			mem_n_threads_inside--;
			mutex_exit(&(pool->mutex));

			return(ut_malloc(size));
		}

		area = UT_LIST_GET_FIRST(pool->free_list[n]);
	}

	if (!mem_area_get_free(area)) {
		fprintf(stderr,
			"InnoDB: Error: Removing element from mem pool"
			" free list %lu though the\n"
			"InnoDB: element is not marked free!\n",
			(ulong) n);

		mem_analyze_corruption(area);

		/* Try to analyze a strange assertion failure reported at
		mysql@lists.mysql.com where the free bit IS 1 in the
		hex dump above */

		if (mem_area_get_free(area)) {
			fprintf(stderr,
				"InnoDB: Probably a race condition"
				" because now the area is marked free!\n");
		}

		ut_error;
	}

	if (UT_LIST_GET_LEN(pool->free_list[n]) == 0) {
		fprintf(stderr,
			"InnoDB: Error: Removing element from mem pool"
			" free list %lu\n"
			"InnoDB: though the list length is 0!\n",
			(ulong) n);
		mem_analyze_corruption(area);

		ut_error;
	}

	ut_ad(mem_area_get_size(area) == ut_2_exp(n));

	mem_area_set_free(area, FALSE);

	UT_LIST_REMOVE(free_list, pool->free_list[n], area);

	pool->reserved += mem_area_get_size(area);

	mem_n_threads_inside--;
	mutex_exit(&(pool->mutex));

	ut_ad(mem_pool_validate(pool));
	UNIV_MEM_ALLOC(MEM_AREA_EXTRA_SIZE + (byte*)area,
		       ut_2_exp(n) - MEM_AREA_EXTRA_SIZE);

	return((void*)(MEM_AREA_EXTRA_SIZE + ((byte*)area)));
}

/************************************************************************
Gets the buddy of an area, if it exists in pool. */
UNIV_INLINE
mem_area_t*
mem_area_get_buddy(
/*===============*/
				/* out: the buddy, NULL if no buddy in pool */
	mem_area_t*	area,	/* in: memory area */
	ulint		size,	/* in: memory area size */
	mem_pool_t*	pool)	/* in: memory pool */
{
	mem_area_t*	buddy;

	ut_ad(size != 0);

	if (((((byte*)area) - pool->buf) % (2 * size)) == 0) {

		/* The buddy is in a higher address */

		buddy = (mem_area_t*)(((byte*)area) + size);

		if ((((byte*)buddy) - pool->buf) + size > pool->size) {

			/* The buddy is not wholly contained in the pool:
			there is no buddy */

			buddy = NULL;
		}
	} else {
		/* The buddy is in a lower address; NOTE that area cannot
		be at the pool lower end, because then we would end up to
		the upper branch in this if-clause: the remainder would be
		0 */

		buddy = (mem_area_t*)(((byte*)area) - size);
	}

	return(buddy);
}

/************************************************************************
Frees memory to a pool. */

void
mem_area_free(
/*==========*/
	void*		ptr,	/* in, own: pointer to allocated memory
				buffer */
	mem_pool_t*	pool)	/* in: memory pool */
{
	mem_area_t*	area;
	mem_area_t*	buddy;
	void*		new_ptr;
	ulint		size;
	ulint		n;

	/* It may be that the area was really allocated from the OS with
	regular malloc: check if ptr points within our memory pool */

	if ((byte*)ptr < pool->buf || (byte*)ptr >= pool->buf + pool->size) {
		ut_free(ptr);

		return;
	}

	area = (mem_area_t*) (((byte*)ptr) - MEM_AREA_EXTRA_SIZE);

	if (mem_area_get_free(area)) {
		fprintf(stderr,
			"InnoDB: Error: Freeing element to mem pool"
			" free list though the\n"
			"InnoDB: element is marked free!\n");

		mem_analyze_corruption(area);
		ut_error;
	}

	size = mem_area_get_size(area);
	UNIV_MEM_FREE(ptr, size - MEM_AREA_EXTRA_SIZE);

	if (size == 0) {
		fprintf(stderr,
			"InnoDB: Error: Mem area size is 0. Possibly a"
			" memory overrun of the\n"
			"InnoDB: previous allocated area!\n");

		mem_analyze_corruption(area);
		ut_error;
	}

#ifdef UNIV_LIGHT_MEM_DEBUG
	if (((byte*)area) + size < pool->buf + pool->size) {

