mem0mem.ic

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

/************************************************************************
The memory management

(c) 1994, 1995 Innobase Oy

Created 6/8/1994 Heikki Tuuri
*************************************************************************/

#include "mem0dbg.ic"

#include "mem0pool.h"

/*******************************************************************
Creates a memory heap block where data can be allocated. */

mem_block_t*
mem_heap_create_block(
/*==================*/
				/* out, own: memory heap block,
				NULL if did not succeed */
	mem_heap_t*	heap,	/* in: memory heap or NULL if first block
				should be created */
	ulint		n,	/* in: number of bytes needed for user data, or
				if init_block is not NULL, its size in bytes */
	void*		init_block, /* in: init block in fast create,
				type must be MEM_HEAP_DYNAMIC */
	ulint		type,	/* in: type of heap: MEM_HEAP_DYNAMIC or
				MEM_HEAP_BUFFER */
	const char*	file_name,/* in: file name where created */
	ulint		line);	/* in: line where created */
/**********************************************************************
Frees a block from a memory heap. */

void
mem_heap_block_free(
/*================*/
	mem_heap_t*	heap,	/* in: heap */
	mem_block_t*	block);	/* in: block to free */
/**********************************************************************
Frees the free_block field from a memory heap. */

void
mem_heap_free_block_free(
/*=====================*/
	mem_heap_t*	heap);	/* in: heap */
/*******************************************************************
Adds a new block to a memory heap. */

mem_block_t*
mem_heap_add_block(
/*===============*/
				/* out: created block, NULL if did not
				succeed */
	mem_heap_t* 	heap,	/* in: memory heap */
	ulint		n);	/* in: number of bytes user needs */

UNIV_INLINE
void
mem_block_set_len(mem_block_t* block, ulint len)
{
	ut_ad(len > 0);

	block->len = len;
}

UNIV_INLINE
ulint
mem_block_get_len(mem_block_t* block)
{
	return(block->len);
}

UNIV_INLINE
void
mem_block_set_type(mem_block_t* block, ulint type)
{
	ut_ad((type == MEM_HEAP_DYNAMIC) || (type == MEM_HEAP_BUFFER)
		|| (type == MEM_HEAP_BUFFER + MEM_HEAP_BTR_SEARCH));

	block->type = type;
}

UNIV_INLINE
ulint
mem_block_get_type(mem_block_t* block)
{
	return(block->type);
}

UNIV_INLINE
void
mem_block_set_free(mem_block_t* block, ulint free)
{
	ut_ad(free > 0);
	ut_ad(free <= mem_block_get_len(block));

	block->free = free;
}

UNIV_INLINE
ulint
mem_block_get_free(mem_block_t* block)
{
	return(block->free);
}

UNIV_INLINE
void
mem_block_set_start(mem_block_t* block, ulint start)
{
	ut_ad(start > 0);

	block->start = start;
}

UNIV_INLINE
ulint
mem_block_get_start(mem_block_t* block)
{
	return(block->start);
}

/*******************************************************************
Allocates n bytes of memory from a memory heap. */
UNIV_INLINE
void*
mem_heap_alloc(
/*===========*/
				/* out: allocated storage */
	mem_heap_t*	heap, 	/* in: memory heap */
	ulint           n)      /* in: number of bytes; if the heap is allowed
				to grow into the buffer pool, this must be
				<= MEM_MAX_ALLOC_IN_BUF */
{
	mem_block_t*	block;
	void*		buf;
	ulint		free;
	
	ut_ad(mem_heap_check(heap));

	block = UT_LIST_GET_LAST(heap->base);

	ut_ad(!(block->type & MEM_HEAP_BUFFER) || (n <= MEM_MAX_ALLOC_IN_BUF));
	
	/* Check if there is enough space in block. If not, create a new
	block to the heap */

	if (mem_block_get_len(block) 
			< mem_block_get_free(block) + MEM_SPACE_NEEDED(n)) {

		block = mem_heap_add_block(heap, n);

		if (block == NULL) {

			return(NULL);
		}
	}

	free = mem_block_get_free(block);

	buf = (byte*)block + free;

	mem_block_set_free(block, free + MEM_SPACE_NEEDED(n));

#ifdef UNIV_MEM_DEBUG

	/* In the debug version write debugging info to the field */
	mem_field_init((byte*)buf, n);

