+#include "db.h"
+#include "turbopfor-encode.h"
+
+#include <algorithm>
+#include <assert.h>
+#include <chrono>
+#include <getopt.h>
+#include <iosfwd>
+#include <math.h>
+#include <memory>
+#include <stdint.h>
#include <stdio.h>
+#include <stdlib.h>
#include <string.h>
-#include <algorithm>
-#include <unordered_map>
#include <string>
-#include <vector>
-#include <chrono>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <arpa/inet.h>
-#include <endian.h>
-#include <sys/types.h>
+#include <string_view>
#include <sys/stat.h>
+#include <utility>
+#include <vector>
+#include <zstd.h>
-#include "vp4.h"
-
-#define P4NENC_BOUND(n) ((n+127)/128+(n+32)*sizeof(uint32_t))
+#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;
-
-static inline uint32_t read_unigram(const string &s, size_t idx)
+
+string zstd_compress(const string &src, string *tempbuf);
+
+constexpr unsigned num_overflow_slots = 16;
+
+static inline uint32_t read_unigram(const string_view s, size_t idx)
{
if (idx < s.size()) {
return (unsigned char)s[idx];
}
}
-static inline uint32_t read_trigram(const string &s, size_t start)
+static inline uint32_t read_trigram(const string_view s, size_t start)
{
return read_unigram(s, start) |
(read_unigram(s, start + 1) << 8) |
(read_unigram(s, start + 2) << 16);
}
-enum
-{
- DBE_NORMAL = 0, /* A non-directory file */
- DBE_DIRECTORY = 1, /* A directory */
- DBE_END = 2 /* End of directory contents; contains no name */
+enum {
+ DBE_NORMAL = 0, /* A non-directory file */
+ DBE_DIRECTORY = 1, /* A directory */
+ DBE_END = 2 /* End of directory contents; contains no name */
};
// From mlocate.
-struct db_header
-{
+struct db_header {
uint8_t magic[8];
uint32_t conf_size;
uint8_t version;
};
// From mlocate.
-struct db_directory
-{
+struct db_directory {
uint64_t time_sec;
uint32_t time_nsec;
uint8_t pad[4];
};
-const char *handle_directory(const char *ptr, vector<string> *files)
+class PostingListBuilder {
+public:
+ inline void add_docid(uint32_t docid);
+ void finish();
+
+ string encoded;
+ size_t num_docids = 0;
+
+private:
+ void write_header(uint32_t docid);
+ void append_block();
+
+ vector<uint32_t> pending_deltas;
+
+ uint32_t last_block_end, last_docid = -1;
+};
+
+void PostingListBuilder::add_docid(uint32_t docid)
+{
+ // Deduplicate against the last inserted value, if any.
+ 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_deltas.push_back(docid - last_docid - 1);
+ last_docid = docid;
+ if (pending_deltas.size() == 128) {
+ append_block();
+ pending_deltas.clear();
+ last_block_end = docid;
+ }
+ ++num_docids;
+}
+
+void PostingListBuilder::finish()
+{
+ if (pending_deltas.empty()) {
+ return;
+ }
+
+ assert(!encoded.empty()); // write_header() should already have run.
+
+ // No interleaving for partial blocks.
+ unsigned char buf[P4NENC_BOUND(128)];
+ unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), pending_deltas.size(), /*interleaved=*/false, buf);
+ encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(end));
+}
+
+void PostingListBuilder::append_block()
+{
+ unsigned char buf[P4NENC_BOUND(128)];
+ assert(pending_deltas.size() == 128);
+ unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), 128, /*interleaved=*/true, buf);
+ encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(end));
+}
+
+void PostingListBuilder::write_header(uint32_t docid)
+{
+ unsigned char buf[P4NENC_BOUND(1)];
+ unsigned char *end = write_baseval(docid, buf);
+ encoded.append(reinterpret_cast<char *>(buf), end - buf);
+}
+
+class Corpus {
+public:
+ Corpus(FILE *outfp, size_t block_size)
+ : invindex(new PostingListBuilder *[NUM_TRIGRAMS]), outfp(outfp), block_size(block_size)
+ {
+ fill(invindex.get(), invindex.get() + NUM_TRIGRAMS, nullptr);
+ }
+ ~Corpus()
+ {
+ for (unsigned i = 0; i < NUM_TRIGRAMS; ++i) {
+ delete invindex[i];
+ }
+ }
+
+ void add_file(string filename);
+ void flush_block();
+
+ vector<uint64_t> filename_blocks;
+ 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];
+ }
+
+private:
+ unique_ptr<PostingListBuilder *[]> invindex;
+ FILE *outfp;
+ string current_block;
+ string tempbuf;
+ const size_t block_size;
+};
+
+void Corpus::add_file(string filename)
+{
+ ++num_files;
+ if (!current_block.empty()) {
+ current_block.push_back('\0');
+ }
+ current_block += filename;
+ if (++num_files_in_block == block_size) {
+ flush_block();
+ }
+}
+
+void Corpus::flush_block()
+{
+ if (current_block.empty()) {
+ return;
+ }
+
+ uint32_t docid = num_blocks;
+
+ // Create trigrams.
