Optimize block log usage

libraries/chain/block_log.cpp

@@ -319,6 +319,14 @@ namespace eosio { namespace chain {
       return result;
    }
 
+   void block_log::read_block_header(block_header& bh, uint64_t pos)const {
+      my->check_open_files();
+
+      my->block_file.seek(pos);
+      auto ds = my->block_file.create_datastream();
+      fc::raw::unpack(ds, bh);
+   }
+
    signed_block_ptr block_log::read_block_by_num(uint32_t block_num)const {
       try {
          signed_block_ptr b;
@@ -332,6 +340,20 @@ namespace eosio { namespace chain {
       } FC_LOG_AND_RETHROW()
    }
 
+   block_id_type block_log::read_block_id_by_num(uint32_t block_num)const {
+      try {
+         uint64_t pos = get_block_pos(block_num);
+         if (pos != npos) {
+            block_header bh;
+            read_block_header(bh, pos);
+            EOS_ASSERT(bh.block_num() == block_num, reversible_blocks_exception,
+                       "Wrong block header was read from block log.", ("returned", bh.block_num())("expected", block_num));
+            return bh.id();
+         }
+         return {};
+      } FC_LOG_AND_RETHROW()
+   }
+
    uint64_t block_log::get_block_pos(uint32_t block_num) const {
       my->check_open_files();
       if (!(my->head && block_num <= block_header::num_from_id(my->head_id) && block_num >= my->first_block_num))
@@ -365,6 +387,10 @@ namespace eosio { namespace chain {
       return my->head;
    }
 
+   const block_id_type&    block_log::head_id()const {
+      return my->head_id;
+   }
+
    uint32_t block_log::first_block_num() const {
       return my->first_block_num;
    }

libraries/chain/controller.cpp

@@ -377,7 +377,7 @@ struct controller_impl {
       auto root_id = fork_db.root()->id;
 
       if( log_head ) {
-         EOS_ASSERT( root_id == log_head->id(), fork_database_exception, "fork database root does not match block log head" );
+         EOS_ASSERT( root_id == blog.head_id(), fork_database_exception, "fork database root does not match block log head" );
       } else {
          EOS_ASSERT( fork_db.root()->block_num == lib_num, fork_database_exception,
                      "empty block log expects the first appended block to build off a block that is not the fork database root" );
@@ -1654,11 +1654,11 @@ struct controller_impl {
             });
          }
 
+         emit( self.accepted_block, bsp );
+
          if( add_to_fork_db ) {
             log_irreversible();
          }
-
-         emit( self.accepted_block, bsp );
       } catch (...) {
          // dont bother resetting pending, instead abort the block
          reset_pending_on_exit.cancel();
@@ -2697,12 +2697,12 @@ block_id_type controller::last_irreversible_block_id() const {
    if( block_header::num_from_id(tapos_block_summary.block_id) == lib_num )
       return tapos_block_summary.block_id;
 
-   auto signed_blk = my->blog.read_block_by_num( lib_num );
+   auto id = my->blog.read_block_id_by_num( lib_num );
 
-   EOS_ASSERT( BOOST_LIKELY( signed_blk != nullptr ), unknown_block_exception,
+   EOS_ASSERT( BOOST_LIKELY( id != block_id_type() ), unknown_block_exception,
                "Could not find block: ${block}", ("block", lib_num) );
 
-   return signed_blk->id();
+   return id;
 }
 
 const dynamic_global_property_object& controller::get_dynamic_global_properties()const {
@@ -2768,12 +2768,12 @@ block_id_type controller::get_block_id_for_num( uint32_t block_num )const { try
       }
    }
 
-   auto signed_blk = my->blog.read_block_by_num(block_num);
+   auto id = my->blog.read_block_id_by_num(block_num);
 
-   EOS_ASSERT( BOOST_LIKELY( signed_blk != nullptr ), unknown_block_exception,
+   EOS_ASSERT( BOOST_LIKELY( id != block_id_type() ), unknown_block_exception,
                "Could not find block: ${block}", ("block", block_num) );
 
-   return signed_blk->id();
+   return id;
 } FC_CAPTURE_AND_RETHROW( (block_num) ) }
 
 sha256 controller::calculate_integrity_hash()const { try {

libraries/chain/include/eosio/chain/block_log.hpp

@@ -43,7 +43,9 @@ namespace eosio { namespace chain {
          void reset( const genesis_state& gs, const signed_block_ptr& genesis_block, uint32_t first_block_num = 1 );
 
          signed_block_ptr read_block(uint64_t file_pos)const;
+         void             read_block_header(block_header& bh, uint64_t file_pos)const;
          signed_block_ptr read_block_by_num(uint32_t block_num)const;
+         block_id_type    read_block_id_by_num(uint32_t block_num)const;
          signed_block_ptr read_block_by_id(const block_id_type& id)const {
             return read_block_by_num(block_header::num_from_id(id));
          }
@@ -54,6 +56,7 @@ namespace eosio { namespace chain {
          uint64_t get_block_pos(uint32_t block_num) const;
          signed_block_ptr        read_head()const;
          const signed_block_ptr& head()const;
+         const block_id_type&    head_id()const;
          uint32_t                first_block_num() const;
 
          static const uint64_t npos = std::numeric_limits<uint64_t>::max();