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

   1 #include "db.h"
   2 #include "io_uring_engine.h"
   3
   4 #include <algorithm>
   5 #include <arpa/inet.h>
   6 #include <assert.h>
   7 #include <chrono>
   8 #include <endian.h>
   9 #include <fcntl.h>
  10 #include <functional>
  11 #include <getopt.h>
  12 #include <limits.h>
  13 #include <memory>
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <string>
  17 #include <unistd.h>
  18 #include <unordered_map>
  19 #include <vector>
  20 #include <zstd.h>
  21
  22 using namespace std;
  23 using namespace std::chrono;
  24
  25 #define dprintf(...)
  26 //#define dprintf(...) fprintf(stderr, __VA_ARGS__);
  27
  28 #include "turbopfor.h"
  29
  30 const char *dbpath = "/var/lib/mlocate/plocate.db";
  31 bool print_nul = false;
  32
  33 class Serializer {
  34 public:
  35         bool ready_to_print(int seq) { return next_seq == seq; }
  36         void print_delayed(int seq, const vector<string> msg);
  37         void release_current();
  38
  39 private:
  40         int next_seq = 0;
  41         struct Element {
  42                 int seq;
  43                 vector<string> msg;
  44
  45                 bool operator<(const Element &other) const
  46                 {
  47                         return seq > other.seq;
  48                 }
  49         };
  50         priority_queue<Element> pending;
  51 };
  52
  53 void Serializer::print_delayed(int seq, const vector<string> msg)
  54 {
  55         pending.push(Element{ seq, move(msg) });
  56 }
  57
  58 void Serializer::release_current()
  59 {
  60         ++next_seq;
  61
  62         // See if any delayed prints can now be dealt with.
  63         while (!pending.empty() && pending.top().seq == next_seq) {
  64                 for (const string &msg : pending.top().msg) {
  65                         if (print_nul) {
  66                                 printf("%s%c", msg.c_str(), 0);
  67                         } else {
  68                                 printf("%s\n", msg.c_str());
  69                         }
  70                 }
  71                 pending.pop();
  72                 ++next_seq;
  73         }
  74 }
  75
  76 static inline uint32_t read_unigram(const string &s, size_t idx)
  77 {
  78         if (idx < s.size()) {
  79                 return (unsigned char)s[idx];
  80         } else {
  81                 return 0;
  82         }
  83 }
  84
  85 static inline uint32_t read_trigram(const string &s, size_t start)
  86 {
  87         return read_unigram(s, start) | (read_unigram(s, start + 1) << 8) |
  88                 (read_unigram(s, start + 2) << 16);
  89 }
  90
  91 bool has_access(const char *filename,
  92                 unordered_map<string, bool> *access_rx_cache)
  93 {
  94         const char *end = strchr(filename + 1, '/');
  95         while (end != nullptr) {
  96                 string parent_path(filename, end);
  97                 auto it = access_rx_cache->find(parent_path);
  98                 bool ok;
  99                 if (it == access_rx_cache->end()) {
 100                         ok = access(parent_path.c_str(), R_OK | X_OK) == 0;
 101                         access_rx_cache->emplace(move(parent_path), ok);
 102                 } else {
 103                         ok = it->second;
 104                 }
 105                 if (!ok) {
 106                         return false;
 107                 }
 108                 end = strchr(end + 1, '/');
 109         }
 110
 111         return true;
 112 }
 113
 114 class Corpus {
 115 public:
 116         Corpus(int fd, IOUringEngine *engine);
 117         ~Corpus();
 118         void find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb);
 119         void get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const;
 120         size_t get_num_filename_blocks() const;
 121         off_t offset_for_block(uint32_t docid) const
 122         {
 123                 return hdr.filename_index_offset_bytes + docid * sizeof(uint64_t);
 124         }
 125
 126 public:
 127         const int fd;
 128         IOUringEngine *const engine;
 129
 130         Header hdr;
 131 };
 132
 133 Corpus::Corpus(int fd, IOUringEngine *engine)
 134         : fd(fd), engine(engine)
 135 {
 136         // Enable to test cold-cache behavior (except for access()).