		ulint	next_size;

		next_size = mem_area_get_size(
			(mem_area_t*)(((byte*)area) + size));
		if (ut_2_power_up(next_size) != next_size) {
			fprintf(stderr,
				"InnoDB: Error: Memory area size %lu,"
				" next area size %lu not a power of 2!\n"
				"InnoDB: Possibly a memory overrun of"
				" the buffer being freed here.\n",
				(ulong) size, (ulong) next_size);
			mem_analyze_corruption(area);

			ut_error;
		}
	}
#endif
	buddy = mem_area_get_buddy(area, size, pool);

	n = ut_2_log(size);

	mutex_enter(&(pool->mutex));
	mem_n_threads_inside++;

	ut_a(mem_n_threads_inside == 1);

	if (buddy && mem_area_get_free(buddy)
	    && (size == mem_area_get_size(buddy))) {

		/* The buddy is in a free list */

		if ((byte*)buddy < (byte*)area) {
			new_ptr = ((byte*)buddy) + MEM_AREA_EXTRA_SIZE;

			mem_area_set_size(buddy, 2 * size);
			mem_area_set_free(buddy, FALSE);
		} else {
			new_ptr = ptr;

			mem_area_set_size(area, 2 * size);
		}

		/* Remove the buddy from its free list and merge it to area */

		UT_LIST_REMOVE(free_list, pool->free_list[n], buddy);

		pool->reserved += ut_2_exp(n);

		mem_n_threads_inside--;
		mutex_exit(&(pool->mutex));

		mem_area_free(new_ptr, pool);

		return;
	} else {
		UT_LIST_ADD_FIRST(free_list, pool->free_list[n], area);

		mem_area_set_free(area, TRUE);

		ut_ad(pool->reserved >= size);

		pool->reserved -= size;
	}

	mem_n_threads_inside--;
	mutex_exit(&(pool->mutex));

	ut_ad(mem_pool_validate(pool));
}

/************************************************************************
Validates a memory pool. */

ibool
mem_pool_validate(
/*==============*/
				/* out: TRUE if ok */
	mem_pool_t*	pool)	/* in: memory pool */
{
	mem_area_t*	area;
	mem_area_t*	buddy;
	ulint		free;
	ulint		i;

	mutex_enter(&(pool->mutex));

	free = 0;

	for (i = 0; i < 64; i++) {

		UT_LIST_VALIDATE(free_list, mem_area_t, pool->free_list[i]);

		area = UT_LIST_GET_FIRST(pool->free_list[i]);

		while (area != NULL) {
			ut_a(mem_area_get_free(area));
			ut_a(mem_area_get_size(area) == ut_2_exp(i));

			buddy = mem_area_get_buddy(area, ut_2_exp(i), pool);

			ut_a(!buddy || !mem_area_get_free(buddy)
			     || (ut_2_exp(i) != mem_area_get_size(buddy)));

			area = UT_LIST_GET_NEXT(free_list, area);

			free += ut_2_exp(i);
		}
	}

	ut_a(free + pool->reserved == pool->size);

	mutex_exit(&(pool->mutex));

	return(TRUE);
}

/************************************************************************
Prints info of a memory pool. */

void
mem_pool_print_info(
/*================*/
	FILE*		outfile,/* in: output file to write to */
	mem_pool_t*	pool)	/* in: memory pool */
{
	ulint		i;

	mem_pool_validate(pool);

	fprintf(outfile, "INFO OF A MEMORY POOL\n");

	mutex_enter(&(pool->mutex));

	for (i = 0; i < 64; i++) {
		if (UT_LIST_GET_LEN(pool->free_list[i]) > 0) {

			fprintf(outfile,
				"Free list length %lu for"
				" blocks of size %lu\n",
				(ulong) UT_LIST_GET_LEN(pool->free_list[i]),
				(ulong) ut_2_exp(i));
		}
	}

	fprintf(outfile, "Pool size %lu, reserved %lu.\n", (ulong) pool->size,
		(ulong) pool->reserved);
	mutex_exit(&(pool->mutex));
}

