xorp

strngmem.h

00001 #ifndef stringmem_h
00002 #define stringmem_h
00003 /*
00004  * Copyright (c) 2000, 2001 by Martin C. Shepherd.
00005  * 
00006  * All rights reserved.
00007  * 
00008  * Permission is hereby granted, free of charge, to any person obtaining a
00009  * copy of this software and associated documentation files (the
00010  * "Software"), to deal in the Software without restriction, including
00011  * without limitation the rights to use, copy, modify, merge, publish,
00012  * distribute, and/or sell copies of the Software, and to permit persons
00013  * to whom the Software is furnished to do so, provided that the above
00014  * copyright notice(s) and this permission notice appear in all copies of
00015  * the Software and that both the above copyright notice(s) and this
00016  * permission notice appear in supporting documentation.
00017  * 
00018  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
00019  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00020  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
00021  * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
00022  * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
00023  * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
00024  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
00025  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
00026  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
00027  * 
00028  * Except as contained in this notice, the name of a copyright holder
00029  * shall not be used in advertising or otherwise to promote the sale, use
00030  * or other dealings in this Software without prior written authorization
00031  * of the copyright holder.
00032  */
00033 
00034 typedef struct StringMem StringMem;
00035 
00036 /*
00037  * Applications that dynamically allocate lots of small strings
00038  * run the risk of significantly fragmenting the heap. This module
00039  * aims to reduce this risk by allocating large arrays of small fixed
00040  * length strings, arranging them as a free-list and allowing
00041  * callers to allocate from the list. Strings that are too long
00042  * to be allocated from the free-list are allocated from the heap.
00043  * Since typical implementations of malloc() eat up a minimum of
00044  * 16 bytes per call to malloc() [because of alignment and space
00045  * management constraints] it makes sense to set the free-list
00046  * string size to 16 bytes. Note that unlike malloc() which typically
00047  * keeps 8 bytes per allocation for its own use, our allocator will
00048  * return all but one of the 16 bytes for use. One hidden byte of overhead
00049  * is reserved for flagging whether the string was allocated directly
00050  * from malloc or from the free-list.
00051  */
00052 
00053 /*
00054  * Set the length of each free-list string. The longest string that
00055  * will be returned without calling malloc() will be one less than
00056  * this number.
00057  */
00058 #define SM_STRLEN 16
00059 
00060 /*
00061  * Create a string free-list container and the first block of its free-list.
00062  */
00063 StringMem *_new_StringMem(const char *caller, unsigned blocking_factor);
00064 
00065 /*
00066  * Delete a string free-list.
00067  */
00068 StringMem *_del_StringMem(const char *caller, StringMem *sm, int force);
00069 
00070 /*
00071  * Allocate an array of 'length' chars.
00072  */
00073 char *_new_StringMemString(StringMem *sm, size_t size);
00074 
00075 /*
00076  * Free a string that was previously returned by _new_StringMemString().
00077  */
00078 char *_del_StringMemString(StringMem *sm, char *s);
00079 
00080 #endif
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