+ const char *ptr = current_block.c_str();
+ while (ptr < current_block.c_str() + current_block.size()) {
+ string_view s(ptr);
+ if (s.size() >= 3) {
+ for (size_t j = 0; j < s.size() - 2; ++j) {
+ uint32_t trgm = read_trigram(s, j);
+ get_pl_builder(trgm).add_docid(docid);
+ }
+ }
+ ptr += s.size() + 1;
+ }
+
+ // Compress and add the filename block.
+ filename_blocks.push_back(ftell(outfp));
+ string compressed = zstd_compress(current_block, &tempbuf);
+ if (fwrite(compressed.data(), compressed.size(), 1, outfp) != 1) {
+ perror("fwrite()");
+ exit(1);
+ }
+
+ current_block.clear();
+ num_files_in_block = 0;
+ ++num_blocks;
+}
+
+string read_cstr(FILE *fp)
{
- ptr += sizeof(db_directory);
+ 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, Corpus *corpus)
+{
+ 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++;
+
+ for (;;) {
+ int type = getc(fp);
if (type == DBE_NORMAL) {
- string filename = ptr;
- files->push_back(dir_path + "/" + filename);
- ptr += filename.size() + 1;
+ string filename = read_cstr(fp);
+ corpus->add_file(dir_path + "/" + filename);
} else if (type == DBE_DIRECTORY) {
- string dirname = ptr;
- files->push_back(dir_path + "/" + dirname);
- ptr += dirname.size() + 1;
+ string dirname = read_cstr(fp);
+ corpus->add_file(dir_path + "/" + dirname);
} else {
- return ptr;
+ return; // Probably end.
}
}
}
-void read_mlocate(const char *filename, vector<string> *files)
+void read_mlocate(const char *filename, Corpus *corpus)
{
- int fd = open(filename, O_RDONLY);
- if (fd == -1) {
+ FILE *fp = fopen(filename, "rb");
+ if (fp == nullptr) {
perror(filename);
exit(1);
}
- off_t len = lseek(fd, 0, SEEK_END);
- if (len == -1) {
- perror("lseek");
+
+ db_header hdr;
+ if (fread(&hdr, sizeof(hdr), 1, fp) != 1) {
+ perror("short read");
exit(1);
}
- const char *data = (char *)mmap(nullptr, len, PROT_READ, MAP_SHARED, fd, /*offset=*/0);
- if (data == MAP_FAILED) {
- perror("mmap");
- exit(1);
+
+ // TODO: Care about the base path.
+ string path = read_cstr(fp);
+ while (!feof(fp)) {
+ handle_directory(fp, corpus);
+ }
+ fclose(fp);
+}
+
+string zstd_compress(const string &src, string *tempbuf)
+{
+ 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);
+ return string(tempbuf->data(), size);
+}
- const db_header *hdr = (const db_header *)data;
+bool is_prime(uint32_t x)
+{
+ if ((x % 2) == 0 || (x % 3) == 0) {
+ return false;
+ }
+ uint32_t limit = ceil(sqrt(x));
+ for (uint32_t factor = 5; factor <= limit; ++factor) {
+ if ((x % factor) == 0) {
+ return false;
+ }
+ }
+ return true;
+}
- // 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);
+uint32_t next_prime(uint32_t x)
+{
+ if ((x % 2) == 0) {
+ ++x;
+ }
+ while (!is_prime(x)) {
+ x += 2;
+ }
+ return x;
+}
- const char *ptr = data + offset;
- while (ptr < data + len) {
- ptr = handle_directory(ptr, files);
+unique_ptr<Trigram[]> create_hashtable(Corpus &corpus, const vector<uint32_t> &all_trigrams, uint32_t ht_size, uint32_t num_overflow_slots)
+{
+ unique_ptr<Trigram[]> 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) {
+ ht[i].trgm = uint32_t(-1);
+ ht[i].num_docids = 0;
+ ht[i].offset = 0;
}
+ for (uint32_t trgm : all_trigrams) {
+ // We don't know offset yet, so set it to zero.
+ 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;
+ while (ht[bucket].num_docids != 0) {
+ // Robin Hood hashing; reduces the longest distance by a lot.
