coregrind/m_hashtable.c

   1
   2 /*--------------------------------------------------------------------*/
   3 /*--- A separately-chained hash table.               m_hashtable.c ---*/
   4 /*--------------------------------------------------------------------*/
   5
   6 /*
   7    This file is part of Valgrind, a dynamic binary instrumentation
   8    framework.
   9
  10    Copyright (C) 2005-2017 Nicholas Nethercote
  11       njn@valgrind.org
  12
  13    This program is free software; you can redistribute it and/or
  14    modify it under the terms of the GNU General Public License as
  15    published by the Free Software Foundation; either version 2 of the
  16    License, or (at your option) any later version.
  17
  18    This program is distributed in the hope that it will be useful, but
  19    WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21    General Public License for more details.
  22
  23    You should have received a copy of the GNU General Public License
  24    along with this program; if not, see <http://www.gnu.org/licenses/>.
  25
  26    The GNU General Public License is contained in the file COPYING.
  27 */
  28
  29 #include "pub_core_basics.h"
  30 #include "pub_core_debuglog.h"
  31 #include "pub_core_hashtable.h"
  32 #include "pub_core_libcassert.h"
  33 #include "pub_core_libcbase.h"
  34 #include "pub_core_libcprint.h"
  35 #include "pub_core_mallocfree.h"
  36
  37 /*--------------------------------------------------------------------*/
  38 /*--- Declarations                                                 ---*/
  39 /*--------------------------------------------------------------------*/
  40
  41 #define CHAIN_NO(key,tbl) (((UWord)(key)) % tbl->n_chains)
  42
  43 struct _VgHashTable {
  44    UInt         n_chains;   // should be prime
  45    UInt         n_elements;
  46    VgHashNode*  iterNode;   // current iterator node
  47    UInt         iterChain;  // next chain to be traversed by the iterator
  48    Bool         iterOK;     // table safe to iterate over?
  49    VgHashNode** chains;     // expanding array of hash chains
  50    const HChar* name;       // name of table (for debugging only)
  51 };
  52
  53 #define N_HASH_PRIMES 20
  54
  55 static const SizeT primes[N_HASH_PRIMES] = {
  56          769UL,         1543UL,         3079UL,          6151UL,
  57        12289UL,        24593UL,        49157UL,         98317UL,
  58       196613UL,       393241UL,       786433UL,       1572869UL,
  59      3145739UL,      6291469UL,     12582917UL,      25165843UL,
  60     50331653UL,    100663319UL,    201326611UL,     402653189UL
  61 };
  62
  63 /*--------------------------------------------------------------------*/
  64 /*--- Functions                                                    ---*/
  65 /*--------------------------------------------------------------------*/
  66
  67 VgHashTable *VG_(HT_construct) ( const HChar* name )
  68 {
  69    /* Initialises to zero, ie. all entries NULL */
  70    SizeT       n_chains = primes[0];
  71    SizeT       sz       = n_chains * sizeof(VgHashNode*);
  72    VgHashTable *table   = VG_(calloc)("hashtable.Hc.1",
  73                                       1, sizeof(struct _VgHashTable));
  74    table->chains        = VG_(calloc)("hashtable.Hc.2", 1, sz);
  75    table->n_chains      = n_chains;
  76    table->n_elements    = 0;
  77    table->iterOK        = True;
  78    table->name          = name;
  79    vg_assert(name);
  80    return table;
  81 }
  82
  83 UInt VG_(HT_count_nodes) ( const VgHashTable *table )
  84 {
  85    return table->n_elements;
  86 }
  87
  88 static void resize ( VgHashTable *table )
  89 {
  90    Int          i;
  91    SizeT        sz;
  92    SizeT        old_chains = table->n_chains;
  93    SizeT        new_chains = old_chains + 1;
  94    VgHashNode** chains;
  95    VgHashNode * node;
  96
  97    /* If we've run out of primes, do nothing. */
  98    if (old_chains == primes[N_HASH_PRIMES-1])
