Check block CLI command (#4240)

* Check block operation

* Update client/cli/src/lib.rs

* Update client/cli/src/params.rs

substrate/bin/node-template/src/cli.rs

@@ -44,6 +44,8 @@ pub fn run<I, T, E>(args: I, exit: E, version: VersionInfo) -> error::Result<()>
 			Ok(new_full_start!(config).0), load_spec, exit),
 		ParseAndPrepare::ImportBlocks(cmd) => cmd.run_with_builder(|config: Config<_>|
 			Ok(new_full_start!(config).0), load_spec, exit),
+		ParseAndPrepare::CheckBlock(cmd) => cmd.run_with_builder(|config: Config<_>|
+			Ok(new_full_start!(config).0), load_spec, exit),
 		ParseAndPrepare::PurgeChain(cmd) => cmd.run(load_spec),
 		ParseAndPrepare::RevertChain(cmd) => cmd.run_with_builder(|config: Config<_>|
 			Ok(new_full_start!(config).0), load_spec),

substrate/bin/node/cli/src/cli.rs

@@ -136,6 +136,8 @@ pub fn run<I, T, E>(args: I, exit: E, version: substrate_cli::VersionInfo) -> er
 			Ok(new_full_start!(config).0), load_spec, exit),
 		ParseAndPrepare::ImportBlocks(cmd) => cmd.run_with_builder(|config: Config<_, _>|
 			Ok(new_full_start!(config).0), load_spec, exit),
+		ParseAndPrepare::CheckBlock(cmd) => cmd.run_with_builder(|config: Config<_, _>|
+			Ok(new_full_start!(config).0), load_spec, exit),
 		ParseAndPrepare::PurgeChain(cmd) => cmd.run(load_spec),
 		ParseAndPrepare::RevertChain(cmd) => cmd.run_with_builder(|config: Config<_, _>|
 			Ok(new_full_start!(config).0), load_spec),

substrate/bin/node/cli/src/service.rs

@@ -568,6 +568,7 @@ mod tests {
 					auxiliary: Vec::new(),
 					fork_choice: ForkChoiceStrategy::LongestChain,
 					allow_missing_state: false,
+					import_existing: false,
 				};
 
 				block_import.import_block(params, Default::default())

substrate/client/cli/src/lib.rs

@@ -29,7 +29,7 @@ pub mod informant;
 use client_api::execution_extensions::ExecutionStrategies;
 use service::{
 	config::{Configuration, DatabaseConfig},
-	ServiceBuilderExport, ServiceBuilderImport, ServiceBuilderRevert,
+	ServiceBuilderCommand,
 	RuntimeGenesis, ChainSpecExtension, PruningMode, ChainSpec,
 };
 use network::{
@@ -54,7 +54,7 @@ pub use structopt::clap::App;
 use params::{
 	RunCmd, PurgeChainCmd, RevertCmd, ImportBlocksCmd, ExportBlocksCmd, BuildSpecCmd,
 	NetworkConfigurationParams, MergeParameters, TransactionPoolParams,
-	NodeKeyParams, NodeKeyType, Cors,
+	NodeKeyParams, NodeKeyType, Cors, CheckBlockCmd,
 };
 pub use params::{NoCustom, CoreParams, SharedParams, ExecutionStrategy as ExecutionStrategyParam};
 pub use traits::{GetLogFilter, AugmentClap};
@@ -64,6 +64,8 @@ use lazy_static::lazy_static;
 use futures::{Future, FutureExt, TryFutureExt};
 use futures01::{Async, Future as _};
 use substrate_telemetry::TelemetryEndpoints;
+use sr_primitives::generic::BlockId;
+use sr_primitives::traits::Block as BlockT;
 
 /// default sub directory to store network config
 const DEFAULT_NETWORK_CONFIG_PATH : &'static str = "network";
@@ -231,6 +233,9 @@ where
 		params::CoreParams::ImportBlocks(params) => ParseAndPrepare::ImportBlocks(
 			ParseAndPrepareImport { params, version }
 		),
+		params::CoreParams::CheckBlock(params) => ParseAndPrepare::CheckBlock(
+			CheckBlock { params, version }
+		),
 		params::CoreParams::PurgeChain(params) => ParseAndPrepare::PurgeChain(
 			ParseAndPreparePurge { params, version }
 		),
@@ -263,6 +268,8 @@ pub enum ParseAndPrepare<'a, CC, RP> {
 	ExportBlocks(ParseAndPrepareExport<'a>),
 	/// Command ready to import the chain.
 	ImportBlocks(ParseAndPrepareImport<'a>),
+	/// Command to check a block.
+	CheckBlock(CheckBlock<'a>),
 	/// Command ready to purge the chain.
 	PurgeChain(ParseAndPreparePurge<'a>),
 	/// Command ready to revert the chain.
@@ -366,7 +373,7 @@ impl<'a> ParseAndPrepareExport<'a> {
 	) -> error::Result<()>
 	where S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
 		F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
-		B: ServiceBuilderExport,
+		B: ServiceBuilderCommand,
 		C: Default,
 		G: RuntimeGenesis,
 		E: ChainSpecExtension,
@@ -427,19 +434,13 @@ impl<'a> ParseAndPrepareImport<'a> {
 	) -> error::Result<()>
 	where S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
 		F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
-		B: ServiceBuilderImport,
+		B: ServiceBuilderCommand,
 		C: Default,
 		G: RuntimeGenesis,
 		E: ChainSpecExtension,
 		Exit: IntoExit
 	{
-		let mut config = create_config_with_db_path(spec_factory, &self.params.shared_params, self.version)?;
+		let config = create_config_with_db_path(spec_factory, &self.params.shared_params, self.version)?;
-		config.wasm_method = self.params.wasm_method.into();
-		config.execution_strategies = ExecutionStrategies {
-			importing: self.params.execution.into(),
-			other: self.params.execution.into(),
-			..Default::default()
-		};
 
 		let file: Box<dyn ReadPlusSeek + Send> = match self.params.input {
 			Some(filename) => Box::new(File::open(filename)?),
@@ -461,7 +462,7 @@ impl<'a> ParseAndPrepareImport<'a> {
 			let _ = exit_send.send(());
 		});
 
-		let mut import_fut = builder(config)?.import_blocks(file);
+		let mut import_fut = builder(config)?.import_blocks(file, false);
 		let fut = futures01::future::poll_fn(|| {
 			if exit_recv.try_recv().is_ok() {
 				return Ok(Async::Ready(()));
@@ -475,6 +476,49 @@ impl<'a> ParseAndPrepareImport<'a> {
 	}
 }
 
