GH-46 Do not advance LIB past HEAD. It is possible that HEAD is not o…

…n the branch that contains the LIB block. If on a fork, then only advance to our HEAD and only if on the same branch as LIB block.

libraries/chain/controller.cpp

@@ -1398,17 +1398,18 @@ struct controller_impl {
                      ("lib_num", lib_num)("bn", fork_db_root_block_num()) );
       }
 
-      block_id_type irreversible_block_id = if_irreversible_block_id.load();
-      uint32_t if_lib_num = block_header::num_from_id(irreversible_block_id);
-      const uint32_t new_lib_num = if_lib_num > 0 ? if_lib_num : fork_db_head_irreversible_blocknum();
+      const block_id_type irreversible_block_id = if_irreversible_block_id.load();
+      const uint32_t savanna_lib_num = block_header::num_from_id(irreversible_block_id);
+      const bool savanna = savanna_lib_num > 0;
+      const uint32_t new_lib_num = savanna ? savanna_lib_num : fork_db_head_irreversible_blocknum();
 
       if( new_lib_num <= lib_num )
          return;
 
       bool savanna_transistion_required = false;
       auto mark_branch_irreversible = [&, this](auto& forkdb) {
-         auto branch = (if_lib_num > 0) ? forkdb.fetch_branch( irreversible_block_id, new_lib_num)
-                                        : forkdb.fetch_branch( fork_db_head_or_pending(forkdb)->id(), new_lib_num );
+         auto branch = savanna ? forkdb.fetch_head_branch( irreversible_block_id, new_lib_num)
+                               : forkdb.fetch_branch( fork_db_head_or_pending(forkdb)->id(), new_lib_num );
          try {
             auto should_process = [&](auto& bsp) {
                // Only make irreversible blocks that have been validated. Blocks in the fork database may not be on our current best head

libraries/chain/fork_database.cpp

@@ -135,6 +135,7 @@ namespace eosio::chain {
       void             remove_impl( const block_id_type& id );
       branch_t         fetch_branch_impl( const block_id_type& h, uint32_t trim_after_block_num ) const;
       block_branch_t   fetch_block_branch_impl( const block_id_type& h, uint32_t trim_after_block_num ) const;
+      branch_t         fetch_head_branch_impl( const block_id_type& b, uint32_t trim_after_block_num ) const;
       full_branch_t    fetch_full_branch_impl(const block_id_type& h) const;
       bsp_t            search_on_branch_impl( const block_id_type& h, uint32_t block_num, include_root_t include_root ) const;
       bsp_t            search_on_head_branch_impl( uint32_t block_num, include_root_t include_root ) const;
@@ -438,6 +439,30 @@ namespace eosio::chain {
       return result;
    }
 
+   template <class BSP>
+   fork_database_t<BSP>::branch_t
+   fork_database_t<BSP>::fetch_head_branch(const block_id_type& b, uint32_t trim_after_block_num) const {
+      std::lock_guard g(my->mtx);
+      return my->fetch_head_branch_impl(b, trim_after_block_num);
+   }
+
+   template <class BSP>
+   fork_database_t<BSP>::branch_t
+   fork_database_impl<BSP>::fetch_head_branch_impl(const block_id_type& b, uint32_t trim_after_block_num) const {
+      branch_t result;
+      if (!head)
+         return result;
+      result.reserve(index.size());
+      bool found_branch = false;
+      for (auto i = index.find(head->id()); i != index.end(); i = index.find((*i)->previous())) {
+         if ((*i)->id() == b)
+            found_branch = true;
+         if (found_branch && (*i)->block_num() <= trim_after_block_num)
+            result.push_back(*i);
+      }
+      return result;
+   }
+
    template <class BSP>
    block_branch_t
    fork_database_t<BSP>::fetch_block_branch(const block_id_type& h, uint32_t trim_after_block_num) const {
@@ -594,7 +619,7 @@ namespace eosio::chain {
 
       for( uint32_t i = 0; i < remove_queue.size(); ++i ) {
          EOS_ASSERT( remove_queue[i] != head_id, fork_database_exception,
-                     "removing the block and its descendants would remove the current head block" );
+                     "removing the block and its descendants would remove the current head block ${id}", ("id", head_id) );
 
          auto previtr = previdx.lower_bound( remove_queue[i] );
          while( previtr != previdx.end() && (*previtr)->previous() == remove_queue[i] ) {

libraries/chain/include/eosio/chain/fork_database.hpp

@@ -96,6 +96,11 @@ namespace eosio::chain {
       branch_t fetch_branch( const block_id_type& h, uint32_t trim_after_block_num = std::numeric_limits<uint32_t>::max() ) const;
       block_branch_t fetch_block_branch( const block_id_type& h, uint32_t trim_after_block_num = std::numeric_limits<uint32_t>::max() ) const;
 
+      /**
+       * Similar to fetch_branch but only returns up to head or empty if b not on head branch.
+       */
+      branch_t fetch_head_branch( const block_id_type& b, uint32_t trim_after_block_num = std::numeric_limits<uint32_t>::max() ) const;
+
       /**
        *  Returns full branch of block_header_state pointers including the root.
        *  The order of the sequence is in descending block number order.

unittests/fork_db_tests.cpp

@@ -117,6 +117,17 @@ BOOST_AUTO_TEST_CASE(add_remove_test) try {
    BOOST_TEST(branch[1] == bsp12bb);
    BOOST_TEST(branch[2] == bsp11b);
 
+   // test fetch head branch
+   BOOST_TEST(forkdb.head()->id() == root->id());
+   forkdb.mark_valid(bsp13a);
+   BOOST_TEST(forkdb.head()->id() == bsp13a->id());
+   branch = forkdb.fetch_head_branch(bsp11c->id());
+   BOOST_TEST(branch.empty()); // bsp11c not on bsp13a branch
+   branch = forkdb.fetch_head_branch(bsp12a->id());
+   BOOST_REQUIRE(branch.size() == 2);
+   BOOST_TEST(branch[0] == bsp12a);
+   BOOST_TEST(branch[1] == bsp11a);
+
 } FC_LOG_AND_RETHROW();
 
 BOOST_AUTO_TEST_SUITE_END()