/************************************************************************
Returns the amount of reserved memory. */

ulint
mem_pool_get_reserved(
/*==================*/
				/* out: reserved memory in bytes */
	mem_pool_t*	pool)	/* in: memory pool */
{
	ulint	reserved;

	mutex_enter(&(pool->mutex));

	reserved = pool->reserved;

	mutex_exit(&(pool->mutex));

	return(reserved);
}

1 by brian clean slate	1	/************************************************************************
	2	The lowest-level memory management
	3
	4	(c) 1997 Innobase Oy
	5
	6	Created 5/12/1997 Heikki Tuuri
	7	*************************************************************************/
	8
	9	#include "mem0pool.h"
	10	#ifdef UNIV_NONINL
	11	#include "mem0pool.ic"
	12	#endif
	13
	14	#include "sync0sync.h"
	15	#include "ut0mem.h"
	16	#include "ut0lst.h"
	17	#include "ut0byte.h"
	18	#include "mem0mem.h"
	19
	20	/* We would like to use also the buffer frames to allocate memory. This
	21	would be desirable, because then the memory consumption of the database
	22	would be fixed, and we might even lock the buffer pool to the main memory.
	23	The problem here is that the buffer management routines can themselves call
	24	memory allocation, while the buffer pool mutex is reserved.
	25
	26	The main components of the memory consumption are:
	27
	28	1. buffer pool,
	29	2. parsed and optimized SQL statements,
	30	3. data dictionary cache,
	31	4. log buffer,
	32	5. locks for each transaction,
	33	6. hash table for the adaptive index,
	34	7. state and buffers for each SQL query currently being executed,
	35	8. session for each user, and
	36	9. stack for each OS thread.
	37
	38	Items 1 and 2 are managed by an LRU algorithm. Items 5 and 6 can potentially
	39	consume very much memory. Items 7 and 8 should consume quite little memory,
	40	and the OS should take care of item 9, which too should consume little memory.
	41
	42	A solution to the memory management:
	43
	44	1. the buffer pool size is set separately;
	45	2. log buffer size is set separately;
	46	3. the common pool size for all the other entries, except 8, is set separately.
	47
	48	Problems: we may waste memory if the common pool is set too big. Another
	49	problem is the locks, which may take very much space in big transactions.
	50	Then the shared pool size should be set very big. We can allow locks to take
	51	space from the buffer pool, but the SQL optimizer is then unaware of the
	52	usable size of the buffer pool. We could also combine the objects in the
	53	common pool and the buffers in the buffer pool into a single LRU list and
	54	manage it uniformly, but this approach does not take into account the parsing
	55	and other costs unique to SQL statements.
	56
	57	The locks for a transaction can be seen as a part of the state of the
	58	transaction. Hence, they should be stored in the common pool. We still
	59	have the problem of a very big update transaction, for example, which
	60	will set very many x-locks on rows, and the locks will consume a lot
	61	of memory, say, half of the buffer pool size.
	62
	63	Another problem is what to do if we are not able to malloc a requested
	64	block of memory from the common pool. Then we can request memory from
65	the operating system. If it does not help, a system error results.
66
67	Because 5 and 6 may potentially consume very much memory, we let them grow
68	into the buffer pool. We may let the locks of a transaction take frames
69	from the buffer pool, when the corresponding memory heap block has grown to
70	the size of a buffer frame. Similarly for the hash node cells of the locks,
71	and for the adaptive index. Thus, for each individual transaction, its locks
72	can occupy at most about the size of the buffer frame of memory in the common