	/* Advance buf to point at the storage which will be given to the
	caller */
	buf = (byte*)buf + MEM_FIELD_HEADER_SIZE;

#endif
#ifdef UNIV_SET_MEM_TO_ZERO
	memset(buf, '\0', n);
#endif
	return(buf);
}

/*********************************************************************
Returns a pointer to the heap top. */
UNIV_INLINE
byte*
mem_heap_get_heap_top(
/*==================*/     
				/* out: pointer to the heap top */
	mem_heap_t*   	heap) 	/* in: memory heap */
{
	mem_block_t*	block;
	byte*		buf;
	
	ut_ad(mem_heap_check(heap));

	block = UT_LIST_GET_LAST(heap->base);

	buf = (byte*)block + mem_block_get_free(block);

	return(buf);
} 

/*********************************************************************
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. */
UNIV_INLINE
void
mem_heap_free_heap_top(
/*===================*/
	mem_heap_t*   	heap,	/* in: heap from which to free */
	byte*		old_top)/* in: pointer to old top of heap */
{
	mem_block_t*	block;
	mem_block_t*	prev_block;
#ifdef UNIV_MEM_DEBUG
	ibool		error;
	ulint		total_size;	
	ulint		size;
#endif			

	ut_ad(mem_heap_check(heap));
	
#ifdef UNIV_MEM_DEBUG

	/* Validate the heap and get its total allocated size */
	mem_heap_validate_or_print(heap, NULL, FALSE, &error, &total_size,
								NULL, NULL);
	ut_a(!error);

	/* Get the size below top pointer */
	mem_heap_validate_or_print(heap, old_top, FALSE, &error, &size, NULL,
									NULL);
	ut_a(!error);

#endif

	block = UT_LIST_GET_LAST(heap->base);

	while (block != NULL) {
		if (((byte*)block + mem_block_get_free(block) >= old_top)
						&& ((byte*)block <= old_top)) {
			/* Found the right block */

			break;
		}
 
		/* Store prev_block value before freeing the current block
		(the current block will be erased in freeing) */

		prev_block = UT_LIST_GET_PREV(list, block);

		mem_heap_block_free(heap, block);

		block = prev_block;
	}
	
	ut_ad(block);

	/* Set the free field of block */
	mem_block_set_free(block, old_top - (byte*)block); 

#ifdef UNIV_MEM_DEBUG
	ut_ad(mem_block_get_start(block) <= mem_block_get_free(block));

	/* In the debug version erase block from top up */
	
	mem_erase_buf(old_top, (byte*)block + block->len - old_top);

	/* Update allocated memory count */
	mutex_enter(&mem_hash_mutex);
	mem_current_allocated_memory -= (total_size - size);
	mutex_exit(&mem_hash_mutex);

#endif

	/* If free == start, we may free the block if it is not the first
	one */
	
	if ((heap != block) && (mem_block_get_free(block) == 
				  		mem_block_get_start(block))) {
		mem_heap_block_free(heap, block);
	}
}

/*********************************************************************
Empties a memory heap. The first memory block of the heap is not freed. */
UNIV_INLINE
void
mem_heap_empty(
/*===========*/
	mem_heap_t*   	heap)	/* in: heap to empty */
{
	mem_heap_free_heap_top(heap, (byte*)heap + mem_block_get_start(heap));

	if (heap->free_block) {
		mem_heap_free_block_free(heap);
	}
}	

/*********************************************************************
Returns a pointer to the topmost element in a memory heap. The size of the
element must be given. */
UNIV_INLINE
void*
mem_heap_get_top(
/*=============*/     
				/* out: pointer to the topmost element */
	mem_heap_t*   	heap, 	/* in: memory heap */
	ulint           n)      /* in: size of the topmost element */
{
	mem_block_t*	block;
	void*		buf;
	
	ut_ad(mem_heap_check(heap));

	block = UT_LIST_GET_LAST(heap->base);

	buf = (byte*)block + mem_block_get_free(block) - MEM_SPACE_NEEDED(n);

#ifdef UNIV_MEM_DEBUG
	ut_ad(mem_block_get_start(block) <=(ulint)((byte*)buf - (byte*)block));

	/* In the debug version, advance buf to point at the storage which