ston/ston_ht.h

   1 /*!@file
   2   \brief   STON Hash Tables
   3   \details Aligned general purpose hash functions and memory definitions
   4            whose columns are provided, and whose rows, and sizes, are derived.
   5
   6              ht_size = header.ht_columns << header.ht_2pow;
   7              ht_rows = 0x1 << header.ht_2pow;
   8
   9            All generic hashtables in henge must have a power-of-two number of
  10            rows.  An ht_columns value that is also a power-of-two will result in
  11            a power-of-two sized memory imprint for the structure, making it easy
  12            to page align.
  13
  14            Elements in the columns may be of any arbitrary size.
  15
  16              typedef uint32_t my_ht_type;
  17              ht_bytes = ht_size * sizeof(my_ht_type);
  18
  19            implementation covers only 32-bit unit sizes.
  20
  21   \author  Ken Grimes
  22   \date    Feb 2017
  23   ----------------------------------------------------------------------------*/
  24 #ifndef _STON_HT_T_
  25 #define _STON_HT_T_
  26 /* Define STON_NOSTATIC to expose included function symbols */
  27 #ifndef STON_NOSTATIC
  28 #define STON_FUNC_STATIC static
  29 #else
  30 #define STON_FUNC_STATIC
  31 #endif //STON_NOSTATIC
  32 /* If GNUC is detected, uses attributes to stop inlining */
  33 #ifdef  __GNUC__
  34 #define STON_FUNC_NOINLINE __attribute__ ((noinline))
  35 #else
  36 #define STON_FUNC_NOINLINE
  37 #endif //__GNUC__
  38 /* Define STON_NOINLINE to prevent inline compiler hints */
  39 #ifndef STON_NOINLINE
  40 #define STON_FUNC_INLINE inline
  41 #else
  42 #define STON_FUNC_INLINE
  43 #endif //STON_NOINLINE
  44 /* Define STON_FUNC to override the default STON Function attributes */
  45 #ifndef STON_FUNC
  46 #define STON_FUNC STON_FUNC_STATIC STON_FUNC_INLINE
  47 #endif //STON_FUNC
  48 #ifdef STON_HT_FREAD
  49 #include <stdio.h>
  50 #include <errno.h>
  51 #include <alloca.h>
  52 STON_FUNC_STATIC
  53 STON_FUNC_NOINLINE
  54 ston_ht   ston_ht32_fread(FILE*,long,void*(*)(size_t));
  55 size_t    ston_ht32_fwrite(ston_ht,FILE*,long);
  56 #else
  57 #include <stddef.h>
  58 #endif //STON_HT_FREAD
  59 #include <stdint.h>
  60 #include <string.h> //mem*
  61 /* STON Hashtable Structure
  62    Hashtables are stored as dynamically sized two dimensional arrays
  63 */
  64 typedef struct ston_ht_header_t
  65 { uint16_t ht_columns;
  66   uint8_t  ht_2pow, ht_flags;
  67 }ston_ht_h,* ston_ht;
  68
  69 STON_FUNC
  70 uint32_t  ston_up2pow(uint32_t);
  71 STON_FUNC
  72 uint8_t   ston_trailing0(uint32_t);
  73 STON_FUNC
  74 ston_ht   ston_ht32_create(uint16_t,uint8_t,uint8_t,void*(*)(size_t));
  75 STON_FUNC
  76 uint32_t* ston_ht32_row(ston_ht,uint32_t);
  77 STON_FUNC
  78 uint32_t  ston_ht32_insert(ston_ht,uint32_t,uint16_t,uint32_t);
  79 STON_FUNC
