Adds cli interface to allow reseting chain to a particular block

ethcore/blockchain/src/blockchain.rs

@@ -668,6 +668,21 @@ impl BlockChain {
 		self.db.key_value().read_with_cache(db::COL_EXTRA, &self.block_details, parent).map_or(false, |d| d.children.contains(hash))
 	}
 
+	/// fetches the list of blocks from best block to n, and n's parent hash
+	/// where n > 0
+	pub fn block_headers_from_best_block(&self, n: u32) -> Option<(Vec<encoded::Header>, H256)> {
+		let mut blocks = Vec::with_capacity(n as usize);
+		let mut hash = self.best_block_hash();
+
+		for _ in 0..n {
+			let current_hash = self.block_header_data(&hash)?;
+			hash = current_hash.parent_hash();
+			blocks.push(current_hash);
+		}
+
+		Some((blocks, hash))
+	}
+
 	/// Returns a tree route between `from` and `to`, which is a tuple of:
 	///
 	/// - a vector of hashes of all blocks, ordered from `from` to `to`.

ethcore/blockchain/src/lib.rs

@@ -33,5 +33,5 @@ pub use self::cache::CacheSize;
 pub use self::config::Config;
 pub use self::import_route::ImportRoute;
 pub use self::update::ExtrasInsert;
-pub use ethcore_db::keys::{BlockReceipts, BlockDetails, TransactionAddress};
+pub use ethcore_db::keys::{BlockReceipts, BlockDetails, TransactionAddress, BlockNumberKey};
 pub use common_types::tree_route::TreeRoute;

ethcore/src/client/client.rs

@@ -21,7 +21,7 @@ use std::sync::atomic::{AtomicUsize, AtomicBool, Ordering as AtomicOrdering};
 use std::sync::{Arc, Weak};
 use std::time::{Instant, Duration};
 
-use blockchain::{BlockReceipts, BlockChain, BlockChainDB, BlockProvider, TreeRoute, ImportRoute, TransactionAddress, ExtrasInsert};
+use blockchain::{BlockReceipts, BlockChain, BlockChainDB, BlockProvider, TreeRoute, ImportRoute, TransactionAddress, ExtrasInsert, BlockNumberKey};
 use bytes::Bytes;
 use ethcore_miner::pool::VerifiedTransaction;
 use ethereum_types::{H256, Address, U256};
@@ -50,7 +50,7 @@ use client::{
 	RegistryInfo, ReopenBlock, PrepareOpenBlock, ScheduleInfo, ImportSealedBlock,
 	BroadcastProposalBlock, ImportBlock, StateOrBlock, StateInfo, StateClient, Call,
 	AccountData, BlockChain as BlockChainTrait, BlockProducer, SealedBlockImporter,
-	ClientIoMessage,
+	ClientIoMessage, BlockChainReset
 };
 use client::{
 	BlockId, TransactionId, UncleId, TraceId, ClientConfig, BlockChainClient,
@@ -77,12 +77,14 @@ use verification::queue::kind::BlockLike;
 use verification::queue::kind::blocks::Unverified;
 use verification::{PreverifiedBlock, Verifier, BlockQueue};
 use verification;
+use ansi_term::Colour;
 
 // re-export
 pub use types::blockchain_info::BlockChainInfo;
 pub use types::block_status::BlockStatus;
 pub use blockchain::CacheSize as BlockChainCacheSize;
 pub use verification::QueueInfo as BlockQueueInfo;
+use db::Writable;
 
 use_contract!(registry, "res/contracts/registrar.json");
 
@@ -469,6 +471,7 @@ impl Importer {
 	// it is for reconstructing the state transition.
 	//
 	// The header passed is from the original block data and is sealed.
+	// TODO: should return an error if ImportRoute is none, issue #9910
 	fn commit_block<B>(&self, block: B, header: &Header, block_data: encoded::Block, client: &Client) -> ImportRoute where B: Drain {
 		let hash = &header.hash();
 		let number = header.number();
@@ -1328,6 +1331,48 @@ impl snapshot::DatabaseRestore for Client {
 	}
 }
 
