cursor.c

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/***************************************************************
 *                                                             *
 * Copyright (c) 2001-2007 McObject LLC. All Right Reserved.   *
 *                                                             *
 ***************************************************************/

/* This samples demonstartes basic cursor methods */

#include <platform.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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 samples demonstartes basic eXtremeDB cursor 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();

}


void cursor(mco_db_h db)
{
    MCO_RET rc = 0;
    mco_cursor_t csr;
    mco_trans_h trn;
    SimpleClass simple;
    uint2 a, b, size;
    uint4 h;
    char src[64];
    simple_oid oid;
    MCO_CURSOR_TYPE ctype;

    printf("\n\nReading using \"UniqueIndex\"\n");

    /* start read-only transaction and initialize	a cursor.
     */
    mco_trans_start(db, MCO_READ_ONLY, MCO_TRANS_FOREGROUND, &trn);

    /* initialize cursor */
    rc = SimpleClass_Iabc_index_cursor(trn, &csr);

    if (rc != MCO_S_OK)
    {
        /* if not found for whatever reason - close the transaction and
         * bail out
         */
        mco_trans_commit(trn);
        return ;
    }

    /* commit the transaction. This is only done to illuatrate the fact that
     * cursors could be used across the transaction boundaries. In
     * real-life application the "commit" is not needed and shouldn't be
     * issued.
     */
    rc = mco_trans_commit(trn);

    /* re-open a transaction */
    mco_trans_start(db, MCO_READ_ONLY, MCO_TRANS_FOREGROUND, &trn);

    /* check whether the cursor is still valid */
    if (MCO_S_OK != mco_cursor_type(&csr, &ctype))
    {
        /* cursor invalid... */
        printf("\n\tcursor invalid");

        /* ..reinitialize it. */
        rc = SimpleClass_Iabc_index_cursor(trn, &csr);
    }

    for (rc = mco_cursor_first(trn, &csr);  /* position the cursor at the first object */
    rc == MCO_S_OK; rc = mco_cursor_next(trn, &csr) /* advance the cursor (fetch)*/
    )
    {
        /* obtain object handle through the current cursor
         */
        rc = SimpleClass_from_cursor(trn, &csr, &simple);
        if (rc != MCO_S_OK)
        {
            printf("\n\terror:%d", rc);
            break;
        }

        /* read data out from handle
         */
        SimpleClass_a_get(&simple, &a);
        SimpleClass_b_get(&simple, &b);
        SimpleClass_h_get(&simple, &h);
        SimpleClass_c_get(&simple, src, (uint2)sizeof(src), &size);

        /* obtain OID for the object */
        rc = SimpleClass_oid_get(&simple, &oid);

        if (rc == MCO_S_OK)
        {
            printf("\n\tobject with OID=%d\n\ta=%d,b=%d,c=%s(%d)\n\n", oid.seq, a, b, src, size);
        }
        else
        {
            printf("\n\terror:%d", rc);
        }
    }

    /* commit */
    mco_trans_commit(trn);
    return ;
}


/* fatal error handler */
static void errhandler(int n)
{
    printf("\neXtremeDB runtime fatal error: %d", n);
    getchar();
    exit( - 1);
}


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);
        }
    };

    /* set fatal error handler */
    mco_error_set_handler(&errhandler);

    mco_runtime_start();
    /* Create a database - allocate 2M starting from mem. */
    rc = mco_db_open(dbname, simple_get_dictionary(), start_mem, FIRST_SEGSZ, (uint2)PAGESIZE);

    if (rc)
    {
        printf("\nerror creating database");
        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]);
    }

    cursor(db);

    /* 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 key to exit");
    getchar();
    PROG_EXIT(0);
}