delete.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 example demonstrates hash-based serach functionality,
 * erase/delete interfaces and database statistics methods.
 */
#include <platform.h>
#include <stdio.h>
#include <stdlib.h>

#include "samples.h"

static const char   *   dbname = "SimpleDb";
static const int        FIRST_SEGSZ = 1024 * 8000UL;
#ifndef MCO_PLATFORM_X64
static const int        PAGESIZE = 96;
#else
static const int        PAGESIZE = 192;
#endif

const int MAP_ADDRESS =  0x20000000;
void _SH_(void) {

	char text[] = {
		"\nThis example demonstrates eXtremeDB hash-based search interfaces,\n"
		"erase and delete interfaces and database statistics methods.\n"
	};
	char text1[] = {
		"Copyright (c) 2001-2007 McObject LLC. All Right Reserved.\n\n"
	};

	printf("%s\neXtremeDB runtime version %d.%d, build %d\n%s\n\nPress Enter to start",
		text, MCO_COMP_VER_MAJOR, MCO_COMP_VER_MINOR, MCO_COMP_BUILD_NUM,text1);

	getchar();
}


/* Display database statistics
 */
void showStat( mco_db_h db, uint2 class_code ) {
	MCO_RET             rc = 0;
	mco_trans_h         t;
	mco_class_stat_t    stat;

	mco_trans_start( db, MCO_READ_WRITE, MCO_TRANS_FOREGROUND, &t );
	rc = mco_class_stat_get( t, class_code, &stat );
	mco_trans_commit( t );

	if ( rc == MCO_S_OK ) {
		printf
			(
			"\n\tStatistics for the class with code %d:\n\tNumber of objects:\t%ld\n\tTotal pages used:\t%ld\n\tTotal core used:\t%ld\n",
			class_code,
			stat.objects_num,
			stat.core_pages + stat.blob_pages,
			stat.core_space
			);
	}
}


/* Find and object based on hash index created for the class. Ones found
 * delete the object and return all memory back to the pool.
 */
int find_and_delete( mco_db_h db, uint4 vh ) {
	MCO_RET         rc;
	mco_trans_h     t;
	SimpleClass     hClass;
	simple_oid      id;

	mco_trans_start( db, MCO_READ_WRITE, MCO_TRANS_FOREGROUND, &t );

	rc = SimpleClass_SimpleKey_find( t, vh, &hClass );

	if ( rc == MCO_S_OK ) {
		/* delete it!*/
		rc = SimpleClass_oid_get( &hClass, &id );
		printf( "\n\tobject with OID=%d about to be deleted...", id.seq );
		rc = SimpleClass_delete( &hClass );
		if ( rc == MCO_S_OK ) {
			printf( "okay\n" );
			mco_trans_commit( t );
		}
		else {
			printf( "failed (%d)\n", rc );
			mco_trans_rollback( t );
		}
	}
	else {
		printf( "\n\terror(%d) searching for the object with hash value %d", rc, vh );
		mco_trans_rollback( t );
	}

	return(int) rc;
}


int main( void ) {
	MCO_RET   	rc;
	mco_db_h  	db = 0;
	int         num = NUMOBJECTS,
				one_id  [NUMOBJECTS],
				vhash   [NUMOBJECTS];
	char      	* start_mem;
	mco_runtime_info_t info;

	_SH_();
	mco_get_runtime_info( &info);
	if ( info.mco_shm_supported ) {
		start_mem = (char*)MAP_ADDRESS;
	}
	else {
		start_mem = (char*)malloc(FIRST_SEGSZ);
		if (!start_mem) {
			printf("Couldn't allocated memory\n");
			exit (1);
		}
	};

	mco_runtime_start();
	rc = mco_db_open(dbname, simple_get_dictionary(), start_mem, FIRST_SEGSZ, (uint2) PAGESIZE );

	if ( rc ) {
		printf( "\nerror %d creating database", rc);
		if ( !info.mco_shm_supported )
			free( start_mem );
		exit( 1 );
	}

	/* connect to the database, obtain a database handle */
	mco_db_connect( dbname, &db );
	printf( "\ndb handle = %d\n", db );

	srand( (unsigned) time(NULL) );
	while ( 0 < num-- ) {
		/* get some random values */
		one_id[num] = rand();
		vhash[num] = ( uint4 ) rand();

		/* create a new object */
		newobj( db, one_id[num], vhash[num] );
	}

	printf( "\n" );

	/* print out statistics for SimpleClass */
	showStat( db, SimpleClass_code );

	printf( "\n\nHash-based search & delete\n" );

	for ( num = NUMOBJECTS; 0 < num; num-- ) find_and_delete( db, vhash[num-1] );

	showStat( db, SimpleClass_code );

	/* disconnect from the database, db is no longer valid */
	mco_db_disconnect( db );

	/* destroy the db */
	mco_db_close(dbname);
	mco_runtime_stop();

	if ( !info.mco_shm_supported )
		free( start_mem );

	printf( "Press Enter to finish\n" );
	getchar();
  PROG_EXIT(0);
}