SequenceExample.cpp

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: SequenceExample.cpp,v 12.2 2005/06/16 20:22:14 bostic Exp $
 */

#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);
}

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