73	pool, and after that its locks will grow into the buffer pool. */
74
75	/* Mask used to extract the free bit from area->size */
76	#define MEM_AREA_FREE 1
77
78	/* The smallest memory area total size */
79	#define MEM_AREA_MIN_SIZE (2 * MEM_AREA_EXTRA_SIZE)
80
81
82	/* Data structure for a memory pool. The space is allocated using the buddy
83	algorithm, where free list i contains areas of size 2 to power i. */
84	struct mem_pool_struct{
85	byte* buf; /* memory pool */
86	ulint size; /* memory common pool size */
87	ulint reserved; /* amount of currently allocated
88	memory */
89	mutex_t mutex; /* mutex protecting this struct */
90	UT_LIST_BASE_NODE_T(mem_area_t)
91	free_list[64]; /* lists of free memory areas: an
92	area is put to the list whose number
93	is the 2-logarithm of the area size */
94	};
95
96	/* The common memory pool */
97	mem_pool_t* mem_comm_pool = NULL;
98
99	/* We use this counter to check that the mem pool mutex does not leak;
100	this is to track a strange assertion failure reported at
101	mysql@lists.mysql.com */
102
103	ulint mem_n_threads_inside = 0;
104
105	/************************************************************************
106	Reserves the mem pool mutex. */
107
108	void
109	mem_pool_mutex_enter(void)
110	/======================/
111	{
112	mutex_enter(&(mem_comm_pool->mutex));
113	}
114
115	/************************************************************************
116	Releases the mem pool mutex. */
117
118	void
119	mem_pool_mutex_exit(void)
120	/=====================/
121	{
122	mutex_exit(&(mem_comm_pool->mutex));
123	}
124
125	/************************************************************************
126	Returns memory area size. */
127	UNIV_INLINE
128	ulint
129	mem_area_get_size(
130	/==============/
131	/* out: size */
132	mem_area_t* area) /* in: area */
133	{
134	return(area->size_and_free & ~MEM_AREA_FREE);
135	}
136
137	/************************************************************************
138	Sets memory area size. */
139	UNIV_INLINE
140	void
141	mem_area_set_size(
142	/==============/
143	mem_area_t* area, /* in: area */
144	ulint size) /* in: size */
145	{
146	area->size_and_free = (area->size_and_free & MEM_AREA_FREE)
147	\| size;
148	}
149
150	/************************************************************************
151	Returns memory area free bit. */
152	UNIV_INLINE
153	ibool
154	mem_area_get_free(
155	/==============/
156	/* out: TRUE if free */
157	mem_area_t* area) /* in: area */
158	{
159	#if TRUE != MEM_AREA_FREE
160	# error "TRUE != MEM_AREA_FREE"
161	#endif
162	return(area->size_and_free & MEM_AREA_FREE);
163	}
164
165	/************************************************************************
166	Sets memory area free bit. */
167	UNIV_INLINE
168	void
169	mem_area_set_free(
170	/==============/
171	mem_area_t* area, /* in: area */
172	ibool free) /* in: free bit value */
173	{
174	#if TRUE != MEM_AREA_FREE
175	# error "TRUE != MEM_AREA_FREE"
176	#endif
177	area->size_and_free = (area->size_and_free & ~MEM_AREA_FREE)
178	\| free;
179	}
180
181	/************************************************************************
182	Creates a memory pool. */
183
184	mem_pool_t*
185	mem_pool_create(
186	/============/
187	/* out: memory pool */
188	ulint size) /* in: pool size in bytes */
189	{
190	mem_pool_t* pool;
191	mem_area_t* area;
192	ulint i;
193	ulint used;
194
195	ut_a(size > 10000);
196
197	pool = ut_malloc(sizeof(mem_pool_t));
198
199	/* We do not set the memory to zero (FALSE) in the pool,
200	but only when allocated at a higher level in mem0mem.c.
201	This is to avoid masking useful Purify warnings. */
202
203	pool->buf = ut_malloc_low(size, FALSE, TRUE);
204	pool->size = size;
205
206	mutex_create(&pool->mutex, SYNC_MEM_POOL);