+/// Command to check a block.
+pub struct CheckBlock<'a> {
+	params: CheckBlockCmd,
+	version: &'a VersionInfo,
+}
+
+impl<'a> CheckBlock<'a> {
+	/// Runs the command and imports to the chain.
+	pub fn run_with_builder<C, G, E, F, B, S, Exit>(
+		self,
+		builder: F,
+		spec_factory: S,
+		_exit: Exit,
+	) -> error::Result<()>
+		where S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
+			F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
+			B: ServiceBuilderCommand,
+			<<B as ServiceBuilderCommand>::Block as BlockT>::Hash: FromStr,
+			C: Default,
+			G: RuntimeGenesis,
+			E: ChainSpecExtension,
+			Exit: IntoExit
+	{
+		let config = create_config_with_db_path(spec_factory, &self.params.shared_params, self.version)?;
+
+		let input = if self.params.input.starts_with("0x") { &self.params.input[2..] } else { &self.params.input[..] };
+		let block_id = match FromStr::from_str(input) {
+			Ok(hash) => BlockId::hash(hash),
+			Err(_) => match self.params.input.parse::<u32>() {
+				Ok(n) => BlockId::number((n as u32).into()),
+				Err(_) => return Err(error::Error::Input("Invalid hash or number specified".into())),
+			}
+		};
+
+		let start = std::time::Instant::now();
+		let check = builder(config)?.check_block(block_id);
+		let mut runtime = tokio::runtime::current_thread::Runtime::new().unwrap();
+		runtime.block_on(check)?;
+		println!("Completed in {} ms.", start.elapsed().as_millis());
+		Ok(())
+	}
+}
+
 /// Command ready to purge the chain.
 pub struct ParseAndPreparePurge<'a> {
 	params: PurgeChainCmd,
@@ -548,7 +592,7 @@ impl<'a> ParseAndPrepareRevert<'a> {
 	) -> error::Result<()> where
 		S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
 		F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
-		B: ServiceBuilderRevert,
+		B: ServiceBuilderCommand,
 		C: Default,
 		G: RuntimeGenesis,
 		E: ChainSpecExtension,
@@ -694,6 +738,55 @@ fn fill_config_keystore_password<C, G, E>(
 	Ok(())
 }
 
+fn fill_shared_config<C, G, E>(config: &mut Configuration<C, G, E>, cli: &SharedParams, role: service::Roles)
+	-> error::Result<()>
+where
+	C: Default,
+	G: RuntimeGenesis,
+	E: ChainSpecExtension,
+{
+	config.database = DatabaseConfig::Path {
+		path: config.in_chain_config_dir(DEFAULT_DB_CONFIG_PATH).expect("We provided a base_path."),
+		cache_size: Some(cli.database_cache_size),
+	};
+	config.state_cache_size = cli.state_cache_size;
+
+	// by default we disable pruning if the node is an authority (i.e.
+	// `ArchiveAll`), otherwise we keep state for the last 256 blocks. if the
+	// node is an authority and pruning is enabled explicitly, then we error
+	// unless `unsafe_pruning` is set.
+	config.pruning = match &cli.pruning {
+		Some(ref s) if s == "archive" => PruningMode::ArchiveAll,
+		None if role == service::Roles::AUTHORITY => PruningMode::ArchiveAll,
+		None => PruningMode::default(),
+		Some(s) => {
+			if role == service::Roles::AUTHORITY && !cli.unsafe_pruning {
+				return Err(error::Error::Input(
+					"Validators should run with state pruning disabled (i.e. archive). \
+					You can ignore this check with `--unsafe-pruning`.".to_string()
+				));
+			}
+
+			PruningMode::keep_blocks(s.parse()
+				.map_err(|_| error::Error::Input("Invalid pruning mode specified".to_string()))?
+			)
+		},
+	};
+
+	config.wasm_method = cli.wasm_method.into();
+
+	let exec = &cli.execution_strategies;
+	let exec_all_or = |strat: params::ExecutionStrategy| exec.execution.unwrap_or(strat).into();
+	config.execution_strategies = ExecutionStrategies {
+		syncing: exec_all_or(exec.execution_syncing),
+		importing: exec_all_or(exec.execution_import_block),
+		block_construction: exec_all_or(exec.execution_block_construction),
+		offchain_worker: exec_all_or(exec.execution_offchain_worker),
+		other: exec_all_or(exec.execution_other),
+	};
+	Ok(())
+}
+
 fn create_run_node_config<C, G, E, S>(
 	cli: RunCmd, spec_factory: S, impl_name: &'static str, version: &VersionInfo,
 ) -> error::Result<Configuration<C, G, E>>
@@ -709,6 +802,19 @@ where
 
 	fill_config_keystore_password(&mut config, &cli)?;
 
+	let is_dev = cli.shared_params.dev;
+	let is_authority = cli.validator || cli.sentry || is_dev || cli.keyring.account.is_some();
+	let role =
+		if cli.light {
+			service::Roles::LIGHT
+		} else if is_authority {
+			service::Roles::AUTHORITY
+		} else {
+			service::Roles::FULL
+		};
+
+	fill_shared_config(&mut config, &cli.shared_params, role)?;
+
 	config.impl_name = impl_name;
 	config.impl_commit = version.commit;
 	config.impl_version = version.version;
@@ -731,61 +837,9 @@ where
 
 	config.keystore_path = cli.keystore_path.or_else(|| config.in_chain_config_dir(DEFAULT_KEYSTORE_CONFIG_PATH));
 
-	config.database = DatabaseConfig::Path {
-		path: config.in_chain_config_dir(DEFAULT_DB_CONFIG_PATH).expect("We provided a base_path."),
-		cache_size: Some(cli.database_cache_size),
-	};
-	config.state_cache_size = cli.state_cache_size;
-
-	let is_dev = cli.shared_params.dev;
-	let is_authority = cli.validator || cli.sentry || is_dev || cli.keyring.account.is_some();
-
-	let role =
-		if cli.light {
-			service::Roles::LIGHT
-		} else if is_authority {
-			service::Roles::AUTHORITY
-		} else {
-			service::Roles::FULL
-		};
-
 	// set sentry mode (i.e. act as an authority but **never** actively participate)
 	config.sentry_mode = cli.sentry;
 
-	// by default we disable pruning if the node is an authority (i.e.
-	// `ArchiveAll`), otherwise we keep state for the last 256 blocks. if the
-	// node is an authority and pruning is enabled explicitly, then we error
-	// unless `unsafe_pruning` is set.
-	config.pruning = match cli.pruning {
-		Some(ref s) if s == "archive" => PruningMode::ArchiveAll,
-		None if role == service::Roles::AUTHORITY => PruningMode::ArchiveAll,
-		None => PruningMode::default(),
-		Some(s) => {
-			if role == service::Roles::AUTHORITY && !cli.unsafe_pruning {
-				return Err(error::Error::Input(
-					"Validators should run with state pruning disabled (i.e. archive). \
-					You can ignore this check with `--unsafe-pruning`.".to_string()
-				));
-			}
-
-			PruningMode::keep_blocks(s.parse()
-				.map_err(|_| error::Error::Input("Invalid pruning mode specified".to_string()))?
-			)
-		},
-	};
-
-	config.wasm_method = cli.wasm_method.into();
-
-	let exec = cli.execution_strategies;
-	let exec_all_or = |strat: params::ExecutionStrategy| exec.execution.unwrap_or(strat).into();
-	config.execution_strategies = ExecutionStrategies {
-		syncing: exec_all_or(exec.execution_syncing),
-		importing: exec_all_or(exec.execution_import_block),
-		block_construction: exec_all_or(exec.execution_block_construction),
-		offchain_worker: exec_all_or(exec.execution_offchain_worker),
-		other: exec_all_or(exec.execution_other),
-	};
-
 	config.offchain_worker = match (cli.offchain_worker, role) {
 		(params::OffchainWorkerEnabled::WhenValidating, service::Roles::AUTHORITY) => true,
 		(params::OffchainWorkerEnabled::Always, _) => true,
@@ -871,11 +925,7 @@ where
 	let base_path = base_path(cli, version);
 
 	let mut config = service::Configuration::default_with_spec_and_base_path(spec.clone(), Some(base_path));
-	config.database = DatabaseConfig::Path {
+	fill_shared_config(&mut config, &cli, service::Roles::FULL)?;
-		path: config.in_chain_config_dir(DEFAULT_DB_CONFIG_PATH).expect("We provided a base_path."),
-		cache_size: None,
-	};
-
 	Ok(config)
 }
 
