usr.bin/make/hash.c

   1 /*      $NetBSD: hash.c,v 1.18 2008/12/13 15:19:29 dsl Exp $    */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Adam de Boor.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * Copyright (c) 1988, 1989 by Adam de Boor
  37  * Copyright (c) 1989 by Berkeley Softworks
  38  * All rights reserved.
  39  *
  40  * This code is derived from software contributed to Berkeley by
  41  * Adam de Boor.
  42  *
  43  * Redistribution and use in source and binary forms, with or without
  44  * modification, are permitted provided that the following conditions
  45  * are met:
  46  * 1. Redistributions of source code must retain the above copyright
  47  *    notice, this list of conditions and the following disclaimer.
  48  * 2. Redistributions in binary form must reproduce the above copyright
  49  *    notice, this list of conditions and the following disclaimer in the
  50  *    documentation and/or other materials provided with the distribution.
  51  * 3. All advertising materials mentioning features or use of this software
  52  *    must display the following acknowledgement:
  53  *      This product includes software developed by the University of
  54  *      California, Berkeley and its contributors.
  55  * 4. Neither the name of the University nor the names of its contributors
  56  *    may be used to endorse or promote products derived from this software
  57  *    without specific prior written permission.
  58  *
  59  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  69  * SUCH DAMAGE.
  70  */
  71
  72 #ifndef MAKE_NATIVE
  73 static char rcsid[] = "$NetBSD: hash.c,v 1.18 2008/12/13 15:19:29 dsl Exp $";
  74 #else
  75 #include <sys/cdefs.h>
  76 #ifndef lint
  77 #if 0
  78 static char sccsid[] = "@(#)hash.c      8.1 (Berkeley) 6/6/93";
  79 #else
  80 __RCSID("$NetBSD: hash.c,v 1.18 2008/12/13 15:19:29 dsl Exp $");
  81 #endif
  82 #endif /* not lint */
  83 #endif
  84
  85 /* hash.c --
  86  *
  87  *      This module contains routines to manipulate a hash table.
  88  *      See hash.h for a definition of the structure of the hash
  89  *      table.  Hash tables grow automatically as the amount of
  90  *      information increases.
  91  */
  92 #include "sprite.h"
  93 #include "make.h"
  94 #include "hash.h"
  95
  96 /*
  97  * Forward references to local procedures that are used before they're
  98  * defined:
  99  */
 100
 101 static void RebuildTable(Hash_Table *);
 102
 103 /*
 104  * The following defines the ratio of # entries to # buckets
 105  * at which we rebuild the table to make it larger.
 106  */
 107
 108 #define rebuildLimit 3
 109
 110 /*
 111  *---------------------------------------------------------
 112  *
 113  * Hash_InitTable --
 114  *
 115  *      This routine just sets up the hash table.
 116  *
 117  * Input:
 118  *      t               Structure to to hold table.
 119  *      numBuckets      How many buckets to create for starters. This
 120  *                      number is rounded up to a power of two.   If
 121  *                      <= 0, a reasonable default is chosen. The
 122  *                      table will grow in size later as needed.
 123  *
 124  * Results:
 125  *      None.
 126  *
 127  * Side Effects:
 128  *      Memory is allocated for the initial bucket area.
 129  *
 130  *---------------------------------------------------------
 131  */
 132
 133 void
 134 Hash_InitTable(Hash_Table *t, int numBuckets)
 135 {
 136         int i;
 137         struct Hash_Entry **hp;
 138
 139         /*
 140          * Round up the size to a power of two.
 141          */
 142         if (numBuckets <= 0)
 143                 i = 16;
 144         else {
 145                 for (i = 2; i < numBuckets; i <<= 1)
 146                          continue;
 147         }
 148         t->numEntries = 0;
 149         t->size = i;
 150         t->mask = i - 1;
 151         t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i);
 152         while (--i >= 0)
 153                 *hp++ = NULL;
 154 }
 155
 156 /*
 157  *---------------------------------------------------------
 158  *
 159  * Hash_DeleteTable --
 160  *
 161  *      This routine removes everything from a hash table
 162  *      and frees up the memory space it occupied (except for
 163  *      the space in the Hash_Table structure).
 164  *
 165  * Results:
 166  *      None.
 167  *
 168  * Side Effects:
 169  *      Lots of memory is freed up.
