nsz Git - libfirm/blob - ir/adt/hashset.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief   Generic hashset implementation
  23  * @author  Matthias Braun, inspiration from densehash from google sparsehash
  24  *          package
  25  * @date    17.03.2007
  26  *
  27  *
  28  * You have to specialize this file by defining:
  29  *
  30  * <ul>
  31  *  <li><b>HashSet</b>         The name of the hashset type</li>
  32  *  <li><b>HashSetIterator</b> The name of the hashset iterator type</li>
  33  *  <li><b>ValueType</b>       The type of the stored data values</li>
  34  *  <li><b>NullValue</b>       A special value representing no values</li>
  35  *  <li><b>DeletedValue</b>    A special value representing deleted entries</li>
  36  *  <li><b>Hash(hashset,key)</b> calculates the hash value for a given key</li>
  37  * </ul>
  38  *
  39  * Note that by default it is assumed that the data values themselfes are used
  40  * as keys. However you can change that with additional defines:
  41  *
  42  * <ul>
  43  *  <li><b>KeyType</b>         The type of the keys identifying data values.
  44  *                             Defining this implies, that a data value contains
  45  *                             more than just the key.</li>
  46  *  <li><b>GetKey(value)</b>   Extracts the key from a data value</li>
  47  *  <li><b>KeysEqual(hashset,key1,key2)</b>  Tests wether 2 keys are equal</li>
  48  *  <li><b>DO_REHASH</b>       Instead of storing the hash-values, recalculate
  49  *                             them on demand from the datavalues. (useful if
  50  *                             calculating the hash-values takes less time than
  51  *                             a memory access)</li>
  52  * </ul>
  53  *
  54  * You can further fine tune your hashset by defining the following:
  55  *
  56  * <ul>
  57  *  <li><b>JUMP(num_probes)</b> The probing method</li>
  58  *  <li><b>Alloc(count)</b>     Allocates count hashset entries (NOT bytes)</li>
  59  *  <li><b>Free(ptr)</b>        Frees a block of memory allocated by Alloc</li>
  60  *  <li><b>SetRangeEmpty(ptr,count)</b> Efficiently sets a range of elements to
  61  *                                      the Null value</li>
  62  *  <li><b>ADDITIONAL_DATA<b>   Additional fields appended to the hashset struct</li>
  63  * </ul>
  64  */
  65 #ifdef HashSet
  66
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <assert.h>
  70
  71 #include "bitfiddle.h"
  72 #include "util.h"
  73
  74 /* quadratic probing */
  75 #ifndef JUMP
  76 #define JUMP(num_probes)      (num_probes)
  77 #endif /* JUMP */
  78
  79 #ifndef Hash
  80 #define ID_HASH
  81 #define Hash(self,key)        ((unsigned)(((char *)key) - (char *)0))
  82 #endif /* Hash */
  83
  84 #ifdef DO_REHASH
  85 #define HashSetEntry                   ValueType
  86 #define EntrySetHash(entry,new_hash)   (void)0
  87 #define EntryGetHash(self,entry)       Hash(self, GetKey(entry))
  88 #define EntryGetValue(entry)           (entry)
  89 #else /* ! DO_REHASH */
  90 #define EntryGetHash(self,entry)       (entry).hash
  91 #define EntrySetHash(entry,new_hash)   (entry).hash = (new_hash)
  92 #define EntryGetValue(entry)           (entry).data
  93 #endif /* DO_REHASH */
  94
  95 #ifndef Alloc
  96 #include "xmalloc.h"
  97 #define Alloc(size) XMALLOCN(HashSetEntry, (size))
  98 #define Free(ptr)      free(ptr)
  99 #endif /* Alloc */
 100
 101 #ifdef ID_HASH
 102 #define InsertReturnValue                 int
 103 #define GetInsertReturnValue(entry,found) (found)
 104 #define NullReturnValue                   0
 105 #else /* ! ID_HASH */
 106 #ifdef SCALAR_RETURN
 107 #define InsertReturnValue                 ValueType
