git.sesse.net Git - plocate/blob - plocate-build.cpp

   1 #include "db.h"
   2 #include "dprintf.h"
   3 #include "turbopfor-encode.h"
   4
   5 #include <algorithm>
   6 #include <assert.h>
   7 #include <arpa/inet.h>
   8 #include <chrono>
   9 #include <getopt.h>
  10 #include <iosfwd>
  11 #include <math.h>
  12 #include <memory>
  13 #include <random>
  14 #include <stdint.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <string>
  19 #include <string_view>
  20 #include <sys/stat.h>
  21 #include <utility>
  22 #include <vector>
  23 #include <zdict.h>
  24 #include <zstd.h>
  25
  26 #define P4NENC_BOUND(n) ((n + 127) / 128 + (n + 32) * sizeof(uint32_t))
  27
  28 #define NUM_TRIGRAMS 16777216
  29
  30 using namespace std;
  31 using namespace std::chrono;
  32
  33 string zstd_compress(const string &src, ZSTD_CDict *cdict, string *tempbuf);
  34
  35 constexpr unsigned num_overflow_slots = 16;
  36 bool use_debug = false;
  37
  38 static inline uint32_t read_unigram(const string_view s, size_t idx)
  39 {
  40         if (idx < s.size()) {
  41                 return (unsigned char)s[idx];
  42         } else {
  43                 return 0;
  44         }
  45 }
  46
  47 static inline uint32_t read_trigram(const string_view s, size_t start)
  48 {
  49         return read_unigram(s, start) |
  50                 (read_unigram(s, start + 1) << 8) |
  51                 (read_unigram(s, start + 2) << 16);
  52 }
  53
  54 enum {
  55         DBE_NORMAL = 0, /* A non-directory file */
  56         DBE_DIRECTORY = 1, /* A directory */
  57         DBE_END = 2 /* End of directory contents; contains no name */
  58 };
  59
  60 // From mlocate.
  61 struct db_header {
  62         uint8_t magic[8];
  63         uint32_t conf_size;
  64         uint8_t version;
  65         uint8_t check_visibility;
  66         uint8_t pad[2];
  67 };
  68
  69 // From mlocate.
  70 struct db_directory {
  71         uint64_t time_sec;
  72         uint32_t time_nsec;
  73         uint8_t pad[4];
  74 };
  75
  76 class PostingListBuilder {
  77 public:
  78         inline void add_docid(uint32_t docid);
  79         void finish();
  80
  81         string encoded;
  82         size_t num_docids = 0;
  83
  84 private:
  85         void write_header(uint32_t docid);
  86         void append_block();
  87
  88         vector<uint32_t> pending_deltas;
  89
  90         uint32_t last_block_end, last_docid = -1;
  91 };
  92
  93 void PostingListBuilder::add_docid(uint32_t docid)
  94 {
  95         // Deduplicate against the last inserted value, if any.
  96         if (docid == last_docid) {
  97                 return;
  98         }
  99
 100         if (num_docids == 0) {
 101                 // Very first docid.
 102                 write_header(docid);
 103                 ++num_docids;
 104                 last_block_end = last_docid = docid;
 105                 return;
 106         }
 107
 108         pending_deltas.push_back(docid - last_docid - 1);
 109         last_docid = docid;
 110         if (pending_deltas.size() == 128) {
 111                 append_block();
 112                 pending_deltas.clear();
 113                 last_block_end = docid;
 114         }
 115         ++num_docids;
 116 }
 117
 118 void PostingListBuilder::finish()
 119 {
 120         if (pending_deltas.empty()) {
 121                 return;
 122         }
 123
 124         assert(!encoded.empty());  // write_header() should already have run.
 125
 126         // No interleaving for partial blocks.
