xref: /titanic_50/usr/src/lib/libtecla/common/freelist.h (revision c5c4113dfcabb1eed3d4bdf7609de5170027a794)
1 #ifndef freelist_h
2 #define freelist_h
3 
4 /*
5  * Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
6  *
7  * All rights reserved.
8  *
9  * Permission is hereby granted, free of charge, to any person obtaining a
10  * copy of this software and associated documentation files (the
11  * "Software"), to deal in the Software without restriction, including
12  * without limitation the rights to use, copy, modify, merge, publish,
13  * distribute, and/or sell copies of the Software, and to permit persons
14  * to whom the Software is furnished to do so, provided that the above
15  * copyright notice(s) and this permission notice appear in all copies of
16  * the Software and that both the above copyright notice(s) and this
17  * permission notice appear in supporting documentation.
18  *
19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
21  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
22  * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
23  * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
24  * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
25  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
26  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
27  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
28  *
29  * Except as contained in this notice, the name of a copyright holder
30  * shall not be used in advertising or otherwise to promote the sale, use
31  * or other dealings in this Software without prior written authorization
32  * of the copyright holder.
33  */
34 
35 #pragma ident	"%Z%%M%	%I%	%E% SMI"
36 
37 /*
38  * This module provides a memory allocation scheme that helps to
39  * prevent memory fragmentation by allocating large blocks of
40  * fixed sized objects and forming them into a free-list for
41  * subsequent allocations. The free-list is expanded as needed.
42  */
43 typedef struct FreeList FreeList;
44 
45 /*
46  * Allocate a new free-list from blocks of 'blocking_factor' objects of size
47  * node_size. The node_size argument should be determined by applying
48  * the sizeof() operator to the object type that you intend to allocate from
49  * the freelist.
50  */
51 FreeList *_new_FreeList(size_t node_size, unsigned blocking_factor);
52 
53 /*
54  * If it is known that none of the nodes currently allocated from
55  * a freelist are still in use, the following function can be called
56  * to return all nodes to the freelist without the overhead of
57  * having to call del_FreeListNode() for every allocated node. The
58  * nodes of the freelist can then be reused by future callers to
59  * new_FreeListNode().
60  */
61 void _rst_FreeList(FreeList *fl);
62 
63 /*
64  * Delete a free-list.
65  */
66 FreeList *_del_FreeList(FreeList *fl, int force);
67 
68 /*
69  * Determine the number of nodes that are currently in use.
70  */
71 long _busy_FreeListNodes(FreeList *fl);
72 
73 /*
74  * Query the number of allocated nodes in the freelist which are
75  * currently unused.
76  */
77 long _idle_FreeListNodes(FreeList *fl);
78 
79 /*
80  * Allocate a new object from a free-list.
81  */
82 void *_new_FreeListNode(FreeList *fl);
83 
84 /*
85  * Return an object to the free-list that it was allocated from.
86  */
87 void *_del_FreeListNode(FreeList *fl, void *object);
88 
89 #endif
90