@@ -943,14 +993,15 @@ fn init_logger(pattern: &str) {
 			)
 		};
 
-		if !enable_color {
-			output = kill_color(output.as_ref());
-		}
-
 		if !isatty && record.level() <= log::Level::Info && atty::is(atty::Stream::Stdout) {
 			// duplicate INFO/WARN output to console
 			println!("{}", output);
 		}
+
+		if !enable_color {
+			output = kill_color(output.as_ref());
+		}
+
 		writeln!(buf, "{}", output)
 	});
 

substrate/client/cli/src/params.rs

@@ -46,7 +46,7 @@ impl Into<client_api::ExecutionStrategy> for ExecutionStrategy {
 arg_enum! {
 	/// How to execute Wasm runtime code
 	#[allow(missing_docs)]
-	#[derive(Debug, Clone)]
+	#[derive(Debug, Clone, Copy)]
 	pub enum WasmExecutionMethod {
 		// Uses an interpreter.
 		Interpreted,
@@ -109,6 +109,44 @@ pub struct SharedParams {
 	/// Sets a custom logging filter.
 	#[structopt(short = "l", long = "log", value_name = "LOG_PATTERN")]
 	pub log: Option<String>,
+
+	/// Specify the state pruning mode, a number of blocks to keep or 'archive'.
+	///
+	/// Default is to keep all block states if the node is running as a
+	/// validator (i.e. 'archive'), otherwise state is only kept for the last
+	/// 256 blocks.
+	#[structopt(long = "pruning", value_name = "PRUNING_MODE")]
+	pub pruning: Option<String>,
+
+	/// Force start with unsafe pruning settings.
+	///
+	/// When running as a validator it is highly recommended to disable state
+	/// pruning (i.e. 'archive') which is the default. The node will refuse to
+	/// start as a validator if pruning is enabled unless this option is set.
+	#[structopt(long = "unsafe-pruning")]
+	pub unsafe_pruning: bool,
+
+	/// Method for executing Wasm runtime code.
+	#[structopt(
+		long = "wasm-execution",
+		value_name = "METHOD",
+		possible_values = &WasmExecutionMethod::enabled_variants(),
+		case_insensitive = true,
+		default_value = "Interpreted"
+	)]
+	pub wasm_method: WasmExecutionMethod,
+
+	#[allow(missing_docs)]
+	#[structopt(flatten)]
+	pub execution_strategies: ExecutionStrategies,
+
+	/// Limit the memory the database cache can use.
+	#[structopt(long = "db-cache", value_name = "MiB", default_value = "1024")]
+	pub database_cache_size: u32,
+
+	/// Specify the state cache size.
+	#[structopt(long = "state-cache-size", value_name = "Bytes", default_value = "67108864")]
+	pub state_cache_size: usize,
 }
 
 impl GetLogFilter for SharedParams {
@@ -386,14 +424,6 @@ pub struct RunCmd {
 	#[structopt(long = "light")]
 	pub light: bool,
 
-	/// Limit the memory the database cache can use.
-	#[structopt(long = "db-cache", value_name = "MiB", default_value = "1024")]
-	pub database_cache_size: u32,
-
-	/// Specify the state cache size.
-	#[structopt(long = "state-cache-size", value_name = "Bytes", default_value = "67108864")]
-	pub state_cache_size: usize,
-
 	/// Listen to all RPC interfaces.
 	///
 	/// Default is local.
@@ -438,22 +468,6 @@ pub struct RunCmd {
 	#[structopt(long = "grafana-port", value_name = "PORT")]
 	pub grafana_port: Option<u16>,
 
-	/// Specify the state pruning mode, a number of blocks to keep or 'archive'.
-	///
-	/// Default is to keep all block states if the node is running as a
-	/// validator (i.e. 'archive'), otherwise state is only kept for the last
-	/// 256 blocks.
-	#[structopt(long = "pruning", value_name = "PRUNING_MODE")]
-	pub pruning: Option<String>,
-
-	/// Force start with unsafe pruning settings.
-	///
-	/// When running as a validator it is highly recommended to disable state
-	/// pruning (i.e. 'archive') which is the default. The node will refuse to
-	/// start as a validator if pruning is enabled unless this option is set.
-	#[structopt(long = "unsafe-pruning")]
-	pub unsafe_pruning: bool,
-
 	/// The human-readable name for this node.
 	///
 	/// The node name will be reported to the telemetry server, if enabled.
@@ -487,20 +501,6 @@ pub struct RunCmd {
 	)]
 	pub offchain_worker: OffchainWorkerEnabled,
 
-	/// Method for executing Wasm runtime code.
-	#[structopt(
-		long = "wasm-execution",
-		value_name = "METHOD",
-		possible_values = &WasmExecutionMethod::enabled_variants(),
-		case_insensitive = true,
-		default_value = "Interpreted"
-	)]
-	pub wasm_method: WasmExecutionMethod,
-
-	#[allow(missing_docs)]
-	#[structopt(flatten)]
-	pub execution_strategies: ExecutionStrategies,
-
 	#[allow(missing_docs)]
 	#[structopt(flatten)]
 	pub shared_params: SharedParams,
@@ -764,30 +764,30 @@ pub struct ImportBlocksCmd {
 	#[allow(missing_docs)]
 	#[structopt(flatten)]
 	pub shared_params: SharedParams,
-
-	/// Method for executing Wasm runtime code.
-	#[structopt(
-		long = "wasm-execution",
-		value_name = "METHOD",
-		possible_values = &WasmExecutionMethod::variants(),
-		case_insensitive = true,
-		default_value = "Interpreted"
-	)]
-	pub wasm_method: WasmExecutionMethod,
-
-	/// The means of execution used when calling into the runtime while importing blocks.
-	#[structopt(
-		long = "execution",
-		value_name = "STRATEGY",
-		possible_values = &ExecutionStrategy::variants(),
-		case_insensitive = true,
-		default_value = "NativeElseWasm"
-	)]
-	pub execution: ExecutionStrategy,
 }
 
 impl_get_log_filter!(ImportBlocksCmd);
 
+/// The `check-block` command used to validate blocks.
+#[derive(Debug, StructOpt, Clone)]
+pub struct CheckBlockCmd {
+	/// Block hash or number
+	#[structopt(value_name = "HASH or NUMBER")]
+	pub input: String,
+
+	/// The default number of 64KB pages to ever allocate for Wasm execution.
+	///
+	/// Don't alter this unless you know what you're doing.
+	#[structopt(long = "default-heap-pages", value_name = "COUNT")]
+	pub default_heap_pages: Option<u32>,
+
+	#[allow(missing_docs)]
+	#[structopt(flatten)]
+	pub shared_params: SharedParams,
+}
+
+impl_get_log_filter!(CheckBlockCmd);
+
 /// The `revert` command used revert the chain to a previous state.
 #[derive(Debug, StructOpt, Clone)]
 pub struct RevertCmd {
@@ -835,6 +835,9 @@ pub enum CoreParams<CC, RP> {
 	/// Import blocks from file.
 	ImportBlocks(ImportBlocksCmd),
 
+	/// Validte a single block.
+	CheckBlock(CheckBlockCmd),
+
 	/// Revert chain to the previous state.
 	Revert(RevertCmd),
 
