-#include <stdio.h>
-#include <string.h>
+#include "vp4.h"
+
#include <algorithm>
-#include <unordered_map>
-#include <string>
-#include <vector>
+#include <arpa/inet.h>
+#include <assert.h>
#include <chrono>
-#include <unistd.h>
+#include <endian.h>
#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <string>
#include <sys/mman.h>
-#include <arpa/inet.h>
-#include <endian.h>
-#include <sys/types.h>
#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <unordered_map>
+#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__);
using namespace std::chrono;
string zstd_compress(const string &src, string *tempbuf);
-
+
static inline uint32_t read_unigram(const string_view s, size_t idx)
{
if (idx < s.size()) {
(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];
};
+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)
+{
+ // 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;
+ }
+ }
+
+ 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(size_t block_size) : block_size(block_size) {}
+ Corpus(size_t block_size)
+ : block_size(block_size) {}
void add_file(string filename);
void flush_block();
vector<string> filename_blocks;
- unordered_map<uint32_t, vector<uint32_t>> invindex;
+ unordered_map<uint32_t, PostingListBuilder> invindex;
size_t num_files = 0, num_files_in_block = 0, num_blocks = 0;
private:
if (s.size() >= 3) {
for (size_t j = 0; j < s.size() - 2; ++j) {
uint32_t trgm = read_trigram(s, j);
- vector<uint32_t> &docids = invindex[trgm];
- if (docids.empty() || docids.back() != docid) {
- docids.push_back(docid);
- }
+ invindex[trgm].add_docid(docid);
}
}
ptr += s.size() + 1;
if (dir_path == "/") {
dir_path = "";
}
-
- for ( ;; ) {
+
+ for (;;) {
uint8_t type = *ptr++;
if (type == DBE_NORMAL) {
string filename = ptr;
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();
Corpus corpus(block_size);
break;
}
string s(buf);
- if (s.back() == '\n') s.pop_back();
+ 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);
- // Compress posting lists.
- string buf;
size_t trigrams = 0, longest_posting_list = 0;
size_t bytes_used = 0;
- unordered_map<uint32_t, string> pl;
- for (auto &[trigram, docids] : corpus.invindex) {
- longest_posting_list = max(longest_posting_list, docids.size());
- trigrams += docids.size();
-
- 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;
+ 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_used += 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);
-
+ 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_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());
vector<uint32_t> all_trigrams;
- for (auto &[trigram, docids] : corpus.invindex) {
+ for (auto &[trigram, pl_builder] : corpus.invindex) {
all_trigrams.push_back(trigram);
}
sort(all_trigrams.begin(), all_trigrams.end());
// 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();
+ for (auto &[trigram, pl_builder] : corpus.invindex) {
+ filename_index_offset += pl_builder.encoded.size();
}
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;
-
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 = corpus.invindex[trgm].size();
+ const PostingListBuilder &pl_builder = corpus.invindex[trgm];
+ uint32_t num_docids = pl_builder.num_docids;
fwrite(&num_docids, sizeof(num_docids), 1, outfp);
fwrite(&offset, sizeof(offset), 1, outfp);
- offset += pl[trgm].size();
+ offset += pl_builder.encoded.size();
bytes_for_trigrams += 16;
}
// 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();
+ const string &encoded = corpus.invindex[trgm].encoded;
+ fwrite(encoded.data(), encoded.size(), 1, outfp);
+ bytes_for_posting_lists += encoded.size();
}
// Stick an empty block at the end as sentinel.
bytes_for_filename_index += sizeof(offset);
bytes_for_filenames += filename.size();
}
-
+
// Write the actual filenames.
for (const string &filename : corpus.filename_blocks) {
fwrite(filename.data(), filename.size(), 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_trigrams + bytes_for_posting_lists + bytes_for_filename_index + bytes_for_filenames);
dprintf("Block size: %7d files\n", block_size);
dprintf("Trigrams: %'7.1f MB\n", bytes_for_trigrams / 1048576.0);
projects / plocate / blobdiff