 127         unsigned char buf[P4NENC_BOUND(128)];
 128         unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), pending_deltas.size(), /*interleaved=*/false, buf);
 129         encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(end));
 130 }
 131
 132 void PostingListBuilder::append_block()
 133 {
 134         unsigned char buf[P4NENC_BOUND(128)];
 135         assert(pending_deltas.size() == 128);
 136         unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), 128, /*interleaved=*/true, buf);
 137         encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(end));
 138 }
 139
 140 void PostingListBuilder::write_header(uint32_t docid)
 141 {
 142         unsigned char buf[P4NENC_BOUND(1)];
 143         unsigned char *end = write_baseval(docid, buf);
 144         encoded.append(reinterpret_cast<char *>(buf), end - buf);
 145 }
 146
 147 class DatabaseReceiver {
 148 public:
 149         virtual ~DatabaseReceiver() = default;
 150         virtual void add_file(string filename) = 0;
 151         virtual void flush_block() = 0;
 152 };
 153
 154 class DictionaryBuilder : public DatabaseReceiver {
 155 public:
 156         DictionaryBuilder(size_t blocks_to_keep, size_t block_size)
 157                 : blocks_to_keep(blocks_to_keep), block_size(block_size) {}
 158         void add_file(string filename) override;
 159         void flush_block() override;
 160         string train(size_t buf_size);
 161
 162 private:
 163         const size_t blocks_to_keep, block_size;
 164         string current_block;
 165         uint64_t block_num = 0;
 166         size_t num_files_in_block = 0;
 167
 168         std::mt19937 reservoir_rand{ 1234 };  // Fixed seed for reproducibility.
 169         bool keep_current_block = true;
 170         int64_t slot_for_current_block = -1;
 171
 172         vector<string> sampled_blocks;
 173         vector<size_t> lengths;
 174 };
 175
 176 void DictionaryBuilder::add_file(string filename)
 177 {
 178         if (keep_current_block) {  // Only bother saving the filenames if we're actually keeping the block.
 179                 if (!current_block.empty()) {
 180                         current_block.push_back('\0');
 181                 }
 182                 current_block += filename;
 183         }
 184         if (++num_files_in_block == block_size) {
 185                 flush_block();
 186         }
 187 }
 188
 189 void DictionaryBuilder::flush_block()
 190 {
 191         if (keep_current_block) {
 192                 if (slot_for_current_block == -1) {
 193                         lengths.push_back(current_block.size());
 194                         sampled_blocks.push_back(move(current_block));
 195                 } else {
 196                         lengths[slot_for_current_block] = current_block.size();
 197                         sampled_blocks[slot_for_current_block] = move(current_block);
 198                 }
 199         }
 200         current_block.clear();
 201         num_files_in_block = 0;
 202         ++block_num;
 203
 204         if (block_num < blocks_to_keep) {
 205                 keep_current_block = true;
 206                 slot_for_current_block = -1;
 207         } else {
 208                 // Keep every block with equal probability (reservoir sampling).
 209                 uint64_t idx = uniform_int_distribution<uint64_t>(0, block_num)(reservoir_rand);
 210                 keep_current_block = (idx < blocks_to_keep);
 211                 slot_for_current_block = idx;
 212         }
 213 }
 214
 215 string DictionaryBuilder::train(size_t buf_size)
 216 {
 217         string dictionary_buf;
 218         sort(sampled_blocks.begin(), sampled_blocks.end());  // Seemingly important for decompression speed.