  80 size_t    ston_ht32_insertx(ston_ht,uint32_t,uint32_t*,size_t,size_t);
  81
  82 #define   ston_ht32_new(_COL,_N,_F,_FN) (ston_ht32_create(_COL,ston_trailing0(ston_up2pow(_N << 1)),_F,_FN))
  83 #define   ston_ht32_entry(_HT,_KEY,_COL) (ston_ht32_row(_HT,_KEY) + _COL)
  84 #define   ston_ht_size(_HT)            ((_HT)->ht_columns << (_HT)->ht_2pow)
  85 #define   ston_ht_rows(_HT)            (0x1 << (_HT)->ht_2pow)
  86 #define   ston_ht_cols(_HT)            ((_HT)->ht_columns)
  87 #define   ston_ht_start(_HT)           ((uint8_t*)((_HT) + 1))
  88 #define   ston_ht_keyrow(_HT,_KEY)     ((_KEY) & (ston_ht_rows(ht) - 1))
  89 #define   ston_ht32_start(_HT)         ((uint32_t*)ston_ht_start(_HT))
  90 #define   ston_ht32_end(_HT)           (ston_ht32_start(_HT) + ston_ht_size(_HT))
  91 #define   ston_ht32_size(_HT)          (ston_ht_size(_HT) * sizeof(uint32_t))
  92
  93 /** @see http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2 */
  94 STON_FUNC
  95 uint32_t ston_up2pow
  96 ( uint32_t val )
  97 { val = (val << 1) - 1;
  98   val |= val >> 1;
  99   val |= val >> 2;
 100   val |= val >> 4;
 101   val |= val >> 8;
 102   val |= val >> 16;
 103   return ++val;
 104 }
 105
 106 /** @see https://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightParallel */
 107 STON_FUNC
 108 uint8_t ston_trailing0
 109 ( uint32_t v )
 110 { uint8_t c = 32;
 111   v &= -(int32_t)v;
 112   if (v) c--;
 113   if (v & 0x0000FFFF) c -= 16;
 114   if (v & 0x00FF00FF) c -= 8;
 115   if (v & 0x0F0F0F0F) c -= 4;
 116   if (v & 0x33333333) c -= 2;
 117   if (v & 0x55555555) c -= 1;
 118   return c;
 119 }
 120
 121 /* Creates a new hash table, provided a memory allocation function that takes a
 122    single size_t bytes, a column count, and a row count which determines the
 123    size of the table.
 124
 125    use ston_ht32_new to specify the exact or estimated number of unique keys
 126    held in the table.  With ston_ht32_new, the provided ht_rows is doubled, and
 127    rounded up to the nearest power of two to create a hash table with minimal
 128    collisions.
 129 */
 130 STON_FUNC
 131 ston_ht ston_ht32_create
 132 ( uint16_t ht_columns,
 133   uint8_t  ht_2pow,
 134   uint8_t  ht_flags,
 135   void*    (*alloc_fn)(size_t)
 136 )
 137 { size_t  ht_bytes = (ht_columns << ht_2pow) * sizeof(uint32_t);
 138   ston_ht ht = (ston_ht) alloc_fn(sizeof(ston_ht_h) + ht_bytes);
 139   if (ht != NULL)
 140     { ht->ht_columns = ht_columns;
 141       ht->ht_2pow = ht_2pow;
 142       ht->ht_flags = ht_flags;
 143       memset(ht + 1, 0, ht_bytes);
 144     }
 145   return ht;
 146 }
 147
 148 #ifdef STON_HT_FREAD
 149 /* Reads a 32-bit hash table out of the provided file at the provide fpos, into
 150    a buffer allocated by alloc_fn.  Memory is allocated to the stack until the
 151    entire structure is verified, and all file operations are finished.