@@ -868,6 +871,10 @@ impl<CC, RP> StructOpt for CoreParams<CC, RP> where
 			ImportBlocksCmd::augment_clap(SubCommand::with_name("import-blocks"))
 				.about("Import blocks from file.")
 		)
+		.subcommand(
+			CheckBlockCmd::augment_clap(SubCommand::with_name("check-block"))
+				.about("Re-validate a known block.")
+		)
 		.subcommand(
 			RevertCmd::augment_clap(SubCommand::with_name("revert"))
 				.about("Revert chain to the previous state.")
@@ -886,6 +893,8 @@ impl<CC, RP> StructOpt for CoreParams<CC, RP> where
 				CoreParams::ExportBlocks(ExportBlocksCmd::from_clap(matches)),
 			("import-blocks", Some(matches)) =>
 				CoreParams::ImportBlocks(ImportBlocksCmd::from_clap(matches)),
+			("check-block", Some(matches)) =>
+				CoreParams::CheckBlock(CheckBlockCmd::from_clap(matches)),
 			("revert", Some(matches)) => CoreParams::Revert(RevertCmd::from_clap(matches)),
 			("purge-chain", Some(matches)) =>
 				CoreParams::PurgeChain(PurgeChainCmd::from_clap(matches)),
@@ -902,6 +911,7 @@ impl<CC, RP> GetLogFilter for CoreParams<CC, RP> where CC: GetLogFilter {
 			CoreParams::BuildSpec(c) => c.get_log_filter(),
 			CoreParams::ExportBlocks(c) => c.get_log_filter(),
 			CoreParams::ImportBlocks(c) => c.get_log_filter(),
+			CoreParams::CheckBlock(c) => c.get_log_filter(),
 			CoreParams::PurgeChain(c) => c.get_log_filter(),
 			CoreParams::Revert(c) => c.get_log_filter(),
 			CoreParams::Custom(c) => c.get_log_filter(),

substrate/client/consensus/aura/src/lib.rs

@@ -281,6 +281,7 @@ impl<H, B, C, E, I, P, Error, SO> slots::SimpleSlotWorker<B> for AuraWorker<C, E
 				auxiliary: Vec::new(),
 				fork_choice: ForkChoiceStrategy::LongestChain,
 				allow_missing_state: false,
+				import_existing: false,
 			}
 		})
 	}
@@ -590,6 +591,7 @@ impl<B: BlockT, C, P, T> Verifier<B> for AuraVerifier<C, P, T> where
 					auxiliary: Vec::new(),
 					fork_choice: ForkChoiceStrategy::LongestChain,
 					allow_missing_state: false,
+					import_existing: false,
 				};
 
 				Ok((block_import_params, maybe_keys))

substrate/client/consensus/babe/src/lib.rs

@@ -436,6 +436,7 @@ impl<B, C, E, I, Error, SO> slots::SimpleSlotWorker<B> for BabeWorker<B, C, E, I
 				// https://github.com/paritytech/substrate/issues/3623
 				fork_choice: ForkChoiceStrategy::LongestChain,
 				allow_missing_state: false,
+				import_existing: false,
 			}
 		})
 	}
@@ -775,6 +776,7 @@ impl<B, E, Block, RA, PRA> Verifier<Block> for BabeVerifier<B, E, Block, RA, PRA
 					// https://github.com/paritytech/substrate/issues/3623
 					fork_choice: ForkChoiceStrategy::LongestChain,
 					allow_missing_state: false,
+					import_existing: false,
 				};
 
 				Ok((block_import_params, Default::default()))

substrate/client/consensus/babe/src/tests.rs

@@ -579,6 +579,7 @@ fn propose_and_import_block(
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		},
 		Default::default(),
 	).unwrap();

substrate/client/consensus/pow/src/lib.rs

@@ -304,6 +304,7 @@ impl<B: BlockT<Hash=H256>, C, S, Algorithm> Verifier<B> for PowVerifier<B, C, S,
 			auxiliary: vec![(key, Some(aux.encode()))],
 			fork_choice: ForkChoiceStrategy::Custom(aux.total_difficulty > best_aux.total_difficulty),
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		Ok((import_block, None))
@@ -532,6 +533,7 @@ fn mine_loop<B: BlockT<Hash=H256>, C, Algorithm, E, SO, S>(
 			auxiliary: vec![(key, Some(aux.encode()))],
 			fork_choice: ForkChoiceStrategy::Custom(true),
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		block_import.import_block(import_block, HashMap::default())

substrate/client/finality-grandpa/src/light_import.rs

@@ -659,6 +659,7 @@ pub mod tests {
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: true,
+			import_existing: false,
 		};
 		do_import_block::<_, _, _, TestJustification>(
 			&client,

substrate/client/finality-grandpa/src/tests.rs

@@ -975,6 +975,7 @@ fn allows_reimporting_change_blocks() {
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		}
 	};
 
@@ -1028,6 +1029,7 @@ fn test_bad_justification() {
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		}
 	};
 
@@ -1738,6 +1740,7 @@ fn imports_justification_for_regular_blocks_on_import() {
 		auxiliary: Vec::new(),
 		fork_choice: ForkChoiceStrategy::LongestChain,
 		allow_missing_state: false,
+		import_existing: false,
 	};
 
 	assert_eq!(

substrate/client/network/src/protocol/sync.rs

@@ -662,6 +662,7 @@ impl<B: BlockT> ChainSync<B> {
 									justification: block_data.block.justification,
 									origin: block_data.origin,
 									allow_missing_state: false,
+									import_existing: false,
 								}
 							}).collect()
 					}
@@ -675,6 +676,7 @@ impl<B: BlockT> ChainSync<B> {
 								justification: b.justification,
 								origin: Some(who.clone()),
 								allow_missing_state: true,
+								import_existing: false,
 							}
 						}).collect()
 					}

substrate/client/network/src/test/block_import.rs

@@ -41,6 +41,7 @@ fn prepare_good_block() -> (TestClient, Hash, u64, PeerId, IncomingBlock<Block>)
 		justification,
 		origin: Some(peer_id.clone()),
 		allow_missing_state: false,
+		import_existing: false,
 	})
 }
 

substrate/client/network/src/test/mod.rs

@@ -99,6 +99,7 @@ impl<B: BlockT> Verifier<B> for PassThroughVerifier {
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		}, maybe_keys))
 	}
 }

substrate/client/service/src/builder.rs

@@ -25,7 +25,6 @@ use client_api::{
 };
 use client::Client;
 use chain_spec::{RuntimeGenesis, Extension};
-use codec::{Decode, Encode, IoReader};
 use consensus_common::import_queue::ImportQueue;
 use futures::{prelude::*, sync::mpsc};
 use futures03::{
@@ -44,8 +43,7 @@ use rpc;
 use sr_api::ConstructRuntimeApi;
 use sr_primitives::generic::BlockId;
 use sr_primitives::traits::{
-	Block as BlockT, ProvideRuntimeApi, NumberFor, One,
+	Block as BlockT, ProvideRuntimeApi, NumberFor, Header, SaturatedConversion,
-	Zero, Header, SaturatedConversion,
 };
 use substrate_executor::{NativeExecutor, NativeExecutionDispatch};
 use std::{
@@ -80,12 +78,12 @@ pub struct ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImp
 	TNetP, TExPool, TRpc, Backend>
 {
 	config: Configuration<TCfg, TGen, TCSExt>,
-	client: Arc<TCl>,
+	pub (crate) client: Arc<TCl>,
 	backend: Arc<Backend>,
 	keystore: Arc<RwLock<Keystore>>,
 	fetcher: Option<TFchr>,
 	select_chain: Option<TSc>,
-	import_queue: TImpQu,
+	pub (crate) import_queue: TImpQu,
 	finality_proof_request_builder: Option<TFprb>,
 	finality_proof_provider: Option<TFpp>,
 	network_protocol: TNetP,
@@ -660,21 +658,17 @@ impl<TBl, TRtApi, TCfg, TGen, TCSExt, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TNet
 	}
 }
 
