Microoptimizations to docid counting.

diff --git a/database-builder.cpp b/database-builder.cpp
index 75b96f8c02a6c4108f2b0497e2aa5881167db80a..cc88ea0489000618f781a920b4716be48befbae6 100644 (file)
--- a/database-builder.cpp
+++ b/database-builder.cpp
@@ -46,7 +46,11 @@ public:
        void finish();
 
        vector<unsigned char> encoded;
-       size_t num_docids = 0;
+       size_t get_num_docids() const {
+               // Updated only when we flush, so check that we're finished.
+               assert(pending_deltas.empty());
+               return num_docids;
+       }
 
 private:
        void write_header(uint32_t docid);
@@ -54,6 +58,7 @@ private:
 
        vector<uint32_t> pending_deltas;
 
+       uint32_t num_docids = 0;  // Should be size_t, except the format only supports 2^32 docids per posting list anyway.
        uint32_t last_docid = -1;
 };
 
@@ -69,8 +74,8 @@ void PostingListBuilder::add_docid(uint32_t docid)
        if (pending_deltas.size() == 128) {
                append_block();
                pending_deltas.clear();
+               num_docids += 128;
        }
-       ++num_docids;
 }
 
 void PostingListBuilder::add_first_docid(uint32_t docid)
@@ -92,6 +97,9 @@ void PostingListBuilder::finish()
        unsigned char buf[P4NENC_BOUND(128)];
        unsigned char *end = encode_pfor_single_block<128>(pending_deltas.data(), pending_deltas.size(), /*interleaved=*/false, buf);
        encoded.insert(encoded.end(), buf, end);
+
+       num_docids += pending_deltas.size();
+       pending_deltas.clear();
 }
 
 void PostingListBuilder::append_block()
@@ -434,7 +442,7 @@ unique_ptr<Trigram[]> create_hashtable(EncodingCorpus &corpus, const vector<uint
        }
        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 };
+               Trigram to_insert{ trgm, uint32_t(corpus.get_pl_builder(trgm).get_num_docids()), 0 };
 
                uint32_t bucket = hash_trigram(trgm, ht_size);
                unsigned distance = 0;
@@ -570,8 +578,8 @@ void DatabaseBuilder::finish_corpus()
                        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;
+               longest_posting_list = max(longest_posting_list, pl_builder.get_num_docids());
+               trigrams += pl_builder.get_num_docids();
                bytes_for_posting_lists += pl_builder.encoded.size();
        }
        size_t num_trigrams = corpus->num_trigrams();