+ unsigned other_distance = bucket - hash_trigram(ht[bucket].trgm, ht_size);
+ if (distance > other_distance) {
+ swap(to_insert, ht[bucket]);
+ distance = other_distance;
+ }
- munmap((void *)data, len);
- close(fd);
+ ++bucket, ++distance;
+ if (distance > num_overflow_slots) {
+ return nullptr;
+ }
+ }
+ ht[bucket] = to_insert;
+ }
+ return ht;
}
-void do_build(const char *infile, const char *outfile)
+void do_build(const char *infile, const char *outfile, int block_size)
{
- //steady_clock::time_point start = steady_clock::now();
+ steady_clock::time_point start __attribute__((unused)) = steady_clock::now();
+
+ umask(0027);
+ FILE *outfp = fopen(outfile, "wb");
+
+ // Write the header.
+ Header hdr;
+ memcpy(hdr.magic, "\0plocate", 8);
+ 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.filename_index_offset_bytes = -1;
+ fwrite(&hdr, sizeof(hdr), 1, outfp);
+
+ Corpus corpus(outfp, block_size);
- vector<string> files;
- read_mlocate(infile, &files);
+ read_mlocate(infile, &corpus);
if (false) { // To read a plain text file.
FILE *fp = fopen(infile, "r");
while (!feof(fp)) {
break;
}
string s(buf);
- if (s.back() == '\n') s.pop_back();
- files.push_back(move(s));
+ if (s.back() == '\n')
+ s.pop_back();
+ corpus.add_file(move(s));
}
fclose(fp);
}
- dprintf("Read %zu files from %s\n", files.size(), infile);
-
- unordered_map<uint32_t, string> pl;
- size_t trigrams = 0, longest_posting_list = 0;
- unordered_map<uint32_t, vector<uint32_t>> invindex;
- for (size_t i = 0; i < files.size(); ++i) {
- const string &s = files[i];
- if (s.size() >= 3) {
- for (size_t j = 0; j < s.size() - 2; ++j) {
- uint32_t trgm = read_trigram(s, j);
- invindex[trgm].push_back(i);
- }
- }
- }
- string buf;
- size_t bytes_used = 0;
- for (auto &[trigram, docids] : invindex) {
- auto last = unique(docids.begin(), docids.end());
- docids.erase(last, docids.end());
- longest_posting_list = max(longest_posting_list, docids.size());
- trigrams += docids.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));
+ const size_t bytes_for_filenames = corpus.filename_blocks.back() - corpus.filename_blocks.front();
+
+ // Write the offsets to the filenames.
+ hdr.filename_index_offset_bytes = ftell(outfp);
+ const size_t bytes_for_filename_index = corpus.filename_blocks.size() * sizeof(uint64_t);
+ fwrite(corpus.filename_blocks.data(), corpus.filename_blocks.size(), sizeof(uint64_t), outfp);
+ corpus.filename_blocks.clear();
+ corpus.filename_blocks.shrink_to_fit();
- size_t bytes_needed = P4NENC_BOUND(docids.size());
- if (buf.size() < bytes_needed) buf.resize(bytes_needed);
- size_t bytes = p4nd1enc128v32(&docids[0], docids.size(), reinterpret_cast<unsigned char *>(&buf[0]));
- pl[trigram] = string(buf.data(), bytes);
- bytes_used += bytes;
+ // Finish up encoding the posting lists.
+ size_t trigrams = 0, longest_posting_list = 0;
+ size_t bytes_for_posting_lists = 0;
+ 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();
}
dprintf("%zu files, %zu different trigrams, %zu entries, avg len %.2f, longest %zu\n",
- files.size(), invindex.size(), trigrams, double(trigrams) / invindex.size(), longest_posting_list);
+ corpus.num_files, corpus.invindex.size(), trigrams, double(trigrams) / corpus.invindex.size(), 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("%zu bytes used for posting lists (%.2f bits/entry)\n", bytes_used, 8 * bytes_used / double(trigrams));
- //steady_clock::time_point end = steady_clock::now();
- dprintf("Building posting lists took %.1f ms.\n\n", 1e3 * duration<float>(end - start).count());
+ dprintf("Building posting lists took %.1f ms.\n\n", 1e3 * duration<float>(steady_clock::now() - start).count());
+ // Find the used trigrams.
vector<uint32_t> all_trigrams;
- for (auto &[trigram, docids] : 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());
-
- umask(0027);
- FILE *outfp = fopen(outfile, "wb");
- // Write the header.
- uint64_t num_trigrams = invindex.size(); // 64 to get alignment.
- fwrite(&num_trigrams, sizeof(num_trigrams), 1, outfp);
-
- // Find out where the posting lists will end.
- uint64_t offset = sizeof(uint64_t) * 2 + 16 * all_trigrams.size();
- uint64_t filename_index_offset = offset;
- for (uint32_t trgm : all_trigrams) {
- filename_index_offset += pl[trgm].size();
+ // Create the hash table.