 137         if (false) {
 138                 off_t len = lseek(fd, 0, SEEK_END);
 139                 if (len == -1) {
 140                         perror("lseek");
 141                         exit(1);
 142                 }
 143                 posix_fadvise(fd, 0, len, POSIX_FADV_DONTNEED);
 144         }
 145
 146         complete_pread(fd, &hdr, sizeof(hdr), /*offset=*/0);
 147         if (memcmp(hdr.magic, "\0plocate", 8) != 0) {
 148                 fprintf(stderr, "plocate.db is corrupt or an old version; please rebuild it.\n");
 149                 exit(1);
 150         }
 151         if (hdr.version != 0) {
 152                 fprintf(stderr, "plocate.db has version %u, expected 0; please rebuild it.\n", hdr.version);
 153                 exit(1);
 154         }
 155 }
 156
 157 Corpus::~Corpus()
 158 {
 159         close(fd);
 160 }
 161
 162 void Corpus::find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb)
 163 {
 164         uint32_t bucket = hash_trigram(trgm, hdr.hashtable_size);
 165         engine->submit_read(fd, sizeof(Trigram) * (hdr.extra_ht_slots + 2), hdr.hash_table_offset_bytes + sizeof(Trigram) * bucket, [this, trgm, cb{ move(cb) }](string s) {
 166                 const Trigram *trgmptr = reinterpret_cast<const Trigram *>(s.data());
 167                 for (unsigned i = 0; i < hdr.extra_ht_slots + 1; ++i) {
 168                         if (trgmptr[i].trgm == trgm) {
 169                                 cb(trgmptr + i, trgmptr[i + 1].offset - trgmptr[i].offset);
 170                                 return;
 171                         }
 172                 }
 173
 174                 // Not found.
 175                 cb(nullptr, 0);
 176         });
 177 }
 178
 179 void Corpus::get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const
 180 {
 181         // Read the file offset from this docid and the next one.
 182         // This is always allowed, since we have a sentinel block at the end.
 183         engine->submit_read(fd, sizeof(uint64_t) * 2, offset_for_block(docid), [this, cb{ move(cb) }](string s) {
 184                 const uint64_t *ptr = reinterpret_cast<const uint64_t *>(s.data());
 185                 off_t offset = ptr[0];
 186                 size_t len = ptr[1] - ptr[0];
 187                 engine->submit_read(fd, len, offset, cb);
 188         });
 189 }
 190
 191 size_t Corpus::get_num_filename_blocks() const
 192 {
 193         return hdr.num_docids;
 194 }
 195
 196 size_t scan_file_block(const vector<string> &needles, string_view compressed,
 197                        unordered_map<string, bool> *access_rx_cache, int seq,
 198                        Serializer *serializer)
 199 {
 200         size_t matched = 0;
 201
 202         unsigned long long uncompressed_len = ZSTD_getFrameContentSize(compressed.data(), compressed.size());
 203         if (uncompressed_len == ZSTD_CONTENTSIZE_UNKNOWN || uncompressed_len == ZSTD_CONTENTSIZE_ERROR) {
 204                 fprintf(stderr, "ZSTD_getFrameContentSize() failed\n");
 205                 exit(1);
 206         }
 207
 208         string block;
 209         block.resize(uncompressed_len + 1);
 210
 211         size_t err = ZSTD_decompress(&block[0], block.size(), compressed.data(),
 212                                      compressed.size());
 213         if (ZSTD_isError(err)) {
 214                 fprintf(stderr, "ZSTD_decompress(): %s\n", ZSTD_getErrorName(err));
 215                 exit(1);
 216         }
 217         block[block.size() - 1] = '\0';
 218
 219         bool immediate_print = (serializer == nullptr || serializer->ready_to_print(seq));
 220         vector<string> delayed;
 221
 222         for (const char *filename = block.data();
 223              filename != block.data() + block.size();
 224              filename += strlen(filename) + 1) {
 225                 bool found = true;
 226                 for (const string &needle : needles) {
 227                         if (strstr(filename, needle.c_str()) == nullptr) {
 228                                 found = false;
 229                                 break;
 230                         }
 231                 }
 232                 if (found && has_access(filename, access_rx_cache)) {
 233                         ++matched;
 234                         if (immediate_print) {
 235                                 if (print_nul) {
 236                                         printf("%s%c", filename, 0);
 237                                 } else {
 238                                         printf("%s\n", filename);
 239                                 }
 240                         } else {
 241                                 delayed.push_back(filename);
 242                         }
 243                 }
 244         }
 245         if (serializer != nullptr) {
 246                 if (immediate_print) {
 247                         serializer->release_current();
 248                 } else {
 249                         serializer->print_delayed(seq, move(delayed));
 250                 }
 251         }
 252         return matched;
 253 }
 254
 255 size_t scan_docids(const vector<string> &needles, const vector<uint32_t> &docids, const Corpus &corpus, IOUringEngine *engine)
 256 {
 257         Serializer docids_in_order;
 258         unordered_map<string, bool> access_rx_cache;
 259         size_t matched = 0;
 260         for (size_t i = 0; i < docids.size(); ++i) {
 261                 uint32_t docid = docids[i];
 262                 corpus.get_compressed_filename_block(docid, [i, &matched, &needles, &access_rx_cache, &docids_in_order](string compressed) {
 263                         matched += scan_file_block(needles, compressed, &access_rx_cache, i, &docids_in_order);
 264                 });
 265         }
 266         engine->finish();
 267         return matched;
 268 }
 269
 270 // We do this sequentially, as it's faster than scattering
 271 // a lot of I/O through io_uring and hoping the kernel will
 272 // coalesce it plus readahead for us.
