ut0mem.c

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

/************************************************************************
Memory primitives

(c) 1994, 1995 Innobase Oy

Created 5/11/1994 Heikki Tuuri
*************************************************************************/

#include "ut0mem.h"

#ifdef UNIV_NONINL
#include "ut0mem.ic"
#endif

#include "mem0mem.h"
#include "os0sync.h"
#include "os0thread.h"

/* This struct is placed first in every allocated memory block */
typedef struct ut_mem_block_struct ut_mem_block_t;

/* The total amount of memory currently allocated from the OS with malloc */
ulint	ut_total_allocated_memory	= 0;

struct ut_mem_block_struct{
        UT_LIST_NODE_T(ut_mem_block_t) mem_block_list;
			/* mem block list node */
	ulint	size;	/* size of allocated memory */
	ulint	magic_n;
};

#define UT_MEM_MAGIC_N	1601650166

/* List of all memory blocks allocated from the operating system
with malloc */
UT_LIST_BASE_NODE_T(ut_mem_block_t)   ut_mem_block_list;

os_fast_mutex_t ut_list_mutex;  /* this protects the list */

ibool  ut_mem_block_list_inited = FALSE;

ulint*	ut_mem_null_ptr	= NULL;

/**************************************************************************
Initializes the mem block list at database startup. */
static
void
ut_mem_block_list_init(void)
/*========================*/
{
        os_fast_mutex_init(&ut_list_mutex);
        UT_LIST_INIT(ut_mem_block_list);
	ut_mem_block_list_inited = TRUE;
}

/**************************************************************************
Allocates memory. Sets it also to zero if UNIV_SET_MEM_TO_ZERO is
defined and set_to_zero is TRUE. */

void*
ut_malloc_low(
/*==========*/
	                     /* out, own: allocated memory */
        ulint   n,           /* in: number of bytes to allocate */
	ibool   set_to_zero, /* in: TRUE if allocated memory should be set
			     to zero if UNIV_SET_MEM_TO_ZERO is defined */
	ibool	assert_on_error) /* in: if TRUE, we crash mysqld if the memory
				cannot be allocated */
{
	ulint	retry_count	= 0;
	void*	ret;

	ut_ad((sizeof(ut_mem_block_t) % 8) == 0); /* check alignment ok */

	if (!ut_mem_block_list_inited) {
	        ut_mem_block_list_init();
	}
retry:
	os_fast_mutex_lock(&ut_list_mutex);

	ret = malloc(n + sizeof(ut_mem_block_t));

	if (ret == NULL && retry_count < 60) {
		if (retry_count == 0) {
			ut_print_timestamp(stderr);

			fprintf(stderr,
		"  InnoDB: Error: cannot allocate %lu bytes of\n"
		"InnoDB: memory with malloc! Total allocated memory\n"
		"InnoDB: by InnoDB %lu bytes. Operating system errno: %lu\n"
		"InnoDB: Check if you should increase the swap file or\n"
		"InnoDB: ulimits of your operating system.\n"
		"InnoDB: On FreeBSD check you have compiled the OS with\n"
		"InnoDB: a big enough maximum process size.\n"
		"InnoDB: Note that in most 32-bit computers the process\n"
		"InnoDB: memory space is limited to 2 GB or 4 GB.\n"
		"InnoDB: We keep retrying the allocation for 60 seconds...\n",
		                  (ulong) n, (ulong) ut_total_allocated_memory,
#ifdef __WIN__
			(ulong) GetLastError()
#else
			(ulong) errno
#endif
			);
		}

		os_fast_mutex_unlock(&ut_list_mutex);

		/* Sleep for a second and retry the allocation; maybe this is
		just a temporary shortage of memory */

		os_thread_sleep(1000000);
		
		retry_count++;

		goto retry;
	}

	if (ret == NULL) {
		/* Flush stderr to make more probable that the error
		message gets in the error file before we generate a seg
		fault */

		fflush(stderr);

	        os_fast_mutex_unlock(&ut_list_mutex);