207
208	/* Initialize the free lists */
209
210	for (i = 0; i < 64; i++) {
211
212	UT_LIST_INIT(pool->free_list[i]);
213	}
214
215	used = 0;
216
217	while (size - used >= MEM_AREA_MIN_SIZE) {
218
219	i = ut_2_log(size - used);
220
221	if (ut_2_exp(i) > size - used) {
222
223	/* ut_2_log rounds upward */
224
225	i--;
226	}
227
228	area = (mem_area_t*)(pool->buf + used);
229
230	mem_area_set_size(area, ut_2_exp(i));
231	mem_area_set_free(area, TRUE);
232	UNIV_MEM_FREE(MEM_AREA_EXTRA_SIZE + (byte*) area,
233	ut_2_exp(i) - MEM_AREA_EXTRA_SIZE);
234
235	UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area);
236
237	used = used + ut_2_exp(i);
238	}
239
240	ut_ad(size >= used);
241
242	pool->reserved = 0;
243
244	return(pool);
245	}
246
247	/************************************************************************
248	Fills the specified free list. */
249	static
250	ibool
251	mem_pool_fill_free_list(
252	/====================/
253	/* out: TRUE if we were able to insert a
254	block to the free list */
255	ulint i, /* in: free list index */
256	mem_pool_t* pool) /* in: memory pool */
257	{
258	mem_area_t* area;
259	mem_area_t* area2;
260	ibool ret;
261
262	ut_ad(mutex_own(&(pool->mutex)));
263
264	if (i >= 63) {
265	/* We come here when we have run out of space in the
266	memory pool: */
267
268	return(FALSE);
269	}
270
271	area = UT_LIST_GET_FIRST(pool->free_list[i + 1]);
272
273	if (area == NULL) {
274	if (UT_LIST_GET_LEN(pool->free_list[i + 1]) > 0) {
275	ut_print_timestamp(stderr);
276
277	fprintf(stderr,
278	" InnoDB: Error: mem pool free list %lu"
279	" length is %lu\n"
280	"InnoDB: though the list is empty!\n",
281	(ulong) i + 1,
282	(ulong)
283	UT_LIST_GET_LEN(pool->free_list[i + 1]));
284	}
285
286	ret = mem_pool_fill_free_list(i + 1, pool);
287
288	if (ret == FALSE) {
289
290	return(FALSE);
291	}
292
293	area = UT_LIST_GET_FIRST(pool->free_list[i + 1]);
294	}
295
296	if (UT_LIST_GET_LEN(pool->free_list[i + 1]) == 0) {
297	mem_analyze_corruption(area);
298
299	ut_error;
300	}
301
302	UT_LIST_REMOVE(free_list, pool->free_list[i + 1], area);
303
304	area2 = (mem_area_t)(((byte)area) + ut_2_exp(i));
305	UNIV_MEM_ALLOC(area2, MEM_AREA_EXTRA_SIZE);
306
307	mem_area_set_size(area2, ut_2_exp(i));
308	mem_area_set_free(area2, TRUE);
309
310	UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area2);
311
312	mem_area_set_size(area, ut_2_exp(i));
313
314	UT_LIST_ADD_FIRST(free_list, pool->free_list[i], area);
315
316	return(TRUE);
317	}
318
319	/************************************************************************
320	Allocates memory from a pool. NOTE: This low-level function should only be
321	used in mem0mem.! /
322
323	void*
324	mem_area_alloc(
325	/===========/
326	/* out, own: allocated memory buffer */
327	ulint size, /* in: allocated size in bytes; for optimum
328	space usage, the size should be a power of 2
329	minus MEM_AREA_EXTRA_SIZE */
330	mem_pool_t* pool) /* in: memory pool */
331	{
332	mem_area_t* area;
333	ulint n;
334	ibool ret;
335
336	n = ut_2_log(ut_max(size + MEM_AREA_EXTRA_SIZE, MEM_AREA_MIN_SIZE));
337
338	mutex_enter(&(pool->mutex));
339	mem_n_threads_inside++;
340
341	ut_a(mem_n_threads_inside == 1);
342
343	area = UT_LIST_GET_FIRST(pool->free_list[n]);
344
345	if (area == NULL) {
346	ret = mem_pool_fill_free_list(n, pool);
347
348	if (ret == FALSE) {
349	/* Out of memory in memory pool: we try to allocate
350	from the operating system with the regular malloc: */
351
352	mem_n_threads_inside--;
353	mutex_exit(&(pool->mutex));
354
355	return(ut_malloc(size));
356	}
357
358	area = UT_LIST_GET_FIRST(pool->free_list[n]);
359	}
360
361	if (!mem_area_get_free(area)) {
362	fprintf(stderr,
363	"InnoDB: Error: Removing element from mem pool"
364	" free list %lu though the\n"
