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

   1 #include "db.h"
   2 #include "io_uring_engine.h"
   3 #include "vp4.h"
   4
   5 #include <algorithm>
   6 #include <arpa/inet.h>
   7 #include <assert.h>
   8 #include <chrono>
   9 #include <endian.h>
  10 #include <fcntl.h>
  11 #include <functional>
  12 #include <getopt.h>
  13 #include <limits.h>
  14 #include <memory>
  15 #include <stdio.h>
  16 #include <string.h>
  17 #include <string>
  18 #include <unistd.h>
  19 #include <unordered_map>
  20 #include <vector>
  21 #include <zstd.h>
  22
  23 using namespace std;
  24 using namespace std::chrono;
  25
  26 #define dprintf(...)
  27 //#define dprintf(...) fprintf(stderr, __VA_ARGS__);
  28
  29 #include "turbopfor.h"
  30
  31 const char *dbpath = "/var/lib/mlocate/plocate.db";
  32 bool print_nul = false;
  33
  34 class Serializer {
  35 public:
  36         bool ready_to_print(int seq) { return next_seq == seq; }
  37         void print_delayed(int seq, const vector<string> msg);
  38         void release_current();
  39
  40 private:
  41         int next_seq = 0;
  42         struct Element {
  43                 int seq;
  44                 vector<string> msg;
  45
  46                 bool operator<(const Element &other) const
  47                 {
  48                         return seq > other.seq;
  49                 }
  50         };
  51         priority_queue<Element> pending;
  52 };
  53
  54 void Serializer::print_delayed(int seq, const vector<string> msg)
  55 {
  56         pending.push(Element{ seq, move(msg) });
  57 }
  58
  59 void Serializer::release_current()
  60 {
  61         ++next_seq;
  62
  63         // See if any delayed prints can now be dealt with.
  64         while (!pending.empty() && pending.top().seq == next_seq) {
  65                 for (const string &msg : pending.top().msg) {
  66                         if (print_nul) {
  67                                 printf("%s%c", msg.c_str(), 0);
  68                         } else {
  69                                 printf("%s\n", msg.c_str());
  70                         }
  71                 }
  72                 pending.pop();
  73                 ++next_seq;
  74         }
  75 }
  76
  77 static inline uint32_t read_unigram(const string &s, size_t idx)
  78 {
  79         if (idx < s.size()) {
  80                 return (unsigned char)s[idx];
  81         } else {
  82                 return 0;
  83         }
  84 }
  85
  86 static inline uint32_t read_trigram(const string &s, size_t start)
  87 {
  88         return read_unigram(s, start) | (read_unigram(s, start + 1) << 8) |
  89                 (read_unigram(s, start + 2) << 16);
  90 }
  91
  92 bool has_access(const char *filename,
  93                 unordered_map<string, bool> *access_rx_cache)
  94 {
  95         const char *end = strchr(filename + 1, '/');
  96         while (end != nullptr) {
  97                 string parent_path(filename, end);
  98                 auto it = access_rx_cache->find(parent_path);
  99                 bool ok;
 100                 if (it == access_rx_cache->end()) {
 101                         ok = access(parent_path.c_str(), R_OK | X_OK) == 0;
 102                         access_rx_cache->emplace(move(parent_path), ok);
 103                 } else {
 104                         ok = it->second;
 105                 }
 106                 if (!ok) {
 107                         return false;
 108                 }
 109                 end = strchr(end + 1, '/');
 110         }
 111
 112         return true;
 113 }
 114
 115 class Corpus {
 116 public:
 117         Corpus(int fd, IOUringEngine *engine);
 118         ~Corpus();
 119         void find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb);
 120         void get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const;
 121         size_t get_num_filename_blocks() const;
 122         off_t offset_for_block(uint32_t docid) const
 123         {
 124                 return hdr.filename_index_offset_bytes + docid * sizeof(uint64_t);
 125         }
 126
 127 public:
 128         const int fd;
 129         IOUringEngine *const engine;
 130
 131         Header hdr;
 132 };
 133
 134 Corpus::Corpus(int fd, IOUringEngine *engine)
 135         : fd(fd), engine(engine)
 136 {
 137         // Enable to test cold-cache behavior (except for access()).
