2 #include "io_uring_engine.h"
17 #include <unordered_map>
22 using namespace std::chrono;
25 //#define dprintf(...) fprintf(stderr, __VA_ARGS__);
29 void do_or_wait(int seq, function<void()> cb);
37 bool operator<(const Element &other) const
39 return seq > other.seq;
42 priority_queue<Element> pending;
45 void Serializer::do_or_wait(int seq, function<void()> cb)
47 if (seq != next_seq) {
48 pending.emplace(Element{ seq, move(cb) });
55 while (!pending.empty() && pending.top().seq == next_seq) {
62 static inline uint32_t read_unigram(const string &s, size_t idx)
65 return (unsigned char)s[idx];
71 static inline uint32_t read_trigram(const string &s, size_t start)
73 return read_unigram(s, start) | (read_unigram(s, start + 1) << 8) |
74 (read_unigram(s, start + 2) << 16);
77 bool has_access(const char *filename,
78 unordered_map<string, bool> *access_rx_cache)
80 const char *end = strchr(filename + 1, '/');
81 while (end != nullptr) {
82 string parent_path(filename, end);
83 auto it = access_rx_cache->find(parent_path);
85 if (it == access_rx_cache->end()) {
86 ok = access(parent_path.c_str(), R_OK | X_OK) == 0;
87 access_rx_cache->emplace(move(parent_path), ok);
94 end = strchr(end + 1, '/');
102 Corpus(int fd, IOUringEngine *engine);
104 void find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb);
105 void get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const;
106 size_t get_num_filename_blocks() const;
107 off_t offset_for_block(uint32_t docid) const
109 return hdr.filename_index_offset_bytes + docid * sizeof(uint64_t);
114 IOUringEngine *const engine;
119 Corpus::Corpus(int fd, IOUringEngine *engine)
120 : fd(fd), engine(engine)
122 // Enable to test cold-cache behavior (except for access()).
124 off_t len = lseek(fd, 0, SEEK_END);
129 posix_fadvise(fd, 0, len, POSIX_FADV_DONTNEED);
132 complete_pread(fd, &hdr, sizeof(hdr), /*offset=*/0);
133 if (memcmp(hdr.magic, "\0plocate", 8) != 0) {
134 fprintf(stderr, "plocate.db is corrupt or an old version; please rebuild it.\n");
137 if (hdr.version != 0) {
138 fprintf(stderr, "plocate.db has version %u, expected 0; please rebuild it.\n", hdr.version);
148 void Corpus::find_trigram(uint32_t trgm, function<void(const Trigram *trgmptr, size_t len)> cb)
150 uint32_t bucket = hash_trigram(trgm, hdr.hashtable_size);
151 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) {
152 const Trigram *trgmptr = reinterpret_cast<const Trigram *>(s.data());
153 for (unsigned i = 0; i < hdr.extra_ht_slots + 1; ++i) {
154 if (trgmptr[i].trgm == trgm) {
155 cb(trgmptr + i, trgmptr[i + 1].offset - trgmptr[i].offset);
165 void Corpus::get_compressed_filename_block(uint32_t docid, function<void(string)> cb) const
167 // Read the file offset from this docid and the next one.
168 // This is always allowed, since we have a sentinel block at the end.
169 engine->submit_read(fd, sizeof(uint64_t) * 2, offset_for_block(docid), [this, cb{ move(cb) }](string s) {
170 const uint64_t *ptr = reinterpret_cast<const uint64_t *>(s.data());
171 off_t offset = ptr[0];
172 size_t len = ptr[1] - ptr[0];
173 engine->submit_read(fd, len, offset, cb);
177 size_t Corpus::get_num_filename_blocks() const
179 // The beginning of the filename blocks is the end of the filename index blocks.
181 complete_pread(fd, &end, sizeof(end), hdr.filename_index_offset_bytes);
183 // Subtract the sentinel block.
