git.ozlabs.org Git - ccan/blob - ccan/tdb2/hash.c

   1  /*
   2    Trivial Database 2: hash handling
   3    Copyright (C) Rusty Russell 2010
   4
   5    This library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 3 of the License, or (at your option) any later version.
   9
  10    This library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17 */
  18 #include "private.h"
  19 #include <assert.h>
  20 #include <ccan/hash/hash.h>
  21
  22 static uint64_t jenkins_hash(const void *key, size_t length, uint64_t seed,
  23                              void *arg)
  24 {
  25         uint64_t ret;
  26         /* hash64_stable assumes lower bits are more important; they are a
  27          * slightly better hash.  We use the upper bits first, so swap them. */
  28         ret = hash64_stable((const unsigned char *)key, length, seed);
  29         return (ret >> 32) | (ret << 32);
  30 }
  31
  32 void tdb_hash_init(struct tdb_context *tdb)
  33 {
  34         tdb->khash = jenkins_hash;
  35         tdb->hash_priv = NULL;
  36 }
  37
  38 uint64_t tdb_hash(struct tdb_context *tdb, const void *ptr, size_t len)
  39 {
  40         return tdb->khash(ptr, len, tdb->hash_seed, tdb->hash_priv);
  41 }
  42
  43 uint64_t hash_record(struct tdb_context *tdb, tdb_off_t off)
  44 {
  45         struct tdb_used_record pad, *r;
  46         const void *key;
  47         uint64_t klen, hash;
  48
  49         r = tdb_get(tdb, off, &pad, sizeof(pad));
  50         if (!r)
  51                 /* FIXME */
  52                 return 0;
  53
  54         klen = rec_key_length(r);
  55         key = tdb_access_read(tdb, off + sizeof(pad), klen, false);
  56         if (!key)
  57                 return 0;
  58
  59         hash = tdb_hash(tdb, key, klen);
  60         tdb_access_release(tdb, key);
  61         return hash;
  62 }
  63
  64 /* Get bits from a value. */
  65 static uint32_t bits(uint64_t val, unsigned start, unsigned num)
  66 {
  67         assert(num <= 32);
  68         return (val >> start) & ((1U << num) - 1);
  69 }
  70
  71 /* We take bits from the top: that way we can lock whole sections of the hash
  72  * by using lock ranges. */
  73 static uint32_t use_bits(struct hash_info *h, unsigned num)
  74 {
  75         h->hash_used += num;
  76         return bits(h->h, 64 - h->hash_used, num);
  77 }
  78
  79 /* Does entry match? */
  80 static bool match(struct tdb_context *tdb,
  81                   struct hash_info *h,
  82                   const struct tdb_data *key,
  83                   tdb_off_t val,
  84                   struct tdb_used_record *rec)
  85 {
  86         bool ret;
  87         const unsigned char *rkey;
  88         tdb_off_t off;
  89
  90         /* FIXME: Handle hash value truncated. */
  91         if (bits(val, TDB_OFF_HASH_TRUNCATED_BIT, 1))
  92                 abort();
  93
  94         /* Desired bucket must match. */
  95         if (h->home_bucket != (val & TDB_OFF_HASH_GROUP_MASK))
  96                 return false;
  97
  98         /* Top bits of offset == next bits of hash. */
  99         if (bits(val, TDB_OFF_HASH_EXTRA_BIT, TDB_OFF_UPPER_STEAL_EXTRA)
 100             != bits(h->h, 64 - h->hash_used - TDB_OFF_UPPER_STEAL_EXTRA,
 101                     TDB_OFF_UPPER_STEAL_EXTRA))
 102                 return false;
 103
 104         off = val & TDB_OFF_MASK;
 105         if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
 106                 return false;
 107
 108         /* FIXME: check extra bits in header? */
 109         if (rec_key_length(rec) != key->dsize)
 110                 return false;
 111
 112         rkey = tdb_access_read(tdb, off + sizeof(*rec), key->dsize, false);
 113         if (!rkey)
 114                 return false;
 115         ret = (memcmp(rkey, key->dptr, key->dsize) == 0);
 116         tdb_access_release(tdb, rkey);
 117         return ret;
 118 }
 119
 120 static tdb_off_t hbucket_off(tdb_off_t group_start, unsigned bucket)
 121 {
 122         return group_start
 123                 + (bucket % (1 << TDB_HASH_GROUP_BITS)) * sizeof(tdb_off_t);
 124 }
 125
 126 /* Truncated hashes can't be all 1: that's how we spot a sub-hash */
 127 bool is_subhash(tdb_off_t val)
 128 {
 129         return val >> (64-TDB_OFF_UPPER_STEAL) == (1<<TDB_OFF_UPPER_STEAL) - 1;
 130 }
 131
 132 /* This is the core routine which searches the hashtable for an entry.