-/// Implemented on `ServiceBuilder`. Allows importing blocks once you have given all the required
+/// Implemented on `ServiceBuilder`. Allows running block commands, such as import/export/validate
 /// components to the builder.
-pub trait ServiceBuilderImport {
+pub trait ServiceBuilderCommand {
+	/// Block type this API operates on.
+	type Block: BlockT;
 	/// Starts the process of importing blocks.
 	fn import_blocks(
 		self,
 		input: impl Read + Seek + Send + 'static,
+		force: bool,
 	) -> Box<dyn Future<Item = (), Error = Error> + Send>;
-}
-
-/// Implemented on `ServiceBuilder`. Allows exporting blocks once you have given all the required
-/// components to the builder.
-pub trait ServiceBuilderExport {
-	/// Type of block of the builder.
-	type Block: BlockT;
 
 	/// Performs the blocks export.
 	fn export_blocks(
@@ -684,85 +678,18 @@ pub trait ServiceBuilderExport {
 		to: Option<NumberFor<Self::Block>>,
 		json: bool
 	) -> Box<dyn Future<Item = (), Error = Error>>;
-}
 
-/// Implemented on `ServiceBuilder`. Allows reverting the chain once you have given all the
+	/// Performs a revert of `blocks` blocks.
-/// required components to the builder.
-pub trait ServiceBuilderRevert {
-	/// Type of block of the builder.
-	type Block: BlockT;
-
-	/// Performs a revert of `blocks` bocks.
 	fn revert_chain(
 		&self,
 		blocks: NumberFor<Self::Block>
 	) -> Result<(), Error>;
-}
 
-impl<
+	/// Re-validate known block.
-	TBl, TRtApi, TCfg, TGen, TCSExt, TBackend,
+	fn check_block(
-	TExec, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP,
-	TExPool, TRpc, Backend
-> ServiceBuilderImport for ServiceBuilder<
-	TBl, TRtApi, TCfg, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
-	TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, Backend
-> where
-	TBl: BlockT<Hash = <Blake2Hasher as Hasher>::Out>,
-	TBackend: 'static + client_api::backend::Backend<TBl, Blake2Hasher> + Send,
-	TExec: 'static + client::CallExecutor<TBl, Blake2Hasher> + Send + Sync + Clone,
-	TImpQu: 'static + ImportQueue<TBl>,
-	TRtApi: 'static + Send + Sync,
-{
-	fn import_blocks(
 		self,
-		input: impl Read + Seek + Send + 'static,
+		block: BlockId<Self::Block>
-	) -> Box<dyn Future<Item = (), Error = Error> + Send> {
+	) -> Box<dyn Future<Item = (), Error = Error> + Send>;
-		let client = self.client;
-		let mut queue = self.import_queue;
-		Box::new(import_blocks!(TBl, client, queue, input).compat())
-	}
-}
-
-impl<TBl, TRtApi, TCfg, TGen, TCSExt, TBackend, TExec, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc>
-	ServiceBuilderExport for ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
-		TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, TBackend>
-where
-	TBl: BlockT<Hash = <Blake2Hasher as Hasher>::Out>,
-	TBackend: 'static + client_api::backend::Backend<TBl, Blake2Hasher> + Send,
-	TExec: 'static + client::CallExecutor<TBl, Blake2Hasher> + Send + Sync + Clone,
-	TRtApi: 'static + Send + Sync,
-{
-	type Block = TBl;
-
-	fn export_blocks(
-		self,
-		mut output: impl Write + 'static,
-		from: NumberFor<TBl>,
-		to: Option<NumberFor<TBl>>,
-		json: bool
-	) -> Box<dyn Future<Item = (), Error = Error>> {
-		let client = self.client;
-		Box::new(export_blocks!(client, output, from, to, json).compat())
-	}
-}
-
-impl<TBl, TRtApi, TCfg, TGen, TCSExt, TBackend, TExec, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc>
-	ServiceBuilderRevert for ServiceBuilder<TBl, TRtApi, TCfg, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
-		TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, TBackend>
-where
-	TBl: BlockT<Hash = <Blake2Hasher as Hasher>::Out>,
-	TBackend: 'static + client_api::backend::Backend<TBl, Blake2Hasher> + Send,
-	TExec: 'static + client::CallExecutor<TBl, Blake2Hasher> + Send + Sync + Clone
-{
-	type Block = TBl;
-
-	fn revert_chain(
-		&self,
-		blocks: NumberFor<TBl>
-	) -> Result<(), Error> {
-		let client = &self.client;
-		revert_chain!(client, blocks)
-	}
 }
 
 impl<TBl, TRtApi, TCfg, TGen, TCSExt, TBackend, TExec, TSc, TImpQu, TNetP, TExPool, TRpc>

substrate/client/service/src/chain_ops.rs

@@ -17,234 +17,29 @@
 //! Chain utilities.
 
 use crate::error;
+use crate::builder::{ServiceBuilderCommand, ServiceBuilder};
+use crate::error::Error;
 use chain_spec::{ChainSpec, RuntimeGenesis, Extension};
+use log::{warn, info};
+use futures::{future, prelude::*};
+use futures03::{
+	TryFutureExt as _,
+};
+use primitives::{Blake2Hasher, Hasher};
+use sr_primitives::traits::{
+	Block as BlockT, NumberFor, One, Zero, Header, SaturatedConversion
+};
+use sr_primitives::generic::{BlockId, SignedBlock};
+use codec::{Decode, Encode, IoReader};
+use client::Client;
+use consensus_common::import_queue::{IncomingBlock, Link, BlockImportError, BlockImportResult, ImportQueue};
+use consensus_common::BlockOrigin;
 
-/// Defines the logic for an operation exporting blocks within a range.
+use std::{
-#[macro_export]
+	io::{Read, Write, Seek},
-/// Export blocks
+};
-macro_rules! export_blocks {
-($client:ident, $output:ident, $from:ident, $to:ident, $json:ident) => {{
-	let mut block = $from;
 
