/*****************************************************************************
* DikuMUD (C) 1990, 1991 by: *
* Sebastian Hammer, Michael Seifert, Hans Henrik Staefeldt, Tom Madsen, *
* and Katja Nyboe. *
*---------------------------------------------------------------------------*
* MERC 2.1 (C) 1992, 1993 by: *
* Michael Chastain, Michael Quan, and Mitchell Tse. *
*---------------------------------------------------------------------------*
* SMAUG 1.4 (C) 1994, 1995, 1996, 1998 by: Derek Snider. *
* Team: Thoric, Altrag, Blodkai, Narn, Haus, Scryn, Rennard, Swordbearer, *
* gorog, Grishnakh, Nivek, Tricops, and Fireblade. *
*---------------------------------------------------------------------------*
* SMAUG 1.7 FUSS by: Samson and others of the SMAUG community. *
* Their contributions are greatly appreciated. *
*---------------------------------------------------------------------------*
* LoP (C) 2006, 2007, 2008, 2009 by: the LoP team. *
*****************************************************************************
* Advanced string hashing functions (c)1996 D.S.D. Software, written by *
* Derek Snider for use in SMAUG. *
* *
* These functions keep track of how many "links" are pointing to the *
* memory allocated, and will free the memory if all the links are removed. *
* Make absolutely sure you do not mix use of strdup and free with these *
* functions, or nasty stuff will happen! *
* Most occurances of strdup/str_dup should be replaced with str_alloc, and *
* any free/DISPOSE used on the same pointer should be replaced with *
* str_free. If a function uses strdup for temporary use... it is best if *
* it is left as is. Just don't get usage mixed up between conventions. *
* The hashstr_data size is 8 bytes of overhead. Don't be concerned about *
* this as you still save lots of space on duplicate strings. -Thoric *
*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "h/mud.h"
extern bool mud_down;
#define STR_HASH_SIZE 1024
struct hashstr_data
{
struct hashstr_data *next; /* next hash element */
unsigned short int links; /* number of links to this string */
unsigned short int length; /* length of string */
};
struct hashstr_data *string_hash[STR_HASH_SIZE];
/*
* Check hash table for existing occurance of string.
* If found, increase link count, and return pointer,
* otherwise add new string to hash table, and return pointer.
*/
char *str_alloc( const char *str, const char *filename, int line )
{
register int len, hash, psize;
register struct hashstr_data *ptr;
if( !str || str[0] == '\0' )
{
// bug( "%s: %s@%d trying to allocate an empty/null string", __FUNCTION__, filename, line );
return NULL;
}
len = strlen( str );
psize = sizeof( struct hashstr_data );
hash = len % STR_HASH_SIZE;
for( ptr = string_hash[hash]; ptr; ptr = ptr->next )
{
if( len == ptr->length && !strcmp( str, ( char * )ptr + psize ) )
{
if( ( ptr->links + 1 ) > 65500 )
continue;
else
++ptr->links;
return ( char * )ptr + psize;
}
}
ptr = ( struct hashstr_data * )malloc( len + psize + 1 );
ptr->links = 1;
ptr->length = len;
if( len )
strcpy( ( char * )ptr + psize, str );
else
strcpy( ( char * )ptr + psize, "" );
ptr->next = string_hash[hash];
string_hash[hash] = ptr;
return ( char * )ptr + psize;
}
/*
* Used to make a quick copy of a string pointer that is known to be already
* in the hash table. Function increments the link count and returns the
* same pointer passed.
*/
char *quick_link( const char *str, const char *filename, int line )
{
register struct hashstr_data *ptr;
if( !str || str[0] == '\0' )
{
// bug( "%s: %s@%d trying to allocate an empty/null string", __FUNCTION__, filename, line );
return NULL;
}
ptr = ( struct hashstr_data * )( str - sizeof( struct hashstr_data ) );
if( !ptr || ptr->links == 0 )
{
fprintf( stderr, "%s: %s@%d called bad pointer\n", __FUNCTION__, filename, line );
return NULL;
}
if( ( ptr->links + 1 ) > 65500 )
return str_alloc( str, filename, line );
else
++ptr->links;
return (char *)str;
}
/*
* Used to remove a link to a string in the hash table.
* If all existing links are removed, the string is removed from the
* hash table and disposed of.
* returns how many links are left, or -1 if an error occurred.
