mem0mem.h File Reference

The memory management. More...

#include "mach0data.h"
#include "ut0byte.h"
#include "ut0mem.h"
#include "ut0rnd.h"
#include <limits.h>
#include <functional>
#include <memory>
#include <type_traits>
#include "mem0mem.ic"

Go to the source code of this file.

Classes
struct	mem_block_info_t
	The info structure stored at the beginning of a heap block. More...
class	mem_heap_allocator< T >
	A C++ wrapper class to the mem_heap_t routines, so that it can be used as an STL allocator. More...
struct	mem_heap_allocator< T >::rebind< U >
	Allocators are required to supply the below template class member which enables the possibility of obtaining a related allocator, parametrized in terms of a different type. More...
struct	Scoped_heap
	Heap wrapper that destroys the heap instance when it goes out of scope. More...
struct	Scoped_heap::mem_heap_free_functor
	A functor with no state to be used for mem_heap destruction. More...

Macros
#define	MEM_BLOCK_STANDARD_SIZE    (UNIV_PAGE_SIZE >= 16384 ? 8000 : MEM_MAX_ALLOC_IN_BUF)
#define	MEM_MAX_ALLOC_IN_BUF
	If a memory heap is allowed to grow into the buffer pool, the following is the maximum size for a single allocated buffer (from UNIV_PAGE_SIZE we subtract MEM_BLOCK_HEADER_SIZE and 2*MEM_NO_MANS_LAND since it's something we always need to put. More...
#define	MEM_BLOCK_HEADER_SIZE    ut_calc_align(sizeof(mem_block_info_t), UNIV_MEM_ALIGNMENT)

Typedefs
typedef struct mem_block_info_t	mem_block_t
	A block of a memory heap consists of the info structure followed by an area of memory. More...
typedef mem_block_t	mem_heap_t
	A memory heap is a nonempty linear list of memory blocks. More...

Functions
static uint64_t	MEM_SPACE_NEEDED (uint64_t N)
	Space needed when allocating for a user a field of length N. More...
static mem_heap_t *	mem_heap_create (ulint size, ut::Location loc, ulint type=MEM_HEAP_DYNAMIC)
	Creates a memory heap. More...
static void	mem_heap_free (mem_heap_t *heap)
	Frees the space occupied by a memory heap. More...
static void *	mem_heap_zalloc (mem_heap_t *heap, ulint n)
	Allocates and zero-fills n bytes of memory from a memory heap. More...
static void *	mem_heap_alloc (mem_heap_t *heap, ulint n)
	Allocates n bytes of memory from a memory heap. More...
static byte *	mem_heap_get_heap_top (mem_heap_t *heap)
	Returns a pointer to the heap top. More...
static void	mem_heap_free_heap_top (mem_heap_t *heap, byte *old_top)
	Frees the space in a memory heap exceeding the pointer given. More...
static void	mem_heap_empty (mem_heap_t *heap)
	Empties a memory heap. More...
static void *	mem_heap_get_top (mem_heap_t *heap, ulint n)
	Returns a pointer to the topmost element in a memory heap. More...
static bool	mem_heap_is_top (mem_heap_t *heap, const void *buf, ulint buf_sz)
	Checks if a given chunk of memory is the topmost element stored in the heap. More...
static void *	mem_heap_replace (mem_heap_t *heap, const void *top, ulint top_sz, ulint new_sz)
	Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element. More...
static void *	mem_heap_dup_replace (mem_heap_t *heap, const void *top, ulint top_sz, const void *data, ulint data_sz)
	Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element and then copy the specified data to it. More...
static char *	mem_heap_strdup_replace (mem_heap_t *heap, const void *top, ulint top_sz, const char *str)
	Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element and then copy the specified string to it. More...
static void	mem_heap_free_top (mem_heap_t *heap, ulint n)
	Frees the topmost element in a memory heap. More...
static size_t	mem_heap_get_size (mem_heap_t *heap)
	Returns the space in bytes occupied by a memory heap. More...
static char *	mem_strdup (const char *str)
	Duplicates a NUL-terminated string. More...
static char *	mem_strdupl (const char *str, ulint len)
	Makes a NUL-terminated copy of a nonterminated string. More...
char *	mem_heap_strdup (mem_heap_t *heap, const char *str)
	Duplicates a NUL-terminated string, allocated from a memory heap. More...
static char *	mem_heap_strdupl (mem_heap_t *heap, const char *str, ulint len)
	Makes a NUL-terminated copy of a nonterminated string, allocated from a memory heap. More...
char *	mem_heap_strcat (mem_heap_t *heap, const char *s1, const char *s2)
	Concatenate two strings and return the result, using a memory heap. More...
void *	mem_heap_dup (mem_heap_t *heap, const void *data, ulint len)
	Duplicate a block of data, allocated from a memory heap. More...
char *	mem_heap_printf (mem_heap_t *heap, const char *format,...)
	A simple sprintf replacement that dynamically allocates the space for the formatted string from the given heap. More...
static void	mem_block_validate (const mem_heap_t *heap)
	Checks that an object is a memory heap (or a block of it) More...
void	mem_heap_validate (const mem_heap_t *heap)
	Validates the contents of a memory heap. More...
template<class T >
bool	operator== (const mem_heap_allocator< T > &left, const mem_heap_allocator< T > &right)
template<class T >
bool	operator!= (const mem_heap_allocator< T > &left, const mem_heap_allocator< T > &right)