-	let last = match $to {
+use network::message;
-		Some(v) if v.is_zero() => One::one(),
-		Some(v) => v,
-		None => $client.info().chain.best_number,
-	};
-
-	let mut wrote_header = false;
-
-	// Exporting blocks is implemented as a future, because we want the operation to be
-	// interruptible.
-	//
-	// Every time we write a block to the output, the `Future` re-schedules itself and returns
-	// `Poll::Pending`.
-	// This makes it possible either to interleave other operations in-between the block exports,
-	// or to stop the operation completely.
-	futures03::future::poll_fn(move |cx| {
-		if last < block {
-			return std::task::Poll::Ready(Err("Invalid block range specified".into()));
-		}
-
-		if !wrote_header {
-			info!("Exporting blocks from #{} to #{}", block, last);
-			if !$json {
-				let last_: u64 = last.saturated_into::<u64>();
-				let block_: u64 = block.saturated_into::<u64>();
-				let len: u64 = last_ - block_ + 1;
-				$output.write_all(&len.encode())?;
-			}
-			wrote_header = true;
-		}
-
-		match $client.block(&BlockId::number(block))? {
-			Some(block) => {
-				if $json {
-					serde_json::to_writer(&mut $output, &block)
-						.map_err(|e| format!("Error writing JSON: {}", e))?;
-				} else {
-					$output.write_all(&block.encode())?;
-				}
-			},
-			// Reached end of the chain.
-			None => return std::task::Poll::Ready(Ok(())),
-		}
-		if (block % 10000.into()).is_zero() {
-			info!("#{}", block);
-		}
-		if block == last {
-			return std::task::Poll::Ready(Ok(()));
-		}
-		block += One::one();
-
-		// Re-schedule the task in order to continue the operation.
-		cx.waker().wake_by_ref();
-		std::task::Poll::Pending
-	})
-}}
-}
-
-/// Defines the logic for an operation importing blocks from some known import.
-#[macro_export]
-/// Import blocks
-macro_rules! import_blocks {
-($block:ty, $client:ident, $queue:ident, $input:ident) => {{
-	use consensus_common::import_queue::{IncomingBlock, Link, BlockImportError, BlockImportResult};
-	use consensus_common::BlockOrigin;
-	use network::message;
-	use sr_primitives::generic::SignedBlock;
-	use sr_primitives::traits::Block;
-
-	struct WaitLink {
-		imported_blocks: u64,
-		has_error: bool,
-	}
-
-	impl WaitLink {
-		fn new() -> WaitLink {
-			WaitLink {
-				imported_blocks: 0,
-				has_error: false,
-			}
-		}
-	}
-
-	impl<B: Block> Link<B> for WaitLink {
-		fn blocks_processed(
-			&mut self,
-			imported: usize,
-			_count: usize,
-			results: Vec<(Result<BlockImportResult<NumberFor<B>>, BlockImportError>, B::Hash)>
-		) {
-			self.imported_blocks += imported as u64;
-
-			for result in results {
-				if let (Err(err), hash) = result {
-					warn!("There was an error importing block with hash {:?}: {:?}", hash, err);
-					self.has_error = true;
-					break;
-				}
-			}
-		}
-	}
-
-	let mut io_reader_input = IoReader($input);
-	let mut count = None::<u64>;
-	let mut read_block_count = 0;
-	let mut link = WaitLink::new();
-
-	// Importing blocks is implemented as a future, because we want the operation to be
-	// interruptible.
-	//
-	// Every time we read a block from the input or import a bunch of blocks from the import
-	// queue, the `Future` re-schedules itself and returns `Poll::Pending`.
-	// This makes it possible either to interleave other operations in-between the block imports,
-	// or to stop the operation completely.
-	futures03::future::poll_fn(move |cx| {
-		// Start by reading the number of blocks if not done so already.
-		let count = match count {
-			Some(c) => c,
-			None => {
-				let c: u64 = match Decode::decode(&mut io_reader_input) {
-					Ok(c) => c,
-					Err(err) => {
-						let err = format!("Error reading file: {}", err);
-						return std::task::Poll::Ready(Err(From::from(err)));
-					},
-				};
-				info!("Importing {} blocks", c);
-				count = Some(c);
-				c
-			}
-		};
-
-		// Read blocks from the input.
-		if read_block_count < count {
-			match SignedBlock::<$block>::decode(&mut io_reader_input) {
-				Ok(signed) => {
-					let (header, extrinsics) = signed.block.deconstruct();
-					let hash = header.hash();
-					let block  = message::BlockData::<$block> {
-						hash,
-						justification: signed.justification,
-						header: Some(header),
-						body: Some(extrinsics),
-						receipt: None,
-						message_queue: None
-					};
-					// import queue handles verification and importing it into the client
-					$queue.import_blocks(BlockOrigin::File, vec![
-						IncomingBlock::<$block> {
-							hash: block.hash,
-							header: block.header,
-							body: block.body,
-							justification: block.justification,
-							origin: None,
-							allow_missing_state: false,
-						}
-					]);
-				}
-				Err(e) => {
-					warn!("Error reading block data at {}: {}", read_block_count, e);
-					return std::task::Poll::Ready(Ok(()));
-				}
-			}
-
-			read_block_count += 1;
-			if read_block_count % 1000 == 0 {
-				info!("#{} blocks were added to the queue", read_block_count);
-			}
-
-			cx.waker().wake_by_ref();
-			return std::task::Poll::Pending;
-		}
-
-		let blocks_before = link.imported_blocks;
-		$queue.poll_actions(cx, &mut link);
-
-		if link.has_error {
-			info!(
-				"Stopping after #{} blocks because of an error",
-				link.imported_blocks,
-			);
-			return std::task::Poll::Ready(Ok(()));
-		}
-
-		if link.imported_blocks / 1000 != blocks_before / 1000 {
-			info!(
-				"#{} blocks were imported (#{} left)",
-				link.imported_blocks,
-				count - link.imported_blocks
-			);
-		}
-
-		if link.imported_blocks >= count {
-			info!("Imported {} blocks. Best: #{}", read_block_count, $client.info().chain.best_number);
-			return std::task::Poll::Ready(Ok(()));
-
-		} else {
-			// Polling the import queue will re-schedule the task when ready.
-			return std::task::Poll::Pending;
-		}
-	})
-}}
-}
-
-/// Revert the chain some number of blocks.
-#[macro_export]
-macro_rules! revert_chain {
-($client:ident, $blocks:ident) => {{
-	let reverted = $client.revert($blocks)?;
-	let info = $client.info().chain;
-
-	if reverted.is_zero() {
-		info!("There aren't any non-finalized blocks to revert.");
-	} else {
-		info!("Reverted {} blocks. Best: #{} ({})", reverted, info.best_number, info.best_hash);
-	}
-	Ok(())
-}}
-}
 