 219         for (const string &block : sampled_blocks) {
 220                 dictionary_buf += block;
 221         }
 222
 223         string buf;
 224         buf.resize(buf_size);
 225         size_t ret = ZDICT_trainFromBuffer(&buf[0], buf_size, dictionary_buf.data(), lengths.data(), lengths.size());
 226         if (ret == size_t(-1)) {
 227                 return "";
 228         }
 229         dprintf("Sampled %zu bytes in %zu blocks, built a dictionary of size %zu\n", dictionary_buf.size(), lengths.size(), ret);
 230         buf.resize(ret);
 231
 232         sampled_blocks.clear();
 233         lengths.clear();
 234
 235         return buf;
 236 }
 237
 238 class Corpus : public DatabaseReceiver {
 239 public:
 240         Corpus(FILE *outfp, size_t block_size, ZSTD_CDict *cdict)
 241                 : invindex(new PostingListBuilder *[NUM_TRIGRAMS]), outfp(outfp), block_size(block_size), cdict(cdict)
 242         {
 243                 fill(invindex.get(), invindex.get() + NUM_TRIGRAMS, nullptr);
 244         }
 245         ~Corpus() override
 246         {
 247                 for (unsigned i = 0; i < NUM_TRIGRAMS; ++i) {
 248                         delete invindex[i];
 249                 }
 250         }
 251
 252         void add_file(string filename) override;
 253         void flush_block() override;
 254
 255         vector<uint64_t> filename_blocks;
 256         size_t num_files = 0, num_files_in_block = 0, num_blocks = 0;
 257         bool seen_trigram(uint32_t trgm)
 258         {
 259                 return invindex[trgm] != nullptr;
 260         }
 261         PostingListBuilder &get_pl_builder(uint32_t trgm)
 262         {
 263                 if (invindex[trgm] == nullptr) {
 264                         invindex[trgm] = new PostingListBuilder;
 265                 }
 266                 return *invindex[trgm];
 267         }
 268         size_t num_trigrams() const;
 269
 270 private:
 271         unique_ptr<PostingListBuilder *[]> invindex;
 272         FILE *outfp;
 273         string current_block;
 274         string tempbuf;
 275         const size_t block_size;
 276         ZSTD_CDict *cdict;
 277 };
 278
 279 void Corpus::add_file(string filename)
 280 {
 281         ++num_files;
 282         if (!current_block.empty()) {
 283                 current_block.push_back('\0');
 284         }
 285         current_block += filename;
 286         if (++num_files_in_block == block_size) {
 287                 flush_block();
 288         }
 289 }
 290
 291 void Corpus::flush_block()
 292 {
 293         if (current_block.empty()) {
 294                 return;
 295         }
 296
 297         uint32_t docid = num_blocks;
 298
 299         // Create trigrams.
 300         const char *ptr = current_block.c_str();
 301         while (ptr < current_block.c_str() + current_block.size()) {
 302                 string_view s(ptr);
 303                 if (s.size() >= 3) {
 304                         for (size_t j = 0; j < s.size() - 2; ++j) {
 305                                 uint32_t trgm = read_trigram(s, j);
 306                                 get_pl_builder(trgm).add_docid(docid);
 307                         }
 308                 }
 309                 ptr += s.size() + 1;
 310         }
 311
 312         // Compress and add the filename block.
 313         filename_blocks.push_back(ftell(outfp));
 314         string compressed = zstd_compress(current_block, cdict, &tempbuf);
 315         if (fwrite(compressed.data(), compressed.size(), 1, outfp) != 1) {
 316                 perror("fwrite()");
 317                 exit(1);
 318         }
 319
 320         current_block.clear();
 321         num_files_in_block = 0;
 322         ++num_blocks;
 323 }
 324
 325 size_t Corpus::num_trigrams() const
 326 {
 327         size_t num = 0;
 328         for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) {
 329                 if (invindex[trgm] != nullptr) {
 330                         ++num;
 331                 }
 332         }
 333         return num;
 334 }
 335
 336 string read_cstr(FILE *fp)
 337 {
 338         string ret;
 339         for (;;) {
 340                 int ch = getc(fp);
 341                 if (ch == -1) {
 342                         perror("getc");
 343                         exit(1);
 344                 }
 345                 if (ch == 0) {
 346                         return ret;
 347                 }
 348                 ret.push_back(ch);
 349         }
 350 }
 351
 352 void handle_directory(FILE *fp, DatabaseReceiver *receiver)
 353 {
 354         db_directory dummy;
 355         if (fread(&dummy, sizeof(dummy), 1, fp) != 1) {
 356                 if (feof(fp)) {
 357                         return;
 358                 } else {
 359                         perror("fread");
 360                 }
 361         }
 362
 363         string dir_path = read_cstr(fp);
 364         if (dir_path == "/") {
 365                 dir_path = "";
 366         }
 367
 368         for (;;) {
 369                 int type = getc(fp);
 370                 if (type == DBE_NORMAL) {
 371                         string filename = read_cstr(fp);
 372                         receiver->add_file(dir_path + "/" + filename);
 373                 } else if (type == DBE_DIRECTORY) {
 374                         string dirname = read_cstr(fp);
 375                         receiver->add_file(dir_path + "/" + dirname);
 376                 } else {
 377                         return;  // Probably end.