Variables
constexpr uint32_t	MEM_HEAP_DYNAMIC = 0
	Types of allocation for memory heaps: DYNAMIC means allocation from the dynamic memory pool of the C compiler, BUFFER means allocation from the buffer pool; the latter method is used for very big heaps. More...
constexpr uint32_t	MEM_HEAP_BUFFER = 1
constexpr uint32_t	MEM_HEAP_BTR_SEARCH = 2
	this flag can optionally be ORed to MEM_HEAP_BUFFER, in which case heap->free_block is used in some cases for memory allocations, and if it's NULL, the memory allocation functions can return NULL. More...
constexpr uint32_t	MEM_HEAP_FOR_BTR_SEARCH
	Different type of heaps in terms of which data structure is using them. More...
constexpr uint32_t	MEM_HEAP_FOR_PAGE_HASH = MEM_HEAP_DYNAMIC
constexpr uint32_t	MEM_HEAP_FOR_RECV_SYS = MEM_HEAP_BUFFER
constexpr uint32_t	MEM_HEAP_FOR_LOCK_HEAP = MEM_HEAP_BUFFER
constexpr uint32_t	MEM_BLOCK_START_SIZE = 64
	The following start size is used for the first block in the memory heap if the size is not specified, i.e., 0 is given as the parameter in the call of create. More...
constexpr int	MEM_NO_MANS_LAND = 16
const byte	MEM_NO_MANS_LAND_BEFORE_BYTE = 0xCE
const byte	MEM_NO_MANS_LAND_AFTER_BYTE = 0xDF
constexpr uint64_t	MEM_BLOCK_MAGIC_N = 0x445566778899AABB
constexpr uint64_t	MEM_FREED_BLOCK_MAGIC_N = 0xBBAA998877665544

Detailed Description

The memory management.

Created 6/9/1994 Heikki Tuuri

Macro Definition Documentation

MEM_BLOCK_HEADER_SIZE

#define MEM_BLOCK_HEADER_SIZE    ut_calc_align(sizeof(mem_block_info_t), UNIV_MEM_ALIGNMENT)

MEM_BLOCK_STANDARD_SIZE

#define MEM_BLOCK_STANDARD_SIZE    (UNIV_PAGE_SIZE >= 16384 ? 8000 : MEM_MAX_ALLOC_IN_BUF)

MEM_MAX_ALLOC_IN_BUF

#define MEM_MAX_ALLOC_IN_BUF

Value:

  ((UNIV_PAGE_SIZE - MEM_BLOCK_HEADER_SIZE - 2 * MEM_NO_MANS_LAND) & \
   ~(UNIV_MEM_ALIGNMENT - 1))

If a memory heap is allowed to grow into the buffer pool, the following is the maximum size for a single allocated buffer (from UNIV_PAGE_SIZE we subtract MEM_BLOCK_HEADER_SIZE and 2*MEM_NO_MANS_LAND since it's something we always need to put.

