X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=plocate-build.cpp;h=028a1ee06c620d8274ae707ba1905041ac288a17;hb=fd6198891d6fd9642effc0843fef6f23b991af3e;hp=bde72b51fa3d6da02b59216e34d8dbfe695cca80;hpb=1f07faf71217a56ac538189c202ca118d7c993c0;p=plocate

diff --git a/plocate-build.cpp b/plocate-build.cpp
index bde72b5..028a1ee 100644
--- a/plocate-build.cpp
+++ b/plocate-build.cpp
@@ -1,51 +1,29 @@
+#include "database-builder.h"
 #include "db.h"
-#include "vp4.h"
+#include "dprintf.h"
 
 #include <algorithm>
 #include <arpa/inet.h>
 #include <assert.h>
 #include <chrono>
-#include <endian.h>
-#include <fcntl.h>
+#include <getopt.h>
+#include <iosfwd>
 #include <math.h>
 #include <memory>
+#include <random>
+#include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <string>
-#include <sys/mman.h>
 #include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <unordered_map>
+#include <utility>
 #include <vector>
-#include <zstd.h>
-
-#define P4NENC_BOUND(n) ((n + 127) / 128 + (n + 32) * sizeof(uint32_t))
-#define dprintf(...)
-//#define dprintf(...) fprintf(stderr, __VA_ARGS__);
 
 using namespace std;
 using namespace std::chrono;
 
-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];
-	} else {
-		return 0;
-	}
-}
-
-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);
-}
+bool use_debug = false;
 
 enum {
 	DBE_NORMAL = 0, /* A non-directory file */
@@ -69,401 +47,208 @@ struct db_directory {
 	uint8_t pad[4];
 };
 
-class PostingListBuilder {
-public:
-	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_docids;
-
-	uint32_t last_block_end;
-};
-
-void PostingListBuilder::add_docid(uint32_t docid)
+string read_cstr(FILE *fp)
 {
-	// 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;
+	string ret;
+	for (;;) {
+		int ch = getc(fp);
+		if (ch == -1) {
+			perror("getc");
+			exit(1);
 		}
-	} else {
-		if (docid == pending_docids.back()) {
-			return;
+		if (ch == 0) {
+			return ret;
 		}
-	}
-
-	pending_docids.push_back(docid);
-	if (pending_docids.size() == 128) {
-		append_block();
-		pending_docids.clear();
-		last_block_end = docid;
-	}
-	++num_docids;
-}
-
-void PostingListBuilder::finish()
-{
-	if (pending_docids.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 = p4d1enc32(pending_docids.data(), pending_docids.size(), buf, last_block_end);
-	encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(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);
-	encoded.append(reinterpret_cast<char *>(buf), reinterpret_cast<char *>(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<char *>(buf), bytes);
-}
-
-class Corpus {
-public:
-	Corpus(FILE *outfp, size_t block_size)
-		: outfp(outfp), block_size(block_size) {}
-	void add_file(string filename);
-	void flush_block();
-
-	vector<uint64_t> filename_blocks;
-	unordered_map<uint32_t, PostingListBuilder> invindex;
-	size_t num_files = 0, num_files_in_block = 0, num_blocks = 0;
-
-private:
-	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();
+		ret.push_back(ch);
 	}
 }
 
-void Corpus::flush_block()
+void handle_directory(FILE *fp, DatabaseReceiver *receiver)
 {
-	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);
-				invindex[trgm].add_docid(docid);
-			}
+	db_directory dummy;
+	if (fread(&dummy, sizeof(dummy), 1, fp) != 1) {
+		if (feof(fp)) {
+			return;
+		} else {
+			perror("fread");
 		}
-		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;
-}
-
-const char *handle_directory(const char *ptr, Corpus *corpus)
-{
-	ptr += sizeof(db_directory);
-
-	string dir_path = ptr;
-	ptr += dir_path.size() + 1;
+	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, unknown_dir_time);
 		} 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, unknown_dir_time);
 		} else {
-			return ptr;
+			return;  // Probably end.
 		}
 	}
 }
 
