geqo_random.c

Go to the documentation of this file.

/*------------------------------------------------------------------------
 *
 * geqo_random.c
 *     random number generator
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/backend/optimizer/geqo/geqo_random.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "optimizer/geqo_random.h"


void
geqo_set_seed(PlannerInfo *root, double seed)
{
    GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;

    /*
     * XXX. This seeding algorithm could certainly be improved - but it is not
     * critical to do so.
     */
    memset(private->random_state, 0, sizeof(private->random_state));
    memcpy(private->random_state,
           &seed,
           Min(sizeof(private->random_state), sizeof(seed)));
}

double
geqo_rand(PlannerInfo *root)
{
    GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;

    return pg_erand48(private->random_state);
}