  99       return;
 100
 101    vg_assert(old_chains >= primes[0]
 102              && old_chains < primes[N_HASH_PRIMES-1]);
 103
 104    for (i = 0; i < N_HASH_PRIMES; i++) {
 105       if (primes[i] > new_chains) {
 106          new_chains = primes[i];
 107          break;
 108       }
 109    }
 110
 111    vg_assert(new_chains > old_chains);
 112    vg_assert(new_chains > primes[0]
 113              && new_chains <= primes[N_HASH_PRIMES-1]);
 114
 115    VG_(debugLog)(
 116       1, "hashtable",
 117          "resizing table `%s' from %lu to %lu (total elems %lu)\n",
 118          table->name, (UWord)old_chains, (UWord)new_chains,
 119          (UWord)table->n_elements );
 120
 121    table->n_chains = new_chains;
 122    sz = new_chains * sizeof(VgHashNode*);
 123    chains = VG_(calloc)("hashtable.resize.1", 1, sz);
 124
 125    for (i = 0; i < old_chains; i++) {
 126       node = table->chains[i];
 127       while (node != NULL) {
 128          VgHashNode* next = node->next;
 129          UWord chain = CHAIN_NO(node->key, table);
 130          node->next = chains[chain];
 131          chains[chain] = node;
 132          node = next;
 133       }
 134    }
 135
 136    VG_(free)(table->chains);
 137    table->chains = chains;
 138 }
 139
 140 /* Puts a new, heap allocated VgHashNode, into the VgHashTable.  Prepends
 141    the node to the appropriate chain.  No duplicate key detection is done. */
 142 void VG_(HT_add_node) ( VgHashTable *table, void* vnode )
 143 {
 144    VgHashNode* node     = (VgHashNode*)vnode;
 145    UWord chain          = CHAIN_NO(node->key, table);
 146    node->next           = table->chains[chain];
 147    table->chains[chain] = node;
 148    table->n_elements++;
 149    if ( (1 * (ULong)table->n_elements) > (1 * (ULong)table->n_chains) ) {
 150       resize(table);
 151    }
 152
 153    /* Table has been modified; hence HT_Next should assert. */
 154    table->iterOK = False;
 155 }
 156
 157 /* Looks up a VgHashNode by key in the table.  Returns NULL if not found. */
 158 void* VG_(HT_lookup) ( const VgHashTable *table, UWord key )
 159 {
 160    VgHashNode* curr = table->chains[ CHAIN_NO(key, table) ];
 161
 162    while (curr) {
 163       if (key == curr->key) {
 164          return curr;
 165       }
 166       curr = curr->next;
 167    }
 168    return NULL;
 169 }
 170
 171 /* Looks up a VgHashNode by node in the table.  Returns NULL if not found.
 172    GEN!!! marks the lines that differs from VG_(HT_lookup). */
 173 void* VG_(HT_gen_lookup) ( const VgHashTable *table, const void* node,
 174                            HT_Cmp_t cmp )
 175 {
 176    const VgHashNode* hnode = node; // GEN!!!
 177    VgHashNode* curr = table->chains[ CHAIN_NO(hnode->key, table) ]; // GEN!!!
 178
 179    while (curr) {
 180       if (hnode->key == curr->key && cmp (hnode, curr) == 0) { // GEN!!!
 181          return curr;
 182       }
 183       curr = curr->next;
 184    }
 185    return NULL;
 186 }
 187
 188 /* Removes a VgHashNode from the table.  Returns NULL if not found. */
 189 void* VG_(HT_remove) ( VgHashTable *table, UWord key )
 190 {
 191    UWord        chain         = CHAIN_NO(key, table);
 192    VgHashNode*  curr          =   table->chains[chain];
 193    VgHashNode** prev_next_ptr = &(table->chains[chain]);
 194
 195    /* Table has been modified; hence HT_Next should assert. */
 196    table->iterOK = False;
 197
 198    while (curr) {
 199       if (key == curr->key) {
 200          *prev_next_ptr = curr->next;
 201          table->n_elements--;
 202          return curr;
 203       }
 204       prev_next_ptr = &(curr->next);
 205       curr = curr->next;
 206    }
 207    return NULL;
 208 }
 209
 210 /* Removes a VgHashNode by node from the table.  Returns NULL if not found.
 211    GEN!!! marks the lines that differs from VG_(HT_remove). */
 212 void* VG_(HT_gen_remove) ( VgHashTable *table, const void* node, HT_Cmp_t cmp  )
 213 {
 214    const VgHashNode* hnode    = node; // GEN!!!