365	"InnoDB: element is not marked free!\n",
366	(ulong) n);
367
368	mem_analyze_corruption(area);
369
370	/* Try to analyze a strange assertion failure reported at
371	mysql@lists.mysql.com where the free bit IS 1 in the
372	hex dump above */
373
374	if (mem_area_get_free(area)) {
375	fprintf(stderr,
376	"InnoDB: Probably a race condition"
377	" because now the area is marked free!\n");
378	}
379
380	ut_error;
381	}
382
383	if (UT_LIST_GET_LEN(pool->free_list[n]) == 0) {
384	fprintf(stderr,
385	"InnoDB: Error: Removing element from mem pool"
386	" free list %lu\n"
387	"InnoDB: though the list length is 0!\n",
388	(ulong) n);
389	mem_analyze_corruption(area);
390
391	ut_error;
392	}
393
394	ut_ad(mem_area_get_size(area) == ut_2_exp(n));
395
396	mem_area_set_free(area, FALSE);
397
398	UT_LIST_REMOVE(free_list, pool->free_list[n], area);
399
400	pool->reserved += mem_area_get_size(area);
401
402	mem_n_threads_inside--;
403	mutex_exit(&(pool->mutex));
404
405	ut_ad(mem_pool_validate(pool));
406	UNIV_MEM_ALLOC(MEM_AREA_EXTRA_SIZE + (byte*)area,
407	ut_2_exp(n) - MEM_AREA_EXTRA_SIZE);
408
409	return((void)(MEM_AREA_EXTRA_SIZE + ((byte)area)));
410	}
411
412	/************************************************************************
413	Gets the buddy of an area, if it exists in pool. */
414	UNIV_INLINE
415	mem_area_t*
416	mem_area_get_buddy(
417	/===============/
418	/* out: the buddy, NULL if no buddy in pool */
419	mem_area_t* area, /* in: memory area */
420	ulint size, /* in: memory area size */
421	mem_pool_t* pool) /* in: memory pool */
422	{
423	mem_area_t* buddy;
424
425	ut_ad(size != 0);
426
427	if (((((byte)area) - pool->buf) % (2 size)) == 0) {
428
429	/* The buddy is in a higher address */
430
431	buddy = (mem_area_t)(((byte)area) + size);
432
433	if ((((byte*)buddy) - pool->buf) + size > pool->size) {
434
435	/* The buddy is not wholly contained in the pool:
436	there is no buddy */
437
438	buddy = NULL;
439	}
440	} else {
441	/* The buddy is in a lower address; NOTE that area cannot
442	be at the pool lower end, because then we would end up to
443	the upper branch in this if-clause: the remainder would be
444	0 */
445
446	buddy = (mem_area_t)(((byte)area) - size);
447	}
448
449	return(buddy);
450	}
451
452	/************************************************************************
453	Frees memory to a pool. */
454
455	void
456	mem_area_free(
457	/==========/
458	void* ptr, /* in, own: pointer to allocated memory
459	buffer */
460	mem_pool_t* pool) /* in: memory pool */
461	{
462	mem_area_t* area;
463	mem_area_t* buddy;
464	void* new_ptr;
465	ulint size;
466	ulint n;
467
468	/* It may be that the area was really allocated from the OS with
469	regular malloc: check if ptr points within our memory pool */
470
471	if ((byte)ptr < pool->buf \|\| (byte)ptr >= pool->buf + pool->size) {
472	ut_free(ptr);
473
474	return;
475	}
476
477	area = (mem_area_t) (((byte)ptr) - MEM_AREA_EXTRA_SIZE);
478
479	if (mem_area_get_free(area)) {
480	fprintf(stderr,
481	"InnoDB: Error: Freeing element to mem pool"
482	" free list though the\n"
483	"InnoDB: element is marked free!\n");
484
485	mem_analyze_corruption(area);
486	ut_error;
487	}
488
489	size = mem_area_get_size(area);
490	UNIV_MEM_FREE(ptr, size - MEM_AREA_EXTRA_SIZE);
491
492	if (size == 0) {
493	fprintf(stderr,
494	"InnoDB: Error: Mem area size is 0. Possibly a"
495	" memory overrun of the\n"
496	"InnoDB: previous allocated area!\n");
497
498	mem_analyze_corruption(area);
499	ut_error;
500	}
501
502	#ifdef UNIV_LIGHT_MEM_DEBUG
503	if (((byte*)area) + size < pool->buf + pool->size) {
504
505	ulint next_size;
506
507	next_size = mem_area_get_size(
508	(mem_area_t)(((byte)area) + size));
509	if (ut_2_power_up(next_size) != next_size) {