 273 void scan_all_docids(const vector<string> &needles, int fd, const Corpus &corpus, IOUringEngine *engine)
 274 {
 275         unordered_map<string, bool> access_rx_cache;
 276         uint32_t num_blocks = corpus.get_num_filename_blocks();
 277         unique_ptr<uint64_t[]> offsets(new uint64_t[num_blocks + 1]);
 278         complete_pread(fd, offsets.get(), (num_blocks + 1) * sizeof(uint64_t), corpus.offset_for_block(0));
 279         string compressed;
 280         for (uint32_t io_docid = 0; io_docid < num_blocks; io_docid += 32) {
 281                 uint32_t last_docid = std::min(io_docid + 32, num_blocks);
 282                 size_t io_len = offsets[last_docid] - offsets[io_docid];
 283                 if (compressed.size() < io_len) {
 284                         compressed.resize(io_len);
 285                 }
 286                 complete_pread(fd, &compressed[0], io_len, offsets[io_docid]);
 287
 288                 for (uint32_t docid = io_docid; docid < last_docid; ++docid) {
 289                         size_t relative_offset = offsets[docid] - offsets[io_docid];
 290                         size_t len = offsets[docid + 1] - offsets[docid];
 291                         scan_file_block(needles, { &compressed[relative_offset], len }, &access_rx_cache, 0, nullptr);
 292                 }
 293         }
 294 }
 295
 296 void do_search_file(const vector<string> &needles, const char *filename)
 297 {
 298         int fd = open(filename, O_RDONLY);
 299         if (fd == -1) {
 300                 perror(filename);
 301                 exit(1);
 302         }
 303
 304         // Drop privileges.
 305         if (setgid(getgid()) != 0) {
 306                 perror("setgid");
 307                 exit(EXIT_FAILURE);
 308         }
 309
 310         steady_clock::time_point start __attribute__((unused)) = steady_clock::now();
 311         if (access("/", R_OK | X_OK)) {
 312                 // We can't find anything, no need to bother...
 313                 return;
 314         }
 315
 316         IOUringEngine engine;
 317         Corpus corpus(fd, &engine);
 318         dprintf("Corpus init done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
 319
 320         vector<pair<Trigram, size_t>> trigrams;
 321         uint64_t shortest_so_far = numeric_limits<uint32_t>::max();
 322         for (const string &needle : needles) {
 323                 if (needle.size() < 3)
 324                         continue;
 325                 for (size_t i = 0; i < needle.size() - 2; ++i) {
 326                         uint32_t trgm = read_trigram(needle, i);
 327                         corpus.find_trigram(trgm, [trgm, &trigrams, &shortest_so_far](const Trigram *trgmptr, size_t len) {
 328                                 if (trgmptr == nullptr) {
 329                                         dprintf("trigram '%c%c%c' isn't found, we abort the search\n",
 330                                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff);
 331                                         exit(0);
 332                                 }
 333                                 if (trgmptr->num_docids > shortest_so_far * 100) {
 334                                         dprintf("not loading trigram '%c%c%c' with %u docids, it would be ignored later anyway\n",
 335                                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 336                                                 trgmptr->num_docids);
 337                                 } else {
 338                                         trigrams.emplace_back(*trgmptr, len);
 339                                         shortest_so_far = std::min<uint64_t>(shortest_so_far, trgmptr->num_docids);
 340                                 }
 341                         });
 342                 }
 343         }
 344         engine.finish();
 345         dprintf("Hashtable lookups done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
 346
 347         if (trigrams.empty()) {
 348                 // Too short for trigram matching. Apply brute force.
 349                 // (We could have searched through all trigrams that matched
 350                 // the pattern and done a union of them, but that's a lot of
 351                 // work for fairly unclear gain.)