 152    Returns NULL with properly set errno on failure.
 153 */
 154 ston_ht ston_ht32_fread
 155 ( FILE* file,
 156   long  fpos,
 157   void* (*alloc_fn)(size_t)
 158 )
 159 { struct ston_ht_header_t header;
 160   ston_ht                 stack_ht, ht;
 161   long                    fpos_start;
 162   size_t                  table_size, alloc_size;
 163   int                     errno_local;
 164   if ((fpos_start = ftell(file)) == -1)
 165     return NULL;
 166   if (fread(&header, sizeof(header), 1, file) != 1)
 167     goto fail_seekback;
 168   table_size = ston_ht32_size(&header);
 169   alloc_size = sizeof(header) + table_size;
 170   stack_ht = (ston_ht) alloca(alloc_size);
 171   memcpy(stack_ht, &header, sizeof(header));
 172   if (fread(stack_ht + sizeof(header), table_size, 1, file) != 1)
 173     goto fail_seekback;
 174   if (fseek(file, fpos_start, SEEK_SET) != 0)
 175     return NULL;
 176   ht = (ston_ht) alloc_fn(alloc_size);
 177   if (ht != NULL)
 178     memcpy(ht, stack_ht, alloc_size);
 179   return ht;
 180  fail_seekback:
 181   /* Try to seek the file back to origin without clobbering errno */
 182   errno_local = errno;
 183   fseek(file, fpos_start, SEEK_SET);
 184   errno = errno_local;
 185   return NULL;
 186 }
 187
 188 /* Writes a 32-bit hash table from memory into a file at fpos.  Returns the
 189    number of bytes written to the file, errno is set on error. */
 190 size_t ston_ht32_fwrite
 191 ( struct ston_ht_header_t* ht,
 192   FILE*                    file,
 193   long                     fpos
 194 )
 195 { size_t bytes_written;
 196   long   fpos_start;
 197   if ((fpos_start = ftell(file)) == NULL
 198       || (bytes_written = fwrite(file, 1, sizeof(ston_ht_h), file)) < sizeof(ston_ht_h)
 199       || (bytes_written += fwrite(file, 1, ston_ht32_bytes(ht), file)) < (sizeof(ston_ht_h) + ston_ht32_bytes(ht)))
 200     return 0;
 201   return bytes_written;
 202 }
 203 #endif
 204
 205 /* Returns a pointer to the row of data in the hashtable containing the provided
 206    key, inserts if not found.  Returns NULL on overflow.
 207 */
 208 STON_FUNC
 209 uint32_t* ston_ht32_row
 210 ( struct ston_ht_header_t* ht,
 211   uint32_t                key
 212 )
 213 { uint32_t* row;
 214   uint32_t* row_start = ston_ht32_start(ht);
 215   uint32_t* row_end = ston_ht32_end(ht);
 216   uint16_t  ht_cols = ston_ht_cols(ht);
 217   size_t    row_number = ston_ht_keyrow(ht,key);
 218   uint8_t   looped = 0;
 219   row = row_start + (row_number * ht_cols);
 220  next_row:
 221   if (row[0] != 0)
 222     goto populated;
 223  write_position:
 224   row[0] = key;
 225   return row;
 226  populated:
 227   if (row[0] == key)
 228     goto write_position;
 229   if (row + ht_cols < row_end)
 230     row += ht_cols;
 231   else if (looped)
 232       return NULL;
 233   else
 234     { looped++;
 235       row = row_start;
 236     }
 237   goto next_row;
 238 }
 239
 240 /* Inserts a value into a hashtable at the specified column, returning the
 241    previous value */
 242 STON_FUNC
 243 uint32_t ston_ht32_insert
 244 ( struct ston_ht_header_t* ht,
 245   uint32_t                key,
 246   uint16_t                column,
 247   uint32_t                value
 248 )
 249 { uint32_t* value_location, old_value;
 250   value_location = ston_ht32_entry(ht,key,column);
 251   old_value = *value_location;
 252   *value_location = value;
 253   return old_value;
 254 }
 255
 256 /* Inserts a row of units into a hashtable, starting with the specified column.
 257    Returns the number of elements that were written.  This function will not
 258    overflow internal buffers, but will return a short count (lower than the
 259    provided 'units') when truncation of source data occurs. */
 260 STON_FUNC
 261 size_t
 262 ston_ht32_insertx
 263 ( struct ston_ht_header_t* ht,
 264   uint32_t                 key,
 265   uint32_t*                data_src,
 266   size_t                   start_column,
 267   size_t                   units
 268 )
 269 { uint32_t* data_row = ston_ht32_row(ht,key);
 270   uint32_t* data_limit = data_row + ston_ht_cols(ht);
 271   uint32_t* data_trg = data_row + start_column;
 272   if (data_row == NULL)
 273     return 0;
 274   while (units-- && data_trg < data_limit)
 275     *data_trg++ = *data_src++;
 276   return (size_t)(data_trg - data_row);
 277 }
 278
 279
 280 #ifndef STON_DHT_SIZE
 281 #define STON_DHT_SIZE 4096
 282 #endif
 283
 284 /* STON Dynamic Hashtable Structure
 285    A dynamic form of the generic hashtable implementation above which uses
 286    external allocation.