+impl BlockChainReset for Client {
+	fn reset(&self, num: u32) -> Result<(), String> {
+		if num as u64 > self.pruning_history() {
+			return Err("Attempting to reset to block with pruned state".into())
+		}
+
+		let (blocks_to_delete, best_block_hash) = self.chain.read()
+			.block_headers_from_best_block(num)
+			.ok_or("Attempted to reset past genesis block")?;
+
+		let mut db_transaction = DBTransaction::with_capacity((num + 1) as usize);
+
+		for hash in &blocks_to_delete {
+			db_transaction.delete(::db::COL_HEADERS, &hash.hash());
+			db_transaction.delete(::db::COL_BODIES, &hash.hash());
+			db_transaction.delete(::db::COL_EXTRA, &hash.hash());
+			Writable::delete::<H256, BlockNumberKey>
+				(&mut db_transaction, ::db::COL_EXTRA, &hash.number());
+		}
+
+		// update the new best block hash
+		db_transaction.put(::db::COL_EXTRA, b"best", &*best_block_hash);
+
+		self.db.read()
+			.key_value()
+			.write(db_transaction)
+			.map_err(|err| format!("could not complete reset operation; io error occured: {}", err))?;
+
+		let hashes = blocks_to_delete.iter().map(|b| b.hash()).collect::<Vec<_>>();
+
+		info!("Deleting block hashes {}",
+			Colour::Red
+				.bold()
+				.paint(format!("{:#?}", hashes))
+		);
+
+		info!("New best block hash {}", Colour::Green.bold().paint(format!("{:?}", best_block_hash)));
+
+		Ok(())
+	}
+}
+
 impl Nonce for Client {
 	fn nonce(&self, address: &Address, id: BlockId) -> Option<U256> {
 		self.state_at(id).and_then(|s| s.nonce(address).ok())

ethcore/src/client/mod.rs

@@ -37,7 +37,8 @@ pub use self::test_client::{TestBlockChainClient, EachBlockWith};
 pub use self::chain_notify::{ChainNotify, NewBlocks, ChainRoute, ChainRouteType, ChainMessageType};
 pub use self::traits::{
     Nonce, Balance, ChainInfo, BlockInfo, ReopenBlock, PrepareOpenBlock, CallContract, TransactionInfo, RegistryInfo, ScheduleInfo, ImportSealedBlock, BroadcastProposalBlock, ImportBlock,
-    StateOrBlock, StateClient, Call, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter, BadBlocks,
+    StateOrBlock, StateClient, Call, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter,
+	BadBlocks, BlockChainReset
 };
 pub use state::StateInfo;
 pub use self::traits::{BlockChainClient, EngineClient, ProvingBlockChainClient, IoClient};

ethcore/src/client/traits.rs

@@ -482,3 +482,9 @@ pub trait ProvingBlockChainClient: BlockChainClient {
 	/// Get an epoch change signal by block hash.
 	fn epoch_signal(&self, hash: H256) -> Option<Vec<u8>>;
 }
+
+/// resets the blockchain
+pub trait BlockChainReset {
+	/// reset to best_block - n
+	fn reset(&self, num: u32) -> Result<(), String>;
+}

parity/blockchain.rs

@@ -26,7 +26,8 @@ use ethereum_types::{U256, H256, Address};
 use bytes::ToPretty;
 use rlp::PayloadInfo;
 use ethcore::account_provider::AccountProvider;
-use ethcore::client::{Mode, DatabaseCompactionProfile, VMType, Nonce, Balance, BlockChainClient, BlockId, BlockInfo, ImportBlock};
+use ethcore::client::{Mode, DatabaseCompactionProfile, VMType, Nonce, Balance, BlockChainClient, BlockId, BlockInfo,
+	ImportBlock, BlockChainReset};
 use ethcore::error::{ImportErrorKind, ErrorKind as EthcoreErrorKind, Error as EthcoreError};
 use ethcore::miner::Miner;
 use ethcore::verification::queue::VerifierSettings;
@@ -40,6 +41,7 @@ use dir::Directories;
 use user_defaults::UserDefaults;
 use ethcore_private_tx;
 use db;
+use ansi_term::Colour;
 
 #[derive(Debug, PartialEq)]
 pub enum DataFormat {
@@ -71,6 +73,21 @@ pub enum BlockchainCmd {
 	Import(ImportBlockchain),
 	Export(ExportBlockchain),
 	ExportState(ExportState),
+	Reset(ResetBlockchain)
+}
+
+#[derive(Debug, PartialEq)]
+pub struct ResetBlockchain {
+	pub dirs: Directories,
+	pub spec: SpecType,
+	pub pruning: Pruning,
+	pub pruning_history: u64,
+	pub pruning_memory: usize,
+	pub tracing: Switch,
+	pub fat_db: Switch,
+	pub compaction: DatabaseCompactionProfile,
+	pub cache_config: CacheConfig,
+	pub num: u32,
 }
 
