multishard_mutation_query: make multi_range_reader::fill_buffer() wor…

…k even after EOS if fill_buffer() is called after EOS, underlying reader will be fast forwarded to a range pointed to by an invalid iterator, so producing incorrect results. fill_buffer() is changed to return early if EOS was found, meaning that underlying reader already fast forwarded to all ranges managed by multi_range_reader. Usually, consume facilities check for EOS, before calling fill_buffer() but most reader impl check for EOS to avoid correctness issues. Let's do the same here. Signed-off-by: Raphael S. Carvalho <[email protected]> Message-Id: <[email protected]>
StarostaGit · Dec 8, 2021 · c3c23dd · c3c23dd
1 parent f285520
commit c3c23dd
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/multishard_mutation_query.cc b/multishard_mutation_query.cc
@@ -659,6 +659,9 @@ class multi_range_reader : public flat_mutation_reader::impl {
         : impl(std::move(s), std::move(permit)) , _reader(std::move(rd)) , _it(ranges.begin()) , _end(ranges.end()) { }
 
     virtual future<> fill_buffer() override {
+        if (is_end_of_stream()) {
+            co_return;
+        }
         while (is_buffer_empty()) {
             if (_reader.is_buffer_empty() && _reader.is_end_of_stream()) {
                 if (++_it == _end) {