 287 */
 288 typedef struct ston_dht_header_t
 289 { uint16_t  columns;
 290   uint8_t   unit_bytes;
 291   uint8_t   start_depth;
 292 }ston_dht_h;
 293
 294 typedef struct ston_dht_t
 295 { ston_dht_h header;
 296   void*      pages[sizeof(void*) * 8];
 297   void*      (*ht_alloc)(size_t);
 298   void       (*ht_free)(void*);
 299 }* ston_dht;
 300
 301 STON_FUNC
 302 ston_dht  ston_dht_create(uint16_t,uint8_t,uint8_t,void*(*)(size_t),void(*)(void*));
 303 STON_FUNC
 304 uint32_t* ston_dht32_row(ston_dht,uint32_t);
 305 STON_FUNC
 306 uint32_t  ston_dht32_insert(ston_dht,uint32_t,uint16_t,uint32_t);
 307 STON_FUNC
 308 size_t    ston_dht32_insertx(ston_dht,uint32_t,uint32_t*,uint16_t,size_t);
 309 STON_FUNC
 310 ston_dht  ston_dht_free(ston_dht);
 311
 312 #define ston_dht_units(_HT,_DEPTH)           ((_HT)->header.columns << _DEPTH)
 313 #define ston_dht_bytes(_HT,_DEPTH)           (ston_dht_units(_HT,_DEPTH) * (_HT)->header.unit_bytes)
 314 #define ston_dht_new(_COL,_ALOC,_FRE)        (ston_dht_create(_COL,3,sizeof(int),_ALOC,_FRE))
 315 #define ston_dht_sized(_COL,_N,_ALOC,_FRE)   (ston_dht_create(_COL,ston_trailing0(ston_up2pow(_N),sizeof(int),_ALOC,_FRE)))
 316 #define ston_dht32_entry(_HT,_KEY,_COL)      (ston_dht32_row(_HT,_KEY) + _COL)
 317 #define ston_dht32_new(_COL,_ALOC,_FRE)      (ston_dht_create(_COL,0,sizeof(uint32_t),_ALOC,_FRE))
 318 #define ston_dht32_sized(_COL,_N,_ALOC,_FRE) (ston_dht_create(_COL,ston_trailing0(ston_up2pow(_N)),sizeof(uint32_t),_ALOC,_FRE))
 319
 320
 321 /* Creates a new bucketted hash table, provided a memory allocation function
 322    that takes a single size_t bytes, a memory free function, a column count, and
 323    a row count which determines the size of the buckets.
 324 */
 325 STON_FUNC
 326 ston_dht ston_dht_create
 327 ( uint16_t columns,
 328   uint8_t  start_depth,
 329   uint8_t  unit_bytes,
 330   void*    (*ht_alloc)(size_t),
 331   void     (*ht_free)(void*)
 332 )
 333 { ston_dht ht = (ston_dht) ht_alloc(sizeof(struct ston_dht_t));
 334   if (ht != NULL)
 335     { ht->header.columns = columns;
 336       ht->header.start_depth = start_depth;
 337       ht->header.unit_bytes = unit_bytes;
 338       memset(ht->pages, 0, sizeof(void*) * sizeof(void*) * 8);
 339       ht->pages[start_depth] = ht_alloc(ston_dht_bytes(ht, start_depth));
 340       ht->ht_alloc = ht_alloc;
 341       ht->ht_free = ht_free;
 342       if (ht->pages[start_depth] == NULL && ht_free != NULL)
 343         ht_free(ht);
 344       else
 345         memset(ht->pages[start_depth], 0, ston_dht_bytes(ht, start_depth));
 346     }
 347   return ht;
 348 }
 349
 350 /* Returns a pointer to the row of data in the hashtable containing the provided
 351    key, inserts if not found.  Returns NULL on overflow.
