Call strlen() a bit less. Helps ~2% CPU.

diff --git a/database-builder.cpp b/database-builder.cpp
index cc88ea0489000618f781a920b4716be48befbae6..da52cdb57764b6d60247c74e4318a84872503c49 100644 (file)
--- a/database-builder.cpp
+++ b/database-builder.cpp
@@ -29,16 +29,6 @@ constexpr unsigned num_overflow_slots = 16;
 
 string zstd_compress(const string &src, ZSTD_CDict *cdict, string *tempbuf);
 
-// NOTE: Will read one byte past the end of the trigram, but it's OK,
-// since we always call it from contexts where there's a terminating zero byte.
-static inline uint32_t read_trigram(const string_view s, size_t start)
-{
-       uint32_t trgm;
-       memcpy(&trgm, s.data() + start, sizeof(trgm));
-       trgm = le32toh(trgm);
-       return trgm & 0xffffff;
-}
-
 class PostingListBuilder {
 public:
        inline void add_docid(uint32_t docid);
@@ -313,15 +303,36 @@ void EncodingCorpus::flush_block()
 
        // 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);
-                               add_docid(trgm, docid);
+       const char *end = ptr + current_block.size();
+       while (ptr < end - 3) {  // Must be at least one filename left, that's at least three bytes.
+               if (ptr[0] == '\0') {
+                       // This filename is zero bytes, so skip it (and the zero terminator).
+                       ++ptr;
+                       continue;
+               } else if (ptr[1] == '\0') {
+                       // This filename is one byte, so skip it (and the zero terminator).
+                       ptr += 2;
+                       continue;
+               } else if (ptr[2] == '\0') {
+                       // This filename is two bytes, so skip it (and the zero terminator).
+                       ptr += 3;
+                       continue;
+               }
+               for ( ;; ) {
+                       // NOTE: Will read one byte past the end of the trigram, but it's OK,
+                       // since we always call it from contexts where there's a terminating zero byte.
+                       uint32_t trgm;
+                       memcpy(&trgm, ptr, sizeof(trgm));
+                       ++ptr;
+                       trgm = le32toh(trgm);
+                       add_docid(trgm & 0xffffff, docid);
+                       if (trgm <= 0xffffff) {
+                               // Terminating zero byte, so we're done with this filename.
+                               // Skip the remaining two bytes, and the zero terminator.
+                               ptr += 3;
+                               break;
                        }
                }
-               ptr += s.size() + 1;
        }
 
        // Compress and add the filename block.