src/filemap.cc

   1 /*
   2  * $Id: filemap.cc,v 1.16 1997/03/29 04:45:15 wessels Exp $
   3  *
   4  * DEBUG: section 8     Swap File Bitmap
   5  * AUTHOR: Harvest Derived
   6  *
   7  * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
   8  * --------------------------------------------------------
   9  *
  10  *  Squid is the result of efforts by numerous individuals from the
  11  *  Internet community.  Development is led by Duane Wessels of the
  12  *  National Laboratory for Applied Network Research and funded by
  13  *  the National Science Foundation.
  14  *
  15  *  This program is free software; you can redistribute it and/or modify
  16  *  it under the terms of the GNU General Public License as published by
  17  *  the Free Software Foundation; either version 2 of the License, or
  18  *  (at your option) any later version.
  19  *
  20  *  This program is distributed in the hope that it will be useful,
  21  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  *  GNU General Public License for more details.
  24  *
  25  *  You should have received a copy of the GNU General Public License
  26  *  along with this program; if not, write to the Free Software
  27  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  28  *
  29  */
  30
  31 /*
  32  * Copyright (c) 1994, 1995.  All rights reserved.
  33  *
  34  *   The Harvest software was developed by the Internet Research Task
  35  *   Force Research Group on Resource Discovery (IRTF-RD):
  36  *
  37  *         Mic Bowman of Transarc Corporation.
  38  *         Peter Danzig of the University of Southern California.
  39  *         Darren R. Hardy of the University of Colorado at Boulder.
  40  *         Udi Manber of the University of Arizona.
  41  *         Michael F. Schwartz of the University of Colorado at Boulder.
  42  *         Duane Wessels of the University of Colorado at Boulder.
  43  *
  44  *   This copyright notice applies to software in the Harvest
  45  *   ``src/'' directory only.  Users should consult the individual
  46  *   copyright notices in the ``components/'' subdirectories for
  47  *   copyright information about other software bundled with the
  48  *   Harvest source code distribution.
  49  *
  50  * TERMS OF USE
  51  *
  52  *   The Harvest software may be used and re-distributed without
  53  *   charge, provided that the software origin and research team are
  54  *   cited in any use of the system.  Most commonly this is
  55  *   accomplished by including a link to the Harvest Home Page
  56  *   (http://harvest.cs.colorado.edu/) from the query page of any
  57  *   Broker you deploy, as well as in the query result pages.  These
  58  *   links are generated automatically by the standard Broker
  59  *   software distribution.
  60  *
  61  *   The Harvest software is provided ``as is'', without express or
  62  *   implied warranty, and with no support nor obligation to assist
  63  *   in its use, correction, modification or enhancement.  We assume
  64  *   no liability with respect to the infringement of copyrights,
  65  *   trade secrets, or any patents, and are not responsible for
  66  *   consequential damages.  Proper use of the Harvest software is
  67  *   entirely the responsibility of the user.
  68  *
  69  * DERIVATIVE WORKS
  70  *
  71  *   Users may make derivative works from the Harvest software, subject
  72  *   to the following constraints:
  73  *
  74  *     - You must include the above copyright notice and these
  75  *       accompanying paragraphs in all forms of derivative works,
  76  *       and any documentation and other materials related to such
  77  *       distribution and use acknowledge that the software was
  78  *       developed at the above institutions.
  79  *
  80  *     - You must notify IRTF-RD regarding your distribution of
  81  *       the derivative work.
  82  *
  83  *     - You must clearly notify users that your are distributing
  84  *       a modified version and not the original Harvest software.
  85  *
  86  *     - Any derivative product is also subject to these copyright
  87  *       and use restrictions.
  88  *
  89  *   Note that the Harvest software is NOT in the public domain.  We
  90  *   retain copyright, as specified above.
  91  *
  92  * HISTORY OF FREE SOFTWARE STATUS
  93  *
  94  *   Originally we required sites to license the software in cases
  95  *   where they were going to build commercial products/services
  96  *   around Harvest.  In June 1995 we changed this policy.  We now
  97  *   allow people to use the core Harvest software (the code found in
  98  *   the Harvest ``src/'' directory) for free.  We made this change
  99  *   in the interest of encouraging the widest possible deployment of
 100  *   the technology.  The Harvest software is really a reference
 101  *   implementation of a set of protocols and formats, some of which
 102  *   we intend to standardize.  We encourage commercial
 103  *   re-implementations of code complying to this set of standards.