+ unique_ptr<Trigram[]> hashtable;
+ uint32_t ht_size = next_prime(all_trigrams.size());
+ for (;;) {
+ hashtable = create_hashtable(corpus, all_trigrams, ht_size, num_overflow_slots);
+ if (hashtable == nullptr) {
+ dprintf("Failed creating hash table of size %u, increasing by 5%% and trying again.\n", ht_size);
+ ht_size = next_prime(ht_size * 1.05);
+ } else {
+ dprintf("Created hash table of size %u.\n\n", ht_size);
+ break;
+ }
}
- fwrite(&filename_index_offset, sizeof(filename_index_offset), 1, outfp);
- size_t bytes_for_trigrams = 0, bytes_for_posting_lists = 0, bytes_for_filename_index = 0, bytes_for_filenames = 0;
+ // Find the offsets for each posting list.
+ size_t bytes_for_hashtable = (ht_size + num_overflow_slots + 1) * sizeof(Trigram);
+ uint64_t offset = ftell(outfp) + bytes_for_hashtable;
+ for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) {
+ hashtable[i].offset = offset; // Needs to be there even for empty slots.
+ if (hashtable[i].num_docids == 0) {
+ continue;
+ }
- for (uint32_t trgm : all_trigrams) {
- // 16 bytes: trgm (4), number of docids (4), byte offset (8)
- fwrite(&trgm, sizeof(trgm), 1, outfp); // One byte wasted, but OK.
- uint32_t num_docids = invindex[trgm].size();
- fwrite(&num_docids, sizeof(num_docids), 1, outfp);
- fwrite(&offset, sizeof(offset), 1, outfp);
- offset += pl[trgm].size();
- bytes_for_trigrams += 16;
+ const string &encoded = corpus.get_pl_builder(hashtable[i].trgm).encoded;
+ offset += encoded.size();
}
- // Write the actual posting lists.
- for (uint32_t trgm : all_trigrams) {
- fwrite(pl[trgm].data(), pl[trgm].size(), 1, outfp);
- bytes_for_posting_lists += pl[trgm].size();
- }
+ // Write the hash table.
+ hdr.hash_table_offset_bytes = ftell(outfp);
+ hdr.hashtable_size = ht_size;
+ fwrite(hashtable.get(), ht_size + num_overflow_slots + 1, sizeof(Trigram), outfp);
- // Write the offsets to the filenames.
- offset = filename_index_offset + files.size() * sizeof(offset);
- for (const string &filename : files) {
- fwrite(&offset, sizeof(offset), 1, outfp);
- offset += filename.size() + 1;
- bytes_for_filename_index += sizeof(offset);
- bytes_for_filenames += filename.size() + 1;
- }
-
- // Write the actual filenames.
- for (const string &filename : files) {
- fwrite(filename.c_str(), filename.size() + 1, 1, outfp);
+ // Write the actual posting lists.
+ for (unsigned i = 0; i < ht_size + num_overflow_slots + 1; ++i) {
+ if (hashtable[i].num_docids == 0) {
+ continue;
+ }
+ 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;
+ fseek(outfp, 0, SEEK_SET);
+ fwrite(&hdr, sizeof(hdr), 1, outfp);
fclose(outfp);
- size_t total_bytes = (bytes_for_trigrams + bytes_for_posting_lists + bytes_for_filename_index + bytes_for_filenames);
+ size_t total_bytes __attribute__((unused)) = (bytes_for_hashtable + bytes_for_posting_lists + bytes_for_filename_index + bytes_for_filenames);
- dprintf("Trigrams: %'7.1f MB\n", bytes_for_trigrams / 1048576.0);
+ dprintf("Block size: %7d files\n", block_size);
+ 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);
dprintf("Filenames: %'7.1f MB\n", bytes_for_filenames / 1048576.0);
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 <https://gnu.org/licenses/gpl.html>.\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]);
+ static const struct option long_options[] = {
+ { "block-size", required_argument, 0, 'b' },
+ { "help", no_argument, 0, 'h' },
+ { "version", no_argument, 0, 'V' },
+ { 0, 0, 0, 0 }
+ };
+
+ int block_size = 32;
+
+ setlocale(LC_ALL, "");
+ for (;;) {
+ int option_index = 0;
+ int c = getopt_long(argc, argv, "b:hV", 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);
+ default:
+ exit(1);
+ }
+ }
+
+ if (argc - optind != 2) {
+ usage();
+ exit(1);
+ }
+
+ do_build(argv[optind], argv[optind + 1], block_size);
exit(EXIT_SUCCESS);
}
projects / plocate / blobdiff