heap.c

eXtremeDB数据库在Linux平台下的使用源码。内含多个示例程序

/************************************************************
 *                                                          *
 * Copyright (c) 2001-2007 McObject LLC. All Right Reserved.*
 *                                                          *
 ************************************************************/

/*
 * This sample demonstarates heap API usage. The API resembles
 * standard C runtime memory API, only every heap function takes
 * an additional parameter - heap handle that should be obtained via
 * mco_heap_init() call
 */

#include "platform.h"
#include <stdio.h>
#include <stdlib.h>
#ifndef _VXWORKS
  #include <malloc.h>
#endif
#include "mco.h"

/* our application need 8K of dynamic memory, not that it MUST be
 * a power of 2 in size. Try to set otherwise, and get the
 * runtime fatal exception.
 */
#define HEAP_SIZE 8192

/* this is the starting address, could be just taken from the
 * the memory map, or if the OS is kind enough, could be
 * allocated with malloc
 */
void *start_address;
/* The address of the heap control structure must be allocated
 * prior to the heap initialization and must be passed into
 * the heap initialization API. Again this address could be
 * taken from the map, or malloc-ed if possible
 */
mco_heap_h app_heap;

static void _SH_(void) {

	char text[] = {
		"\nThis sample demonstarates heap API usage. The API resembles\n"
		"standard C runtime memory API, only every heap function takes\n"
		"an additional parameter - heap handle that should be obtained via\n"
		"mco_heap_init() call\n"
	};

	char text1[] = {
		"Copyright (c) 2001-2007 McObject LLC. All Right Reserved.\n\n"
	};

	printf("%s\n%s\nPress Enter to start", text,text1);
	getchar();
}


/* If the address is static this is of course not necessary
 */
void free_start_address(void * p) {
	if(p) free(p);
}


static void errhandler( int n ) {
	printf( "\neXtremeDB fatal error: %d", n );
	getchar();
	exit( -1 );
}


int main(void) {
	uint4 *buffer;
	uint4 size;
	int hhsize;

	_SH_();

	/* Get the size of the heap control structure. The heap control structure
	 * address - heap header, must be provided by the application and
	 * passed into the heap initialization API mco_heap_init() along with
	 * the heap start address.
	 */
	mco_runtime_start();
	hhsize = mco_heap_head_size();

	if (!(app_heap = (mco_heap_h)malloc(hhsize))) {
		printf("Invalid address for the heap header.\n");
		exit (0);
	}

	if (! (start_address = malloc(HEAP_SIZE))) {
		printf("Invalid head address\n");
		exit (0);
	}

	/* set fatal error handler */
	mco_error_set_handler( &errhandler );

	/* initialize application's heap */
	mco_heap_init( start_address, HEAP_SIZE, app_heap, "heap" );

	if( (buffer = (uint4 *)mco_malloc(app_heap, 500 * sizeof( uint4 ) )) == NULL)
		exit( 1 );

	size = mco_heap_usedsize(app_heap);
	printf( "Size of block after mco_malloc of 500 longs: %u\n", size );

	/* Reallocate and show new size: */
	if( (buffer = mco_realloc( app_heap, buffer, size + (500 * sizeof( uint4 )) ))	==  NULL )
		exit( 1 );

	size = mco_heap_usedsize(app_heap);
	printf( "Size of block after mco_realloc of 500 more longs: %u\n", size );

	size = mco_heap_freesize(app_heap);
	printf( "Left in the heap after mco_malloc of 1000 longs: %u\n", size );

	mco_free(app_heap, buffer );

	/* destroy application's heap and free up its starting address (if necessary) */
	mco_heap_destroy  ( app_heap);
	mco_runtime_stop();
	free(start_address);
	free(app_heap);
	printf ("Press Enter to exit");
	getchar();
  PROG_EXIT(0);
}