 352 */
 353 STON_FUNC
 354 uint32_t* ston_dht32_row
 355 ( struct ston_dht_t* ht,
 356   uint32_t           key
 357 )
 358 { uint16_t columns = ht->header.columns;
 359   uint8_t  depth = ht->header.start_depth;
 360   uint32_t mask = ((0x1 << depth) - 1) >> 1;
 361   void* page;
 362   uint32_t* row;
 363   uint32_t  row_key;
 364  next_page:
 365   if (ht->pages[depth] == NULL)
 366     { ht->pages[depth] = ht->ht_alloc(ston_dht_bytes(ht, depth));
 367       if (ht->pages[depth] == NULL)
 368         return NULL;
 369       memset(ht->pages[depth], 0, ston_dht_bytes(ht, depth));
 370     }
 371   page = ht->pages[depth];
 372   row = (uint32_t*)page + ((key & mask) * columns);
 373   row_key = *row;
 374   if (row_key == key || row_key == 0)
 375     { row[0] = key;
 376       return row;
 377     }
 378   depth++;
 379   mask = (mask << 1) | 0x1;
 380   goto next_page;
 381 }
 382
 383 /* Inserts a value into a hashtable at the specified column, returning the
 384    previous value */
 385 STON_FUNC
 386 uint32_t ston_dht32_insert
 387 ( struct ston_dht_t* ht,
 388   uint32_t           key,
 389   uint16_t           column,
 390   uint32_t           value
 391 )
 392 { uint32_t* value_location, old_value;
 393   value_location = ston_dht32_entry(ht,key,column);
 394   old_value = *value_location;
 395   *value_location = value;
 396   return old_value;
 397 }
 398
 399 /* Insert multiple values, returning the number of bytes written */
 400 STON_FUNC
 401 size_t
 402 ston_dht32_insertx
 403 ( struct ston_dht_t* ht,
 404   uint32_t           key,
 405   uint32_t*          data_src,
 406   uint16_t           start_column,
 407   size_t             units
 408 )
 409 { uint32_t* data_row = ston_dht32_row(ht,key);
 410   uint32_t* data_limit = data_row + ht->header.columns;
 411   uint32_t* data_trg = data_row + start_column;
 412   if (data_row == NULL)
 413     return 0;
 414   while (units-- && data_trg < data_limit)
 415     *data_trg++ = *data_src++;
 416   return (size_t)(data_trg - data_row);
 417 }
 418
 419 /* Free the dynamic hash table */
 420 STON_FUNC
 421 struct ston_dht_t* ston_dht_free
 422 ( struct ston_dht_t* ht )
 423 { void (*ht_free)(void*) = ht->ht_free;
 424   uint8_t depth = ht->header.start_depth;
 425   void**  pages = ht->pages;
 426   if (ht_free != NULL)
 427     { while (pages[depth] != NULL)
 428         ht_free(pages[depth++]);
 429       ht_free(ht);
 430       return NULL;
 431     }
 432   return ht;
 433 }
 434
 435 /********************************************************************************
 436 *********************************************************************************
 437 *********************************************************************************
 438 ********************************************************************************/
 439 typedef struct ston_dht2_header_t
 440 { uint16_t  val_bytes;
 441   uint8_t   key_bytes;
 442   uint8_t   flags;
 443 }ston_dht2_h;
 444
 445 typedef struct ston_dht2_bucket_t
 446 { uint8_t  depth;
 447   void*    page;
 448   uint32_t count;
 449 }ston_dht2_bucket_h,* ston_dht2_bucket;
 450
 451 #define STON_DHT_BUCKETS_SIZE (sizeof(void*) * 8)
 452 typedef struct ston_dht2_t
 453 { ston_dht2_h        header;