*/
int str_free( const char *str, const char *filename, int line )
{
register int len, hash;
register struct hashstr_data *ptr, *ptr2, *ptr2_next;
if( !str || str[0] == '\0' )
{
// bug( "%s: %s@%d trying to free an empty/null string", __FUNCTION__, filename, line );
return -1;
}
len = strlen( str );
hash = len % STR_HASH_SIZE;
ptr = ( struct hashstr_data * )( str - sizeof( struct hashstr_data ) );
if( !ptr || ptr->links == 0 )
{
fprintf( stderr, "%s: %s@%d calling bad pointer\n", __FUNCTION__, filename, line );
return -1;
}
if( --ptr->links == 0 )
{
if( string_hash[hash] == ptr )
{
string_hash[hash] = ptr->next;
free( ptr );
return 0;
}
for( ptr2 = string_hash[hash]; ptr2; ptr2 = ptr2_next )
{
ptr2_next = ptr2->next;
if( ptr2_next == ptr )
{
ptr2->next = ptr->next;
free( ptr );
return 0;
}
}
fprintf( stderr, "%s: %s@%d calling pointer thats not found for string: %s\n", __FUNCTION__, filename, line, str );
return -1;
}
return ptr->links;
}
void show_hash( int count )
{
struct hashstr_data *ptr;
int x, c;
for( x = 0; x < count; x++ )
{
for( c = 0, ptr = string_hash[x]; ptr; ptr = ptr->next, c++ );
fprintf( stderr, " %d", c );
}
fprintf( stderr, "\n" );
}
void hash_dump( int hash )
{
struct hashstr_data *ptr;
char *str;
int c, psize;
if( hash > STR_HASH_SIZE || hash < 0 )
{
fprintf( stderr, "%s: invalid hash size\n", __FUNCTION__ );
return;
}
psize = sizeof( struct hashstr_data );
for( c = 0, ptr = string_hash[hash]; ptr; ptr = ptr->next, c++ )
{
str = ( char * )( ( ( long )ptr ) + psize );
fprintf( stderr, "Len: %4d Lnks: %5d Str: %s\r\n", ptr->length, ptr->links, strip_cr( str ) );
}
if( !mud_down || ( mud_down && c > 0 ) )
fprintf( stderr, "Total strings in hash %d: %d\r\n", hash, c );
}
char *check_hash( const char *str )
{
static char buf[1024];
int len, hash, psize, p = 0, c;
struct hashstr_data *ptr, *fnd;
buf[0] = '\0';
len = strlen( str );
psize = sizeof( struct hashstr_data );
hash = len % STR_HASH_SIZE;
for( fnd = NULL, ptr = string_hash[hash], c = 0; ptr; ptr = ptr->next, c++ )
if( len == ptr->length && !strcmp( str, ( char * )ptr + psize ) )
{
fnd = ptr;
p = c + 1;
}
if( fnd )
snprintf( buf, sizeof( buf ), "Hash info on string: %s\r\nLinks: %d Position: %d/%d Hash: %d Length: %d\r\n",
str, fnd->links, p, c, hash, fnd->length );
else
snprintf( buf, sizeof( buf ), "%s not found.\r\n", str );
return buf;
}
char *hash_stats( void )
{
static char buf[1024];
struct hashstr_data *ptr;
int x, c, total = 0, totlinks = 0, unique = 0, bytesused = 0, wouldhave = 0, hilink = 0, saved = 0;
int hashsize = sizeof( struct hashstr_data );
for( x = 0; x < STR_HASH_SIZE; x++ )
{
for( c = 0, ptr = string_hash[x]; ptr; ptr = ptr->next, c++ )
{
total++;
if( ptr->links == 1 )
unique++;
if( ptr->links > hilink )
hilink = ptr->links;
totlinks += ptr->links;
bytesused += ( ptr->length + 1 + hashsize );
/*
* Wouldhave is done in what str_dup would use instead of the hash if bytes saved shows -
* your wasteing memory because of to many unique links
*/
wouldhave += ( ptr->links * ( ptr->length + 1 ) );
}
}
saved = ( wouldhave - bytesused );
snprintf( buf, sizeof( buf ),
"Total Strings: %8d Bytes Used : %8d\r\n"
"Total Links : %8d Bytes %s: %8d\r\n"
"Unique Links : %8d\r\n"
"Hi Link Count: %8d\r\n",
total, bytesused, totlinks, saved >= 0 ? "Saved " : "Wasted", abs( saved ), unique, hilink );
return buf;
}
void show_high_hash( int top )
{
struct hashstr_data *ptr;
int x, psize;
char *str;
psize = sizeof( struct hashstr_data );
for( x = 0; x < STR_HASH_SIZE; x++ )
{
for( ptr = string_hash[x]; ptr; ptr = ptr->next )
{
if( ptr->links >= top )
{
str = ( char * )( ( ( long )ptr ) + psize );
fprintf( stderr, "Links: %5d String: >%s<\r\n", ptr->links, strip_cr( str ) );
}
}
}
}
bool in_hash_table( const char *str )
{
register int len, hash, psize;
register struct hashstr_data *ptr;
len = strlen( str );
psize = sizeof( struct hashstr_data );
hash = len % STR_HASH_SIZE;
for( ptr = string_hash[hash]; ptr; ptr = ptr->next )
if( len == ptr->length && str == ( ( char * )ptr + psize ) )
return true;
return false;
}