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/* $Id: atom.c,v 1.3 2002/02/01 16:49:11 jan Exp $
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: jan@swi.psy.uva.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2002, University of Amsterdam
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <SWI-Stream.h>
#include "db4pl.h"
#include <sys/types.h>
#include <stdlib.h>
#include <assert.h>
#include "error.h"
#define DEBUG(g) (void)0
/*******************************
* TMP HACKS *
*******************************/
extern int unboundStringHashValue(const char *t, unsigned int len);
typedef unsigned long plhash_t;
unsigned long
PL_atom_hash(atom_t a)
{ const char *s;
unsigned int len;
s = PL_atom_nchars(a, &len);
return unboundStringHashValue(s, len);
}
/*******************************
* ATOM MANAGEMENT *
*******************************/
static int maxdupl;
static int
equal_dbt(DBT *a, DBT *b)
{ if ( a->size == b->size )
{ if ( a->data == b->data )
return TRUE;
if ( memcmp(a->data, b->data, a->size) == 0 )
return TRUE;
}
return FALSE;
}
int
db_atom_id(dbh *db, atom_t a, atomid_t *id, int flags)
{ unsigned long hash = PL_atom_hash(a) & 0xffffL;
unsigned long idx = 0;
int rval;
DBC *cursor;
DBT k, v;
DBT av;
if ( (rval = db->db->cursor(db->db, NULL, &cursor, 0)) != 0 )
return db_status(rval);
memset(&av, 0, sizeof(av));
memset(&v, 0, sizeof(v));
memset(&k, 0, sizeof(k));
k.data = &hash;
k.size = sizeof(hash);
av.data = (void *)PL_atom_nchars(a, &av.size);
if ( (rval=cursor->c_get(cursor, &k, &v, DB_SET)) == 0 )
{ DBT k2;
if ( equal_dbt(&v, &av) )
{ cursor->c_close(cursor);
*id = (idx<<16) | hash;
return TRUE;
}
memset(&k2, 0, sizeof(k2));
for(;;)
{ if ( (rval=cursor->c_get(cursor, &k2, &v, DB_NEXT)) == 0 &&
k2.size == sizeof(hash) &&
*((plhash_t *)k2.data) == hash )
{ idx++;
if ( equal_dbt(&v, &av) )
{ cursor->c_close(cursor);
*id = (idx<<16) | hash;
if ( idx > maxdupl )
{ Sdprintf("\n%% %s: max-duplicates: %d\n", av.data, idx);
maxdupl = idx;
}
return TRUE;
}
continue;
}
if ( rval > 0 ) /* some error */
{ cursor->c_close(cursor);
return db_status(rval);
}
cursor->c_close(cursor);
idx++;
if ( idx >= 1<<16 )
return pl_error(ERR_LIMIT, "atoms_per_key", 1<<16);
DEBUG(Sdprintf("Added '%s' at %ld\n", av.data, (idx<<16)|hash));
goto add;
}
} else if ( rval == DB_NOTFOUND )
{ cursor->c_close(cursor);
if ( (flags & DB4PL_ATOM_CREATE) )
{
add:
rval = db_status(db->db->put(db->db, NULL, &k, &av, 0));
if ( rval )
*id = (idx<<16)|hash;
return rval;
} else
return FALSE;
} else
{ cursor->c_close(cursor);
return db_status(rval);
}
}
int
pl_atom_from_db(dbh *db, atomid_t id, atom_t *a)
{ unsigned long idx = (id>>16) & 0xffff;
unsigned long kv = id & 0xffff;
int rval;
DBT k, v;
memset(&v, 0, sizeof(v));
memset(&k, 0, sizeof(k));
k.size = sizeof(kv);
k.data = &kv;
if ( idx == 0 ) /* first, common case */
{ if ( (rval=db->db->get(db->db, NULL, &k, &v, 0)) == 0 )
{ *a = PL_new_atom_nchars(v.size, v.data);
return TRUE;
}
} else
{ DBC *cursor;
unsigned long i = 0;
if ( (rval = db->db->cursor(db->db, NULL, &cursor, 0)) != 0 )
return db_status(rval);
if ( (rval=cursor->c_get(cursor, &k, &v, DB_SET)) == 0 )
{ DBT k2;
memset(&k2, 0, sizeof(k2));
while(i<idx)
{ if ( (rval=cursor->c_get(cursor, &k2, &v, DB_NEXT)) == 0 )
i++;
else
{ cursor->c_close(cursor);
return db_status(rval);
}
}
*a = PL_new_atom_nchars(v.size, v.data);
cursor->c_close(cursor);
return TRUE;
}
}
assert(0);
return FALSE; /* exception */
}
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