184 return (end - hdr.filename_index_offset_bytes) / sizeof(uint64_t) - 1;
187 size_t scan_file_block(const vector<string> &needles, string_view compressed,
188 unordered_map<string, bool> *access_rx_cache)
192 unsigned long long uncompressed_len = ZSTD_getFrameContentSize(compressed.data(), compressed.size());
193 if (uncompressed_len == ZSTD_CONTENTSIZE_UNKNOWN || uncompressed_len == ZSTD_CONTENTSIZE_ERROR) {
194 fprintf(stderr, "ZSTD_getFrameContentSize() failed\n");
199 block.resize(uncompressed_len + 1);
201 size_t err = ZSTD_decompress(&block[0], block.size(), compressed.data(),
203 if (ZSTD_isError(err)) {
204 fprintf(stderr, "ZSTD_decompress(): %s\n", ZSTD_getErrorName(err));
207 block[block.size() - 1] = '\0';
209 for (const char *filename = block.data();
210 filename != block.data() + block.size();
211 filename += strlen(filename) + 1) {
213 for (const string &needle : needles) {
214 if (strstr(filename, needle.c_str()) == nullptr) {
219 if (found && has_access(filename, access_rx_cache)) {
221 printf("%s\n", filename);
227 size_t scan_docids(const vector<string> &needles, const vector<uint32_t> &docids, const Corpus &corpus, IOUringEngine *engine)
229 Serializer docids_in_order;
230 unordered_map<string, bool> access_rx_cache;
232 for (size_t i = 0; i < docids.size(); ++i) {
233 uint32_t docid = docids[i];
234 corpus.get_compressed_filename_block(docid, [i, &matched, &needles, &access_rx_cache, &docids_in_order](string compressed) {
235 docids_in_order.do_or_wait(i, [&matched, &needles, compressed{ move(compressed) }, &access_rx_cache] {
236 matched += scan_file_block(needles, compressed, &access_rx_cache);
244 // We do this sequentially, as it's faster than scattering
245 // a lot of I/O through io_uring and hoping the kernel will
246 // coalesce it plus readahead for us.
247 void scan_all_docids(const vector<string> &needles, int fd, const Corpus &corpus, IOUringEngine *engine)
249 unordered_map<string, bool> access_rx_cache;
250 uint32_t num_blocks = corpus.get_num_filename_blocks();
251 unique_ptr<uint64_t[]> offsets(new uint64_t[num_blocks + 1]);
252 complete_pread(fd, offsets.get(), (num_blocks + 1) * sizeof(uint64_t), corpus.offset_for_block(0));
254 for (uint32_t io_docid = 0; io_docid < num_blocks; io_docid += 32) {
255 uint32_t last_docid = std::min(io_docid + 32, num_blocks);
256 size_t io_len = offsets[last_docid] - offsets[io_docid];
257 if (compressed.size() < io_len) {
258 compressed.resize(io_len);
260 complete_pread(fd, &compressed[0], io_len, offsets[io_docid]);
262 for (uint32_t docid = io_docid; docid < last_docid; ++docid) {
263 size_t relative_offset = offsets[docid] - offsets[io_docid];
264 size_t len = offsets[docid + 1] - offsets[docid];
265 scan_file_block(needles, { &compressed[relative_offset], len }, &access_rx_cache);
270 void do_search_file(const vector<string> &needles, const char *filename)
272 int fd = open(filename, O_RDONLY);
279 if (setgid(getgid()) != 0) {
284 steady_clock::time_point start __attribute__((unused)) = steady_clock::now();
285 if (access("/", R_OK | X_OK)) {
286 // We can't find anything, no need to bother...
290 IOUringEngine engine;
291 Corpus corpus(fd, &engine);
292 dprintf("Corpus init done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
294 vector<pair<Trigram, size_t>> trigrams;
295 for (const string &needle : needles) {
296 if (needle.size() < 3) continue;
297 for (size_t i = 0; i < needle.size() - 2; ++i) {
298 uint32_t trgm = read_trigram(needle, i);
299 corpus.find_trigram(trgm, [trgm, &trigrams](const Trigram *trgmptr, size_t len) {
300 if (trgmptr == nullptr) {
301 dprintf("trigram %06x isn't found, we abort the search\n", trgm);
304 trigrams.emplace_back(*trgmptr, len);
309 dprintf("Hashtable lookups done after %.1f ms.\n", 1e3 * duration<float>(steady_clock::now() - start).count());
311 if (trigrams.empty()) {
312 // Too short for trigram matching. Apply brute force.