 138         if (false) {
 139                 off_t len = lseek(fd, 0, SEEK_END);
 140                 if (len == -1) {
 141                         perror("lseek");
 142                         exit(1);
 143                 }
 144                 posix_fadvise(fd, 0, len, POSIX_FADV_DONTNEED);
 145         }
 146
 147         complete_pread(fd, &hdr, sizeof(hdr), /*offset=*/0);
 148         if (memcmp(hdr.magic, "\0plocate", 8) != 0) {
 149                 fprintf(stderr, "plocate.db is corrupt or an old version; please rebuild it.\n");
 150                 exit(1);
 151         }
 152         if (hdr.version != 0) {
 153                 fprintf(stderr, "plocate.db has version %u, expected 0; please rebuild it.\n", hdr.version);
 154                 exit(1);
 155         }
 156 }
 157
 158 Corpus::~Corpus()
 159 {
 160         close(fd);
 161 }
 162
 163 void Corpus::find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb)
 164 {
 165         uint32_t bucket = hash_trigram(trgm, hdr.hashtable_size);
 166         engine->submit_read(fd, sizeof(Trigram) * (hdr.extra_ht_slots + 2), hdr.hash_table_offset_bytes + sizeof(Trigram) * bucket, [this, trgm, bucket, cb{ move(cb) }](string s) {
 167                 const Trigram *trgmptr = reinterpret_cast<const Trigram *>(s.data());
 168                 for (unsigned i = 0; i < hdr.extra_ht_slots + 1; ++i) {
 169                         if (trgmptr[i].trgm == trgm) {
 170                                 cb(trgmptr + i, trgmptr[i + 1].offset - trgmptr[i].offset);
 171                                 return;
 172                         }
 173                 }
 174
 175                 // Not found.
 176                 cb(nullptr, 0);
 177         });
 178 }
 179
 180 void Corpus::get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const
 181 {
 182         // Read the file offset from this docid and the next one.
 183         // This is always allowed, since we have a sentinel block at the end.
 184         engine->submit_read(fd, sizeof(uint64_t) * 2, offset_for_block(docid), [this, cb{ move(cb) }](string s) {
 185                 const uint64_t *ptr = reinterpret_cast<const uint64_t *>(s.data());
 186                 off_t offset = ptr[0];
 187                 size_t len = ptr[1] - ptr[0];
 188                 engine->submit_read(fd, len, offset, cb);
 189         });
 190 }
 191
 192 size_t Corpus::get_num_filename_blocks() const
 193 {
 194         return hdr.num_docids;
 195 }
 196
 197 size_t scan_file_block(const vector<string> &needles, string_view compressed,
 198                        unordered_map<string, bool> *access_rx_cache, int seq,
 199                        Serializer *serializer)
 200 {
 201         size_t matched = 0;
 202
 203         unsigned long long uncompressed_len = ZSTD_getFrameContentSize(compressed.data(), compressed.size());
 204         if (uncompressed_len == ZSTD_CONTENTSIZE_UNKNOWN || uncompressed_len == ZSTD_CONTENTSIZE_ERROR) {
 205                 fprintf(stderr, "ZSTD_getFrameContentSize() failed\n");
 206                 exit(1);
 207         }
 208
 209         string block;
 210         block.resize(uncompressed_len + 1);
 211
 212         size_t err = ZSTD_decompress(&block[0], block.size(), compressed.data(),
 213                                      compressed.size());
 214         if (ZSTD_isError(err)) {
 215                 fprintf(stderr, "ZSTD_decompress(): %s\n", ZSTD_getErrorName(err));
 216                 exit(1);
 217         }
 218         block[block.size() - 1] = '\0';
 219
 220         bool immediate_print = (serializer == nullptr || serializer->ready_to_print(seq));
 221         vector<string> delayed;
 222
 223         for (const char *filename = block.data();
 224              filename != block.data() + block.size();
 225              filename += strlen(filename) + 1) {
 226                 bool found = true;
 227                 for (const string &needle : needles) {
 228                         if (strstr(filename, needle.c_str()) == nullptr) {
 229                                 found = false;
 230                                 break;
 231                         }
 232                 }
 233                 if (found && has_access(filename, access_rx_cache)) {
 234                         ++matched;
 235                         if (immediate_print) {
 236                                 if (print_nul) {
 237                                         printf("%s%c", filename, 0);
 238                                 } else {
 239                                         printf("%s\n", filename);
 240                                 }
 241                         } else {
 242                                 delayed.push_back(filename);
 243                         }
 244                 }
 245         }
 246         if (serializer != nullptr) {
 247                 if (immediate_print) {
 248                         serializer->release_current();
 249                 } else {
 250                         serializer->print_delayed(seq, move(delayed));
 251                 }
 252         }
 253         return matched;
 254 }
 255
 256 size_t scan_docids(const vector<string> &needles, const vector<uint32_t> &docids, const Corpus &corpus, IOUringEngine *engine)
 257 {
 258         Serializer docids_in_order;
 259         unordered_map<string, bool> access_rx_cache;
 260         size_t matched = 0;
 261         for (size_t i = 0; i < docids.size(); ++i) {
 262                 uint32_t docid = docids[i];
 263                 corpus.get_compressed_filename_block(docid, [i, &matched, &needles, &access_rx_cache, &docids_in_order](string compressed) {
 264                         matched += scan_file_block(needles, compressed, &access_rx_cache, i, &docids_in_order);
 265                 });
 266         }
 267         engine->finish();
 268         return matched;
 269 }
 270
 271 // We do this sequentially, as it's faster than scattering
 272 // a lot of I/O through io_uring and hoping the kernel will
 273 // coalesce it plus readahead for us.