 /// Build a chain spec json
 pub fn build_spec<G, E>(spec: ChainSpec<G, E>, raw: bool) -> error::Result<String> where
@@ -253,3 +48,266 @@ pub fn build_spec<G, E>(spec: ChainSpec<G, E>, raw: bool) -> error::Result<Strin
 {
 	Ok(spec.to_json(raw)?)
 }
+
+impl<
+	TBl, TRtApi, TCfg, TGen, TCSExt, TBackend,
+	TExec, TFchr, TSc, TImpQu, TFprb, TFpp, TNetP,
+	TExPool, TRpc, Backend
+> ServiceBuilderCommand for ServiceBuilder<
+	TBl, TRtApi, TCfg, TGen, TCSExt, Client<TBackend, TExec, TBl, TRtApi>,
+	TFchr, TSc, TImpQu, TFprb, TFpp, TNetP, TExPool, TRpc, Backend
+> where
+	TBl: BlockT<Hash = <Blake2Hasher as Hasher>::Out>,
+	TBackend: 'static + client_api::backend::Backend<TBl, Blake2Hasher> + Send,
+	TExec: 'static + client::CallExecutor<TBl, Blake2Hasher> + Send + Sync + Clone,
+	TImpQu: 'static + ImportQueue<TBl>,
+	TRtApi: 'static + Send + Sync,
+{
+	type Block = TBl;
+
+	fn import_blocks(
+		self,
+		input: impl Read + Seek + Send + 'static,
+		force: bool,
+	) -> Box<dyn Future<Item = (), Error = Error> + Send> {
+		struct WaitLink {
+			imported_blocks: u64,
+			has_error: bool,
+		}
+
+		impl WaitLink {
+			fn new() -> WaitLink {
+				WaitLink {
+					imported_blocks: 0,
+					has_error: false,
+				}
+			}
+		}
+
+		impl<B: BlockT> Link<B> for WaitLink {
+			fn blocks_processed(
+				&mut self,
+				imported: usize,
+				_count: usize,
+				results: Vec<(Result<BlockImportResult<NumberFor<B>>, BlockImportError>, B::Hash)>
+			) {
+				self.imported_blocks += imported as u64;
+
+				for result in results {
+					if let (Err(err), hash) = result {
+						warn!("There was an error importing block with hash {:?}: {:?}", hash, err);
+						self.has_error = true;
+						break;
+					}
+				}
+			}
+		}
+
+		let client = self.client;
+		let mut queue = self.import_queue;
+
+		let mut io_reader_input = IoReader(input);
+		let mut count = None::<u64>;
+		let mut read_block_count = 0;
+		let mut link = WaitLink::new();
+
+		// Importing blocks is implemented as a future, because we want the operation to be
+		// interruptible.
+		//
+		// Every time we read a block from the input or import a bunch of blocks from the import
+		// queue, the `Future` re-schedules itself and returns `Poll::Pending`.
+		// This makes it possible either to interleave other operations in-between the block imports,
+		// or to stop the operation completely.
+		let import = futures03::future::poll_fn(move |cx| {
+			// Start by reading the number of blocks if not done so already.
+			let count = match count {
+				Some(c) => c,
+				None => {
+					let c: u64 = match Decode::decode(&mut io_reader_input) {
+						Ok(c) => c,
+						Err(err) => {
+							let err = format!("Error reading file: {}", err);
+							return std::task::Poll::Ready(Err(From::from(err)));
+						},
+					};
+					info!("Importing {} blocks", c);
+					count = Some(c);
+					c
+				}
+			};
+
+			// Read blocks from the input.
+			if read_block_count < count {
+				match SignedBlock::<Self::Block>::decode(&mut io_reader_input) {
+					Ok(signed) => {
+						let (header, extrinsics) = signed.block.deconstruct();
+						let hash = header.hash();
+						let block  = message::BlockData::<Self::Block> {
+							hash,
+							justification: signed.justification,
+							header: Some(header),
+							body: Some(extrinsics),
+							receipt: None,
+							message_queue: None
+						};
+						// import queue handles verification and importing it into the client
+						queue.import_blocks(BlockOrigin::File, vec![
+							IncomingBlock::<Self::Block> {
+								hash: block.hash,
+								header: block.header,
+								body: block.body,
+								justification: block.justification,
+								origin: None,
+								allow_missing_state: false,
+								import_existing: force,
+							}
+						]);
+					}
+					Err(e) => {
+						warn!("Error reading block data at {}: {}", read_block_count, e);
+						return std::task::Poll::Ready(Ok(()));
+					}
+				}
+
+				read_block_count += 1;
+				if read_block_count % 1000 == 0 {
+					info!("#{} blocks were added to the queue", read_block_count);
+				}
+
+				cx.waker().wake_by_ref();
+				return std::task::Poll::Pending;
+			}
+
+			let blocks_before = link.imported_blocks;
+			queue.poll_actions(cx, &mut link);
+
+			if link.has_error {
+				info!(
+					"Stopping after #{} blocks because of an error",
+					link.imported_blocks,
+				);
+				return std::task::Poll::Ready(Ok(()));
+			}
+
+			if link.imported_blocks / 1000 != blocks_before / 1000 {
+				info!(
+					"#{} blocks were imported (#{} left)",
+					link.imported_blocks,
+					count - link.imported_blocks
+				);
+			}
+
+			if link.imported_blocks >= count {
+				info!("Imported {} blocks. Best: #{}", read_block_count, client.info().chain.best_number);
+				return std::task::Poll::Ready(Ok(()));
+
+			} else {
+				// Polling the import queue will re-schedule the task when ready.
+				return std::task::Poll::Pending;
+			}
+		});
+		Box::new(import.compat())
+	}
+
+	fn export_blocks(
+		self,
+		mut output: impl Write + 'static,
+		from: NumberFor<TBl>,
+		to: Option<NumberFor<TBl>>,
+		json: bool
+	) -> Box<dyn Future<Item = (), Error = Error>> {
+		let client = self.client;
+		let mut block = from;
+
+		let last = match to {
+			Some(v) if v.is_zero() => One::one(),
+			Some(v) => v,
+			None => client.info().chain.best_number,
+		};
+
+		let mut wrote_header = false;
+
+		// Exporting blocks is implemented as a future, because we want the operation to be
+		// interruptible.
+		//
+		// Every time we write a block to the output, the `Future` re-schedules itself and returns
+		// `Poll::Pending`.
+		// This makes it possible either to interleave other operations in-between the block exports,
+		// or to stop the operation completely.
+		let export = futures03::future::poll_fn(move |cx| {
+			if last < block {
+				return std::task::Poll::Ready(Err("Invalid block range specified".into()));
+			}
+
+			if !wrote_header {
+				info!("Exporting blocks from #{} to #{}", block, last);
+				if !json {
+					let last_: u64 = last.saturated_into::<u64>();
+					let block_: u64 = block.saturated_into::<u64>();
+					let len: u64 = last_ - block_ + 1;
+					output.write_all(&len.encode())?;
+				}
+				wrote_header = true;
+			}
+
+			match client.block(&BlockId::number(block))? {
+				Some(block) => {
+					if json {
+						serde_json::to_writer(&mut output, &block)
+							.map_err(|e| format!("Error writing JSON: {}", e))?;
+						} else {
+							output.write_all(&block.encode())?;
+					}
+				},
+				// Reached end of the chain.
+				None => return std::task::Poll::Ready(Ok(())),
+			}
+			if (block % 10000.into()).is_zero() {
+				info!("#{}", block);
+			}
+			if block == last {
+				return std::task::Poll::Ready(Ok(()));
+			}
+			block += One::one();
+
+			// Re-schedule the task in order to continue the operation.
+			cx.waker().wake_by_ref();
+			std::task::Poll::Pending
+		});
+
+		Box::new(export.compat())
+	}
+
+	fn revert_chain(
+		&self,
+		blocks: NumberFor<TBl>
+	) -> Result<(), Error> {
+		let reverted = self.client.revert(blocks)?;
+		let info = self.client.info().chain;
+
+		if reverted.is_zero() {
+			info!("There aren't any non-finalized blocks to revert.");
+		} else {
+			info!("Reverted {} blocks. Best: #{} ({})", reverted, info.best_number, info.best_hash);
+		}
+		Ok(())
+	}
+
+	fn check_block(
+		self,
+		block_id: BlockId<TBl>
+	) -> Box<dyn Future<Item = (), Error = Error> + Send> {
+		match self.client.block(&block_id) {
+			Ok(Some(block)) => {
+				let mut buf = Vec::new();
+				1u64.encode_to(&mut buf);
+				block.encode_to(&mut buf);
+				let reader = std::io::Cursor::new(buf);
+				self.import_blocks(reader, true)
+			}
+			Ok(None) => Box::new(future::err("Unknown block".into())),
+			Err(e) => Box::new(future::err(format!("Error reading block: {:?}", e).into())),
+		}
+	}
+}
+

substrate/client/service/src/lib.rs

@@ -53,9 +53,7 @@ use sr_primitives::generic::BlockId;
 use sr_primitives::traits::{NumberFor, Block as BlockT};
 
 pub use self::error::Error;
-pub use self::builder::{
+pub use self::builder::{ServiceBuilder, ServiceBuilderCommand};
-	ServiceBuilder, ServiceBuilderExport, ServiceBuilderImport, ServiceBuilderRevert,
-};
 pub use config::{Configuration, Roles, PruningMode};
 pub use chain_spec::{ChainSpec, Properties, RuntimeGenesis, Extension as ChainSpecExtension};
 pub use txpool_api::{TransactionPool, TransactionPoolMaintainer, InPoolTransaction, IntoPoolError};

substrate/client/src/client.rs

@@ -756,6 +756,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 			auxiliary,
 			fork_choice,
 			allow_missing_state,
+			import_existing,
 		} = import_block;
 
