Implement maintenance_flag in dynamic_global_properties

libraries/chain/db_block.cpp

@@ -395,6 +395,7 @@ void database::_apply_block( const signed_block& next_block )
    const witness_object& signing_witness = validate_block_header(skip, next_block);
    const auto& global_props = get_global_properties();
    const auto& dynamic_global_props = get<dynamic_global_property_object>(dynamic_global_property_id_type());
+   bool maint_needed = (dynamic_global_props.next_maintenance_time <= next_block.timestamp);
 
    _current_block_num    = next_block.block_num();
    _current_trx_in_block = 0;
@@ -418,7 +419,7 @@ void database::_apply_block( const signed_block& next_block )
    auto current_block_interval = global_props.parameters.block_interval;
 
    // Are we at the maintenance interval?
-   if( dynamic_global_props.next_maintenance_time <= next_block.timestamp )
+   if( maint_needed )
       // This will update _pending_block.timestamp if the block interval has changed
       perform_chain_maintenance(next_block, global_props);
 
@@ -429,6 +430,13 @@ void database::_apply_block( const signed_block& next_block )
    update_expired_feeds();
    update_withdraw_permissions();
 
+   // n.b., update_maintenance_flag() happens this late
+   // because get_slot_time() / get_slot_at_time() is needed above
+   // TODO:  figure out if we could collapse this function into
+   // update_global_dynamic_data() as perhaps these methods only need
+   // to be called for header validation?
+   update_maintenance_flag( maint_needed );
+
    // notify observers that the block has been applied
    applied_block( next_block ); //emit
    _applied_ops.clear();

libraries/chain/db_init.cpp

@@ -312,6 +312,7 @@ void database::init_genesis(const genesis_state_type& genesis_state)
    });
    create<dynamic_global_property_object>([&](dynamic_global_property_object& p) {
       p.time = genesis_state.initial_timestamp;
+      p.dynamic_flags = 0;
       p.witness_budget = 0;
    });
    create<block_summary_object>([&](block_summary_object&) {});

libraries/chain/db_update.cpp

@@ -261,6 +261,18 @@ void database::update_expired_feeds()
    }
 }
 
+void database::update_maintenance_flag( bool new_maintenance_flag )
+{
+   modify( get_dynamic_global_properties(), [&]( dynamic_global_property_object& dpo )
+   {
+      auto maintenance_flag = dynamic_global_property_object::maintenance_flag;
+      dpo.dynamic_flags =
+           (dpo.dynamic_flags & ~maintenance_flag)
+         | (new_maintenance_flag ? maintenance_flag : 0);
+   } );
+   return;
+}
+
 void database::update_withdraw_permissions()
 {
    auto& permit_index = get_index_type<withdraw_permission_index>().indices().get<by_expiration>();

libraries/chain/include/graphene/chain/database.hpp

@@ -447,6 +447,7 @@ namespace graphene { namespace chain {
          void clear_expired_proposals();
          void clear_expired_orders();
          void update_expired_feeds();
+         void update_maintenance_flag( bool new_maintenance_flag );
          void update_withdraw_permissions();
 
          //////////////////// db_witness_schedule.cpp ////////////////////

libraries/chain/include/graphene/chain/global_property_object.hpp

@@ -82,13 +82,25 @@ namespace graphene { namespace chain {
           */
          uint32_t          recently_missed_count = 0;
 
-         /** if the interval changes then how we calculate witness participation will
-          * also change.  Normally witness participation is defined as % of blocks
-          * produced in the last round which is calculated by dividing the delta
-          * time between block N and N-NUM_WITNESSES by the block interval to calculate
-          * the number of blocks produced.
+         /**
+          * dynamic_flags specifies chain state properties that can be
+          * expressed in one bit.
           */
-         uint32_t          first_maintenance_block_with_current_interval = 0;
+         uint32_t dynamic_flags = 0;
+
+         enum dynamic_flag_bits
+         {
+            /**
+             * If maintenance_flag is set, then the head block is a
+             * maintenance block.  This means
+             * get_time_slot(1) - head_block_time() will have a gap
+             * due to maintenance duration.
+             *
+             * This flag answers the question, "Was maintenance
+             * performed in the last call to apply_block()?"
+             */
+            maintenance_flag = 0x01
+         };
    };
 }}
 
@@ -102,7 +114,7 @@ FC_REFLECT_DERIVED( graphene::chain::dynamic_global_property_object, (graphene::
                     (witness_budget)
                     (accounts_registered_this_interval)
                     (recently_missed_count)
-                    (first_maintenance_block_with_current_interval)
+                    (dynamic_flags)
                   )
 
 FC_REFLECT_DERIVED( graphene::chain::global_property_object, (graphene::db::object),