313 // (We could have searched through all trigrams that matched
314 // the pattern and done a union of them, but that's a lot of
315 // work for fairly unclear gain.)
316 scan_all_docids(needles, fd, corpus, &engine);
319 sort(trigrams.begin(), trigrams.end());
321 auto last = unique(trigrams.begin(), trigrams.end());
322 trigrams.erase(last, trigrams.end());
324 sort(trigrams.begin(), trigrams.end(),
325 [&](const pair<Trigram, size_t> &a, const pair<Trigram, size_t> &b) {
326 return a.first.num_docids < b.first.num_docids;
329 vector<uint32_t> in1, in2, out;
331 for (auto [trgmptr, len] : trigrams) {
332 if (!in1.empty() && trgmptr.num_docids > in1.size() * 100) {
333 uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
334 dprintf("trigram '%c%c%c' (%zu bytes) has %u entries, ignoring the rest (will "
335 "weed out false positives later)\n",
336 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
337 len, trgmptr.num_docids);
341 // Only stay a certain amount ahead, so that we don't spend I/O
342 // on reading the latter, large posting lists. We are unlikely
343 // to need them anyway, even if they should come in first.
344 if (engine.get_waiting_reads() >= 5) {
349 engine.submit_read(fd, len, trgmptr.offset, [trgmptr, len, &done, &in1, &in2, &out](string s) {
352 uint32_t trgm __attribute__((unused)) = trgmptr.trgm;
353 size_t num = trgmptr.num_docids;
354 unsigned char *pldata = reinterpret_cast<unsigned char *>(s.data());
356 in1.resize(num + 128);
357 p4nd1dec128v32(pldata, num, &in1[0]);
359 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries\n", trgm & 0xff,
360 (trgm >> 8) & 0xff, (trgm >> 16) & 0xff, len, num);
362 if (in2.size() < num + 128) {
363 in2.resize(num + 128);
365 p4nd1dec128v32(pldata, num, &in2[0]);
368 set_intersection(in1.begin(), in1.end(), in2.begin(), in2.begin() + num,
371 dprintf("trigram '%c%c%c' (%zu bytes) decoded to %zu entries, %zu left\n",
372 trgm & 0xff, (trgm >> 8) & 0xff, (trgm >> 16) & 0xff,
373 len, num, in1.size());
375 dprintf("no matches (intersection list is empty)\n");
385 dprintf("Intersection done after %.1f ms. Doing final verification and printing:\n",
386 1e3 * duration<float>(steady_clock::now() - start).count());
388 size_t matched __attribute__((unused)) = scan_docids(needles, in1, corpus, &engine);
389 dprintf("Done in %.1f ms, found %zu matches.\n",
390 1e3 * duration<float>(steady_clock::now() - start).count(), matched);
393 const char *dbpath = "/var/lib/mlocate/plocate.db";
397 printf("Usage: slocate [OPTION]... PATTERN...\n");
398 printf(" -d, --database DBPATH use DBPATH instead of default database (which is\n");
399 printf(" %s)\n", dbpath);
400 printf(" -h, --help print this help\n");
403 int main(int argc, char **argv)
405 static const struct option long_options[] = {
406 { "help", no_argument, 0, 'h' },
407 { "database", required_argument, 0, 'd' },
412 int option_index = 0;
413 int c = getopt_long(argc, argv, "d:h:", long_options, &option_index);
419 dbpath = strdup(optarg);
427 vector<string> needles;
428 for (int i = optind; i < argc; ++i) {
429 needles.push_back(argv[i]);
431 if (needles.empty()) {
432 fprintf(stderr, "slocate: no pattern to search for specified\n");
435 do_search_file(needles, dbpath);