 133  * On error, no locks are held and TDB_OFF_ERR is returned.
 134  * Otherwise, hinfo is filled in.
 135  * If not found, the return value is 0.
 136  * If found, the return value is the offset, and *rec is the record. */
 137 tdb_off_t find_and_lock(struct tdb_context *tdb,
 138                         struct tdb_data key,
 139                         int ltype,
 140                         struct hash_info *h,
 141                         struct tdb_used_record *rec)
 142 {
 143         uint32_t i, group;
 144         tdb_off_t hashtable;
 145
 146         h->h = tdb_hash(tdb, key.dptr, key.dsize);
 147         h->hash_used = 0;
 148         group = use_bits(h, TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS);
 149         h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
 150
 151         /* FIXME: Guess the depth, don't over-lock! */
 152         h->hlock_start = (tdb_off_t)group
 153                 << (64 - (TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS));
 154         h->hlock_range = 1ULL << (64 - (TDB_TOPLEVEL_HASH_BITS
 155                                         - TDB_HASH_GROUP_BITS));
 156         if (tdb_lock_hashes(tdb, h->hlock_start, h->hlock_range, ltype,
 157                             TDB_LOCK_WAIT))
 158                 return TDB_OFF_ERR;
 159
 160         hashtable = offsetof(struct tdb_header, hashtable);
 161
 162         while (likely(h->hash_used < 64)) {
 163                 /* Read in the hash group. */
 164                 h->group_start = hashtable
 165                         + group * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
 166
 167                 if (tdb_read_convert(tdb, h->group_start, &h->group,
 168                                      sizeof(h->group)) == -1)
 169                         goto fail;
 170
 171                 /* Pointer to another hash table?  Go down... */
 172                 if (is_subhash(h->group[h->home_bucket])) {
 173                         hashtable = (h->group[h->home_bucket] & TDB_OFF_MASK)
 174                                 + sizeof(struct tdb_used_record);
 175                         group = use_bits(h, TDB_SUBLEVEL_HASH_BITS
 176                                          - TDB_HASH_GROUP_BITS);
 177                         h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
 178                         continue;
 179                 }
 180
 181                 /* It's in this group: search (until 0 or all searched) */
 182                 for (i = 0, h->found_bucket = h->home_bucket;
 183                      i < (1 << TDB_HASH_GROUP_BITS);
 184                      i++, h->found_bucket = ((h->found_bucket+1)
 185                                              % (1 << TDB_HASH_GROUP_BITS))) {
 186                         if (is_subhash(h->group[h->found_bucket]))
 187                                 continue;
 188
 189                         if (!h->group[h->found_bucket])
 190                                 break;
 191
 192                         if (match(tdb, h, &key, h->group[h->found_bucket], rec))
 193                                 return h->group[h->found_bucket] & TDB_OFF_MASK;
 194                 }
 195                 /* Didn't find it: h indicates where it would go. */
 196                 return 0;
 197         }
 198
 199         /* FIXME: We hit the bottom.  Chain! */
 200         abort();
 201
 202 fail:
 203         tdb_unlock_hashes(tdb, h->hlock_start, h->hlock_range, ltype);
 204         return TDB_OFF_ERR;
 205 }
 206
 207 /* I wrote a simple test, expanding a hash to 2GB, for the following
 208  * cases:
 209  * 1) Expanding all the buckets at once,
 210  * 2) Expanding the most-populated bucket,
 211  * 3) Expanding the bucket we wanted to place the new entry ito.
