X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=plocate-build.cpp;h=f08afd063d651e82ea9666f6547bbccc631d0a7d;hb=97c57726bc81c979386c623ad7586c2677fdd865;hp=bde72b51fa3d6da02b59216e34d8dbfe695cca80;hpb=1f07faf71217a56ac538189c202ca118d7c993c0;p=plocate diff --git a/plocate-build.cpp b/plocate-build.cpp index bde72b5..f08afd0 100644 --- a/plocate-build.cpp +++ b/plocate-build.cpp @@ -1,35 +1,38 @@ #include "db.h" -#include "vp4.h" +#include "dprintf.h" +#include "turbopfor-encode.h" #include -#include #include #include -#include -#include +#include +#include #include #include +#include +#include #include +#include #include #include -#include +#include #include -#include -#include -#include +#include #include +#include #include #define P4NENC_BOUND(n) ((n + 127) / 128 + (n + 32) * sizeof(uint32_t)) -#define dprintf(...) -//#define dprintf(...) fprintf(stderr, __VA_ARGS__); + +#define NUM_TRIGRAMS 16777216 using namespace std; using namespace std::chrono; -string zstd_compress(const string &src, string *tempbuf); +string zstd_compress(const string &src, ZSTD_CDict *cdict, string *tempbuf); constexpr unsigned num_overflow_slots = 16; +bool use_debug = false; static inline uint32_t read_unigram(const string_view s, size_t idx) { @@ -71,7 +74,7 @@ struct db_directory { class PostingListBuilder { public: - void add_docid(uint32_t docid); + inline void add_docid(uint32_t docid); void finish(); string encoded; @@ -81,34 +84,31 @@ private: void write_header(uint32_t docid); void append_block(); - vector pending_docids; + vector pending_deltas; - uint32_t last_block_end; + uint32_t last_block_end, last_docid = -1; }; void PostingListBuilder::add_docid(uint32_t docid) { // Deduplicate against the last inserted value, if any. - if (pending_docids.empty()) { - if (encoded.empty()) { - // Very first docid. - write_header(docid); - ++num_docids; - last_block_end = docid; - return; - } else if (docid == last_block_end) { - return; - } - } else { - if (docid == pending_docids.back()) { - return; - } + if (docid == last_docid) { + return; + } + + if (num_docids == 0) { + // Very first docid. + write_header(docid); + ++num_docids; + last_block_end = last_docid = docid; + return; } - pending_docids.push_back(docid); - if (pending_docids.size() == 128) { + pending_deltas.push_back(docid - last_docid - 1); + last_docid = docid; + if (pending_deltas.size() == 128) { append_block(); - pending_docids.clear(); + pending_deltas.clear(); last_block_end = docid; } ++num_docids; @@ -116,7 +116,7 @@ void PostingListBuilder::add_docid(uint32_t docid) void PostingListBuilder::finish() { - if (pending_docids.empty()) { + if (pending_deltas.empty()) { return; } @@ -124,41 +124,152 @@ void PostingListBuilder::finish() // No interleaving for partial blocks. unsigned char buf[P4NENC_BOUND(128)]; - unsigned char *end = p4d1enc32(pending_docids.data(), pending_docids.size(), buf, last_block_end); + unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), pending_deltas.size(), /*interleaved=*/false, buf); encoded.append(reinterpret_cast(buf), reinterpret_cast(end)); } void PostingListBuilder::append_block() { unsigned char buf[P4NENC_BOUND(128)]; - assert(pending_docids.size() == 128); - unsigned char *end = p4d1enc128v32(pending_docids.data(), 128, buf, last_block_end); + assert(pending_deltas.size() == 128); + unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), 128, /*interleaved=*/true, buf); encoded.append(reinterpret_cast(buf), reinterpret_cast(end)); } void PostingListBuilder::write_header(uint32_t docid) { unsigned char buf[P4NENC_BOUND(1)]; - size_t bytes = p4nd1enc128v32(&docid, 1, buf); - encoded.append(reinterpret_cast(buf), bytes); + unsigned char *end = write_baseval(docid, buf); + encoded.append(reinterpret_cast(buf), end - buf); } -class Corpus { +class DatabaseReceiver { +public: + virtual ~DatabaseReceiver() = default; + virtual void add_file(string filename) = 0; + virtual void flush_block() = 0; +}; + +class DictionaryBuilder : public DatabaseReceiver { public: - Corpus(FILE *outfp, size_t block_size) - : outfp(outfp), block_size(block_size) {} - void add_file(string filename); - void flush_block(); + DictionaryBuilder(size_t blocks_to_keep, size_t block_size) + : blocks_to_keep(blocks_to_keep), block_size(block_size) {} + void add_file(string filename) override; + void flush_block() override; + string train(size_t buf_size); + +private: + const size_t blocks_to_keep, block_size; + string current_block; + uint64_t block_num = 0; + size_t num_files_in_block = 0; + + std::mt19937 reservoir_rand{ 1234 }; // Fixed seed for reproducibility. + bool keep_current_block = true; + int64_t slot_for_current_block = -1; + + vector sampled_blocks; + vector lengths; +}; + +void DictionaryBuilder::add_file(string filename) +{ + if (keep_current_block) { // Only bother saving the filenames if we're actually keeping the block. + if (!current_block.empty()) { + current_block.push_back('\0'); + } + current_block += filename; + } + if (++num_files_in_block == block_size) { + flush_block(); + } +} + +void DictionaryBuilder::flush_block() +{ + if (keep_current_block) { + if (slot_for_current_block == -1) { + lengths.push_back(current_block.size()); + sampled_blocks.push_back(move(current_block)); + } else { + lengths[slot_for_current_block] = current_block.size(); + sampled_blocks[slot_for_current_block] = move(current_block); + } + } + current_block.clear(); + num_files_in_block = 0; + ++block_num; + + if (block_num < blocks_to_keep) { + keep_current_block = true; + slot_for_current_block = -1; + } else { + // Keep every block with equal probability (reservoir sampling). + uint64_t idx = uniform_int_distribution(0, block_num)(reservoir_rand); + keep_current_block = (idx < blocks_to_keep); + slot_for_current_block = idx; + } +} + +string DictionaryBuilder::train(size_t buf_size) +{ + string dictionary_buf; + sort(sampled_blocks.begin(), sampled_blocks.end()); // Seemingly important for decompression speed. + for (const string &block : sampled_blocks) { + dictionary_buf += block; + } + + string buf; + buf.resize(buf_size); + size_t ret = ZDICT_trainFromBuffer(&buf[0], buf_size, dictionary_buf.data(), lengths.data(), lengths.size()); + dprintf("Sampled %zu bytes in %zu blocks, built a dictionary of size %zu\n", dictionary_buf.size(), lengths.size(), ret); + buf.resize(ret); + + sampled_blocks.clear(); + lengths.clear(); + + return buf; +} + +class Corpus : public DatabaseReceiver { +public: + Corpus(FILE *outfp, size_t block_size, ZSTD_CDict *cdict) + : invindex(new PostingListBuilder *[NUM_TRIGRAMS]), outfp(outfp), block_size(block_size), cdict(cdict) + { + fill(invindex.get(), invindex.get() + NUM_TRIGRAMS, nullptr); + } + ~Corpus() override + { + for (unsigned i = 0; i < NUM_TRIGRAMS; ++i) { + delete invindex[i]; + } + } + + void add_file(string filename) override; + void flush_block() override; vector filename_blocks; - unordered_map invindex; size_t num_files = 0, num_files_in_block = 0, num_blocks = 0; + bool seen_trigram(uint32_t trgm) + { + return invindex[trgm] != nullptr; + } + PostingListBuilder &get_pl_builder(uint32_t trgm) + { + if (invindex[trgm] == nullptr) { + invindex[trgm] = new PostingListBuilder; + } + return *invindex[trgm]; + } + size_t num_trigrams() const; private: + unique_ptr invindex; FILE *outfp; string current_block; string tempbuf; const size_t block_size; + ZSTD_CDict *cdict; }; void Corpus::add_file(string filename) @@ -188,7 +299,7 @@ void Corpus::flush_block() if (s.size() >= 3) { for (size_t j = 0; j < s.size() - 2; ++j) { uint32_t trgm = read_trigram(s, j); - invindex[trgm].add_docid(docid); + get_pl_builder(trgm).add_docid(docid); } } ptr += s.size() + 1; @@ -196,7 +307,7 @@ void Corpus::flush_block() // Compress and add the filename block. filename_blocks.push_back(ftell(outfp)); - string compressed = zstd_compress(current_block, &tempbuf); + string compressed = zstd_compress(current_block, cdict, &tempbuf); if (fwrite(compressed.data(), compressed.size(), 1, outfp) != 1) { perror("fwrite()"); exit(1); @@ -207,72 +318,100 @@ void Corpus::flush_block() ++num_blocks; } -const char *handle_directory(const char *ptr, Corpus *corpus) +size_t Corpus::num_trigrams() const { - ptr += sizeof(db_directory); + size_t num = 0; + for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) { + if (invindex[trgm] != nullptr) { + ++num; + } + } + return num; +} + +string read_cstr(FILE *fp) +{ + string ret; + for (;;) { + int ch = getc(fp); + if (ch == -1) { + perror("getc"); + exit(1); + } + if (ch == 0) { + return ret; + } + ret.push_back(ch); + } +} - string dir_path = ptr; - ptr += dir_path.size() + 1; +void handle_directory(FILE *fp, DatabaseReceiver *receiver) +{ + db_directory dummy; + if (fread(&dummy, sizeof(dummy), 1, fp) != 1) { + if (feof(fp)) { + return; + } else { + perror("fread"); + } + } + + string dir_path = read_cstr(fp); if (dir_path == "/") { dir_path = ""; } for (;;) { - uint8_t type = *ptr++; + int type = getc(fp); if (type == DBE_NORMAL) { - string filename = ptr; - corpus->add_file(dir_path + "/" + filename); - ptr += filename.size() + 1; + string filename = read_cstr(fp); + receiver->add_file(dir_path + "/" + filename); } else if (type == DBE_DIRECTORY) { - string dirname = ptr; - corpus->add_file(dir_path + "/" + dirname); - ptr += dirname.size() + 1; + string dirname = read_cstr(fp); + receiver->add_file(dir_path + "/" + dirname); } else { - return ptr; + return; // Probably end. } } } -void read_mlocate(const char *filename, Corpus *corpus) +void read_mlocate(FILE *fp, DatabaseReceiver *receiver) { - int fd = open(filename, O_RDONLY); - if (fd == -1) { - perror(filename); - exit(1); - } - off_t len = lseek(fd, 0, SEEK_END); - if (len == -1) { - perror("lseek"); + if (fseek(fp, 0, SEEK_SET) != 0) { + perror("fseek"); exit(1); } - const char *data = (char *)mmap(nullptr, len, PROT_READ, MAP_SHARED, fd, /*offset=*/0); - if (data == MAP_FAILED) { - perror("mmap"); + + db_header hdr; + if (fread(&hdr, sizeof(hdr), 1, fp) != 1) { + perror("short read"); exit(1); } - const db_header *hdr = (const db_header *)data; - // TODO: Care about the base path. - string path = data + sizeof(db_header); - uint64_t offset = sizeof(db_header) + path.size() + 1 + ntohl(hdr->conf_size); - - const char *ptr = data + offset; - while (ptr < data + len) { - ptr = handle_directory(ptr, corpus); + string path = read_cstr(fp); + while (!feof(fp)) { + handle_directory(fp, receiver); } - - munmap((void *)data, len); - close(fd); } -string zstd_compress(const string &src, string *tempbuf) +string zstd_compress(const string &src, ZSTD_CDict *cdict, string *tempbuf) { + static ZSTD_CCtx *ctx = nullptr; + if (ctx == nullptr) { + ctx = ZSTD_createCCtx(); + } + size_t max_size = ZSTD_compressBound(src.size()); if (tempbuf->size() < max_size) { tempbuf->resize(max_size); } - size_t size = ZSTD_compress(&(*tempbuf)[0], max_size, src.data(), src.size(), /*level=*/6); + size_t size; + if (cdict == nullptr) { + size = ZSTD_compressCCtx(ctx, &(*tempbuf)[0], max_size, src.data(), src.size(), /*level=*/6); + } else { + size = ZSTD_compress_usingCDict(ctx, &(*tempbuf)[0], max_size, src.data(), src.size(), cdict); + } return string(tempbuf->data(), size); } @@ -301,7 +440,7 @@ uint32_t next_prime(uint32_t x) return