 274 void scan_all_docids(const vector<string> &needles, int fd, const Corpus &corpus, IOUringEngine *engine)
 275 {
 276         unordered_map<string, bool> access_rx_cache;
 277         uint32_t num_blocks = corpus.get_num_filename_blocks();
 278         unique_ptr<uint64_t[]> offsets(new uint64_t[num_blocks + 1]);
 279         complete_pread(fd, offsets.get(), (num_blocks + 1) * sizeof(uint64_t), corpus.offset_for_block(0));
 280         string compressed;
 281         for (uint32_t io_docid = 0; io_docid < num_blocks; io_docid += 32) {
 282                 uint32_t last_docid = std::min(io_docid + 32, num_blocks);
 283                 size_t io_len = offsets[last_docid] - offsets[io_docid];
 284                 if (compressed.size() < io_len) {
 285                         compressed.resize(io_len);
 286                 }
 287                 complete_pread(fd, &compressed[0], io_len, offsets[io_docid]);
 288
 289                 for (uint32_t docid = io_docid; docid < last_docid; ++docid) {
 290                         size_t relative_offset = offsets[docid] - offsets[io_docid];
 291                         size_t len = offsets[docid + 1] - offsets[docid];
 292                         scan_file_block(needles, { &compressed[relative_offset], len }, &access_rx_cache, 0, nullptr);
 293                 }
 294         }
 295 }
 296
 297 void do_search_file(const vector<string> &needles, const char *filename)
 298 {
 299         int fd = open(filename, O_RDONLY);
 300         if (fd == -1) {
 301                 perror(filename);
 302                 exit(1);
 303         }
 304
 305         // Drop privileges.
 306         if (setgid(getgid()) != 0) {
 307                 perror("setgid");
 308                 exit(EXIT_FAILURE);
 309         }
 310
 311         steady_clock::time_point start __attribute__((unused)) = steady_clock::now();
 312         if (access("/", R_OK | X_OK)) {
 313                 // We can't find anything, no need to bother...
 314                 return;
 315         }
 316
 317         IOUringEngine engine;
 318         Corpus corpus(fd, &engine);
 319         dprintf("Corpus init done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
 320
 321         vector<pair<Trigram, size_t>> trigrams;
 322         uint64_t shortest_so_far = numeric_limits<uint32_t>::max();
 323         for (const string &needle : needles) {
 324                 if (needle.size() < 3)
 325                         continue;
 326                 for (size_t i = 0; i < needle.size() - 2; ++i) {
 327                         uint32_t trgm = read_trigram(needle, i);
 328                         corpus.find_trigram(trgm, [trgm, &trigrams, &shortest_so_far](const Trigram *trgmptr, size_t len) {
 329                                 if (trgmptr == nullptr) {
 330                                         dprintf("trigram '%c%c%c' isn't found, we abort the search\n",
 331                                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff);
 332                                         exit(0);
 333                                 }
 334                                 if (trgmptr->num_docids > shortest_so_far * 100) {
 335                                         dprintf("not loading trigram '%c%c%c' with %u docids, it would be ignored later anyway\n",
 336                                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 337                                                 trgmptr->num_docids);
 338                                 } else {
 339                                         trigrams.emplace_back(*trgmptr, len);
 340                                         shortest_so_far = std::min<uint64_t>(shortest_so_far, trgmptr->num_docids);
 341                                 }
 342                         });
 343                 }
 344         }
 345         engine.finish();
 346         dprintf("Hashtable lookups done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
 347
 348         if (trigrams.empty()) {
 349                 // Too short for trigram matching. Apply brute force.
 350                 // (We could have searched through all trigrams that matched
 351                 // the pattern and done a union of them, but that's a lot of
 352                 // work for fairly unclear gain.)