 212  *
 213  * I measured the worst/average/best density during this process.
 214  * 1) 3%/16%/30%
 215  * 2) 4%/20%/38%
 216  * 3) 6%/22%/41%
 217  *
 218  * So we figure out the busiest bucket for the moment.
 219  */
 220 static unsigned fullest_bucket(struct tdb_context *tdb,
 221                                const tdb_off_t *group,
 222                                unsigned new_bucket)
 223 {
 224         unsigned counts[1 << TDB_HASH_GROUP_BITS] = { 0 };
 225         unsigned int i, best_bucket;
 226
 227         /* Count the new entry. */
 228         counts[new_bucket]++;
 229         best_bucket = new_bucket;
 230
 231         for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
 232                 unsigned this_bucket;
 233
 234                 if (is_subhash(group[i]))
 235                         continue;
 236                 this_bucket = group[i] & TDB_OFF_HASH_GROUP_MASK;
 237                 if (++counts[this_bucket] > counts[best_bucket])
 238                         best_bucket = this_bucket;
 239         }
 240
 241         return best_bucket;
 242 }
 243
 244 static bool put_into_group(tdb_off_t *group,
 245                            unsigned bucket, tdb_off_t encoded)
 246 {
 247         unsigned int i;
 248
 249         for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
 250                 unsigned b = (bucket + i) % (1 << TDB_HASH_GROUP_BITS);
 251
 252                 if (group[b] == 0) {
 253                         group[b] = encoded;
 254                         return true;
 255                 }
 256         }
 257         return false;
 258 }
 259
 260 static void force_into_group(tdb_off_t *group,
 261                              unsigned bucket, tdb_off_t encoded)
 262 {
 263         if (!put_into_group(group, bucket, encoded))
 264                 abort();
 265 }
 266
 267 static tdb_off_t encode_offset(tdb_off_t new_off, struct hash_info *h)
 268 {
 269         return h->home_bucket
 270                 | new_off
 271                 | ((uint64_t)bits(h->h,
 272                                   64 - h->hash_used - TDB_OFF_UPPER_STEAL_EXTRA,
 273                                   TDB_OFF_UPPER_STEAL_EXTRA)
 274                    << TDB_OFF_HASH_EXTRA_BIT);
 275 }
 276
 277 /* Simply overwrite the hash entry we found before. */
 278 int replace_in_hash(struct tdb_context *tdb,
 279                     struct hash_info *h,
 280                     tdb_off_t new_off)
 281 {
 282         return tdb_write_off(tdb, hbucket_off(h->group_start, h->found_bucket),
 283                              encode_offset(new_off, h));
 284 }
 285
 286 /* Add into a newly created subhash. */
 287 static int add_to_subhash(struct tdb_context *tdb, tdb_off_t subhash,
 288                           unsigned hash_used, tdb_off_t val)
 289 {
 290         tdb_off_t off = (val & TDB_OFF_MASK), *group;
 291         struct hash_info h;
 292         unsigned int gnum;
 293
 294         h.hash_used = hash_used;
 295
 296         /* FIXME chain if hash_used == 64 */
 297         if (hash_used + TDB_SUBLEVEL_HASH_BITS > 64)
 298                 abort();
 299
 300         /* FIXME: Do truncated hash bits if we can! */
 301         h.h = hash_record(tdb, off);
 302         gnum = use_bits(&h, TDB_SUBLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS);
 303         h.group_start = subhash + sizeof(struct tdb_used_record)
 304                 + gnum * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
 305         h.home_bucket = use_bits(&h, TDB_HASH_GROUP_BITS);
 306
 307         group = tdb_access_write(tdb, h.group_start,
 308                                  sizeof(*group) << TDB_HASH_GROUP_BITS, true);
 309         if (!group)
 310                 return -1;
 311         force_into_group(group, h.home_bucket, encode_offset(off, &h));
 312         return tdb_access_commit(tdb, group);
 313 }
 314
 315 static int expand_group(struct tdb_context *tdb, struct hash_info *h)
 316 {
 317         unsigned bucket, num_vals, i;
 318         tdb_off_t subhash;
