Cache witness signing key for block producing bitshares#125

Author: abitmore

libraries/chain/db_block.cpp

@@ -352,10 +352,19 @@ signed_block database::_generate_block(
    witness_id_type scheduled_witness = get_scheduled_witness( slot_num );
    FC_ASSERT( scheduled_witness == witness_id );
 
-   const auto& witness_obj = witness_id(*this);
-
    if( !(skip & skip_witness_signature) )
-      FC_ASSERT( witness_obj.signing_key == block_signing_private_key.get_public_key() );
+   {
+      auto signing_key = find_witness_key_from_cache( witness_id );
+      if( signing_key.valid() ) // witness in cache
+      {
+         FC_ASSERT( *signing_key == block_signing_private_key.get_public_key() );
+      }
+      else // witness not in cache
+      {
+         const auto& witness_obj = witness_id(*this);
+         FC_ASSERT( witness_obj.signing_key == block_signing_private_key.get_public_key() );
+      }
+   }
 
    static const size_t max_block_header_size = fc::raw::pack_size( signed_block_header() ) + 4;
    auto maximum_block_size = get_global_properties().parameters.maximum_block_size;
@@ -374,11 +383,12 @@ signed_block database::_generate_block(
    // the value of the "when" variable is known, which means we need to
    // re-apply pending transactions in this method.
    //
+
+   // pop pending state (reset to head block state)
    _pending_tx_session.reset();
    _pending_tx_session = _undo_db.start_undo_session();
 
    uint64_t postponed_tx_count = 0;
-   // pop pending state (reset to head block state)
    for( const processed_transaction& tx : _pending_tx )
    {
       size_t new_total_size = total_block_size + fc::raw::pack_size( tx );
@@ -457,6 +467,9 @@ void database::pop_block()
 
    _popped_tx.insert( _popped_tx.begin(), head_block->transactions.begin(), head_block->transactions.end() );
 
+   // Note: for better performance, can move this to where calls pop_block();
+   refresh_witness_key_cache();
+
 } FC_CAPTURE_AND_RETHROW() }
 
 void database::clear_pending()
@@ -532,6 +545,9 @@ void database::_apply_block( const signed_block& next_block )
 
    _issue_453_affected_assets.clear();
 
+   if( !(skip&skip_witness_key_cache_update) )
+      skip |= force_witness_key_cache_update;
+
    for( const auto& trx : next_block.transactions )
    {
       /* We do not need to push the undo state for each transaction
@@ -720,4 +736,43 @@ bool database::before_last_checkpoint()const
    return (_checkpoints.size() > 0) && (_checkpoints.rbegin()->first >= head_block_num());
 }
 
+void database::init_witness_key_cache( std::set<witness_id_type>& witnesses )
+{
+   for( const witness_id_type& wit : witnesses )
+      _witness_key_cache[wit]; // add it
+}
+
+void database::update_witness_key_cache( witness_id_type wit, const public_key_type& pub_key )
+{
+   if( _witness_key_cache.empty() )
+      return;
+   uint32_t skip = get_node_properties().skip_flags;
+   if( (skip&force_witness_key_cache_update) )
+   {
+      auto itr = _witness_key_cache.find( wit );
+      if( itr != _witness_key_cache.end() )
+         itr->second = pub_key;
+   }
+}
+
+void database::refresh_witness_key_cache()
+{
+   for( auto& wit_key : _witness_key_cache )
+   {
+      const witness_object* wit_obj = find( wit_key.first );
+      if( wit_obj )
+         wit_key.second = wit_obj->signing_key;
+      else
+         wit_key.second.reset();
+   }
+}
+
+optional<public_key_type> database::find_witness_key_from_cache( witness_id_type wit ) const
+{
+   auto itr = _witness_key_cache.find( wit );
+   if( itr != _witness_key_cache.end() )
+      return itr->second;
+   return optional<public_key_type>();
+}
+
 } }

libraries/chain/db_management.cpp

@@ -108,6 +108,7 @@ void database::reindex( fc::path data_dir )
                              skip_transaction_dupe_check |
                              skip_tapos_check |
                              skip_witness_schedule_check |
+                             skip_witness_key_cache_update |
                              skip_authority_check);
       else
       {
@@ -185,6 +186,7 @@ void database::open(
                     ("last_block->id", last_block)("head_block_id",head_block_num()) );
          reindex( data_dir );
       }
+      refresh_witness_key_cache();
       _opened = true;
    }
    FC_CAPTURE_LOG_AND_RETHROW( (data_dir) )