 353                 scan_all_docids(needles, fd, corpus, &engine);
 354                 return;
 355         }
 356         sort(trigrams.begin(), trigrams.end());
 357         {
 358                 auto last = unique(trigrams.begin(), trigrams.end());
 359                 trigrams.erase(last, trigrams.end());
 360         }
 361         sort(trigrams.begin(), trigrams.end(),
 362              [&](const pair<Trigram, size_t> &a, const pair<Trigram, size_t> &b) {
 363                      return a.first.num_docids < b.first.num_docids;
 364              });
 365
 366         vector<uint32_t> in1, in2, out;
 367         bool done = false;
 368         for (auto [trgmptr, len] : trigrams) {
 369                 if (!in1.empty() && trgmptr.num_docids > in1.size() * 100) {
 370                         uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
 371                         dprintf("trigram '%c%c%c' (%zu bytes) has %u entries, ignoring the rest (will "
 372                                 "weed out false positives later)\n",
 373                                 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 374                                 len, trgmptr.num_docids);
 375                         break;
 376                 }
 377
 378                 // Only stay a certain amount ahead, so that we don't spend I/O
 379                 // on reading the latter, large posting lists. We are unlikely
 380                 // to need them anyway, even if they should come in first.
 381                 if (engine.get_waiting_reads() >= 5) {
 382                         engine.finish();
 383                         if (done)
 384                                 break;
 385                 }
 386                 engine.submit_read(fd, len, trgmptr.offset, [trgmptr, len, &done, &in1, &in2, &out](string s) {
 387                         if (done)
 388                                 return;
 389                         uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
 390                         size_t num = trgmptr.num_docids;
 391                         unsigned char *pldata = reinterpret_cast<unsigned char *>(s.data());
 392                         if (in1.empty()) {
 393                                 in1.resize(num + 128);
 394                                 decode_pfor_delta1<128>(pldata, num, /*interleaved=*/true, &in1[0]);
 395                                 in1.resize(num);
 396                                 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries\n", trgm & 0xff,
 397                                         (trgm >> 8) & 0xff, (trgm >> 16) & 0xff, len, num);
 398                         } else {
 399                                 if (in2.size() < num + 128) {
 400                                         in2.resize(num + 128);
 401                                 }
 402                                 decode_pfor_delta1<128>(pldata, num, /*interleaved=*/true, &in2[0]);
 403
 404                                 out.clear();
 405                                 set_intersection(in1.begin(), in1.end(), in2.begin(), in2.begin() + num,
 406                                                  back_inserter(out));
 407                                 swap(in1, out);
 408                                 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries, %zu left\n",
 409                                         trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
 410                                         len, num, in1.size());
 411                                 if (in1.empty()) {
 412                                         dprintf("no matches (intersection list is empty)\n");
 413                                         done = true;
 414                                 }
 415                         }
 416                 });
 417         }
 418         engine.finish();
 419         if (done) {
 420                 return;
 421         }
 422         dprintf("Intersection done after %.1f ms. Doing final verification and printing:\n",
 423                 1e3 * duration<float>(steady_clock::now() - start).count());
 424
 425         size_t matched __attribute__((unused)) = scan_docids(needles, in1, corpus, &engine);
 426         dprintf("Done in %.1f ms, found %zu matches.\n",
 427                 1e3 * duration<float>(steady_clock::now() - start).count(), matched);
 428 }
 429
 430 void usage()
 431 {
 432         // The help text comes from mlocate.
 433         printf("Usage: plocate [OPTION]... PATTERN...\n");
 434         printf("\n");
 435         printf("  -d, --database DBPATH  use DBPATH instead of default database (which is\n");
 436         printf("                         %s)\n", dbpath);
 437         printf("  -h, --help             print this help\n");
 438         printf("  -0, --null             separate entries with NUL on output\n");
 439 }
 440
 441 int main(int argc, char **argv)
 442 {
 443         static const struct option long_options[] = {
 444                 { "help", no_argument, 0, 'h' },
 445                 { "database", required_argument, 0, 'd' },
 446                 { "null", no_argument, 0, '0' },
 447                 { 0, 0, 0, 0 }
 448         };
 449
 450         for (;;) {
 451                 int option_index = 0;
 452                 int c = getopt_long(argc, argv, "d:h0", long_options, &option_index);
 453                 if (c == -1) {
 454                         break;
 455                 }
 456                 switch (c) {
 457                 case 'd':
 458                         dbpath = strdup(optarg);
 459                         break;
 460                 case 'h':
 461                         usage();
 462                         exit(0);
 463                 case '0':
 464                         print_nul = true;
 465                         break;
 466                 default:
 467                         exit(1);
 468                 }
 469         }
 470
 471         vector<string> needles;
 472         for (int i = optind; i < argc; ++i) {
 473                 needles.push_back(argv[i]);
 474         }
 475         if (needles.empty()) {
 476                 fprintf(stderr, "plocate: no pattern to search for specified\n");
 477                 exit(0);
 478         }
 479         do_search_file(needles, dbpath);
 480 }