diff options
Diffstat (limited to 'table/block.cc')
-rw-r--r-- | table/block.cc | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/table/block.cc b/table/block.cc index 2fe89ea..3b15257 100644 --- a/table/block.cc +++ b/table/block.cc @@ -166,6 +166,24 @@ class Block::Iter : public Iterator { // with a key < target uint32_t left = 0; uint32_t right = num_restarts_ - 1; + int current_key_compare = 0; + + if (Valid()) { + // If we're already scanning, use the current position as a starting + // point. This is beneficial if the key we're seeking to is ahead of the + // current position. + current_key_compare = Compare(key_, target); + if (current_key_compare < 0) { + // key_ is smaller than target + left = restart_index_; + } else if (current_key_compare > 0) { + right = restart_index_; + } else { + // We're seeking to the key we're already at. + return; + } + } + while (left < right) { uint32_t mid = (left + right + 1) / 2; uint32_t region_offset = GetRestartPoint(mid); @@ -189,8 +207,15 @@ class Block::Iter : public Iterator { } } + // We might be able to use our current position within the restart block. + // This is true if we determined the key we desire is in the current block + // and is after than the current key. + assert(current_key_compare == 0 || Valid()); + bool skip_seek = left == restart_index_ && current_key_compare < 0; + if (!skip_seek) { + SeekToRestartPoint(left); + } // Linear search (within restart block) for first key >= target - SeekToRestartPoint(left); while (true) { if (!ParseNextKey()) { return; |