flush block log/artifacts when it becomes full and new part is opened

Previously files could remain not flushed until they were closed at the end, which could cause them to be broken in case of node crash.

Author: ABW

libraries/chain/block_log.cpp

@@ -460,6 +460,7 @@ namespace hive { namespace chain {
   // no restrictions
   void block_log::flush()
   {
+    my->_artifacts->flush();
     // writes to file descriptors are flushed automatically
   }
 

libraries/chain/block_log_artifacts.cpp

@@ -1044,6 +1044,12 @@ void block_log_artifacts::truncate(uint32_t new_head_block_num)
   _impl->truncate_file(new_head_block_num);
 }
 
+void block_log_artifacts::flush()
+{
+  dlog( "flushing artifacts" );
+  _impl->flush_header();
+}
+
 std::string block_log_artifacts::get_artifacts_contents(const fc::optional<uint32_t>& starting_block_number, const fc::optional<uint32_t>& ending_block_number, bool header_only) const
 {
   return _impl->get_artifacts_contents(starting_block_number, ending_block_number, header_only);

libraries/chain/block_log_wrapper.cpp

@@ -770,6 +770,12 @@ void block_log_wrapper::internal_append( uint32_t first_block_num, size_t block_
   // Is it time to switch to a new file & append there?
   if( is_last_number_of_the_file( first_block_num -1 ) && ( block_part_number > _logs.size() ) )
   {
+    if( not _logs.empty() )
+    {
+      auto current_part_log = get_head_log();
+      if( current_part_log )
+        current_part_log->flush();
+    }
     fc::path new_path = _open_args.data_dir / block_log_file_name_info::get_nth_part_file_name( block_part_number ).c_str();
     const auto new_part_log = std::make_shared<block_log>( _app );
     internal_open_and_init( new_part_log, new_path, false /*read_only*/ );

libraries/chain/include/hive/chain/block_log_artifacts.hpp

@@ -110,6 +110,7 @@ class block_log_artifacts final
   void store_block_artifacts(artifact_data_container_t& artifacts_data, const bool is_at_live_sync);
 
   void truncate(uint32_t new_head_block_num);
+  void flush();
 
   // for block_log_util
   std::string get_artifacts_contents(const fc::optional<uint32_t>& starting_block_number, const fc::optional<uint32_t>& ending_block_number, bool header_only) const;