 170  *
 171  *---------------------------------------------------------
 172  */
 173
 174 void
 175 Hash_DeleteTable(Hash_Table *t)
 176 {
 177         struct Hash_Entry **hp, *h, *nexth = NULL;
 178         int i;
 179
 180         for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
 181                 for (h = *hp++; h != NULL; h = nexth) {
 182                         nexth = h->next;
 183                         free(h);
 184                 }
 185         }
 186         free(t->bucketPtr);
 187
 188         /*
 189          * Set up the hash table to cause memory faults on any future access
 190          * attempts until re-initialization.
 191          */
 192         t->bucketPtr = NULL;
 193 }
 194
 195 /*
 196  *---------------------------------------------------------
 197  *
 198  * Hash_FindEntry --
 199  *
 200  *      Searches a hash table for an entry corresponding to key.
 201  *
 202  * Input:
 203  *      t               Hash table to search.
 204  *      key             A hash key.
 205  *
 206  * Results:
 207  *      The return value is a pointer to the entry for key,
 208  *      if key was present in the table.  If key was not
 209  *      present, NULL is returned.
 210  *
 211  * Side Effects:
 212  *      None.
 213  *
 214  *---------------------------------------------------------
 215  */
 216
 217 Hash_Entry *
 218 Hash_FindEntry(Hash_Table *t, const char *key)
 219 {
 220         Hash_Entry *e;
 221         unsigned h;
 222         const char *p;
 223
 224         for (h = 0, p = key; *p;)
 225                 h = (h << 5) - h + *p++;
 226         p = key;
 227         for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
 228                 if (e->namehash == h && strcmp(e->name, p) == 0)
 229                         return (e);
 230         return NULL;
 231 }
 232
 233 /*
 234  *---------------------------------------------------------
 235  *
 236  * Hash_CreateEntry --
 237  *
 238  *      Searches a hash table for an entry corresponding to
 239  *      key.  If no entry is found, then one is created.
 240  *
 241  * Input:
 242  *      t               Hash table to search.
 243  *      key             A hash key.
 244  *      newPtr          Filled in with TRUE if new entry created,
 245  *                      FALSE otherwise.
 246  *
 247  * Results:
 248  *      The return value is a pointer to the entry.  If *newPtr
 249  *      isn't NULL, then *newPtr is filled in with TRUE if a
 250  *      new entry was created, and FALSE if an entry already existed
 251  *      with the given key.
 252  *
 253  * Side Effects:
 254  *      Memory may be allocated, and the hash buckets may be modified.
 255  *---------------------------------------------------------
 256  */
 257
 258 Hash_Entry *
 259 Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr)
 260 {
 261         Hash_Entry *e;
 262         unsigned h;
 263         const char *p;
 264         int keylen;
 265         struct Hash_Entry **hp;
 266
 267         /*
 268          * Hash the key.  As a side effect, save the length (strlen) of the
 269          * key in case we need to create the entry.
 270          */
 271         for (h = 0, p = key; *p;)
 272                 h = (h << 5) - h + *p++;
 273         keylen = p - key;
 274         p = key;
 275         for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
 276                 if (e->namehash == h && strcmp(e->name, p) == 0) {
 277                         if (newPtr != NULL)
 278                                 *newPtr = FALSE;
 279                         return (e);
 280                 }
 281         }
 282
 283         /*
 284          * The desired entry isn't there.  Before allocating a new entry,
 285          * expand the table if necessary (and this changes the resulting
 286          * bucket chain).
 287          */
 288         if (t->numEntries >= rebuildLimit * t->size)
 289                 RebuildTable(t);
 290         e = bmake_malloc(sizeof(*e) + keylen);
 291         hp = &t->bucketPtr[h & t->mask];
 292         e->next = *hp;
 293         *hp = e;
 294         Hash_SetValue(e, NULL);
 295         e->namehash = h;
 296         (void)strcpy(e->name, p);
 297         t->numEntries++;
 298
 299         if (newPtr != NULL)
 300                 *newPtr = TRUE;
 301         return (e);
 302 }
 303
 304 /*
 305  *---------------------------------------------------------
 306  *
 307  * Hash_DeleteEntry --
 308  *
 309  *      Delete the given hash table entry and free memory associated with
 310  *      it.
 311  *
 312  * Results:
 313  *      None.
 314  *
 315  * Side Effects:
 316  *      Hash chain that entry lives in is modified and memory is freed.