x; } -unique_ptr create_hashtable(const Corpus &corpus, const vector &all_trigrams, uint32_t ht_size, uint32_t num_overflow_slots) +unique_ptr create_hashtable(Corpus &corpus, const vector &all_trigrams, uint32_t ht_size, uint32_t num_overflow_slots) { unique_ptr ht(new Trigram[ht_size + num_overflow_slots + 1]); // 1 for the sentinel element at the end. for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) { @@ -311,7 +450,7 @@ unique_ptr create_hashtable(const Corpus &corpus, const vectorsecond.num_docids), 0 }; + Trigram to_insert{ trgm, uint32_t(corpus.get_pl_builder(trgm).num_docids), 0 }; uint32_t bucket = hash_trigram(trgm, ht_size); unsigned distance = 0; @@ -337,8 +476,18 @@ void do_build(const char *infile, const char *outfile, int block_size) { steady_clock::time_point start __attribute__((unused)) = steady_clock::now(); + FILE *infp = fopen(infile, "rb"); + if (infp == nullptr) { + perror(infile); + exit(1); + } + umask(0027); FILE *outfp = fopen(outfile, "wb"); + if (outfp == nullptr) { + perror(outfile); + exit(1); + } // Write the header. Header hdr; @@ -346,13 +495,30 @@ void do_build(const char *infile, const char *outfile, int block_size) hdr.version = -1; // Mark as broken. hdr.hashtable_size = 0; // Not known yet. hdr.extra_ht_slots = num_overflow_slots; + hdr.num_docids = 0; hdr.hash_table_offset_bytes = -1; // We don't know these offsets yet. + hdr.max_version = 1; hdr.filename_index_offset_bytes = -1; + hdr.zstd_dictionary_length_bytes = -1; fwrite(&hdr, sizeof(hdr), 1, outfp); - Corpus corpus(outfp, block_size); + // Train the dictionary by sampling real blocks. + // The documentation for ZDICT_trainFromBuffer() claims that a reasonable + // dictionary size is ~100 kB, but 1 kB seems to actually compress better for us, + // and decompress just as fast. + DictionaryBuilder builder(/*blocks_to_keep=*/1000, block_size); + read_mlocate(infp, &builder); + string dictionary = builder.train(1024); + ZSTD_CDict *cdict = ZSTD_createCDict(dictionary.data(), dictionary.size(), /*level=*/6); + + hdr.zstd_dictionary_offset_bytes = ftell(outfp); + fwrite(dictionary.data(), dictionary.size(), 1, outfp); + hdr.zstd_dictionary_length_bytes = dictionary.size(); + + Corpus corpus(outfp, block_size, cdict); + read_mlocate(infp, &corpus); + fclose(infp); - read_mlocate(infile, &corpus); if (false) { // To read a plain text file. FILE *fp = fopen(infile, "r"); while (!feof(fp)) { @@ -369,6 +535,7 @@ void do_build(const char *infile, const char *outfile, int block_size) } corpus.flush_block(); dprintf("Read %zu files from %s\n", corpus.num_files, infile); + hdr.num_docids = corpus.filename_blocks.size(); // Stick an empty block at the end as sentinel. corpus.filename_blocks.push_back(ftell(outfp)); @@ -384,25 +551,29 @@ void do_build(const char *infile, const char *outfile, int block_size) // Finish up encoding the posting lists. size_t trigrams = 0, longest_posting_list = 0; size_t bytes_for_posting_lists = 0; - for (auto &[trigram, pl_builder] : corpus.invindex) { + for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) { + if (!corpus.seen_trigram(trgm)) + continue; + PostingListBuilder &pl_builder = corpus.get_pl_builder(trgm); pl_builder.finish(); longest_posting_list = max(longest_posting_list, pl_builder.num_docids); trigrams += pl_builder.num_docids; bytes_for_posting_lists += pl_builder.encoded.size(); } + size_t num_trigrams = corpus.num_trigrams(); dprintf("%zu files, %zu different trigrams, %zu entries, avg len %.2f, longest %zu\n", - corpus.num_files, corpus.invindex.size(), trigrams, double(trigrams) / corpus.invindex.size(), longest_posting_list); + corpus.num_files, num_trigrams, trigrams, double(trigrams) / num_trigrams, longest_posting_list); dprintf("%zu bytes used for posting lists (%.2f bits/entry)\n", bytes_for_posting_lists, 8 * bytes_for_posting_lists / double(trigrams)); dprintf("Building posting lists took %.1f ms.