 108 #define GetInsertReturnValue(entry,found) EntryGetValue(entry)
 109 #define NullReturnValue                   NullValue
 110 #else
 111 #define InsertReturnValue                 ValueType*
 112 #define GetInsertReturnValue(entry,found) & EntryGetValue(entry)
 113 #define NullReturnValue                   & NullValue
 114 #endif
 115 #endif /* ID_HASH */
 116
 117 #ifndef KeyType
 118 #define KeyType                  ValueType
 119 #define GetKey(value)            (value)
 120 #define InitData(self,value,key) (value) = (key)
 121 #endif /* KeyType */
 122
 123 #ifndef ConstKeyType
 124 #define ConstKeyType             const KeyType
 125 #endif /* ConstKeyType */
 126
 127 #ifndef EntrySetEmpty
 128 #define EntrySetEmpty(entry)    EntryGetValue(entry) = NullValue
 129 #endif /* EntrySetEmpty */
 130 #ifndef EntrySetDeleted
 131 #define EntrySetDeleted(entry)  EntryGetValue(entry) = DeletedValue
 132 #endif /* EntrySetDeleted */
 133 #ifndef EntryIsEmpty
 134 #define EntryIsEmpty(entry)     (EntryGetValue(entry) == NullValue)
 135 #endif /* EntryIsEmpty */
 136 #ifndef EntryIsDeleted
 137 #define EntryIsDeleted(entry)   (EntryGetValue(entry) == DeletedValue)
 138 #endif /* EntryIsDeleted */
 139 #ifndef SetRangeEmpty
 140 #define SetRangeEmpty(ptr,size)                \
 141 {                                              \
 142         size_t _i;                                 \
 143         size_t _size = (size);                     \
 144         HashSetEntry *entries = (ptr);             \
 145         for (_i = 0; _i < _size; ++_i) {            \
 146                 HashSetEntry *entry = & entries[_i];   \
 147                 EntrySetEmpty(*entry);                 \
 148         }                                          \
 149 }
 150 #endif /* SetRangeEmpty */
 151
 152 #ifndef HT_OCCUPANCY_FLT
 153 /** how full before we double size */
 154 #define HT_OCCUPANCY_FLT(x) ((x)/2)
 155 #endif /* HT_OCCUPANCY_FLT */
 156 #ifndef HT_1_DIV_OCCUPANCY_FLT
 157 #define HT_1_DIV_OCCUPANCY_FLT 2
 158 #endif
 159
 160 #ifndef HT_EMPTY_FLT
 161 /** how empty before we half size */
 162 #define HT_EMPTY_FLT(x)     ((x)/5)
 163 #endif /* HT_EMPTY_FLT */
 164
 165 #ifndef HT_MIN_BUCKETS
 166 /** default smallest bucket size */
 167 #define HT_MIN_BUCKETS    32
 168 #endif /* HT_MIN_BUCKETS */
 169
 170 #define ILLEGAL_POS       ((size_t)-1)
 171
 172 /* check that all needed functions are defined */
 173 #ifndef hashset_init
 174 #error You have to redefine hashset_init
 175 #endif
 176 #ifndef hashset_init_size
 177 #error You have to redefine hashset_init_size
 178 #endif
 179 #ifndef hashset_destroy
 180 #error You have to redefine hashset_destroy
 181 #endif
 182 #ifndef hashset_insert
 183 #error You have to redefine hashset_insert
 184 #endif
 185 #ifndef hashset_remove
 186 #error You have to redefine hashset_remove
 187 #endif
 188 #ifndef hashset_find
 189 #error You have to redefine hashset_find
 190 #endif
 191 #ifndef hashset_size
 192 #error You have to redefine hashset_size
 193 #endif
 194
 195 #ifndef NO_ITERATOR
 196 #ifndef hashset_iterator_init
 197 #error You have to redefine hashset_iterator_init
 198 #endif
 199 #ifndef hashset_iterator_next
 200 #error You have to redefine hashset_iterator_next
 201 #endif
 202 #ifndef hashset_remove_iterator
 203 #error You have to redefine hashset_remove_iterator
 204 #endif
 205 #endif
 206
 207 /**
 208  * Returns the number of elements in the hashset
 209  */
 210 size_t hashset_size(const HashSet *self)
 211 {
 212         return self->num_elements - self->num_deleted;
 213 }
 214
 215 /**
 216  * Inserts an element into a hashset without growing the set (you have to make
 217  * sure there's enough room for that.