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

@@ -75,8 +75,10 @@ namespace graphene { namespace chain {
             skip_merkle_check           = 1 << 7,  ///< used while reindexing
             skip_assert_evaluation      = 1 << 8,  ///< used while reindexing
             skip_undo_history_check     = 1 << 9,  ///< used while reindexing
-            skip_witness_schedule_check = 1 << 10,  ///< used while reindexing
-            skip_validate               = 1 << 11 ///< used prior to checkpoint, skips validate() call on transaction
+            skip_witness_schedule_check = 1 << 10, ///< used while reindexing
+            skip_validate               = 1 << 11, ///< used prior to checkpoint, skips validate() call on transaction
+            skip_witness_key_cache_update  = 1 << 12, ///< used while reindexing -- do not update cache
+            force_witness_key_cache_update = 1 << 13  ///< used while applying a block but not applying pending transactions
          };
 
          /**
@@ -439,11 +441,19 @@ namespace graphene { namespace chain {
          void                  apply_block( const signed_block& next_block, uint32_t skip = skip_nothing );
          processed_transaction apply_transaction( const signed_transaction& trx, uint32_t skip = skip_nothing );
          operation_result      apply_operation( transaction_evaluation_state& eval_state, const operation& op );
+
+         void                  init_witness_key_cache( std::set<witness_id_type>& witnesses );
+         void                  update_witness_key_cache( witness_id_type wit, const public_key_type& pub_key );
+         void                  refresh_witness_key_cache();
+         optional<public_key_type> find_witness_key_from_cache( witness_id_type wit ) const;
+
       private:
          void                  _apply_block( const signed_block& next_block );
          processed_transaction _apply_transaction( const signed_transaction& trx );
          void                  _cancel_bids_and_revive_mpa( const asset_object& bitasset, const asset_bitasset_data_object& bad );
 
+         flat_map< witness_id_type, optional<public_key_type> > _witness_key_cache;
+
          ///Steps involved in applying a new block
          ///@{
 

libraries/chain/witness_evaluator.cpp

@@ -38,17 +38,21 @@ void_result witness_create_evaluator::do_evaluate( const witness_create_operatio
 
 object_id_type witness_create_evaluator::do_apply( const witness_create_operation& op )
 { try {
+   database& _db = db();
    vote_id_type vote_id;
-   db().modify(db().get_global_properties(), [&vote_id](global_property_object& p) {
+   _db.modify( _db.get_global_properties(), [&vote_id](global_property_object& p) {
       vote_id = get_next_vote_id(p, vote_id_type::witness);
    });
 
-   const auto& new_witness_object = db().create<witness_object>( [&]( witness_object& obj ){
+   const auto& new_witness_object = _db.create<witness_object>( [&op,&vote_id]( witness_object& obj ){
          obj.witness_account  = op.witness_account;
          obj.signing_key      = op.block_signing_key;
          obj.vote_id          = vote_id;
          obj.url              = op.url;
    });
+
+   _db.update_witness_key_cache( new_witness_object.id, op.block_signing_key );
+
    return new_witness_object.id;
 } FC_CAPTURE_AND_RETHROW( (op) ) }
 
@@ -63,13 +67,17 @@ void_result witness_update_evaluator::do_apply( const witness_update_operation&
    database& _db = db();
    _db.modify(
       _db.get(op.witness),
-      [&]( witness_object& wit )
+      [&op]( witness_object& wit )
       {
          if( op.new_url.valid() )
             wit.url = *op.new_url;
          if( op.new_signing_key.valid() )
             wit.signing_key = *op.new_signing_key;
       });
+
+   if( op.new_signing_key.valid() )
+      _db.update_witness_key_cache( op.witness, *op.new_signing_key );
+
    return void_result();
 } FC_CAPTURE_AND_RETHROW( (op) ) }
 

libraries/plugins/witness/witness.cpp

@@ -130,6 +130,9 @@ void witness_plugin::plugin_startup()
             new_chain_banner(d);
          _production_skip_flags |= graphene::chain::database::skip_undo_history_check;
       }
+
+      d.init_witness_key_cache( _witnesses );
+
       schedule_production_loop();
    } else
       elog("No witnesses configured! Please add witness IDs and private keys to configuration.");
@@ -250,7 +253,7 @@ block_production_condition::block_production_condition_enum witness_plugin::mayb
    }
 
    fc::time_point_sec scheduled_time = db.get_slot_time( slot );
-   graphene::chain::public_key_type scheduled_key = scheduled_witness( db ).signing_key;
+   graphene::chain::public_key_type scheduled_key = *db.find_witness_key_from_cache( scheduled_witness ); // should be valid
    auto private_key_itr = _private_keys.find( scheduled_key );
 
    if( private_key_itr == _private_keys.end() )

tests/tests/block_tests.cpp

@@ -264,6 +264,12 @@ BOOST_AUTO_TEST_CASE( change_signing_key )
             PUSH_TX( db, wu_trx, 0 );
          };
 
+         // Initialize witness key cache
+         std::set< witness_id_type > witnesses;
+         for( uint32_t i = 0; i <= 11; ++i ) // 11 init witnesses and 0 is reserved
+            witnesses.insert( witness_id_type(i) );
+         db.init_witness_key_cache( witnesses );
+
          // open database
          db.open(data_dir.path(), make_genesis, "TEST");