		/* Make an intentional seg fault so that we get a stack
		trace */
		/* Intentional segfault on NetWare causes an abend. Avoid this 
		by graceful exit handling in ut_a(). */
#if (!defined __NETWARE__) 
		if (assert_on_error) {
			ut_print_timestamp(stderr);

			fprintf(stderr,
		"  InnoDB: We now intentionally generate a seg fault so that\n"
		"InnoDB: on Linux we get a stack trace.\n");

			if (*ut_mem_null_ptr) ut_mem_null_ptr = 0;
		} else {
			return(NULL);
		}
#else
		ut_a(0);
#endif
	}		

	if (set_to_zero) {
#ifdef UNIV_SET_MEM_TO_ZERO
	        memset(ret, '\0', n + sizeof(ut_mem_block_t));
#endif
	}

	((ut_mem_block_t*)ret)->size = n + sizeof(ut_mem_block_t);
	((ut_mem_block_t*)ret)->magic_n = UT_MEM_MAGIC_N;

	ut_total_allocated_memory += n + sizeof(ut_mem_block_t);
	
	UT_LIST_ADD_FIRST(mem_block_list, ut_mem_block_list,
			                         ((ut_mem_block_t*)ret));
	os_fast_mutex_unlock(&ut_list_mutex);

	return((void*)((byte*)ret + sizeof(ut_mem_block_t)));
}

/**************************************************************************
Allocates memory. Sets it also to zero if UNIV_SET_MEM_TO_ZERO is
defined. */

void*
ut_malloc(
/*======*/
	                /* out, own: allocated memory */
        ulint   n)      /* in: number of bytes to allocate */
{
        return(ut_malloc_low(n, TRUE, TRUE));
}

/**************************************************************************
Tests if malloc of n bytes would succeed. ut_malloc() asserts if memory runs
out. It cannot be used if we want to return an error message. Prints to
stderr a message if fails. */

ibool
ut_test_malloc(
/*===========*/
			/* out: TRUE if succeeded */
	ulint	n)	/* in: try to allocate this many bytes */
{
	void*	ret;

	ret = malloc(n);

	if (ret == NULL) {
		ut_print_timestamp(stderr);
		fprintf(stderr,
		"  InnoDB: Error: cannot allocate %lu bytes of memory for\n"
		"InnoDB: a BLOB with malloc! Total allocated memory\n"
		"InnoDB: by InnoDB %lu bytes. Operating system errno: %d\n"
		"InnoDB: Check if you should increase the swap file or\n"
		"InnoDB: ulimits of your operating system.\n"
		"InnoDB: On FreeBSD check you have compiled the OS with\n"
		"InnoDB: a big enough maximum process size.\n",
		                  (ulong) n,
			          (ulong) ut_total_allocated_memory,
				  (int) errno);
		return(FALSE);
	}

	free(ret);

	return(TRUE);
}	

/**************************************************************************
Frees a memory block allocated with ut_malloc. */

void
ut_free(
/*====*/
	void* ptr)  /* in, own: memory block */
{
        ut_mem_block_t* block;

	block = (ut_mem_block_t*)((byte*)ptr - sizeof(ut_mem_block_t));

	os_fast_mutex_lock(&ut_list_mutex);

	ut_a(block->magic_n == UT_MEM_MAGIC_N);
	ut_a(ut_total_allocated_memory >= block->size);

	ut_total_allocated_memory -= block->size;
	
	UT_LIST_REMOVE(mem_block_list, ut_mem_block_list, block);
	free(block);
	
	os_fast_mutex_unlock(&ut_list_mutex);
}

/**************************************************************************
Implements realloc. This is needed by /pars/lexyy.c. Otherwise, you should not
use this function because the allocation functions in mem0mem.h are the
recommended ones in InnoDB.

man realloc in Linux, 2004:

       realloc()  changes the size of the memory block pointed to
       by ptr to size bytes.  The contents will be  unchanged  to
       the minimum of the old and new sizes; newly allocated mem