 454   ston_dht2_bucket_h buckets[1 + STON_DHT_BUCKETS_SIZE];
 455   ston_dht2_bucket   bsp;
 456   uint32_t           row_bytes;
 457   uint8_t            buckets_len;
 458   void*              (*ht_alloc)(size_t);
 459   void               (*ht_free)(void*);
 460 }* ston_dht2;
 461
 462 STON_FUNC
 463 ston_dht2  ston_dht2_create(uint16_t,uint8_t,void*(*)(size_t),void(*)(void*));
 464 STON_FUNC
 465 uint32_t* ston_dht232_row(ston_dht2,uint32_t);
 466 STON_FUNC
 467 uint32_t  ston_dht232_insert(ston_dht2,uint32_t,uint16_t,uint32_t);
 468 STON_FUNC
 469 size_t    ston_dht232_insertx(ston_dht2,uint32_t,uint32_t*,uint16_t,size_t);
 470 STON_FUNC
 471 ston_dht2  ston_dht2_free(ston_dht2);
 472
 473 #define ston_dht2_bytes(_HT,_DEPTH)      ((_HT)->row_bytes << (_DEPTH))
 474 #define ston_dht2_new(_COL,_ALOC,_FRE)   (ston_dht2_create(_COL,sizeof(int),_ALOC,_FRE))
 475 #define ston_dht232_new(_COL,_ALOC,_FRE) (ston_dht2_create(_COL,sizeof(uint32_t),_ALOC,_FRE))
 476 #define ston_dht232_entry(_HT,_KEY,_COL) (ston_dht232_row(_HT,_KEY) + _COL)
 477
 478
 479 /* Creates a new bucketted hash table, provided a memory allocation function
 480    that takes a single size_t bytes, a memory free function, a column count, and
 481    a row count which determines the size of the buckets.
 482 */
 483 static ston_dht2_bucket_h dummy_bucket = { (uint8_t)-1, NULL, (uint32_t)-1 };
 484
 485 STON_FUNC
 486 ston_dht2 ston_dht2_create
 487 ( uint16_t val_bytes,
 488   uint8_t  key_bytes,
 489   void*    (*ht_alloc)(size_t),
 490   void     (*ht_free)(void*)
 491 )
 492 { ston_dht2 ht = (ston_dht2) ht_alloc(sizeof(struct ston_dht2_t));
 493   if (ht != NULL)
 494     { ht->header.val_bytes = val_bytes;
 495       ht->header.key_bytes = key_bytes;
 496       ht->row_bytes = val_bytes + key_bytes;
 497       ht->ht_alloc = ht_alloc;
 498       ht->ht_free = ht_free;
 499       size_t i;
 500       for (i = 0; i <= STON_DHT_BUCKETS_SIZE; i++)
 501         ht->buckets[i] = dummy_bucket;
 502       ht->bsp = ht->buckets + STON_DHT_BUCKETS_SIZE - 1;
 503       ht->bsp->page = ht_alloc(ston_dht2_bytes(ht, 4));
 504       if (ht->bsp->page == NULL && ht_free != NULL)
 505         ht_free(ht);
 506       else
 507         { memset((ht->bsp->page), 0, ston_dht2_bytes(ht,4));
 508           ht->bsp->depth = 4;
 509           ht->bsp->count = 0;
 510           ht->buckets_len = 1;
 511         }
 512     }
 513   return ht;
 514 }
 515
 516
 517 /* Returns a pointer to the row of data in the hashtable containing the provided
 518    key, inserting if not found, or NULL if a memory error occurs */
 519 STON_FUNC
 520 uint32_t* ston_dht232_row
 521 ( struct ston_dht2_t* ht,
 522   uint32_t            key
 523 )
 524 { int8_t    bucket_no = (int8_t)ht->buckets_len - 1;
 525   uint32_t* row, row_key, mask;
 526   size_t    bytes;
 527   int8_t    zero_bucket = (int8_t)-1;
 528   ston_dht2_bucket   bsp = ht->bsp;
 529   ston_dht2_bucket_h bucket;
 530  next_bucket:
 531   bucket = bsp[bucket_no];
 532   /* Find until out of allocated pages, then insert at last empty bucket position */
 533   if (bucket.page == NULL)
 534     { if (zero_bucket != (int8_t)-1)
 535         { bucket = bsp[zero_bucket];
 536           mask = (0x1 << bucket.depth) - 1;
