AccessExample.cpp   [plain text]

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997,2008 Oracle.  All rights reserved.
 *
 * $Id: AccessExample.cpp,v 12.6 2008/01/08 20:58:26 bostic Exp $
 */

#include <sys/types.h>

#include <iostream>
#include <iomanip>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#ifdef _WIN32
extern "C" {
  extern int getopt(int, char * const *, const char *);
  extern int optind;
}
#else
#include <unistd.h>
#endif

#include <db_cxx.h>

#define	DATABASE	"access.db"

using std::cin;
using std::cout;
using std::cerr;

class AccessExample
{
public:
	AccessExample();
	void run(bool removeExistingDatabase, const char *fileName);

private:
	// no need for copy and assignment
	AccessExample(const AccessExample &);
	void operator = (const AccessExample &);
};

int
usage()
{
	(void)fprintf(stderr, "usage: AccessExample [-r] [database]\n");
	return (EXIT_FAILURE);
}

int
main(int argc, char *argv[])
{
	int ch, rflag;
	const char *database;

	rflag = 0;
	while ((ch = getopt(argc, argv, "r")) != EOF)
		switch (ch) {
		case 'r':
			rflag = 1;
			break;
		case '?':
		default:
			return (usage());
		}
	argc -= optind;
	argv += optind;

	/* Accept optional database name. */
	database = *argv == NULL ? DATABASE : argv[0];

	// Use a try block just to report any errors.
	// An alternate approach to using exceptions is to
	// use error models (see DbEnv::set_error_model()) so
	// that error codes are returned for all Berkeley DB methods.
	//
	try {
		AccessExample app;
		app.run((bool)(rflag == 1 ? true : false), database);
		return (EXIT_SUCCESS);
	}
	catch (DbException &dbe) {
		cerr << "AccessExample: " << dbe.what() << "\n";
		return (EXIT_FAILURE);
	}
}

AccessExample::AccessExample()
{
}

void AccessExample::run(bool removeExistingDatabase, const char *fileName)
{
	// Remove the previous database.
	if (removeExistingDatabase)
		(void)remove(fileName);

	// Create the database object.
	// There is no environment for this simple example.
	Db db(0, 0);

	db.set_error_stream(&cerr);
	db.set_errpfx("AccessExample");
	db.set_pagesize(1024);		/* Page size: 1K. */
	db.set_cachesize(0, 32 * 1024, 0);
	db.open(NULL, fileName, NULL, DB_BTREE, DB_CREATE, 0664);

	//
	// Insert records into the database, where the key is the user
	// input and the data is the user input in reverse order.
	//
	char buf[1024], rbuf[1024];
	char *p, *t;
	int ret;
	u_int32_t len;

	for (;;) {
		cout << "input> ";
		cout.flush();

		cin.getline(buf, sizeof(buf));
		if (cin.eof())
			break;

		if ((len = (u_int32_t)strlen(buf)) <= 0)
			continue;
		for (t = rbuf, p = buf + (len - 1); p >= buf;)
			*t++ = *p--;
		*t++ = '\0';

		Dbt key(buf, len + 1);
		Dbt data(rbuf, len + 1);

		ret = db.put(0, &key, &data, DB_NOOVERWRITE);
		if (ret == DB_KEYEXIST) {
			cout << "Key " << buf << " already exists.\n";
		}
	}
	cout << "\n";

	// We put a try block around this section of code
	// to ensure that our database is properly closed
	// in the event of an error.
	//
	try {
		// Acquire a cursor for the table.
		Dbc *dbcp;
		db.cursor(NULL, &dbcp, 0);

		// Walk through the table, printing the key/data pairs.
		Dbt key;
		Dbt data;
		while (dbcp->get(&key, &data, DB_NEXT) == 0) {
			char *key_string = (char *)key.get_data();
			char *data_string = (char *)data.get_data();
			cout << key_string << " : " << data_string << "\n";
		}
		dbcp->close();
	}
	catch (DbException &dbe) {
		cerr << "AccessExample: " << dbe.what() << "\n";
	}

	db.close(0);
}