• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 
2 /*--------------------------------------------------------------------*/
3 /*--- A hash table implementation.            pub_tool_hashtable.h ---*/
4 /*--------------------------------------------------------------------*/
5 
6 /*
7    This file is part of Valgrind, a dynamic binary instrumentation
8    framework.
9 
10    Copyright (C) 2005-2010 Nicholas Nethercote
11       njn@valgrind.org
12 
13    This program is free software; you can redistribute it and/or
14    modify it under the terms of the GNU General Public License as
15    published by the Free Software Foundation; either version 2 of the
16    License, or (at your option) any later version.
17 
18    This program is distributed in the hope that it will be useful, but
19    WITHOUT ANY WARRANTY; without even the implied warranty of
20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
21    General Public License for more details.
22 
23    You should have received a copy of the GNU General Public License
24    along with this program; if not, write to the Free Software
25    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
26    02111-1307, USA.
27 
28    The GNU General Public License is contained in the file COPYING.
29 */
30 
31 #ifndef __PUB_TOOL_HASHTABLE_H
32 #define __PUB_TOOL_HASHTABLE_H
33 
34 /* Generic type for a separately-chained hash table.  Via a kind of dodgy
35    C-as-C++ style inheritance, tools can extend the VgHashNode type, so long
36    as the first two fields match the sizes of these two fields.  Requires
37    a bit of casting by the tool. */
38 
39 // Problems with this data structure:
40 // - Separate chaining gives bad cache behaviour.  Hash tables with linear
41 //   probing give better cache behaviour.
42 
43 typedef
44    struct _VgHashNode {
45       struct _VgHashNode * next;
46       UWord              key;
47    }
48    VgHashNode;
49 
50 typedef struct _VgHashTable * VgHashTable;
51 
52 /* Make a new table.  Allocates the memory with VG_(calloc)(), so can
53    be freed with VG_(free)().  The table starts small but will
54    periodically be expanded.  This is transparent to the users of this
55    module. */
56 extern VgHashTable VG_(HT_construct) ( HChar* name );
57 
58 /* Count the number of nodes in a table. */
59 extern Int VG_(HT_count_nodes) ( VgHashTable table );
60 
61 /* Add a node to the table.  Duplicate keys are permitted. */
62 extern void VG_(HT_add_node) ( VgHashTable t, void* node );
63 
64 /* Looks up a VgHashNode in the table.  Returns NULL if not found.  If entries
65  * with duplicate keys are present, the most recently-added of the dups will
66  * be returned, but it's probably better to avoid dups altogether. */
67 extern void* VG_(HT_lookup) ( VgHashTable table, UWord key );
68 
69 /* Removes a VgHashNode from the table.  Returns NULL if not found. */
70 extern void* VG_(HT_remove) ( VgHashTable table, UWord key );
71 
72 /* Allocates a suitably-sized array, copies pointers to all the hashtable
73    elements into it, then returns both the array and the size of it.  The
74    array must be freed with VG_(free). */
75 extern VgHashNode** VG_(HT_to_array) ( VgHashTable t, /*OUT*/ UInt* n_elems );
76 
77 /* Reset the table's iterator to point to the first element. */
78 extern void VG_(HT_ResetIter) ( VgHashTable table );
79 
80 /* Return the element pointed to by the iterator and move on to the
81    next one.  Returns NULL if the last one has been passed, or if
82    HT_ResetIter() has not been called previously.  Asserts if the
83    table has been modified (HT_add_node, HT_remove) since
84    HT_ResetIter.  This guarantees that callers cannot screw up by
85    modifying the table whilst iterating over it (and is necessary to
86    make the implementation safe; specifically we must guarantee that
87    the table will not get resized whilst iteration is happening.
88    Since resizing only happens as a result of calling HT_add_node,
89    disallowing HT_add_node during iteration should give the required
90    assurance. */
91 extern void* VG_(HT_Next) ( VgHashTable table );
92 
93 /* Destroy a table. */
94 extern void VG_(HT_destruct) ( VgHashTable t );
95 
96 
97 #endif   // __PUB_TOOL_HASHTABLE_H
98 
99 /*--------------------------------------------------------------------*/
100 /*--- end                                                          ---*/
101 /*--------------------------------------------------------------------*/
102