 319         tdb_off_t vals[1 << TDB_HASH_GROUP_BITS];
 320
 321         /* Attach new empty subhash under fullest bucket. */
 322         bucket = fullest_bucket(tdb, h->group, h->home_bucket);
 323
 324         subhash = alloc(tdb, 0, sizeof(tdb_off_t) << TDB_SUBLEVEL_HASH_BITS,
 325                         0, false);
 326         if (subhash == TDB_OFF_ERR)
 327                 return -1;
 328
 329         if (zero_out(tdb, subhash + sizeof(struct tdb_used_record),
 330                      sizeof(tdb_off_t) << TDB_SUBLEVEL_HASH_BITS) == -1)
 331                 return -1;
 332
 333         /* Remove any which are destined for bucket or are in wrong place. */
 334         num_vals = 0;
 335         for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
 336                 unsigned home_bucket = h->group[i] & TDB_OFF_HASH_GROUP_MASK;
 337                 if (!h->group[i] || is_subhash(h->group[i]))
 338                         continue;
 339                 if (home_bucket == bucket || home_bucket != i) {
 340                         vals[num_vals++] = h->group[i];
 341                         h->group[i] = 0;
 342                 }
 343         }
 344         /* FIXME: This assert is valid, but we do this during unit test :( */
 345         /* assert(num_vals); */
 346
 347         /* Overwrite expanded bucket with subhash pointer. */
 348         h->group[bucket] = subhash | ~((1ULL << (64 - TDB_OFF_UPPER_STEAL))-1);
 349
 350         /* Put values back. */
 351         for (i = 0; i < num_vals; i++) {
 352                 unsigned this_bucket = vals[i] & TDB_OFF_HASH_GROUP_MASK;
 353
 354                 if (this_bucket == bucket) {
 355                         if (add_to_subhash(tdb, subhash, h->hash_used, vals[i]))
 356                                 return -1;
 357                 } else {
 358                         /* There should be room to put this back. */
 359                         force_into_group(h->group, this_bucket, vals[i]);
 360                 }
 361         }
 362         return 0;
 363 }
 364
 365 int delete_from_hash(struct tdb_context *tdb, struct hash_info *h)
 366 {
 367         unsigned int i, num_movers = 0;
 368         tdb_off_t movers[1 << TDB_HASH_GROUP_BITS];
 369
 370         h->group[h->found_bucket] = 0;
 371         for (i = 1; i < (1 << TDB_HASH_GROUP_BITS); i++) {
 372                 unsigned this_bucket;
 373
 374                 this_bucket = (h->found_bucket+i) % (1 << TDB_HASH_GROUP_BITS);
 375                 /* Empty bucket?  We're done. */
 376                 if (!h->group[this_bucket])
 377                         break;
 378
 379                 /* Ignore subhashes. */
 380                 if (is_subhash(h->group[this_bucket]))
 381                         continue;
 382
 383                 /* If this one is not happy where it is, we'll move it. */
 384                 if ((h->group[this_bucket] & TDB_OFF_HASH_GROUP_MASK)
 385                     != this_bucket) {
 386                         movers[num_movers++] = h->group[this_bucket];
 387                         h->group[this_bucket] = 0;
 388                 }
 389         }
 390
 391         /* Put back the ones we erased. */
 392         for (i = 0; i < num_movers; i++) {
 393                 force_into_group(h->group, movers[i] & TDB_OFF_HASH_GROUP_MASK,
 394                                  movers[i]);
 395         }
 396
 397         /* Now we write back the hash group */
 398         return tdb_write_convert(tdb, h->group_start,
 399                                  h->group, sizeof(h->group));
 400 }
 401
 402 int add_to_hash(struct tdb_context *tdb, struct hash_info *h, tdb_off_t new_off)
 403 {
 404         /* FIXME: chain! */
 405         if (h->hash_used >= 64)
 406                 abort();
 407
 408         /* We hit an empty bucket during search?  That's where it goes. */
 409         if (!h->group[h->found_bucket]) {
 410                 h->group[h->found_bucket] = encode_offset(new_off, h);
 411                 /* Write back the modified group. */
 412                 return tdb_write_convert(tdb, h->group_start,