 378                 }
 379         }
 380 }
 381
 382 void read_plaintext(FILE *fp, DatabaseReceiver *receiver)
 383 {
 384         if (fseek(fp, 0, SEEK_SET) != 0) {
 385                 perror("fseek");
 386                 exit(1);
 387         }
 388
 389         while (!feof(fp)) {
 390                 char buf[1024];
 391                 if (fgets(buf, sizeof(buf), fp) == nullptr) {
 392                         break;
 393                 }
 394                 string s(buf);
 395                 assert(!s.empty());
 396                 while (s.back() != '\n' && !feof(fp)) {
 397                         // The string was longer than the buffer, so read again.
 398                         if (fgets(buf, sizeof(buf), fp) == nullptr) {
 399                                 break;
 400                         }
 401                         s += buf;
 402                 }
 403                 if (!s.empty() && s.back() == '\n')
 404                         s.pop_back();
 405                 receiver->add_file(move(s));
 406         }
 407 }
 408
 409 void read_mlocate(FILE *fp, DatabaseReceiver *receiver)
 410 {
 411         if (fseek(fp, 0, SEEK_SET) != 0) {
 412                 perror("fseek");
 413                 exit(1);
 414         }
 415
 416         db_header hdr;
 417         if (fread(&hdr, sizeof(hdr), 1, fp) != 1) {
 418                 perror("short read");
 419                 exit(1);
 420         }
 421
 422         // TODO: Care about the base path.
 423         string path = read_cstr(fp);
 424
 425         if (fseek(fp, ntohl(hdr.conf_size), SEEK_CUR) != 0) {
 426                 perror("skip conf block");
 427                 exit(1);
 428         }
 429
 430         while (!feof(fp)) {
 431                 handle_directory(fp, receiver);
 432         }
 433 }
 434
 435 string zstd_compress(const string &src, ZSTD_CDict *cdict, string *tempbuf)
 436 {
 437         static ZSTD_CCtx *ctx = nullptr;
 438         if (ctx == nullptr) {
 439                 ctx = ZSTD_createCCtx();
 440         }
 441
 442         size_t max_size = ZSTD_compressBound(src.size());
 443         if (tempbuf->size() < max_size) {
 444                 tempbuf->resize(max_size);
 445         }
 446         size_t size;
 447         if (cdict == nullptr) {
 448                 size = ZSTD_compressCCtx(ctx, &(*tempbuf)[0], max_size, src.data(), src.size(), /*level=*/6);
 449         } else {
 450                 size = ZSTD_compress_usingCDict(ctx, &(*tempbuf)[0], max_size, src.data(), src.size(), cdict);
 451         }
 452         return string(tempbuf->data(), size);
 453 }
 454
 455 bool is_prime(uint32_t x)
 456 {
 457         if ((x % 2) == 0 || (x % 3) == 0) {
 458                 return false;
 459         }
 460         uint32_t limit = ceil(sqrt(x));
 461         for (uint32_t factor = 5; factor <= limit; ++factor) {
 462                 if ((x % factor) == 0) {
 463                         return false;
 464                 }
 465         }
 466         return true;
 467 }
 468
 469 uint32_t next_prime(uint32_t x)
 470 {
 471         if ((x % 2) == 0) {
 472                 ++x;
 473         }
 474         while (!is_prime(x)) {
 475                 x += 2;
 476         }
 477         return x;
 478 }
 479
 480 unique_ptr<Trigram[]> create_hashtable(Corpus &corpus, const vector<uint32_t> &all_trigrams, uint32_t ht_size, uint32_t num_overflow_slots)
 481 {
 482         unique_ptr<Trigram[]> ht(new Trigram[ht_size + num_overflow_slots + 1]);  // 1 for the sentinel element at the end.
 483         for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) {
 484                 ht[i].trgm = uint32_t(-1);
 485                 ht[i].num_docids = 0;
 486                 ht[i].offset = 0;
 487         }
 488         for (uint32_t trgm : all_trigrams) {
 489                 // We don't know offset yet, so set it to zero.
