Try to improve update_last_irreversible_block performance

libraries/chain/db_init.cpp

@@ -680,6 +680,8 @@ void database::init_genesis(const genesis_state_type& genesis_state)
          p.active_witnesses.insert(witness_id_type(i));
       }
    });
+   for( const auto witness : get_global_properties().active_witnesses )
+      modify( get<witness_object>( witness ), [] ( witness_object& w ) { w.is_active = true; } );
 
    // Enable fees
    modify(get_global_properties(), [&genesis_state](global_property_object& p) {

libraries/chain/db_maint.cpp

@@ -286,6 +286,15 @@ void database::update_active_witnesses()
       }
    } );
 
+   const witness_object& last_witness = wits.back();
+   for( const auto witness_id : gpo.active_witnesses )
+   {
+      const auto& witness = get<witness_object>( witness_id );
+      if( _vote_tally_buffer[witness.vote_id] < _vote_tally_buffer[last_witness.vote_id]
+             || (_vote_tally_buffer[witness.vote_id] == _vote_tally_buffer[last_witness.vote_id]
+                 && witness.id > last_witness.id) )
+         modify( witness, [] ( witness_object& w ) { w.is_active = false; } );
+   }
    modify( gpo, [&wits]( global_property_object& gp )
    {
       gp.active_witnesses.clear();
@@ -296,6 +305,12 @@ void database::update_active_witnesses()
          return w.id;
       });
    });
+   for( const auto witness_id : gpo.active_witnesses )
+   {
+      const auto& witness = get<witness_object>( witness_id );
+      if( !witness.is_active )
+         modify( witness, [] ( witness_object& w ) { w.is_active = true; } );
+   }
 
 } FC_CAPTURE_AND_RETHROW() }
 

libraries/chain/db_update.cpp

@@ -107,32 +107,19 @@ void database::update_last_irreversible_block()
    const global_property_object& gpo = get_global_properties();
    const dynamic_global_property_object& dpo = get_dynamic_global_properties();
 
-   // TODO for better performance, move this to db_maint, because only need to do it once per maintenance interval
-   vector< const witness_object* > wit_objs;
-   wit_objs.reserve( gpo.active_witnesses.size() );
-   for( const witness_id_type& wid : gpo.active_witnesses )
-      wit_objs.push_back( &(wid(*this)) );
-
    static_assert( GRAPHENE_IRREVERSIBLE_THRESHOLD > 0, "irreversible threshold must be nonzero" );
 
-   // 1 1 1 2 2 2 2 2 2 2 -> 2     .3*10 = 3
-   // 1 1 1 1 1 1 1 2 2 2 -> 1
-   // 3 3 3 3 3 3 3 3 3 3 -> 3
-   // 3 3 3 4 4 4 4 4 4 4 -> 4
-
-   size_t offset = ((GRAPHENE_100_PERCENT - GRAPHENE_IRREVERSIBLE_THRESHOLD) * wit_objs.size() / GRAPHENE_100_PERCENT);
-
-   std::nth_element( wit_objs.begin(), wit_objs.begin() + offset, wit_objs.end(),
-      []( const witness_object* a, const witness_object* b )
-      {
-         return a->last_confirmed_block_num < b->last_confirmed_block_num;
-      } );
-
-   uint32_t new_last_irreversible_block_num = wit_objs[offset]->last_confirmed_block_num;
+   const size_t offset = (GRAPHENE_100_PERCENT - GRAPHENE_IRREVERSIBLE_THRESHOLD)
+                         * gpo.active_witnesses.size() / GRAPHENE_100_PERCENT;
+   const auto& witness_idx = get_index_type<witness_index>().indices().get<by_last_block>();
+   auto itr = witness_idx.end();
+   for( uint32_t i = gpo.active_witnesses.size() - offset; i > 0; --i )
+      --itr;
+   const auto new_last_irreversible_block_num = itr->last_confirmed_block_num;
 
    if( new_last_irreversible_block_num > dpo.last_irreversible_block_num )
    {
-      modify( dpo, [&]( dynamic_global_property_object& _dpo )
+      modify( dpo, [new_last_irreversible_block_num]( dynamic_global_property_object& _dpo )
       {
          _dpo.last_irreversible_block_num = new_last_irreversible_block_num;
       } );

libraries/chain/include/graphene/chain/witness_object.hpp

@@ -26,6 +26,8 @@
 #include <graphene/protocol/asset.hpp>
 #include <graphene/db/generic_index.hpp>
 
+#include <boost/multi_index/composite_key.hpp>
+
 namespace graphene { namespace chain {
    using namespace graphene::db;
 
@@ -44,6 +46,7 @@ namespace graphene { namespace chain {
          string           url;
          int64_t          total_missed = 0;
          uint32_t         last_confirmed_block_num = 0;
+         bool             is_active = false;
 
          witness_object() : vote_id(vote_id_type::witness) {}
    };
@@ -62,6 +65,12 @@ namespace graphene { namespace chain {
          >,
          ordered_unique< tag<by_vote_id>,
             member<witness_object, vote_id_type, &witness_object::vote_id>
+         >,
+         ordered_non_unique< tag<by_last_block>, // non-unique because multiple can have last == 0
+            composite_key<witness_object,
+               member<witness_object, bool, &witness_object::is_active>,
+               member<witness_object, uint32_t, &witness_object::last_confirmed_block_num>
+            >
          >
       >
    >;

libraries/chain/small_objects.cpp

@@ -163,6 +163,7 @@ FC_REFLECT_DERIVED_NO_TYPENAME( graphene::chain::witness_object, (graphene::db::
                     (url)
                     (total_missed)
                     (last_confirmed_block_num)
+                    (is_active)
                   )
 
 FC_REFLECT_DERIVED_NO_TYPENAME(