 218  * @note also see comments for hashset_insert()
 219  * @internal
 220  */
 221 static inline InsertReturnValue insert_nogrow(HashSet *self, KeyType key)
 222 {
 223         size_t   num_probes  = 0;
 224         size_t   num_buckets = self->num_buckets;
 225         size_t   hashmask    = num_buckets - 1;
 226         unsigned hash        = Hash(self, key);
 227         size_t   bucknum     = hash & hashmask;
 228         size_t   insert_pos  = ILLEGAL_POS;
 229
 230         assert((num_buckets & (num_buckets - 1)) == 0);
 231
 232         for (;;) {
 233                 HashSetEntry *entry = & self->entries[bucknum];
 234
 235                 if (EntryIsEmpty(*entry)) {
 236                         size_t p;
 237                         HashSetEntry *nentry;
 238
 239                         if (insert_pos != ILLEGAL_POS) {
 240                                 p = insert_pos;
 241                         } else {
 242                                 p = bucknum;
 243                         }
 244
 245                         nentry = &self->entries[p];
 246                         InitData(self, EntryGetValue(*nentry), key);
 247                         EntrySetHash(*nentry, hash);
 248                         self->num_elements++;
 249                         return GetInsertReturnValue(*nentry, 0);
 250                 }
 251                 if (EntryIsDeleted(*entry)) {
 252                         if (insert_pos == ILLEGAL_POS)
 253                                 insert_pos = bucknum;
 254                 } else if (EntryGetHash(self, *entry) == hash) {
 255                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 256                                 // Value already in the set, return it
 257                                 return GetInsertReturnValue(*entry, 1);
 258                         }
 259                 }
 260
 261                 ++num_probes;
 262                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 263                 assert(num_probes < num_buckets);
 264         }
 265 }
 266
 267 /**
 268  * calculate shrink and enlarge limits
 269  * @internal
 270  */
 271 static inline void reset_thresholds(HashSet *self)
 272 {
 273         self->enlarge_threshold = (size_t) HT_OCCUPANCY_FLT(self->num_buckets);
 274         self->shrink_threshold  = (size_t) HT_EMPTY_FLT(self->num_buckets);
 275         self->consider_shrink   = 0;
 276 }
 277
 278 #ifndef HAVE_OWN_RESIZE
 279 /**
 280  * Inserts an element into a hashset under the assumption that the hashset
 281  * contains no deleted entries and the element doesn't exist in the hashset yet.
 282  * @internal
 283  */
 284 static void insert_new(HashSet *self, unsigned hash, ValueType value)
 285 {
 286         size_t num_probes  = 0;
 287         size_t num_buckets = self->num_buckets;
 288         size_t hashmask    = num_buckets - 1;
 289         size_t bucknum     = hash & hashmask;
 290         size_t insert_pos  = ILLEGAL_POS;
 291
 292         //assert(value != NullValue);
 293
 294         for (;;) {
 295                 HashSetEntry *entry = & self->entries[bucknum];
 296
 297                 if (EntryIsEmpty(*entry)) {
 298                         size_t        p;
 299                         HashSetEntry *nentry;
 300
 301                         if (insert_pos != ILLEGAL_POS) {
 302                                 p = insert_pos;
 303                         } else {
 304                                 p = bucknum;
 305                         }
 306                         nentry = &self->entries[p];
 307
 308                         EntryGetValue(*nentry) = value;
 309                         EntrySetHash(*nentry, hash);
 310                         self->num_elements++;
 311                         return;
 312                 }
 313                 assert(!EntryIsDeleted(*entry));
 314
 315                 ++num_probes;
 316                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 317                 assert(num_probes < num_buckets);
 318         }
 319 }
 320
 321 /**
 322  * Resize the hashset
 323  * @internal
 324  */
 325 static inline void resize(HashSet *self, size_t new_size)
 326 {
 327         size_t num_buckets = self->num_buckets;
 328         size_t i;
 329         HashSetEntry *old_entries = self->entries;
 330         HashSetEntry *new_entries;
 331
 332         /* allocate a new array with double size */
 333         new_entries = Alloc(new_size);