Since in MEM_SPACE_NEEDED we round n to the next multiple of UNIV_MEM_ALINGMENT, we need to cut from the rest the part that cannot be divided by UNIV_MEM_ALINGMENT):

Typedef Documentation

mem_block_t

typedef struct mem_block_info_t mem_block_t

A block of a memory heap consists of the info structure followed by an area of memory.

mem_heap_t

typedef mem_block_t mem_heap_t

A memory heap is a nonempty linear list of memory blocks.

Function Documentation

mem_block_validate()

static void mem_block_validate ( const mem_heap_t *  heap )

inlinestatic

Checks that an object is a memory heap (or a block of it)

Parameters

[in]

heap

Memory heap to check

mem_heap_alloc()

static void * mem_heap_alloc ( mem_heap_t *  heap, ulint  n  )

inlinestatic

Allocates n bytes of memory from a memory heap.

Parameters

[in]	heap	memory heap
[in]	n	number of bytes; if the heap is allowed to grow into the buffer pool, this must be <= MEM_MAX_ALLOC_IN_BUF

Returns

allocated storage, NULL if did not succeed (only possible for MEM_HEAP_BTR_SEARCH type heaps)

mem_heap_create()

static mem_heap_t * mem_heap_create ( ulint  size, ut::Location  loc, ulint  type = MEM_HEAP_DYNAMIC  )

inlinestatic

Creates a memory heap.

A single user buffer of 'size' will fit in the block. 0 creates a default size block.

Parameters

[in]	size	Desired start block size.
[in]	loc	Location where created
[in]	type	Heap type

Returns

own: memory heap, NULL if did not succeed (only possible for MEM_HEAP_BTR_SEARCH type heaps)

mem_heap_dup()

void * mem_heap_dup	(	mem_heap_t *	heap,
		const void *	data,
		ulint	len
	)

Duplicate a block of data, allocated from a memory heap.

Returns

own: a copy of the data in: length of data, in bytes

own: a copy of the data

Parameters

heap	in: memory heap where copy is allocated
data	in: data to be copied
len	in: length of data, in bytes

mem_heap_dup_replace()

static void * mem_heap_dup_replace ( mem_heap_t *  heap, const void *  top, ulint  top_sz, const void *  data, ulint  data_sz  )

inlinestatic

Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element and then copy the specified data to it.

If the memory chunk specified with (top, top_sz) is the topmost element, then it will be discarded, otherwise it will be left untouched and this function will be equivalent to mem_heap_dup().

Parameters

[in,out]	heap	memory heap
[in]	top	chunk to discard if possible
[in]	top_sz	size of top in bytes
[in]	data	new data to duplicate
[in]	data_sz	size of data in bytes

Returns

allocated storage, NULL if did not succeed (only possible for MEM_HEAP_BTR_SEARCH type heaps)

mem_heap_empty()

static void mem_heap_empty ( mem_heap_t *  heap )

inlinestatic

Empties a memory heap.

The first memory block of the heap is not freed.

Parameters

[in]

heap

heap to empty

mem_heap_free()

static void mem_heap_free ( mem_heap_t *  heap )

inlinestatic

Frees the space occupied by a memory heap.

Parameters

[in]

heap

Heap to be freed

mem_heap_free_heap_top()

static void mem_heap_free_heap_top ( mem_heap_t *  heap, byte *  old_top  )

inlinestatic

Frees the space in a memory heap exceeding the pointer given.

The pointer must have been acquired from mem_heap_get_heap_top. The first memory block of the heap is not freed.

Parameters

[in]	heap	heap from which to free
[in]	old_top	pointer to old top of heap

mem_heap_free_top()

static void mem_heap_free_top ( mem_heap_t *  heap, ulint  n  )

inlinestatic

Frees the topmost element in a memory heap.

Parameters

[in]	heap	memory heap
[in]	n	size of the topmost element The size of the element must be given.

mem_heap_get_heap_top()

static byte * mem_heap_get_heap_top ( mem_heap_t *  heap )

inlinestatic

Returns a pointer to the heap top.