-void read_mlocate(const char *filename, Corpus *corpus)
+void read_plaintext(FILE *fp, DatabaseReceiver *receiver)
 {
-	int fd = open(filename, O_RDONLY);
-	if (fd == -1) {
-		perror(filename);
+	if (fseek(fp, 0, SEEK_SET) != 0) {
+		perror("fseek");
 		exit(1);
 	}
-	off_t len = lseek(fd, 0, SEEK_END);
-	if (len == -1) {
-		perror("lseek");
-		exit(1);
+
+	while (!feof(fp)) {
+		char buf[1024];
+		if (fgets(buf, sizeof(buf), fp) == nullptr) {
+			break;
+		}
+		string s(buf);
+		assert(!s.empty());
+		while (s.back() != '\n' && !feof(fp)) {
+			// The string was longer than the buffer, so read again.
+			if (fgets(buf, sizeof(buf), fp) == nullptr) {
+				break;
+			}
+			s += buf;
+		}
+		if (!s.empty() && s.back() == '\n')
+			s.pop_back();
+		receiver->add_file(move(s), unknown_dir_time);
 	}
-	const char *data = (char *)mmap(nullptr, len, PROT_READ, MAP_SHARED, fd, /*offset=*/0);
-	if (data == MAP_FAILED) {
-		perror("mmap");
+}
+
+void read_mlocate(FILE *fp, DatabaseReceiver *receiver)
+{
+	if (fseek(fp, 0, SEEK_SET) != 0) {
+		perror("fseek");
 		exit(1);
 	}
 
-	const db_header *hdr = (const db_header *)data;
+	db_header hdr;
+	if (fread(&hdr, sizeof(hdr), 1, fp) != 1) {
+		perror("short read");
+		exit(1);
+	}
 
 	// 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);
+	string path = read_cstr(fp);
 
-	const char *ptr = data + offset;
-	while (ptr < data + len) {
-		ptr = handle_directory(ptr, corpus);
+	if (fseek(fp, ntohl(hdr.conf_size), SEEK_CUR) != 0) {
+		perror("skip conf block");
+		exit(1);
 	}
 
-	munmap((void *)data, len);
-	close(fd);
+	while (!feof(fp)) {
+		handle_directory(fp, receiver);
+	}
 }
 
-string zstd_compress(const string &src, string *tempbuf)
+void do_build(const char *infile, const char *outfile, int block_size, bool plaintext)
 {
-	size_t max_size = ZSTD_compressBound(src.size());
-	if (tempbuf->size() < max_size) {
-		tempbuf->resize(max_size);
+	FILE *infp = fopen(infile, "rb");
+	if (infp == nullptr) {
+		perror(infile);
+		exit(1);
 	}
-	size_t size = ZSTD_compress(&(*tempbuf)[0], max_size, src.data(), src.size(), /*level=*/6);
-	return string(tempbuf->data(), size);
-}
 
-bool is_prime(uint32_t x)
-{
-	if ((x % 2) == 0 || (x % 3) == 0) {
-		return false;
+	// 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);
+	if (plaintext) {
+		read_plaintext(infp, &builder);
+	} else {
+		read_mlocate(infp, &builder);
 	}
-	uint32_t limit = ceil(sqrt(x));
-	for (uint32_t factor = 5; factor <= limit; ++factor) {
-		if ((x % factor) == 0) {
-			return false;
-		}
+	string dictionary = builder.train(1024);
+
+	DatabaseBuilder db(outfile, /*owner=*/-1, block_size, dictionary, /*check_visibility=*/true);
+	DatabaseReceiver *corpus = db.start_corpus(/*store_dir_times=*/false);
+	if (plaintext) {
+		read_plaintext(infp, corpus);
+	} else {
+		read_mlocate(infp, corpus);
 	}
-	return true;
+	fclose(infp);
+
+	dprintf("Read %zu files from %s\n", corpus->num_files_seen(), infile);
+	db.finish_corpus();
 }
 
-uint32_t next_prime(uint32_t x)
+void usage()
 {
-	if ((x % 2) == 0) {
-		++x;
-	}
-	while (!is_prime(x)) {
-		x += 2;
-	}
-	return x;
+	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"
+		"  -p, --plaintext        input is a plaintext file, not an mlocate database\n"
+		"      --help             print this help\n"
+		"      --version          print version information\n");
 }
 
