gecko-dev/db/examples_cxx/MpoolExample.cpp

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997, 1998
 *	Sleepycat Software.  All rights reserved.
 *
 *	@(#)MpoolExample.cpp	10.7 (Sleepycat) 5/2/98
 */

#include "config.h"

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <errno.h>
#include <fcntl.h>
#include <iostream.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#endif

#include <db_cxx.h>

#define	MPOOL	"mpool"

void init(char *, int, int);
void run(DB_ENV *, int, int, int);

static void usage();

char *progname = "MpoolExample";			// Program name.

class MpoolExample : public DbEnv
{
public:
    MpoolExample();
    void initdb(const char *home, int cachesize);
    void run(int hits, int pagesize, int npages);

private:
    static const char FileName[];

    // no need for copy and assignment
    MpoolExample(const MpoolExample &);
    operator = (const MpoolExample &);
};

int main(int argc, char *argv[])
{
    int cachesize = 20 * 1024;
    int hits = 1000;
    int npages = 50;
    int pagesize = 1024;

    for (int i = 1; i < argc; ++i)
    {
        if (strcmp(argv[i], "-c") == 0)
        {
            if ((cachesize = atoi(argv[++i])) < 20 * 1024)
                usage();
        }
        else if (strcmp(argv[i], "-h") == 0)
        {
            if ((hits = atoi(argv[++i])) <= 0)
                usage();
        }
        else if (strcmp(argv[i], "-n") == 0)
        {
            if ((npages = atoi(argv[++i])) <= 0)
                usage();
        }
        else if (strcmp(argv[i], "-p") == 0)
        {
            if ((pagesize = atoi(argv[++i])) <= 0)
                usage();
        }
        else
        {
            usage();
        }
    }

    // Initialize the file.
    init(MPOOL, pagesize, npages);

    try {
        MpoolExample app;
        app.initdb(NULL, cachesize);
        app.run(hits, pagesize, npages);
        cout << "MpoolExample: completed\n";
        return 0;
    }
    catch (DbException &dbe)
    {
        cerr << "MpoolExample: " << dbe.what() << "\n";
        return 1;
    }
}

//
// init --
//	Create a backing file.
//
void
init(char *file, int pagesize, int npages)
{
    //
    // Create a file with the right number of pages, and store a page
    // number on each page.
    //
    int fd;
    int flags = O_CREAT | O_RDWR | O_TRUNC;
#ifdef WIN32
    flags |= O_BINARY;
#endif
    if ((fd = open(file, flags, 0666)) < 0) {
        cerr << "MpoolExample: " << file << ": " << strerror(errno) << "\n";
        exit(1);
    }
    char *p = new char[pagesize];
    memset(p, 0, pagesize);

    // The pages are numbered from 0.
    for (int cnt = 0; cnt <= npages; ++cnt) {
        *(db_pgno_t *)p = cnt;
        if (write(fd, p, pagesize) != pagesize) {
            cerr << "MpoolExample: " << file << ": " << strerror(errno) << "\n";
            exit(1);
        }
    }
    delete [] p;
}

static void
usage()
{
    cerr << "usage: MpoolExample [-c cachesize] "
         << "[-h hits] [-n npages] [-p pagesize]\n";
    exit(1);
}

MpoolExample::MpoolExample()
:   DbEnv()         // using default constructor means we must call appinit()
{
}

void MpoolExample::initdb(const char *home, int cachesize)
{
    set_error_stream(&cerr);
    set_errpfx("MpoolExample");
    set_mp_size(cachesize);

    appinit(home, NULL, DB_MPOOL_PRIVATE);
}


//
// run --
//	Get a set of pages.
//
void
MpoolExample::run(int hits, int pagesize, int npages)
{
    db_pgno_t pageno;
    int cnt;
    void *p;

    // Open a memory pool.
    DbMpool *dbmp;
    DbMpool::open(NULL, DB_CREATE, 0666, this, &dbmp);

    // Open the file in the pool.
    DbMpoolFile *dbmfp;

    DbMpoolFile::open(dbmp, MPOOL, 0, 0, pagesize, NULL, &dbmfp);

    // get explicit error returns rather than exceptions so
    // we can report more information with each error.
    //
    set_error_model(DbEnv::ErrorReturn);

    srand((unsigned int)time(NULL));
    for (cnt = 0; cnt < hits; ++cnt) {
        pageno = (rand() % npages) + 1;
        if ((errno = dbmfp->get(&pageno, 0, &p)) != 0) {
            cerr << "MpoolExample: unable to retrieve page "
                 << (unsigned long)pageno << ": " << strerror(errno) << "\n";
            exit(1);
        }
        if (*(db_pgno_t *)p != pageno) {
            cerr << "MpoolExample: wrong page retrieved ("
                 << (unsigned long)pageno << " != " << *(int *)p << ")\n";
            exit(1);
        }
        if ((errno = dbmfp->put(p, 0)) != 0) {
            cerr << "MpoolExample: unable to return page "
                 << (unsigned long)pageno << ": " << strerror(errno) << "\n";
            exit(1);
        }
    }

    // Close the pool.
    if ((errno = dbmp->close()) != 0) {
        cerr << "MpoolExample: " << strerror(errno) << "\n";
        exit(1);
    }
}