/***************************************************************************** * 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 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( char *str, 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( char *str, 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 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( char *str, 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( 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( 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; }