01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.ext;
22:
23: /**
24: * provides information about system state and system settings.
25: */
26: public interface SystemInfo {
27:
28: /**
29: * returns the number of entries in the Freespace Manager.
30: * <br><br>A high value for the number of freespace entries
31: * is an indication that the database is fragmented and
32: * that defragment should be run.
33: * @return the number of entries in the Freespace Manager.
34: */
35: public int freespaceEntryCount();
36:
37: /**
38: * returns the freespace size in the database in bytes.
39: * <br><br>When db4o stores modified objects, it allocates
40: * a new slot for it. During commit the old slot is freed.
41: * Free slots are collected in the freespace manager, so
42: * they can be reused for other objects.
43: * <br><br>This method returns a sum of the size of all
44: * free slots in the database file.
45: * <br><br>To reclaim freespace run defragment.
46: * @return the freespace size in the database in bytes.
47: */
48: public long freespaceSize();
49:
50: /**
51: * Returns the total size of the database on disk.
52: * @return total size of database on disk
53: */
54: public long totalSize();
55:
56: }
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