 413                                          h->group, sizeof(h->group));
 414         }
 415
 416         /* We're full.  Expand. */
 417         if (expand_group(tdb, h) == -1)
 418                 return -1;
 419
 420         if (is_subhash(h->group[h->home_bucket])) {
 421                 /* We were expanded! */
 422                 tdb_off_t hashtable;
 423                 unsigned int gnum;
 424
 425                 /* Write back the modified group. */
 426                 if (tdb_write_convert(tdb, h->group_start, h->group,
 427                                       sizeof(h->group)))
 428                         return -1;
 429
 430                 /* Move hashinfo down a level. */
 431                 hashtable = (h->group[h->home_bucket] & TDB_OFF_MASK)
 432                         + sizeof(struct tdb_used_record);
 433                 gnum = use_bits(h,TDB_SUBLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS);
 434                 h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
 435                 h->group_start = hashtable
 436                         + gnum * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
 437                 if (tdb_read_convert(tdb, h->group_start, &h->group,
 438                                      sizeof(h->group)) == -1)
 439                         return -1;
 440         }
 441
 442         /* Expanding the group must have made room if it didn't choose this
 443          * bucket. */
 444         if (put_into_group(h->group, h->home_bucket, encode_offset(new_off, h)))
 445                 return tdb_write_convert(tdb, h->group_start,
 446                                          h->group, sizeof(h->group));
 447
 448         /* This can happen if all hashes in group (and us) dropped into same
 449          * group in subhash. */
 450         return add_to_hash(tdb, h, new_off);
 451 }
 452
 453 /* No point holding references/copies of db once we drop lock. */
 454 static void release_entries(struct tdb_context *tdb,
 455                             struct traverse_info *tinfo)
 456 {
 457         unsigned int i;
 458
 459         for (i = 0; i < tinfo->num_levels; i++) {
 460                 if (tinfo->levels[i].entries) {
 461                         tdb_access_release(tdb, tinfo->levels[i].entries);
 462                         tinfo->levels[i].entries = NULL;
 463                 }
 464         }
 465 }
 466
 467 /* Traverse support: returns offset of record, or 0 or TDB_OFF_ERR. */
 468 static tdb_off_t iterate_hash(struct tdb_context *tdb,
 469                               struct traverse_info *tinfo)
 470 {
 471         tdb_off_t off;
 472         unsigned int i;
 473         struct traverse_level *tlevel;
 474
 475         tlevel = &tinfo->levels[tinfo->num_levels-1];
 476
 477 again:
 478         if (!tlevel->entries) {
 479                 tlevel->entries = tdb_access_read(tdb, tlevel->hashtable,
 480                                                   sizeof(tdb_off_t)
 481                                                   * tlevel->total_buckets,
 482                                                   true);
 483                 if (!tlevel->entries)
 484                         return TDB_OFF_ERR;
 485         }
 486
 487         /* FIXME: Use tdb_find_nonzero_off? */
 488         for (i = tlevel->entry; i < tlevel->total_buckets; i++) {
 489                 if (!tlevel->entries[i] || tlevel->entries[i] == tinfo->prev)
 490                         continue;
 491
 492                 tlevel->entry = i;
 493                 off = tlevel->entries[i] & TDB_OFF_MASK;
 494
 495                 if (!is_subhash(tlevel->entries[i])) {
 496                         /* Found one. */
 497                         tinfo->prev = tlevel->entries[i];
 498                         release_entries(tdb, tinfo);
 499                         return off;
 500                 }
 501
 502                 /* When we come back, we want tne next one */
 503                 tlevel->entry++;
 504                 tinfo->num_levels++;