 104  */
 105
 106 #include "squid.h"
 107 #include "filemap.h"
 108
 109 /* Number of bits in a long */
 110 #if SIZEOF_LONG == 8
 111 #define LONG_BIT_SHIFT 6
 112 #define BITS_IN_A_LONG 0x40
 113 #define LONG_BIT_MASK  0x3F
 114 #define ALL_ONES (unsigned long) 0xFFFFFFFFFFFFFFFF
 115 #elif SIZEOF_LONG == 4
 116 #define LONG_BIT_SHIFT 5
 117 #define BITS_IN_A_LONG 0x20
 118 #define LONG_BIT_MASK  0x1F
 119 #define ALL_ONES (unsigned long) 0xFFFFFFFF
 120 #else
 121 #define LONG_BIT_SHIFT 5
 122 #define BITS_IN_A_LONG 0x20
 123 #define LONG_BIT_MASK  0x1F
 124 #define ALL_ONES (unsigned long) 0xFFFFFFFF
 125 #endif
 126
 127 fileMap *
 128 file_map_create(int n)
 129 {
 130     fileMap *fm = xcalloc(1, sizeof(fileMap));
 131     fm->max_n_files = n;
 132     fm->nwords = n >> LONG_BIT_SHIFT;
 133     debug(8, 1, "file_map_create: creating space for %d files\n", n);
 134     debug(8, 5, "--> %d words of %d bytes each\n",
 135         fm->nwords, sizeof(unsigned long));
 136     fm->file_map = xcalloc(fm->nwords, sizeof(unsigned long));
 137     meta_data.misc += fm->nwords * sizeof(unsigned long);
 138     return fm;
 139 }
 140
 141 int
 142 file_map_bit_set(fileMap * fm, int file_number)
 143 {
 144     unsigned long bitmask = (1L << (file_number & LONG_BIT_MASK));
 145     fm->file_map[file_number >> LONG_BIT_SHIFT] |= bitmask;
 146     fm->n_files_in_map++;
 147     if (!fm->toggle && (fm->n_files_in_map > ((fm->max_n_files * 7) >> 3))) {
 148         fm->toggle++;
 149         debug(8, 0, "You should increment MAX_SWAP_FILE\n");
 150     } else if (fm->n_files_in_map > (fm->max_n_files - 100)) {
 151         debug(8, 0, "You've run out of swap file numbers. Freeing 1MB\n");
 152         storeGetSwapSpace(1000000);
 153     }
 154     return (file_number);
 155 }
 156
 157 void
 158 file_map_bit_reset(fileMap * fm, int file_number)
 159 {
 160     unsigned long bitmask = (1L << (file_number & LONG_BIT_MASK));
 161     fm->file_map[file_number >> LONG_BIT_SHIFT] &= ~bitmask;
 162     fm->n_files_in_map--;
 163 }
 164
 165 int
 166 file_map_bit_test(fileMap * fm, int file_number)
 167 {
 168     unsigned long bitmask = (1L << (file_number & LONG_BIT_MASK));
 169     /* be sure the return value is an int, not a u_long */
 170     return (fm->file_map[file_number >> LONG_BIT_SHIFT] & bitmask ? 1 : 0);
 171 }
 172
 173 int
 174 file_map_allocate(fileMap * fm, int suggestion)
 175 {
 176     int word;
 177     int bit;
 178     int count;
 179     if (!file_map_bit_test(fm, suggestion)) {
 180         fm->last_file_number_allocated = suggestion;
 181         return file_map_bit_set(fm, suggestion);
 182     }
 183     word = suggestion >> LONG_BIT_SHIFT;
 184     for (count = 0; count < fm->nwords; count++) {
 185         if (fm->file_map[word] != ALL_ONES)
 186             break;
 187         word = (word + 1) % fm->nwords;
 188     }
 189     for (bit = 0; bit < BITS_IN_A_LONG; bit++) {
 190         suggestion = ((unsigned long) word << LONG_BIT_SHIFT) | bit;
 191         if (!file_map_bit_test(fm, suggestion)) {
 192             fm->last_file_number_allocated = suggestion;
 193             return file_map_bit_set(fm, suggestion);
 194         }
 195     }
 196     fatal_dump("file_map_allocate: Exceeded filemap limit");
 197     return 0;                   /* NOTREACHED */
 198 }
 199
 200 void
 201 filemapFreeMemory(fileMap * fm)
 202 {
 203     safe_free(fm->file_map);
 204     safe_free(fm);
 205 }
 206
 207 #ifdef TEST
 208
 209 #define TEST_SIZE 1<<16
 210 main(argc, argv)
 211 {
 212     int i;
 213
 214     fm = file_map_create(TEST_SIZE);
 215
 216     for (i = 0; i < TEST_SIZE; ++i) {
 217         file_map_bit_set(i);
 218         if (!file_map_bit_test(i))
 219             fatal_dump(NULL);
 220         file_map_bit_reset(i);
 221     }
 222 }
 223 #endif