510	fprintf(stderr,
511	"InnoDB: Error: Memory area size %lu,"
512	" next area size %lu not a power of 2!\n"
513	"InnoDB: Possibly a memory overrun of"
514	" the buffer being freed here.\n",
515	(ulong) size, (ulong) next_size);
516	mem_analyze_corruption(area);
517
518	ut_error;
519	}
520	}
521	#endif
522	buddy = mem_area_get_buddy(area, size, pool);
523
524	n = ut_2_log(size);
525
526	mutex_enter(&(pool->mutex));
527	mem_n_threads_inside++;
528
529	ut_a(mem_n_threads_inside == 1);
530
531	if (buddy && mem_area_get_free(buddy)
532	&& (size == mem_area_get_size(buddy))) {
533
534	/* The buddy is in a free list */
535
536	if ((byte)buddy < (byte)area) {
537	new_ptr = ((byte*)buddy) + MEM_AREA_EXTRA_SIZE;
538
539	mem_area_set_size(buddy, 2 * size);
540	mem_area_set_free(buddy, FALSE);
541	} else {
542	new_ptr = ptr;
543
544	mem_area_set_size(area, 2 * size);
545	}
546
547	/* Remove the buddy from its free list and merge it to area */
548
549	UT_LIST_REMOVE(free_list, pool->free_list[n], buddy);
550
551	pool->reserved += ut_2_exp(n);
552
553	mem_n_threads_inside--;
554	mutex_exit(&(pool->mutex));
555
556	mem_area_free(new_ptr, pool);
557
558	return;
559	} else {
560	UT_LIST_ADD_FIRST(free_list, pool->free_list[n], area);
561
562	mem_area_set_free(area, TRUE);
563
564	ut_ad(pool->reserved >= size);
565
566	pool->reserved -= size;
567	}
568
569	mem_n_threads_inside--;
570	mutex_exit(&(pool->mutex));
571
572	ut_ad(mem_pool_validate(pool));
573	}
574
575	/************************************************************************
576	Validates a memory pool. */
577
578	ibool
579	mem_pool_validate(
580	/==============/
581	/* out: TRUE if ok */
582	mem_pool_t* pool) /* in: memory pool */
583	{
584	mem_area_t* area;
585	mem_area_t* buddy;
586	ulint free;
587	ulint i;
588
589	mutex_enter(&(pool->mutex));
590
591	free = 0;
592
593	for (i = 0; i < 64; i++) {
594
595	UT_LIST_VALIDATE(free_list, mem_area_t, pool->free_list[i]);
596
597	area = UT_LIST_GET_FIRST(pool->free_list[i]);
598
599	while (area != NULL) {
600	ut_a(mem_area_get_free(area));
601	ut_a(mem_area_get_size(area) == ut_2_exp(i));
602
603	buddy = mem_area_get_buddy(area, ut_2_exp(i), pool);
604
605	ut_a(!buddy \|\| !mem_area_get_free(buddy)
606	\|\| (ut_2_exp(i) != mem_area_get_size(buddy)));
607
608	area = UT_LIST_GET_NEXT(free_list, area);
609
610	free += ut_2_exp(i);
611	}
612	}
613
614	ut_a(free + pool->reserved == pool->size);
615
616	mutex_exit(&(pool->mutex));
617
618	return(TRUE);
619	}
620
621	/************************************************************************
622	Prints info of a memory pool. */
623
624	void
625	mem_pool_print_info(
626	/================/
627	FILE* outfile,/* in: output file to write to */
628	mem_pool_t* pool) /* in: memory pool */
629	{
630	ulint i;
631
632	mem_pool_validate(pool);
633
634	fprintf(outfile, "INFO OF A MEMORY POOL\n");
635
636	mutex_enter(&(pool->mutex));
637
638	for (i = 0; i < 64; i++) {
639	if (UT_LIST_GET_LEN(pool->free_list[i]) > 0) {
640
641	fprintf(outfile,
642	"Free list length %lu for"
643	" blocks of size %lu\n",
644	(ulong) UT_LIST_GET_LEN(pool->free_list[i]),
645	(ulong) ut_2_exp(i));
646	}
647	}
648
649	fprintf(outfile, "Pool size %lu, reserved %lu.\n", (ulong) pool->size,
650	(ulong) pool->reserved);
651	mutex_exit(&(pool->mutex));
652	}
653
654	/************************************************************************
655	Returns the amount of reserved memory. */
656
657	ulint
658	mem_pool_get_reserved(
659	/==================/
660	/* out: reserved memory in bytes */
661	mem_pool_t* pool) /* in: memory pool */
662	{
663	ulint reserved;
664
665	mutex_enter(&(pool->mutex));
666
667	reserved = pool->reserved;
668
669	mutex_exit(&(pool->mutex));
670
671	return(reserved);
672	}