 490                 Trigram to_insert{ trgm, uint32_t(corpus.get_pl_builder(trgm).num_docids), 0 };
 491
 492                 uint32_t bucket = hash_trigram(trgm, ht_size);
 493                 unsigned distance = 0;
 494                 while (ht[bucket].num_docids != 0) {
 495                         // Robin Hood hashing; reduces the longest distance by a lot.
 496                         unsigned other_distance = bucket - hash_trigram(ht[bucket].trgm, ht_size);
 497                         if (distance > other_distance) {
 498                                 swap(to_insert, ht[bucket]);
 499                                 distance = other_distance;
 500                         }
 501
 502                         ++bucket, ++distance;
 503                         if (distance > num_overflow_slots) {
 504                                 return nullptr;
 505                         }
 506                 }
 507                 ht[bucket] = to_insert;
 508         }
 509         return ht;
 510 }
 511
 512 class DatabaseBuilder {
 513 public:
 514         DatabaseBuilder(const char *outfile, int block_size, string dictionary);
 515         Corpus *start_corpus();
 516         void finish_corpus();
 517
 518 private:
 519         FILE *outfp;
 520         Header hdr;
 521         const int block_size;
 522         steady_clock::time_point corpus_start;
 523         Corpus *corpus = nullptr;
 524         ZSTD_CDict *cdict = nullptr;
 525 };
 526
 527 DatabaseBuilder::DatabaseBuilder(const char *outfile, int block_size, string dictionary)
 528         : block_size(block_size)
 529 {
 530         umask(0027);
 531         outfp = fopen(outfile, "wb");
 532         if (outfp == nullptr) {
 533                 perror(outfile);
 534                 exit(1);
 535         }
 536
 537         // Write the header.
 538         memcpy(hdr.magic, "\0plocate", 8);
 539         hdr.version = -1;  // Mark as broken.
 540         hdr.hashtable_size = 0;  // Not known yet.
 541         hdr.extra_ht_slots = num_overflow_slots;
 542         hdr.num_docids = 0;
 543         hdr.hash_table_offset_bytes = -1;  // We don't know these offsets yet.
 544         hdr.max_version = 1;
 545         hdr.filename_index_offset_bytes = -1;
 546         hdr.zstd_dictionary_length_bytes = -1;
 547         fwrite(&hdr, sizeof(hdr), 1, outfp);
 548
 549         if (dictionary.empty()) {
 550                 hdr.zstd_dictionary_offset_bytes = 0;
 551                 hdr.zstd_dictionary_length_bytes = 0;
 552         } else {
 553                 hdr.zstd_dictionary_offset_bytes = ftell(outfp);
 554                 fwrite(dictionary.data(), dictionary.size(), 1, outfp);
 555                 hdr.zstd_dictionary_length_bytes = dictionary.size();
 556                 cdict = ZSTD_createCDict(dictionary.data(), dictionary.size(), /*level=*/6);
 557         }
 558 }
 559
 560 Corpus *DatabaseBuilder::start_corpus()
 561 {
 562         corpus_start = steady_clock::now();
 563         corpus = new Corpus(outfp, block_size, cdict);
 564         return corpus;
 565 }
 566
 567 void DatabaseBuilder::finish_corpus()
 568 {
 569         corpus->flush_block();
 570         hdr.num_docids = corpus->filename_blocks.size();
 571
 572         // Stick an empty block at the end as sentinel.
 573         corpus->filename_blocks.push_back(ftell(outfp));
 574         const size_t bytes_for_filenames = corpus->filename_blocks.back() - corpus->filename_blocks.front();
 575
 576         // Write the offsets to the filenames.
 577         hdr.filename_index_offset_bytes = ftell(outfp);
 578         const size_t bytes_for_filename_index = corpus->filename_blocks.size() * sizeof(uint64_t);
 579         fwrite(corpus->filename_blocks.data(), corpus->filename_blocks.size(), sizeof(uint64_t), outfp);
 580         corpus->filename_blocks.clear();
 581         corpus->filename_blocks.shrink_to_fit();
 582
 583         // Finish up encoding the posting lists.