Parameters

[in]

heap

memory heap

Returns

pointer to the heap top

mem_heap_get_size()

static size_t mem_heap_get_size ( mem_heap_t *  heap )

inlinestatic

Returns the space in bytes occupied by a memory heap.

in: heap

mem_heap_get_top()

static void * mem_heap_get_top ( mem_heap_t *  heap, ulint  n  )

inlinestatic

Returns a pointer to the topmost element in a memory heap.

The size of the element must be given.

Parameters

[in]	heap	memory heap
[in]	n	size of the topmost element

Returns

pointer to the topmost element

mem_heap_is_top()

static bool mem_heap_is_top ( mem_heap_t *  heap, const void *  buf, ulint  buf_sz  )

inlinestatic

Checks if a given chunk of memory is the topmost element stored in the heap.

If this is the case, then calling mem_heap_free_top() would free that element from the heap.

Parameters

[in]	heap	memory heap
[in]	buf	presumed topmost element
[in]	buf_sz	size of buf in bytes

Returns

true if topmost

mem_heap_printf()

char * mem_heap_printf	(	mem_heap_t *	heap,
		const char *	format,
			...
	)

A simple sprintf replacement that dynamically allocates the space for the formatted string from the given heap.

This supports a very limited set of the printf syntax: types 's' and 'u' and length modifier 'l' (which is required for the 'u' type).

Returns

heap-allocated formatted string

Parameters

heap	in: memory heap
format	in: format string

mem_heap_replace()

static void * mem_heap_replace ( mem_heap_t *  heap, const void *  top, ulint  top_sz, ulint  new_sz  )

inlinestatic

Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element.

If the memory chunk specified with (top, top_sz) is the topmost element, then it will be discarded, otherwise it will be left untouched and this function will be equivallent to mem_heap_alloc().

Parameters

[in,out]	heap	memory heap
[in]	top	chunk to discard if possible
[in]	top_sz	size of top in bytes
[in]	new_sz	desired size of the new chunk

Returns

allocated storage, NULL if did not succeed (only possible for MEM_HEAP_BTR_SEARCH type heaps)

mem_heap_strcat()

char * mem_heap_strcat	(	mem_heap_t *	heap,
		const char *	s1,
		const char *	s2
	)

Concatenate two strings and return the result, using a memory heap.

Returns

own: the result in: string 2

own: the result

Parameters

heap	in: memory heap where string is allocated
s1	in: string 1
s2	in: string 2

mem_heap_strdup()

char * mem_heap_strdup	(	mem_heap_t *	heap,
		const char *	str
	)

Duplicates a NUL-terminated string, allocated from a memory heap.

Parameters

[in]	heap	memory heap where string is allocated
[in]	str	string to be copied

Returns

own: a copy of the string

mem_heap_strdup_replace()

static char * mem_heap_strdup_replace ( mem_heap_t *  heap, const void *  top, ulint  top_sz, const char *  str  )

inlinestatic

Allocate a new chunk of memory from a memory heap, possibly discarding the topmost element and then copy the specified string to it.

If the memory chunk specified with (top, top_sz) is the topmost element, then it will be discarded, otherwise it will be left untouched and this function will be equivalent to mem_heap_strdup().

Parameters

[in,out]	heap	memory heap
[in]	top	chunk to discard if possible
[in]	top_sz	size of top in bytes
[in]	str	new data to duplicate

Returns

allocated string, NULL if did not succeed (only possible for MEM_HEAP_BTR_SEARCH type heaps)

mem_heap_strdupl()

static char * mem_heap_strdupl ( mem_heap_t *  heap, const char *  str, ulint  len  )

inlinestatic

Makes a NUL-terminated copy of a nonterminated string, allocated from a memory heap.

Parameters

[in]	heap	memory heap where string is allocated
[in]	str	string to be copied
[in]	len	length of str, in bytes

Returns

own: a copy of the string

mem_heap_validate()

void mem_heap_validate

(

const mem_heap_t *

heap

)

Validates the contents of a memory heap.

Checks a memory heap for consistency, prints the contents if any error is detected. A fatal error is logged if an error is detected.

Parameters

[in]

heap

Memory heap to validate.

mem_heap_zalloc()

static void * mem_heap_zalloc ( mem_heap_t *  heap, ulint  n  )

inlinestatic

Allocates and zero-fills n bytes of memory from a memory heap.