 #[derive(Debug, PartialEq)]
@@ -153,6 +170,7 @@ pub fn execute(cmd: BlockchainCmd) -> Result<(), String> {
 		}
 		BlockchainCmd::Export(export_cmd) => execute_export(export_cmd),
 		BlockchainCmd::ExportState(export_cmd) => execute_export_state(export_cmd),
+		BlockchainCmd::Reset(reset_cmd) => execute_reset(reset_cmd),
 	}
 }
 
@@ -709,6 +727,28 @@ fn execute_export_state(cmd: ExportState) -> Result<(), String> {
 	Ok(())
 }
 
+fn execute_reset(cmd: ResetBlockchain) -> Result<(), String> {
+	let service = start_client(
+		cmd.dirs,
+		cmd.spec,
+		cmd.pruning,
+		cmd.pruning_history,
+		cmd.pruning_memory,
+		cmd.tracing,
+		cmd.fat_db,
+		cmd.compaction,
+		cmd.cache_config,
+		false,
+		0,
+	)?;
+
+	let client = service.client();
+	client.reset(cmd.num)?;
+	info!("{}", Colour::Green.bold().paint("Successfully reset db!"));
+
+	Ok(())
+}
+
 pub fn kill_db(cmd: KillBlockchain) -> Result<(), String> {
 	let spec = cmd.spec.spec(&cmd.dirs.cache)?;
 	let genesis_hash = spec.genesis_header().hash();

parity/cli/mod.rs

@@ -217,6 +217,15 @@ usage! {
 			CMD cmd_db_kill {
 				"Clean the database of the given --chain (default: mainnet)",
 			}
+
+			CMD cmd_db_reset {
+				"Removes NUM latests blocks from the db",
+
+				ARG arg_db_reset_num: (u32) = 10u32,
+				"<NUM>",
+				"Number of blocks to revert",
+			}
+
 		}
 
 		CMD cmd_export_hardcoded_sync
@@ -1612,6 +1621,7 @@ mod tests {
 			cmd_tools_hash: false,
 			cmd_db: false,
 			cmd_db_kill: false,
+			cmd_db_reset: false,
 			cmd_export_hardcoded_sync: false,
 
 			// Arguments
@@ -1631,6 +1641,7 @@ mod tests {
 			arg_dapp_path: None,
 			arg_account_import_path: None,
 			arg_wallet_import_path: None,
+			arg_db_reset_num: 10,
 
 			// -- Operating Options
 			arg_mode: "last".into(),

parity/configuration.rs

@@ -48,7 +48,7 @@ use ethcore_private_tx::{ProviderConfig, EncryptorConfig};
 use secretstore::{NodeSecretKey, Configuration as SecretStoreConfiguration, ContractAddress as SecretStoreContractAddress};
 use updater::{UpdatePolicy, UpdateFilter, ReleaseTrack};
 use run::RunCmd;
-use blockchain::{BlockchainCmd, ImportBlockchain, ExportBlockchain, KillBlockchain, ExportState, DataFormat};
+use blockchain::{BlockchainCmd, ImportBlockchain, ExportBlockchain, KillBlockchain, ExportState, DataFormat, ResetBlockchain};
 use export_hardcoded_sync::ExportHsyncCmd;
 use presale::ImportWallet;
 use account::{AccountCmd, NewAccount, ListAccounts, ImportAccounts, ImportFromGethAccounts};
@@ -176,6 +176,19 @@ impl Configuration {
 			}
 		} else if self.args.cmd_tools && self.args.cmd_tools_hash {
 			Cmd::Hash(self.args.arg_tools_hash_file)
+		} else if self.args.cmd_db && self.args.cmd_db_reset {
+			Cmd::Blockchain(BlockchainCmd::Reset(ResetBlockchain {
+				dirs,
+				spec,
+				pruning,
+				pruning_history,
+				pruning_memory: self.args.arg_pruning_memory,
+				tracing,
+				fat_db,
+				compaction,
+				cache_config,
+				num: self.args.arg_db_reset_num,
+			}))
 		} else if self.args.cmd_db && self.args.cmd_db_kill {
 			Cmd::Blockchain(BlockchainCmd::Kill(KillBlockchain {
 				spec: spec,