 		assert!(justification.is_some() && finalized || justification.is_none());
@@ -800,6 +801,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 			auxiliary,
 			fork_choice,
 			enact_state,
+			import_existing,
 		);
 
 		if let Ok(ImportResult::Imported(ref aux)) = result {
@@ -828,13 +830,17 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		aux: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 		fork_choice: ForkChoiceStrategy,
 		enact_state: bool,
+		import_existing: bool,
 	) -> sp_blockchain::Result<ImportResult> where
 		E: CallExecutor<Block, Blake2Hasher> + Send + Sync + Clone,
 	{
 		let parent_hash = import_headers.post().parent_hash().clone();
-		match self.backend.blockchain().status(BlockId::Hash(hash))? {
+		let status = self.backend.blockchain().status(BlockId::Hash(hash))?;
-			blockchain::BlockStatus::InChain => return Ok(ImportResult::AlreadyInChain),
+		match (import_existing, status) {
-			blockchain::BlockStatus::Unknown => {},
+			(false, blockchain::BlockStatus::InChain) => return Ok(ImportResult::AlreadyInChain),
+			(false, blockchain::BlockStatus::Unknown) => {},
+			(true, blockchain::BlockStatus::InChain) =>  {},
+			(true, blockchain::BlockStatus::Unknown) => return Err(Error::UnknownBlock(format!("{:?}", hash))),
 		}
 
 		let info = self.backend.blockchain().info();
@@ -1454,7 +1460,7 @@ impl<'a, B, E, Block, RA> consensus::BlockImport<Block> for &'a Client<B, E, Blo
 		&mut self,
 		block: BlockCheckParams<Block>,
 	) -> Result<ImportResult, Self::Error> {
-		let BlockCheckParams { hash, number, parent_hash, allow_missing_state } = block;
+		let BlockCheckParams { hash, number, parent_hash, allow_missing_state, import_existing } = block;
 
 		if let Some(h) = self.fork_blocks.as_ref().and_then(|x| x.get(&number)) {
 			if &hash != h  {
@@ -1473,7 +1479,8 @@ impl<'a, B, E, Block, RA> consensus::BlockImport<Block> for &'a Client<B, E, Blo
 		match self.block_status(&BlockId::Hash(hash))
 			.map_err(|e| ConsensusError::ClientImport(e.to_string()))?
 		{
-			BlockStatus::InChainWithState | BlockStatus::Queued => return Ok(ImportResult::AlreadyInChain),
+			BlockStatus::InChainWithState | BlockStatus::Queued if !import_existing  => return Ok(ImportResult::AlreadyInChain),
+			BlockStatus::InChainWithState | BlockStatus::Queued => {},
 			BlockStatus::InChainPruned => return Ok(ImportResult::AlreadyInChain),
 			BlockStatus::Unknown => {},
 			BlockStatus::KnownBad => return Ok(ImportResult::KnownBad),
@@ -2773,7 +2780,8 @@ pub(crate) mod tests {
 			hash: a1.hash().clone(),
 			number: 0,
 			parent_hash: a1.header().parent_hash().clone(),
-			allow_missing_state: false
+			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		assert_eq!(client.check_block(check_block_a1.clone()).unwrap(), ImportResult::imported(false));
@@ -2792,7 +2800,8 @@ pub(crate) mod tests {
 			hash: a2.hash().clone(),
 			number: 1,
 			parent_hash: a1.header().parent_hash().clone(),
-			allow_missing_state: false
+			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		assert_eq!(client.check_block(check_block_a1.clone()).unwrap(), ImportResult::AlreadyInChain);
@@ -2808,7 +2817,8 @@ pub(crate) mod tests {
 			hash: a3.hash().clone(),
 			number: 2,
 			parent_hash: a2.header().parent_hash().clone(),
-			allow_missing_state: false
+			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		// a1 and a2 are both pruned at this point
@@ -2823,7 +2833,8 @@ pub(crate) mod tests {
 			hash: b1.hash().clone(),
 			number: 0,
 			parent_hash: b1.header().parent_hash().clone(),
-			allow_missing_state: false
+			allow_missing_state: false,
+			import_existing: false,
 		};
 		assert_eq!(client.check_block(check_block_b1.clone()).unwrap(), ImportResult::MissingState);
 		check_block_b1.allow_missing_state = true;

substrate/primitives/consensus/common/src/block_import.rs

@@ -105,6 +105,8 @@ pub struct BlockCheckParams<Block: BlockT> {
 	pub parent_hash: Block::Hash,
 	/// Allow importing the block skipping state verification if parent state is missing.
 	pub allow_missing_state: bool,
+	/// Re-validate existing block.
+	pub import_existing: bool,
 }
 
 /// Data required to import a Block.
@@ -142,6 +144,8 @@ pub struct BlockImportParams<Block: BlockT> {
 	pub fork_choice: ForkChoiceStrategy,
 	/// Allow importing the block skipping state verification if parent state is missing.
 	pub allow_missing_state: bool,
+	/// Re-validate existing block.
+	pub import_existing: bool,
 }
 
 impl<Block: BlockT> BlockImportParams<Block> {

substrate/primitives/consensus/common/src/import_queue.rs

@@ -65,6 +65,8 @@ pub struct IncomingBlock<B: BlockT> {
 	pub origin: Option<Origin>,
 	/// Allow importing the block skipping state verification if parent state is missing.
 	pub allow_missing_state: bool,
+	/// Re-validate existing block.
+	pub import_existing: bool,
 }
 
 /// Type of keys in the blockchain cache that consensus module could use for its needs.
@@ -230,6 +232,7 @@ pub fn import_single_block<B: BlockT, V: Verifier<B>>(
 		number,
 		parent_hash,
 		allow_missing_state: block.allow_missing_state,
+		import_existing: block.import_existing,
 	}))? {
 		BlockImportResult::ImportedUnknown { .. } => (),
 		r => return Ok(r), // Any other successful result means that the block is already imported.

substrate/test/utils/client/src/client_ext.rs

@@ -83,6 +83,7 @@ impl<B, E, RA, Block> ClientExt<Block> for Client<B, E, Block, RA>
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		BlockImport::import_block(&mut (&*self), import, HashMap::new()).map(|_| ())
@@ -102,6 +103,7 @@ impl<B, E, RA, Block> ClientExt<Block> for Client<B, E, Block, RA>
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::Custom(true),
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		BlockImport::import_block(&mut (&*self), import, HashMap::new()).map(|_| ())
@@ -121,6 +123,7 @@ impl<B, E, RA, Block> ClientExt<Block> for Client<B, E, Block, RA>
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::Custom(true),
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		BlockImport::import_block(&mut (&*self), import, HashMap::new()).map(|_| ())
@@ -143,6 +146,7 @@ impl<B, E, RA, Block> ClientExt<Block> for Client<B, E, Block, RA>
 			auxiliary: Vec::new(),
 			fork_choice: ForkChoiceStrategy::LongestChain,
 			allow_missing_state: false,
+			import_existing: false,
 		};
 
 		BlockImport::import_block(&mut (&*self), import, HashMap::new()).map(|_| ())

substrate/test/utils/transaction-factory/src/lib.rs

@@ -199,6 +199,7 @@ fn import_block<Backend, Exec, Block, RtApi>(
 		auxiliary: Vec::new(),
 		fork_choice: ForkChoiceStrategy::LongestChain,
 		allow_missing_state: false,
+		import_existing: false,
 	};
 	(&**client).import_block(import, HashMap::new()).expect("Failed to import block");
 }