\n\n", 1e3 * duration(steady_clock::now() - start).count()); - // Sort the trigrams, mostly to get a consistent result every time - // (the hash table will put things in random order anyway). + // Find the used trigrams. vector all_trigrams; - for (auto &[trigram, pl_builder] : corpus.invindex) { - all_trigrams.push_back(trigram); + for (unsigned trgm = 0; trgm < NUM_TRIGRAMS; ++trgm) { + if (corpus.seen_trigram(trgm)) { + all_trigrams.push_back(trgm); + } } - sort(all_trigrams.begin(), all_trigrams.end()); // Create the hash table. unique_ptr hashtable; @@ -427,7 +598,7 @@ void do_build(const char *infile, const char *outfile, int block_size) continue; } - const string &encoded = corpus.invindex[hashtable[i].trgm].encoded; + const string &encoded = corpus.get_pl_builder(hashtable[i].trgm).encoded; offset += encoded.size(); } @@ -441,12 +612,12 @@ void do_build(const char *infile, const char *outfile, int block_size) if (hashtable[i].num_docids == 0) { continue; } - const string &encoded = corpus.invindex[hashtable[i].trgm].encoded; + const string &encoded = corpus.get_pl_builder(hashtable[i].trgm).encoded; fwrite(encoded.data(), encoded.size(), 1, outfp); } // Rewind, and write the updated header. - hdr.version = 0; + hdr.version = 1; fseek(outfp, 0, SEEK_SET); fwrite(&hdr, sizeof(hdr), 1, outfp); fclose(outfp); @@ -454,6 +625,7 @@ void do_build(const char *infile, const char *outfile, int block_size) size_t total_bytes __attribute__((unused)) = (bytes_for_hashtable + bytes_for_posting_lists + bytes_for_filename_index + bytes_for_filenames); dprintf("Block size: %7d files\n", block_size); + dprintf("Dictionary: %'7.1f MB\n", dictionary.size() / 1048576.0); dprintf("Hash table: %'7.1f MB\n", bytes_for_hashtable / 1048576.0); dprintf("Posting lists: %'7.1f MB\n", bytes_for_posting_lists / 1048576.0); dprintf("Filename index: %'7.1f MB\n", bytes_for_filename_index / 1048576.0); @@ -462,8 +634,70 @@ void do_build(const char *infile, const char *outfile, int block_size) dprintf("\n"); } +void usage() +{ + printf( + "Usage: plocate-build MLOCATE_DB PLOCATE_DB\n" + "\n" + "Generate plocate index from mlocate.db, typically /var/lib/mlocate/mlocate.db.\n" + "Normally, the destination should be /var/lib/mlocate/plocate.db.\n" + "\n" + " -b, --block-size SIZE number of filenames to store in each block (default 32)\n" + " --help print this help\n" + " --version print version information\n"); +} + +void version() +{ + printf("plocate-build %s\n", PLOCATE_VERSION); + printf("Copyright 2020 Steinar H. Gunderson\n"); + printf("License GPLv2+: GNU GPL version 2 or later .\n"); + printf("This is free software: you are free to change and redistribute it.\n"); + printf("There is NO WARRANTY, to the extent permitted by law.\n"); +} + int main(int argc, char **argv) { - do_build(argv[1], argv[2], 32); + static const struct option long_options[] = { + { "block-size", required_argument, 0, 'b' }, + { "help", no_argument, 0, 'h' }, + { "version", no_argument, 0, 'V' }, + { "debug", no_argument, 0, 'D' }, // Not documented. + { 0, 0, 0, 0 } + }; + + int block_size = 32; + + setlocale(LC_ALL, ""); + for (;;) { + int option_index = 0; + int c = getopt_long(argc, argv, "b:hVD", long_options, &option_index); + if (c == -1) { + break; + } + switch (c) { + case 'b': + block_size = atoi(optarg); + break; + case 'h': + usage(); + exit(0); + case 'V': + version(); + exit(0); + case 'D': + use_debug = true; + break; + default: + exit(1); + } + } + + if (argc - optind != 2) { + usage(); + exit(1); + } + + do_build(argv[optind], argv[optind + 1], block_size); exit(EXIT_SUCCESS); }