 584         size_t trigrams = 0, longest_posting_list = 0;
 585         size_t bytes_for_posting_lists = 0;
 586         for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) {
 587                 if (!corpus->seen_trigram(trgm))
 588                         continue;
 589                 PostingListBuilder &pl_builder = corpus->get_pl_builder(trgm);
 590                 pl_builder.finish();
 591                 longest_posting_list = max(longest_posting_list, pl_builder.num_docids);
 592                 trigrams += pl_builder.num_docids;
 593                 bytes_for_posting_lists += pl_builder.encoded.size();
 594         }
 595         size_t num_trigrams = corpus->num_trigrams();
 596         dprintf("%zu files, %zu different trigrams, %zu entries, avg len %.2f, longest %zu\n",
 597                 corpus->num_files, num_trigrams, trigrams, double(trigrams) / num_trigrams, longest_posting_list);
 598         dprintf("%zu bytes used for posting lists (%.2f bits/entry)\n", bytes_for_posting_lists, 8 * bytes_for_posting_lists / double(trigrams));
 599
 600         dprintf("Building posting lists took %.1f ms.\n\n", 1e3 * duration<float>(steady_clock::now() - corpus_start).count());
 601
 602         // Find the used trigrams.
 603         vector<uint32_t> all_trigrams;
 604         for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) {
 605                 if (corpus->seen_trigram(trgm)) {
 606                         all_trigrams.push_back(trgm);
 607                 }
 608         }
 609
 610         // Create the hash table.
 611         unique_ptr<Trigram[]> hashtable;
 612         uint32_t ht_size = next_prime(all_trigrams.size());
 613         for (;;) {
 614                 hashtable = create_hashtable(*corpus, all_trigrams, ht_size, num_overflow_slots);
 615                 if (hashtable == nullptr) {
 616                         dprintf("Failed creating hash table of size %u, increasing by 5%% and trying again.\n", ht_size);
 617                         ht_size = next_prime(ht_size * 1.05);
 618                 } else {
 619                         dprintf("Created hash table of size %u.\n\n", ht_size);
 620                         break;
 621                 }
 622         }
 623
 624         // Find the offsets for each posting list.
 625         size_t bytes_for_hashtable = (ht_size + num_overflow_slots + 1) * sizeof(Trigram);
 626         uint64_t offset = ftell(outfp) + bytes_for_hashtable;
 627         for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) {
 628                 hashtable[i].offset = offset;  // Needs to be there even for empty slots.
 629                 if (hashtable[i].num_docids == 0) {
 630                         continue;
 631                 }
 632
 633                 const string &encoded = corpus->get_pl_builder(hashtable[i].trgm).encoded;
 634                 offset += encoded.size();
 635         }
 636
 637         // Write the hash table.
 638         hdr.hash_table_offset_bytes = ftell(outfp);
 639         hdr.hashtable_size = ht_size;
 640         fwrite(hashtable.get(), ht_size + num_overflow_slots + 1, sizeof(Trigram), outfp);
 641
 642         // Write the actual posting lists.
 643         for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) {
 644                 if (hashtable[i].num_docids == 0) {
 645                         continue;
 646                 }
 647                 const string &encoded = corpus->get_pl_builder(hashtable[i].trgm).encoded;
 648                 fwrite(encoded.data(), encoded.size(), 1, outfp);
 649         }
 650
 651         // Rewind, and write the updated header.
 652         hdr.version = 1;
 653         fseek(outfp, 0, SEEK_SET);
 654         fwrite(&hdr, sizeof(hdr), 1, outfp);
 655         fclose(outfp);
 656
 657         size_t total_bytes = (bytes_for_hashtable + bytes_for_posting_lists + bytes_for_filename_index + bytes_for_filenames);
 658
 659         dprintf("Block size:     %7d files\n", block_size);
 660         dprintf("Dictionary:     %'7.1f MB\n", hdr.zstd_dictionary_length_bytes / 1048576.0);
 661         dprintf("Hash table:     %'7.1f MB\n", bytes_for_hashtable / 1048576.0);
 662         dprintf("Posting lists:  %'7.1f MB\n", bytes_for_posting_lists / 1048576.0);
 663         dprintf("Filename index: %'7.1f MB\n", bytes_for_filename_index / 1048576.0);
 664         dprintf("Filenames:      %'7.1f MB\n", bytes_for_filenames / 1048576.0);
 665         dprintf("Total:          %'7.1f MB\n", total_bytes / 1048576.0);
 666         dprintf("\n");
 667 }
 668
 669 void do_build(const char *infile, const char *outfile, int block_size, bool plaintext)
 670 {
 671         FILE *infp = fopen(infile, "rb");
 672         if (infp == nullptr) {
 673                 perror(infile);
 674                 exit(1);
 675         }
 676
 677         // Train the dictionary by sampling real blocks.