 317  *
 318  *---------------------------------------------------------
 319  */
 320
 321 void
 322 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
 323 {
 324         Hash_Entry **hp, *p;
 325
 326         if (e == NULL)
 327                 return;
 328         for (hp = &t->bucketPtr[e->namehash & t->mask];
 329              (p = *hp) != NULL; hp = &p->next) {
 330                 if (p == e) {
 331                         *hp = p->next;
 332                         free(p);
 333                         t->numEntries--;
 334                         return;
 335                 }
 336         }
 337         (void)write(2, "bad call to Hash_DeleteEntry\n", 29);
 338         abort();
 339 }
 340
 341 /*
 342  *---------------------------------------------------------
 343  *
 344  * Hash_EnumFirst --
 345  *      This procedure sets things up for a complete search
 346  *      of all entries recorded in the hash table.
 347  *
 348  * Input:
 349  *      t               Table to be searched.
 350  *      searchPtr       Area in which to keep state about search.
 351  *
 352  * Results:
 353  *      The return value is the address of the first entry in
 354  *      the hash table, or NULL if the table is empty.
 355  *
 356  * Side Effects:
 357  *      The information in searchPtr is initialized so that successive
 358  *      calls to Hash_Next will return successive HashEntry's
 359  *      from the table.
 360  *
 361  *---------------------------------------------------------
 362  */
 363
 364 Hash_Entry *
 365 Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr)
 366 {
 367         searchPtr->tablePtr = t;
 368         searchPtr->nextIndex = 0;
 369         searchPtr->hashEntryPtr = NULL;
 370         return Hash_EnumNext(searchPtr);
 371 }
 372
 373 /*
 374  *---------------------------------------------------------
 375  *
 376  * Hash_EnumNext --
 377  *    This procedure returns successive entries in the hash table.
 378  *
 379  * Input:
 380  *      searchPtr       Area used to keep state about search.
 381  *
 382  * Results:
 383  *    The return value is a pointer to the next HashEntry
 384  *    in the table, or NULL when the end of the table is
 385  *    reached.
 386  *
 387  * Side Effects:
 388  *    The information in searchPtr is modified to advance to the
 389  *    next entry.
 390  *
 391  *---------------------------------------------------------
 392  */
 393
 394 Hash_Entry *
 395 Hash_EnumNext(Hash_Search *searchPtr)
 396 {
 397         Hash_Entry *e;
 398         Hash_Table *t = searchPtr->tablePtr;
 399
 400         /*
 401          * The hashEntryPtr field points to the most recently returned
 402          * entry, or is nil if we are starting up.  If not nil, we have
 403          * to start at the next one in the chain.
 404          */
 405         e = searchPtr->hashEntryPtr;
 406         if (e != NULL)
 407                 e = e->next;
 408         /*
 409          * If the chain ran out, or if we are starting up, we need to
 410          * find the next nonempty chain.
 411          */
 412         while (e == NULL) {
 413                 if (searchPtr->nextIndex >= t->size)
 414                         return NULL;
 415                 e = t->bucketPtr[searchPtr->nextIndex++];
 416         }
 417         searchPtr->hashEntryPtr = e;
 418         return (e);
 419 }
 420
 421 /*
 422  *---------------------------------------------------------
 423  *
 424  * RebuildTable --
 425  *      This local routine makes a new hash table that
 426  *      is larger than the old one.
 427  *
 428  * Results:
 429  *      None.
 430  *
 431  * Side Effects:
 432  *      The entire hash table is moved, so any bucket numbers
 433  *      from the old table are invalid.
 434  *
 435  *---------------------------------------------------------
 436  */
 437
 438 static void
 439 RebuildTable(Hash_Table *t)
 440 {
 441         Hash_Entry *e, *next = NULL, **hp, **xp;
 442         int i, mask;
 443         Hash_Entry **oldhp;
 444         int oldsize;
 445
 446         oldhp = t->bucketPtr;
 447         oldsize = i = t->size;
 448         i <<= 1;
 449         t->size = i;
 450         t->mask = mask = i - 1;
 451         t->bucketPtr = hp = bmake_malloc(sizeof(*hp) * i);
 452         while (--i >= 0)
 453                 *hp++ = NULL;
 454         for (hp = oldhp, i = oldsize; --i >= 0;) {
 455                 for (e = *hp++; e != NULL; e = next) {
 456                         next = e->next;
 457                         xp = &t->bucketPtr[e->namehash & mask];
 458                         e->next = *xp;
 459                         *xp = e;
 460                 }
 461         }
 462         free(oldhp);
 463 }