 215    UWord        chain         = CHAIN_NO(hnode->key, table); // GEN!!!
 216    VgHashNode*  curr          =   table->chains[chain];
 217    VgHashNode** prev_next_ptr = &(table->chains[chain]);
 218
 219    /* Table has been modified; hence HT_Next should assert. */
 220    table->iterOK = False;
 221
 222    while (curr) {
 223       if (hnode->key == curr->key && cmp(hnode, curr) == 0) { // GEN!!!
 224          *prev_next_ptr = curr->next;
 225          table->n_elements--;
 226          return curr;
 227       }
 228       prev_next_ptr = &(curr->next);
 229       curr = curr->next;
 230    }
 231    return NULL;
 232 }
 233
 234 void VG_(HT_print_stats) ( const VgHashTable *table, HT_Cmp_t cmp )
 235 {
 236    #define MAXOCCUR 20
 237    UInt elt_occurences[MAXOCCUR+1];
 238    UInt key_occurences[MAXOCCUR+1];
 239    UInt cno_occurences[MAXOCCUR+1];
 240    /* Key occurence  : how many ht elements have the same key.
 241       elt_occurences : how many elements are inserted multiple time.
 242       cno_occurences : how many chains have that length.
 243       The last entry in these arrays collects all occurences >= MAXOCCUR. */
 244    #define INCOCCUR(occur,n) (n >= MAXOCCUR ? occur[MAXOCCUR]++ : occur[n]++)
 245    UInt i;
 246    UInt nkey, nelt, ncno;
 247    VgHashNode *cnode, *node;
 248
 249    VG_(memset)(key_occurences, 0, sizeof(key_occurences));
 250    VG_(memset)(elt_occurences, 0, sizeof(elt_occurences));
 251    VG_(memset)(cno_occurences, 0, sizeof(cno_occurences));
 252
 253    // Note that the below algorithm is quadractic in nr of elements in a chain
 254    // but if that happens, the hash table/function is really bad and that
 255    // should be fixed.
 256    for (i = 0; i < table->n_chains; i++) {
 257       ncno = 0;
 258       for (cnode = table->chains[i]; cnode != NULL; cnode = cnode->next) {
 259          ncno++;
 260
 261          nkey = 0;
 262          // Is the same cnode->key existing before cnode ?
 263          for (node = table->chains[i]; node != cnode; node = node->next) {
 264             if (node->key == cnode->key)
 265                nkey++;
 266          }
 267          // If cnode->key not in a previous node, count occurences of key.
 268          if (nkey == 0) {
 269             for (node = cnode; node != NULL; node = node->next) {
 270                if (node->key == cnode->key)
 271                   nkey++;
 272             }
 273             INCOCCUR(key_occurences, nkey);
 274          }
 275
 276          nelt = 0;
 277          // Is the same cnode element existing before cnode ?
 278          for (node = table->chains[i]; node != cnode; node = node->next) {
 279             if (node->key == cnode->key
 280                 && (cmp == NULL || cmp (node, cnode) == 0)) {
 281                nelt++;
 282             }
 283          }
 284          // If cnode element not in a previous node, count occurences of elt.
 285          if (nelt == 0) {
 286             for (node = cnode; node != NULL; node = node->next) {
 287                if (node->key == cnode->key
 288                    && (cmp == NULL || cmp (node, cnode) == 0)) {
 289                   nelt++;
 290                }
 291             }
 292             INCOCCUR(elt_occurences, nelt);
 293          }
 294       }
 295       INCOCCUR(cno_occurences, ncno);
 296    }
 297
 298    VG_(message)(Vg_DebugMsg,
 299                 "nr occurrences of"
 300                 " chains of len N,"
 301                 " N-plicated keys,"
 302                 " N-plicated elts\n");
 303    nkey = nelt = ncno = 0;
 304    for (i = 0; i <= MAXOCCUR; i++) {
 305       if (elt_occurences[i] > 0
 306           || key_occurences[i] > 0
 307           || cno_occurences[i] > 0)
 308          VG_(message)(Vg_DebugMsg,
 309                       "%s=%2u : nr chain %6u, nr keys %6u, nr elts %6u\n",
 310                       i == MAXOCCUR ? ">" : "N", i,
 311                       cno_occurences[i], key_occurences[i], elt_occurences[i]);
 312       nkey += key_occurences[i];
 313       nelt += elt_occurences[i];
 314       ncno += cno_occurences[i];
 315    }
 316    VG_(message)(Vg_DebugMsg,
 317                 "total nr of unique   slots: %6u, keys %6u, elts %6u."