 678         // The documentation for ZDICT_trainFromBuffer() claims that a reasonable
 679         // dictionary size is ~100 kB, but 1 kB seems to actually compress better for us,
 680         // and decompress just as fast.
 681         DictionaryBuilder builder(/*blocks_to_keep=*/1000, block_size);
 682         if (plaintext) {
 683                 read_plaintext(infp, &builder);
 684         } else {
 685                 read_mlocate(infp, &builder);
 686         }
 687         string dictionary = builder.train(1024);
 688
 689         DatabaseBuilder db(outfile, block_size, dictionary);
 690         Corpus *corpus = db.start_corpus();
 691         if (plaintext) {
 692                 read_plaintext(infp, corpus);
 693         } else {
 694                 read_mlocate(infp, corpus);
 695         }
 696         fclose(infp);
 697
 698         dprintf("Read %zu files from %s\n", corpus->num_files, infile);
 699         db.finish_corpus();
 700 }
 701
 702 void usage()
 703 {
 704         printf(
 705                 "Usage: plocate-build MLOCATE_DB PLOCATE_DB\n"
 706                 "\n"
 707                 "Generate plocate index from mlocate.db, typically /var/lib/mlocate/mlocate.db.\n"
 708                 "Normally, the destination should be /var/lib/mlocate/plocate.db.\n"
 709                 "\n"
 710                 "  -b, --block-size SIZE  number of filenames to store in each block (default 32)\n"
 711                 "  -p, --plaintext        input is a plaintext file, not an mlocate database\n"
 712                 "      --help             print this help\n"
 713                 "      --version          print version information\n");
 714 }
 715
 716 void version()
 717 {
 718         printf("plocate-build %s\n", PLOCATE_VERSION);
 719         printf("Copyright 2020 Steinar H. Gunderson\n");
 720         printf("License GPLv2+: GNU GPL version 2 or later <https://gnu.org/licenses/gpl.html>.\n");
 721         printf("This is free software: you are free to change and redistribute it.\n");
 722         printf("There is NO WARRANTY, to the extent permitted by law.\n");
 723 }
 724
 725 int main(int argc, char **argv)
 726 {
 727         static const struct option long_options[] = {
 728                 { "block-size", required_argument, 0, 'b' },
 729                 { "plaintext", no_argument, 0, 'p' },
 730                 { "help", no_argument, 0, 'h' },
 731                 { "version", no_argument, 0, 'V' },
 732                 { "debug", no_argument, 0, 'D' },  // Not documented.
 733                 { 0, 0, 0, 0 }
 734         };
 735
 736         int block_size = 32;
 737         bool plaintext = false;
 738
 739         setlocale(LC_ALL, "");
 740         for (;;) {
 741                 int option_index = 0;
 742                 int c = getopt_long(argc, argv, "b:hpVD", long_options, &option_index);
 743                 if (c == -1) {
 744                         break;
 745                 }
 746                 switch (c) {
 747                 case 'b':
 748                         block_size = atoi(optarg);
 749                         break;
 750                 case 'p':
 751                         plaintext = true;
 752                         break;
 753                 case 'h':
 754                         usage();
 755                         exit(0);
 756                 case 'V':
 757                         version();
 758                         exit(0);
 759                 case 'D':
 760                         use_debug = true;
 761                         break;
 762                 default:
 763                         exit(1);
 764                 }
 765         }
 766
 767         if (argc - optind != 2) {
 768                 usage();
 769                 exit(1);
 770         }
 771
 772         do_build(argv[optind], argv[optind + 1], block_size, plaintext);
 773         exit(EXIT_SUCCESS);
 774 }