Parameters

[in]	heap	memory heap
[in]	n	number of bytes; if the heap is allowed to grow into the buffer pool, this must be <= MEM_MAX_ALLOC_IN_BUF

Returns

allocated, zero-filled storage

MEM_SPACE_NEEDED()

static uint64_t MEM_SPACE_NEEDED ( uint64_t  N )

inlinestatic

Space needed when allocating for a user a field of length N.

The space is allocated only in multiples of UNIV_MEM_ALIGNMENT. In debug mode contains two areas of no mans lands before and after the buffer requested.

mem_strdup()

static char * mem_strdup ( const char *  str )

inlinestatic

Duplicates a NUL-terminated string.

Parameters

[in]

str

string to be copied

Returns

own: a copy of the string, must be deallocated with ut_free

mem_strdupl()

static char * mem_strdupl ( const char *  str, ulint  len  )

inlinestatic

Makes a NUL-terminated copy of a nonterminated string.

Parameters

[in]	str	string to be copied
[in]	len	length of str, in bytes

Returns

own: a copy of the string, must be deallocated with ut_free

operator!=()

template<class T >

bool operator!=	(	const mem_heap_allocator< T > &	left,
		const mem_heap_allocator< T > &	right
	)

operator==()

template<class T >

bool operator==	(	const mem_heap_allocator< T > &	left,
		const mem_heap_allocator< T > &	right
	)

Variable Documentation

MEM_BLOCK_MAGIC_N

constexpr uint64_t MEM_BLOCK_MAGIC_N = 0x445566778899AABB

constexpr

MEM_BLOCK_START_SIZE

constexpr uint32_t MEM_BLOCK_START_SIZE = 64

constexpr

The following start size is used for the first block in the memory heap if the size is not specified, i.e., 0 is given as the parameter in the call of create.

The standard size is the maximum (payload) size of the blocks used for allocations of small buffers.

MEM_FREED_BLOCK_MAGIC_N

constexpr uint64_t MEM_FREED_BLOCK_MAGIC_N = 0xBBAA998877665544

constexpr

MEM_HEAP_BTR_SEARCH

constexpr uint32_t MEM_HEAP_BTR_SEARCH = 2

constexpr

this flag can optionally be ORed to MEM_HEAP_BUFFER, in which case heap->free_block is used in some cases for memory allocations, and if it's NULL, the memory allocation functions can return NULL.

MEM_HEAP_BUFFER

constexpr uint32_t MEM_HEAP_BUFFER = 1

constexpr

MEM_HEAP_DYNAMIC

constexpr uint32_t MEM_HEAP_DYNAMIC = 0

constexpr

Types of allocation for memory heaps: DYNAMIC means allocation from the dynamic memory pool of the C compiler, BUFFER means allocation from the buffer pool; the latter method is used for very big heaps.

the most common type

MEM_HEAP_FOR_BTR_SEARCH

constexpr uint32_t MEM_HEAP_FOR_BTR_SEARCH

constexpr

Initial value:

=
    MEM_HEAP_BTR_SEARCH | MEM_HEAP_BUFFER

Different type of heaps in terms of which data structure is using them.

MEM_HEAP_FOR_LOCK_HEAP

constexpr uint32_t MEM_HEAP_FOR_LOCK_HEAP = MEM_HEAP_BUFFER

constexpr

MEM_HEAP_FOR_PAGE_HASH

constexpr uint32_t MEM_HEAP_FOR_PAGE_HASH = MEM_HEAP_DYNAMIC

constexpr

MEM_HEAP_FOR_RECV_SYS

constexpr uint32_t MEM_HEAP_FOR_RECV_SYS = MEM_HEAP_BUFFER

constexpr

MEM_NO_MANS_LAND

constexpr int MEM_NO_MANS_LAND = 16

constexpr

MEM_NO_MANS_LAND_AFTER_BYTE

const byte MEM_NO_MANS_LAND_AFTER_BYTE = 0xDF

MEM_NO_MANS_LAND_BEFORE_BYTE

const byte MEM_NO_MANS_LAND_BEFORE_BYTE = 0xCE