-unique_ptr<Trigram[]> create_hashtable(const Corpus &corpus, const vector<uint32_t> &all_trigrams, uint32_t ht_size, uint32_t num_overflow_slots)
+void version()
 {
-	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.invindex.find(trgm)->second.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;
-			}
-
-			++bucket, ++distance;
-			if (distance > num_overflow_slots) {
-				return nullptr;
-			}
-		}
-		ht[bucket] = to_insert;
-	}
-	return ht;
+	printf("plocate-build %s\n", PACKAGE_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");
 }
 
-void do_build(const char *infile, const char *outfile, int block_size)
+int main(int argc, char **argv)
 {
-	steady_clock::time_point start __attribute__((unused)) = steady_clock::now();
-
-	umask(0027);
-	FILE *outfp = fopen(outfile, "wb");
+	static const struct option long_options[] = {
+		{ "block-size", required_argument, 0, 'b' },
+		{ "plaintext", no_argument, 0, 'p' },
+		{ "help", no_argument, 0, 'h' },
+		{ "version", no_argument, 0, 'V' },
+		{ "debug", no_argument, 0, 'D' },  // Not documented.
+		{ 0, 0, 0, 0 }
+	};
 
-	// 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.hash_table_offset_bytes = -1;  // We don't know these offsets yet.
-	hdr.filename_index_offset_bytes = -1;
-	fwrite(&hdr, sizeof(hdr), 1, outfp);
+	int block_size = 32;
+	bool plaintext = false;
 
-	Corpus corpus(outfp, block_size);
-
-	read_mlocate(infile, &corpus);
-	if (false) {  // To read a plain text file.
-		FILE *fp = fopen(infile, "r");
-		while (!feof(fp)) {
-			char buf[1024];
-			if (fgets(buf, 1024, fp) == nullptr || feof(fp)) {
-				break;
-			}
-			string s(buf);
-			if (s.back() == '\n')
-				s.pop_back();
-			corpus.add_file(move(s));
-		}
-		fclose(fp);
-	}
-	corpus.flush_block();
-	dprintf("Read %zu files from %s\n", corpus.num_files, infile);
-
-	// 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();
-
-	// 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) {
-		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",
-	        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("Building posting lists took %.1f ms.\n\n", 1e3 * duration<float>(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).
-	vector<uint32_t> all_trigrams;
-	for (auto &[trigram, pl_builder] : corpus.invindex) {
-		all_trigrams.push_back(trigram);
-	}
-	sort(all_trigrams.begin(), all_trigrams.end());
-
-	// Create the hash table.
-	unique_ptr<Trigram[]> hashtable;
-	uint32_t ht_size = next_prime(all_trigrams.size());
+	setlocale(LC_ALL, "");
 	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);
+		int option_index = 0;
+		int c = getopt_long(argc, argv, "b:hpVD", long_options, &option_index);
+		if (c == -1) {
 			break;
 		}
-	}
-
-	// 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;
+		switch (c) {
+		case 'b':
+			block_size = atoi(optarg);
+			break;
+		case 'p':
+			plaintext = true;
+			break;
+		case 'h':
+			usage();
+			exit(0);
+		case 'V':
+			version();
+			exit(0);
+		case 'D':
+			use_debug = true;
+			break;
+		default:
+			exit(1);
 		}
-
-		const string &encoded = corpus.invindex[hashtable[i].trgm].encoded;
-		offset += encoded.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 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.invindex[hashtable[i].trgm].encoded;
-		fwrite(encoded.data(), encoded.size(), 1, outfp);
+	if (argc - optind != 2) {
+		usage();
+		exit(1);
 	}
 
-	// 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 __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("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("Total:          %'7.1f MB\n", total_bytes / 1048576.0);
-	dprintf("\n");
-}
-
-int main(int argc, char **argv)
-{
-	do_build(argv[1], argv[2], 32);
+	do_build(argv[optind], argv[optind + 1], block_size, plaintext);
 	exit(EXIT_SUCCESS);
 }