 537           row = (uint32_t*)bucket.page + (key & mask);
 538           *row = key;
 539           bucket.count++;
 540           /* Swap the buckets up a level if the count has exceeded its parent's count */
 541           if (bucket.count > bsp[zero_bucket + 1].count)
 542             { bsp[zero_bucket] = bsp[zero_bucket + 1];
 543               bsp[zero_bucket + 1] = bucket;
 544             }
 545           else
 546             bsp[zero_bucket].count = bucket.count;
 547           return row;
 548         }
 549       /* No buckets with a slot, shift the key right by depth, try again add a new bucket */
 550       bsp--;
 551       bucket.depth = 4 + (ht->buckets_len >> 1);
 552       bucket.count = 1;
 553       bytes = ston_dht2_bytes(ht,bucket.depth);
 554       if ((bucket.page = ht->ht_alloc(bytes)) == NULL)
 555         { printf("Failed to allocate %lu bytes, bucket %i at with len %i\n",
 556                  bytes, bucket_no, ht->buckets_len);
 557           return NULL;
 558         }
 559       memset(bucket.page,0,bytes);
 560       *bsp = bucket;
 561       ht->bsp = bsp;
 562       ht->buckets_len++;
 563       mask = (0x1 << bucket.depth) - 1;
 564       row = (uint32_t*)bucket.page + (key & mask);
 565       *row = key;
 566       return row;
 567     }
 568   /* Compute mask, and use it to find the row in the page */
 569   mask = (0x1 << bucket.depth) - 1;
 570   row = (uint32_t*)bucket.page + (key & mask);
 571   /* Look at the key at row[0], branch */
 572   row_key = *row;
 573   if (row_key == key)
 574     return row;
 575   if (row_key == 0)
 576     zero_bucket = bucket_no;
 577   bucket_no--;
 578   goto next_bucket;
 579 }
 580
 581 /* Inserts a value into a hashtable at the specified column, returning the
 582    previous value */
 583 STON_FUNC
 584 uint32_t ston_dht232_insert
 585 ( struct ston_dht2_t* ht,
 586   uint32_t           key,
 587   uint16_t           column,
 588   uint32_t           value
 589 )
 590 { uint32_t* value_location, old_value;
 591   value_location = ston_dht232_entry(ht,key,column);
 592   old_value = *value_location;
 593   *value_location = value;
 594   return old_value;
 595 }
 596
 597 /* Insert multiple values, returning the number of bytes written */
 598 STON_FUNC
 599 size_t
 600 ston_dht232_insertx
 601 ( struct ston_dht2_t* ht,
 602   uint32_t           key,
 603   uint32_t*          data_src,
 604   uint16_t           start_column,
 605   size_t             units
 606 )
 607 { uint32_t* data_row = ston_dht232_row(ht,key);
 608   uint32_t* data_limit = data_row + ht->row_bytes;
 609   uint32_t* data_trg = data_row + start_column;
 610   if (data_row == NULL)
 611     return 0;
 612   while (units-- && data_trg < data_limit)
 613     *data_trg++ = *data_src++;
 614   return (size_t)(data_trg - data_row);
 615 }
 616
 617 /* Free the dynamic hash table */
 618 STON_FUNC
 619 struct ston_dht2_t* ston_dht2_free
 620 ( struct ston_dht2_t* ht )
 621 { void (*ht_free)(void*) = ht->ht_free;
 622   uint8_t bucket = ht->buckets_len;
 623   if (ht_free != NULL)
 624     { while (bucket--)
 625         ht_free(ht->buckets[bucket].page);
 626       ht_free(ht);
 627       return NULL;
 628     }
 629   return ht;
 630 }
 631
 632
 633 #endif //_STON_HT_H_