libdb/examples/cxx/SequenceExample.cpp

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997, 2011 Oracle and/or its affiliates.  All rights reserved.
 *
 * $Id$
 */

#include <sys/types.h>

#include <iostream>
#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	"sequence.db"
#define	SEQUENCE	"my_sequence"

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

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

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

int
usage()
{
	(void)fprintf(stderr, "usage: SequenceExample [-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 {
		SequenceExample app;
		app.run((bool)(rflag == 1 ? true : false), database);
		return (EXIT_SUCCESS);
	}
	catch (DbException &dbe) {
		cerr << "SequenceExample: " << dbe.what() << "\n";
		return (EXIT_FAILURE);
	}
}

SequenceExample::SequenceExample()
{
}

void SequenceExample::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("SequenceExample");
	db.open(NULL, fileName, NULL, DB_BTREE, DB_CREATE, 0664);

	// 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 {
		Dbt key((void *)SEQUENCE, (u_int32_t)strlen(SEQUENCE));
		DbSequence seq(&db, 0);
		seq.open(0, &key, DB_CREATE);

		for (int i = 0; i < 10; i++) {
			db_seq_t seqnum;
			seq.get(0, 1, &seqnum, 0);

			// We don't have a portable way to print 64-bit numbers.
			cout << "Got sequence number (" <<
			    (int)(seqnum >> 32) << ", " << (unsigned)seqnum <<
			    ")\n";
		}

		seq.close(0);
	} catch (DbException &dbe) {
		cerr << "SequenceExample: " << dbe.what() << "\n";
	}

	db.close(0);
}