Added database_backend config setting

nano/lib/rocksdbconfig.cpp

@@ -4,7 +4,6 @@
 
 nano::error nano::rocksdb_config::serialize_toml (nano::tomlconfig & toml) const
 {
-	toml.put ("enable", enable, "Whether to use the RocksDB backend for the ledger database.\ntype:bool");
 	toml.put ("io_threads", io_threads, "Number of threads to use with the background compaction and flushing.\ntype:uint32");
 	toml.put ("read_cache", read_cache, "Amount of megabytes per table allocated to read cache. Valid range is 1 - 1024. Default is 32.\nCarefully monitor memory usage if non-default values are used\ntype:long");
 	toml.put ("write_cache", write_cache, "Total amount of megabytes allocated to write cache. Valid range is 1 - 256. Default is 64.\nCarefully monitor memory usage if non-default values are used\ntype:long");
@@ -14,7 +13,7 @@ nano::error nano::rocksdb_config::serialize_toml (nano::tomlconfig & toml) const
 
 nano::error nano::rocksdb_config::deserialize_toml (nano::tomlconfig & toml)
 {
-	toml.get_optional<bool> ("enable", enable);
+	toml.get_optional<bool> ("enable", enable); // TODO: This setting can be removed in future versions
 	toml.get_optional<unsigned> ("io_threads", io_threads);
 	toml.get_optional<long> ("read_cache", read_cache);
 	toml.get_optional<long> ("write_cache", write_cache);

nano/node/make_store.cpp

@@ -6,10 +6,17 @@
 
 std::unique_ptr<nano::store::component> nano::make_store (nano::logger & logger, std::filesystem::path const & path, nano::ledger_constants & constants, bool read_only, bool add_db_postfix, nano::node_config const & node_config)
 {
-	if (node_config.rocksdb_config.enable)
+	if (node_config.database_backend == nano::database_backend::rocksdb)
 	{
 		return std::make_unique<nano::store::rocksdb::component> (logger, add_db_postfix ? path / "rocksdb" : path, constants, node_config.rocksdb_config, read_only);
 	}
+	if (node_config.rocksdb_config.enable && node_config.database_backend == nano::database_backend::lmdb)
+	{
+		// rocksdb.enable is true in config, but database_backend is set to LMDB in config
+		logger.critical (nano::log::type::config, "Legacy RocksDb setting detected in config file.");
+		logger.info (nano::log::type::config, "Edit node_config.toml and use 'database_backend' in the node section to re-enable RocksDb");
+		std::exit (EXIT_FAILURE);
+	}
 
 	return std::make_unique<nano::store::lmdb::component> (logger, add_db_postfix ? path / "data.ldb" : path, constants, node_config.diagnostics_config.txn_tracking, node_config.block_processor_batch_max_time, node_config.lmdb_config, node_config.backup_before_upgrade);
 }

nano/node/nodeconfig.cpp

@@ -537,6 +537,8 @@ nano::error nano::node_config::deserialize_toml (nano::tomlconfig & toml)
 		toml.get<bool> ("allow_local_peers", allow_local_peers);
 		toml.get<unsigned> (signature_checker_threads_key, signature_checker_threads);
 
+		database_backend = get_database_backend (toml);
+
 		if (toml.has_key ("lmdb"))
 		{
 			auto lmdb_config_l (toml.get_required_child ("lmdb"));
@@ -659,6 +661,35 @@ void nano::node_config::deserialize_address (std::string const & entry_a, std::v
 	}
 }
 
+std::string nano::node_config::serialize_database_backend (nano::database_backend mode_a) const
+{
+	switch (mode_a)
+	{
+		case nano::database_backend::rocksdb:
+			return "rocksdb";
+		case nano::database_backend::lmdb:
+			return "lmdb";
+	}
+	debug_assert (false);
+}
+
+nano::database_backend nano::node_config::get_database_backend (nano::tomlconfig & toml)
+{
+	if (toml.has_key ("database_backend"))
+	{
+		auto backend_string (toml.get<std::string> ("database_backend"));
+		if (backend_string == "rocksdb")
+			return database_backend::rocksdb;
+		if (backend_string == "lmdb")
+			return database_backend::lmdb;
+
+		toml.get_error ().set ("Unknown database_backend type: " + backend_string);
+		return nano::database_backend::lmdb;
+	}
+	// Default to LMDB
+	return nano::database_backend::lmdb;
+}
+
 nano::account nano::node_config::random_representative () const
 {
 	debug_assert (!preconfigured_representatives.empty ());

nano/node/nodeconfig.hpp

@@ -43,6 +43,12 @@ namespace nano
 {
 class tomlconfig;
 
+enum class database_backend
+{
+	lmdb,
+	rocksdb
+};
+
 /**
  * Node configuration
  */
@@ -133,6 +139,7 @@ class node_config
 	uint64_t max_pruning_depth{ 0 };
 	nano::rocksdb_config rocksdb_config;
 	nano::lmdb_config lmdb_config;
+	nano::database_backend database_backend{ std::string (std::getenv ("BACKEND") ? std::getenv ("BACKEND") : "") == "rocksdb" ? nano::database_backend::rocksdb : nano::database_backend::lmdb };
 	bool enable_upnp{ true };
 	std::size_t max_ledger_notifications{ 8 };
 
@@ -156,6 +163,8 @@ class node_config
 public:
 	/** Entry is ignored if it cannot be parsed as a valid address:port */
 	void deserialize_address (std::string const &, std::vector<std::pair<std::string, uint16_t>> &) const;
+	std::string serialize_database_backend (nano::database_backend) const;
+	nano::database_backend get_database_backend (nano::tomlconfig & toml);
 
 private:
 	static std::optional<unsigned> env_io_threads ();