 318                 " Avg chain len %3.1f\n",
 319                 ncno, nkey, nelt,
 320                 (Double)nelt/(Double)(ncno == cno_occurences[0] ?
 321                                       1 : ncno - cno_occurences[0]));
 322 }
 323
 324
 325 /* Allocates a suitably-sized array, copies pointers to all the hashtable
 326    elements into it, then returns both the array and the size of it.  The
 327    array must be freed with VG_(free).
 328 */
 329 VgHashNode** VG_(HT_to_array) (const VgHashTable *table, /*OUT*/ UInt* n_elems)
 330 {
 331    UInt       i, j;
 332    VgHashNode** arr;
 333    VgHashNode*  node;
 334
 335    *n_elems = table->n_elements;
 336    if (*n_elems == 0)
 337       return NULL;
 338
 339    arr = VG_(malloc)( "hashtable.Hta.1", *n_elems * sizeof(VgHashNode*) );
 340
 341    j = 0;
 342    for (i = 0; i < table->n_chains; i++) {
 343       for (node = table->chains[i]; node != NULL; node = node->next) {
 344          arr[j++] = node;
 345       }
 346    }
 347    vg_assert(j == *n_elems);
 348
 349    return arr;
 350 }
 351
 352 void VG_(HT_ResetIter)(VgHashTable *table)
 353 {
 354    vg_assert(table);
 355    table->iterNode  = NULL;
 356    table->iterChain = 0;
 357    table->iterOK    = True;
 358 }
 359
 360 void* VG_(HT_Next)(VgHashTable *table)
 361 {
 362    Int i;
 363    vg_assert(table);
 364    /* See long comment on HT_Next prototype in pub_tool_hashtable.h.
 365       In short if this fails, it means the caller tried to modify the
 366       table whilst iterating over it, which is a bug.
 367       One exception: HT_remove_at_Iter can remove the current entry and
 368       leave the iterator in a valid state for HT_Next. */
 369    vg_assert(table->iterOK);
 370
 371    if (table->iterNode && table->iterNode->next) {
 372       table->iterNode = table->iterNode->next;
 373       return table->iterNode;
 374    }
 375
 376    for (i = table->iterChain; i < table->n_chains; i++) {
 377       if (table->chains[i]) {
 378          table->iterNode  = table->chains[i];
 379          table->iterChain = i + 1;  // Next chain to be traversed
 380          return table->iterNode;
 381       }
 382    }
 383    return NULL;
 384 }
 385
 386 void VG_(HT_remove_at_Iter)(VgHashTable *table)
 387 {
 388    vg_assert(table);
 389    vg_assert(table->iterOK);
 390    vg_assert(table->iterNode);
 391
 392    const UInt curChain = table->iterChain - 1; // chain of iterNode.
 393
 394
 395    if (table->chains[curChain] == table->iterNode) {
 396       /* iterNode is the first of its chain -> remove it from the chain. */
 397       table->chains[curChain] = table->iterNode->next;
 398       /* Setup the iterator to visit first node of curChain: */
 399       table->iterNode  = NULL;
 400       table->iterChain = curChain;
 401    } else {
 402       /* iterNode is somewhere inside curChain chain */
 403       VgHashNode* prev = table->chains[curChain];
 404
 405       while (prev->next != table->iterNode)
 406          prev = prev->next;
 407       /* Remove iterNode from the chain. */
 408       prev->next = table->iterNode->next;
 409       /* Setup the iterator to visit prev->next, which is the node
 410          that was after the deleted node. */
 411       table->iterNode = prev;
 412    }
 413
 414    table->n_elements--;
 415 }
 416
 417 void VG_(HT_destruct)(VgHashTable *table, void(*freenode_fn)(void*))
 418 {
 419    UInt       i;
 420    VgHashNode *node, *node_next;
 421
 422    for (i = 0; i < table->n_chains; i++) {
 423       for (node = table->chains[i]; node != NULL; node = node_next) {
 424          node_next = node->next;
 425          freenode_fn(node);
 426       }
 427    }
 428    VG_(free)(table->chains);
 429    VG_(free)(table);
 430 }
 431
 432 /*--------------------------------------------------------------------*/
 433 /*--- end                                                          ---*/
 434 /*--------------------------------------------------------------------*/