 352                 scan_all_docids(needles, fd, corpus, &engine);
 353                 return;
 354         }
 355         sort(trigrams.begin(), trigrams.end());
 356         {
 357                 auto last = unique(trigrams.begin(), trigrams.end());
 358                 trigrams.erase(last, trigrams.end());
 359         }
 360         sort(trigrams.begin(), trigrams.end(),
 361              [&](const pair<Trigram, size_t> &a, const pair<Trigram, size_t> &b) {
 362                      return a.first.num_docids < b.first.num_docids;
 363              });
 364
 365         vector<uint32_t> in1, in2, out;
 366         bool done = false;
 367         for (auto [trgmptr, len] : trigrams) {
 368                 if (!in1.empty() && trgmptr.num_docids > in1.size() * 100) {
 369                         uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
 370                         dprintf("trigram '%c%c%c' (%zu bytes) has %u entries, ignoring the rest (will "
 371                                 "weed out false positives later)\n",
 372                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 373                                 len, trgmptr.num_docids);
 374                         break;
 375                 }
 376
 377                 // Only stay a certain amount ahead, so that we don't spend I/O
 378                 // on reading the latter, large posting lists. We are unlikely
 379                 // to need them anyway, even if they should come in first.
 380                 if (engine.get_waiting_reads() >= 5) {
 381                         engine.finish();
 382                         if (done)
 383                                 break;
 384                 }
 385                 engine.submit_read(fd, len, trgmptr.offset, [trgmptr{trgmptr}, len{len}, &done, &in1, &in2, &out](string s) {
 386                         if (done)
 387                                 return;
 388                         uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
 389                         size_t num = trgmptr.num_docids;
 390                         unsigned char *pldata = reinterpret_cast<unsigned char *>(s.data());
 391                         if (in1.empty()) {
 392                                 in1.resize(num + 128);
 393                                 decode_pfor_delta1<128>(pldata, num, /*interleaved=*/true, &in1[0]);
 394                                 in1.resize(num);
 395                                 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries\n", trgm & 0xff,
 396                                         (trgm >> 8) & 0xff, (trgm >> 16) & 0xff, len, num);
 397                         } else {
 398                                 if (in2.size() < num + 128) {
 399                                         in2.resize(num + 128);
 400                                 }
 401                                 decode_pfor_delta1<128>(pldata, num, /*interleaved=*/true, &in2[0]);
 402
 403                                 out.clear();
 404                                 set_intersection(in1.begin(), in1.end(), in2.begin(), in2.begin() + num,
 405                                                  back_inserter(out));
 406                                 swap(in1, out);
 407                                 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries, %zu left\n",
 408                                         trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 409                                         len, num, in1.size());
 410                                 if (in1.empty()) {
 411                                         dprintf("no matches (intersection list is empty)\n");
 412                                         done = true;
 413                                 }
 414                         }
 415                 });
 416         }
 417         engine.finish();
 418         if (done) {
 419                 return;
 420         }
 421         dprintf("Intersection done after %.1f ms. Doing final verification and printing:\n",
 422                 1e3 * duration<float>(steady_clock::now() - start).count());
 423
 424         size_t matched __attribute__((unused)) = scan_docids(needles, in1, corpus, &engine);
 425         dprintf("Done in %.1f ms, found %zu matches.\n",
 426                 1e3 * duration<float>(steady_clock::now() - start).count(), matched);
 427 }
 428
 429 void usage()
 430 {
 431         // The help text comes from mlocate.
 432         printf("Usage: plocate [OPTION]... PATTERN...\n");
 433         printf("\n");
 434         printf("  -d, --database DBPATH  use DBPATH instead of default database (which is\n");
 435         printf("                         %s)\n", dbpath);
 436         printf("  -h, --help             print this help\n");
 437         printf("  -0, --null             separate entries with NUL on output\n");
 438 }
 439
 440 int main(int argc, char **argv)
 441 {
 442         static const struct option long_options[] = {
 443                 { "help", no_argument, 0, 'h' },
 444                 { "database", required_argument, 0, 'd' },
 445                 { "null", no_argument, 0, '0' },
 446                 { 0, 0, 0, 0 }
 447         };
 448
 449         for (;;) {
 450                 int option_index = 0;
 451                 int c = getopt_long(argc, argv, "d:h0", long_options, &option_index);
 452                 if (c == -1) {
 453                         break;
 454                 }
 455                 switch (c) {
 456                 case 'd':
 457                         dbpath = strdup(optarg);
 458                         break;
 459                 case 'h':
 460                         usage();
 461                         exit(0);
 462                 case '0':
 463                         print_nul = true;
 464                         break;
 465                 default:
 466                         exit(1);
 467                 }
 468         }
 469
 470         vector<string> needles;
 471         for (int i = optind; i < argc; ++i) {
 472                 needles.push_back(argv[i]);
 473         }
 474         if (needles.empty()) {
 475                 fprintf(stderr, "plocate: no pattern to search for specified\n");
 476                 exit(0);
 477         }
 478         do_search_file(needles, dbpath);
 479 }