 334         SetRangeEmpty(new_entries, new_size);
 335
 336         /* use the new array */
 337         self->entries      = new_entries;
 338         self->num_buckets  = new_size;
 339         self->num_elements = 0;
 340         self->num_deleted  = 0;
 341 #ifndef NDEBUG
 342         self->entries_version++;
 343 #endif
 344         reset_thresholds(self);
 345
 346         /* reinsert all elements */
 347         for (i = 0; i < num_buckets; ++i) {
 348                 HashSetEntry *entry = & old_entries[i];
 349                 if (EntryIsEmpty(*entry) || EntryIsDeleted(*entry))
 350                         continue;
 351
 352                 insert_new(self, EntryGetHash(self, *entry), EntryGetValue(*entry));
 353         }
 354
 355         /* now we can free the old array */
 356         Free(old_entries);
 357 }
 358 #else
 359
 360 /* resize must be defined outside */
 361 static inline void resize(HashSet *self, size_t new_size);
 362
 363 #endif
 364
 365 /**
 366  * grow the hashset if adding 1 more elements would make it too crowded
 367  * @internal
 368  */
 369 static inline void maybe_grow(HashSet *self)
 370 {
 371         size_t resize_to;
 372
 373         if (LIKELY(self->num_elements + 1 <= self->enlarge_threshold))
 374                 return;
 375
 376         /* double table size */
 377         resize_to = self->num_buckets * 2;
 378         resize(self, resize_to);
 379 }
 380
 381 /**
 382  * shrink the hashset if it is only sparsely filled
 383  * @internal
 384  */
 385 static inline void maybe_shrink(HashSet *self)
 386 {
 387         size_t size;
 388         size_t resize_to;
 389
 390         if (!self->consider_shrink)
 391                 return;
 392
 393         self->consider_shrink = 0;
 394         size                  = hashset_size(self);
 395         if (size <= HT_MIN_BUCKETS)
 396                 return;
 397
 398         if (LIKELY(size > self->shrink_threshold))
 399                 return;
 400
 401         resize_to = ceil_po2(size);
 402
 403         if (resize_to < 4)
 404                 resize_to = 4;
 405
 406         resize(self, resize_to);
 407 }
 408
 409 /**
 410  * Insert an element into the hashset. If no element with the given key exists yet,
 411  * then a new one is created and initialized with the InitData function.
 412  * Otherwise the existing element is returned (for hashs where key is equal to
 413  * value, nothing is returned.)
 414  *
 415  * @param self   the hashset
 416  * @param key    the key that identifies the data
 417  * @returns      the existing or newly created data element (or nothing in case of hashs where keys are the while value)
 418  */
 419 InsertReturnValue hashset_insert(HashSet *self, KeyType key)
 420 {
 421 #ifndef NDEBUG
 422         self->entries_version++;
 423 #endif
 424
 425         maybe_shrink(self);
 426         maybe_grow(self);
 427         return insert_nogrow(self, key);
 428 }
 429
 430 /**
 431  * Searches for an element with key @p key.
 432  *
 433  * @param self      the hashset
 434  * @param key       the key to search for
 435  * @returns         the found value or NullValue if nothing was found
 436  */
 437 InsertReturnValue hashset_find(const HashSet *self, ConstKeyType key)
 438 {
 439         size_t   num_probes  = 0;
 440         size_t   num_buckets = self->num_buckets;
 441         size_t   hashmask    = num_buckets - 1;
 442         unsigned hash        = Hash(self, key);
 443         size_t   bucknum     = hash & hashmask;
 444
 445         for (;;) {
 446                 HashSetEntry *entry = & self->entries[bucknum];
 447
 448                 if (EntryIsEmpty(*entry)) {
 449                         return NullReturnValue;
 450                 }
 451                 if (EntryIsDeleted(*entry)) {
 452                         // value is deleted
 453                 } else if (EntryGetHash(self, *entry) == hash) {
 454                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 455                                 // found the value
 456                                 return GetInsertReturnValue(*entry, 1);
 457                         }
 458                 }
 459
 460                 ++num_probes;
 461                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 462                 assert(num_probes < num_buckets);
 463         }
 464 }
 465
 466 /**
 467  * Removes an element from a hashset. Does nothing if the set doesn't contain
 468  * the element.