 505                 tlevel++;
 506                 tlevel->hashtable = off + sizeof(struct tdb_used_record);
 507                 tlevel->entry = 0;
 508                 tlevel->entries = NULL;
 509                 tlevel->total_buckets = (1 << TDB_SUBLEVEL_HASH_BITS);
 510                 goto again;
 511         }
 512
 513         /* Nothing there? */
 514         if (tinfo->num_levels == 1) {
 515                 release_entries(tdb, tinfo);
 516                 return 0;
 517         }
 518
 519         /* Go back up and keep searching. */
 520         tdb_access_release(tdb, tlevel->entries);
 521         tinfo->num_levels--;
 522         tlevel--;
 523         goto again;
 524 }
 525
 526 /* Return 1 if we find something, 0 if not, -1 on error. */
 527 int next_in_hash(struct tdb_context *tdb, int ltype,
 528                  struct traverse_info *tinfo,
 529                  TDB_DATA *kbuf, unsigned int *dlen)
 530 {
 531         const unsigned group_bits = TDB_TOPLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS;
 532         tdb_off_t hlock_start, hlock_range, off;
 533
 534         while (tinfo->toplevel_group < (1 << group_bits)) {
 535                 hlock_start = (tdb_off_t)tinfo->toplevel_group
 536                         << (64 - group_bits);
 537                 hlock_range = 1ULL << group_bits;
 538                 if (tdb_lock_hashes(tdb, hlock_start, hlock_range, ltype,
 539                                     TDB_LOCK_WAIT) != 0)
 540                         return -1;
 541
 542                 off = iterate_hash(tdb, tinfo);
 543                 if (off) {
 544                         struct tdb_used_record rec;
 545
 546                         if (tdb_read_convert(tdb, off, &rec, sizeof(rec))) {
 547                                 tdb_unlock_hashes(tdb,
 548                                                   hlock_start, hlock_range,
 549                                                   ltype);
 550                                 return -1;
 551                         }
 552                         kbuf->dsize = rec_key_length(&rec);
 553
 554                         /* They want data as well? */
 555                         if (dlen) {
 556                                 *dlen = rec_data_length(&rec);
 557                                 kbuf->dptr = tdb_alloc_read(tdb,
 558                                                             off + sizeof(rec),
 559                                                             kbuf->dsize
 560                                                             + *dlen);
 561                         } else {
 562                                 kbuf->dptr = tdb_alloc_read(tdb,
 563                                                             off + sizeof(rec),
 564                                                             kbuf->dsize);
 565                         }
 566                         tdb_unlock_hashes(tdb, hlock_start, hlock_range, ltype);
 567                         return kbuf->dptr ? 1 : -1;
 568                 }
 569
 570                 tdb_unlock_hashes(tdb, hlock_start, hlock_range, ltype);
 571
 572                 tinfo->toplevel_group++;
 573                 tinfo->levels[0].hashtable
 574                         += (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
 575                 tinfo->levels[0].entry = 0;
 576         }
 577         return 0;
 578 }
 579
 580 /* Return 1 if we find something, 0 if not, -1 on error. */
 581 int first_in_hash(struct tdb_context *tdb, int ltype,
 582                   struct traverse_info *tinfo,
 583                   TDB_DATA *kbuf, unsigned int *dlen)
 584 {
 585         tinfo->prev = 0;
 586         tinfo->toplevel_group = 0;
 587         tinfo->num_levels = 1;
 588         tinfo->levels[0].hashtable = offsetof(struct tdb_header, hashtable);
 589         tinfo->levels[0].entries = NULL;
 590         tinfo->levels[0].entry = 0;
 591         tinfo->levels[0].total_buckets = (1 << TDB_HASH_GROUP_BITS);
 592
 593         return next_in_hash(tdb, ltype, tinfo, kbuf, dlen);
 594 }