 469  *
 470  * @param self    the hashset
 471  * @param key     key that identifies the data to remove
 472  */
 473 void hashset_remove(HashSet *self, ConstKeyType key)
 474 {
 475         size_t   num_probes  = 0;
 476         size_t   num_buckets = self->num_buckets;
 477         size_t   hashmask    = num_buckets - 1;
 478         unsigned hash        = Hash(self, key);
 479         size_t   bucknum     = hash & hashmask;
 480
 481 #ifndef NDEBUG
 482         self->entries_version++;
 483 #endif
 484
 485         for (;;) {
 486                 HashSetEntry *entry = & self->entries[bucknum];
 487
 488                 if (EntryIsEmpty(*entry)) {
 489                         return;
 490                 }
 491                 if (EntryIsDeleted(*entry)) {
 492                         // entry is deleted
 493                 } else if (EntryGetHash(self, *entry) == hash) {
 494                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 495                                 EntrySetDeleted(*entry);
 496                                 self->num_deleted++;
 497                                 self->consider_shrink = 1;
 498                                 return;
 499                         }
 500                 }
 501
 502                 ++num_probes;
 503                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 504                 assert(num_probes < num_buckets);
 505         }
 506 }
 507
 508 /**
 509  * Initializes hashset with a specific size
 510  * @internal
 511  */
 512 static inline void init_size(HashSet *self, size_t initial_size)
 513 {
 514         if (initial_size < 4)
 515                 initial_size = 4;
 516
 517         self->entries         = Alloc(initial_size);
 518         SetRangeEmpty(self->entries, initial_size);
 519         self->num_buckets     = initial_size;
 520         self->consider_shrink = 0;
 521         self->num_elements    = 0;
 522         self->num_deleted     = 0;
 523 #ifndef NDEBUG
 524         self->entries_version = 0;
 525 #endif
 526 #ifdef ADDITIONAL_INIT
 527         ADDITIONAL_INIT
 528 #endif
 529
 530         reset_thresholds(self);
 531 }
 532
 533 /**
 534  * Initializes a hashset with the default size. The memory for the set has to
 535  * already allocated.
 536  */
 537 void hashset_init(HashSet *self)
 538 {
 539         init_size(self, HT_MIN_BUCKETS);
 540 }
 541
 542 /**
 543  * Destroys a hashset, freeing all used memory (except the memory for the
 544  * HashSet struct itself).
 545  */
 546 void hashset_destroy(HashSet *self)
 547 {
 548 #ifdef ADDITIONAL_TERM
 549         ADDITIONAL_TERM
 550 #endif
 551         Free(self->entries);
 552 #ifndef NDEBUG
 553         self->entries = NULL;
 554 #endif
 555 }
 556
 557 /**
 558  * Initializes a hashset expecting expected_element size.
 559  */
 560 void hashset_init_size(HashSet *self, size_t expected_elements)
 561 {
 562         size_t needed_size;
 563         size_t po2size;
 564
 565         if (expected_elements >= UINT_MAX/2) {
 566                 abort();
 567         }
 568
 569         needed_size = expected_elements * HT_1_DIV_OCCUPANCY_FLT;
 570         po2size     = ceil_po2(needed_size);
 571         init_size(self, po2size);
 572 }
 573
 574 #ifndef NO_ITERATOR
 575 /**
 576  * Initializes a hashset iterator. The memory for the allocator has to be
 577  * already allocated.
 578  * @note it is not allowed to remove or insert elements while iterating
 579  */
 580 void hashset_iterator_init(HashSetIterator *self, const HashSet *hashset)
 581 {
 582         self->current_bucket = hashset->entries - 1;
 583         self->end            = hashset->entries + hashset->num_buckets;
 584 #ifndef NDEBUG
 585         self->set             = hashset;
 586         self->entries_version = hashset->entries_version;
 587 #endif
 588 }
 589
 590 /**
 591  * Returns the next value in the iterator or NULL if no value is left
 592  * in the hashset.
 593  * @note it is not allowed to remove or insert elements while iterating
 594  */
 595 ValueType hashset_iterator_next(HashSetIterator *self)
 596 {
 597         HashSetEntry *current_bucket = self->current_bucket;
 598         HashSetEntry *end            = self->end;
 599
 600         /* using hashset_insert or hashset_remove is not allowed while iterating */
 601         assert(self->entries_version == self->set->entries_version);
 602
 603         do {
 604                 current_bucket++;
 605                 if (current_bucket >= end)
 606                         return NullValue;
 607         } while (EntryIsEmpty(*current_bucket) || EntryIsDeleted(*current_bucket));
 608
 609         self->current_bucket = current_bucket;
 610         return EntryGetValue(*current_bucket);
 611 }
 612
 613 /**
 614  * Removes the element the iterator points to. Removing an element a second time
 615  * has no result.
 616  */
 617 void hashset_remove_iterator(HashSet *self, const HashSetIterator *iter)
 618 {
 619         HashSetEntry *entry = iter->current_bucket;
 620
 621         /* iterator_next needs to have been called at least once */
 622         assert(entry >= self->entries);
 623         /* needs to be on a valid element */
 624         assert(entry < self->entries + self->num_buckets);
 625
 626         if (EntryIsDeleted(*entry))
 627                 return;
 628
 629         EntrySetDeleted(*entry);
 630         self->num_deleted++;
 631         self->consider_shrink = 1;
 632 }
 633 #endif /* NO_ITERATOR */
 634
 635 #endif /* HashSet */