client.rs

// Copyright 2017-2018 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Substrate Client

use std::{marker::PhantomData, collections::{HashSet, BTreeMap}, sync::Arc};
use error::Error;
use futures::sync::mpsc;
use parking_lot::{Mutex, RwLock};
use primitives::AuthorityId;
use runtime_primitives::{
	Justification,
	generic::{BlockId, SignedBlock},
};
use consensus::{Error as ConsensusError, ErrorKind as ConsensusErrorKind, ImportBlock, ImportResult, BlockOrigin};
use runtime_primitives::traits::{
	Block as BlockT, Header as HeaderT, Zero, As, NumberFor, CurrentHeight, BlockNumberToHash,
	ApiRef, ProvideRuntimeApi, Digest, DigestItem,
};
use runtime_primitives::BuildStorage;
use runtime_api::{Core as CoreAPI, CallRuntimeAt, ConstructRuntimeApi};
use primitives::{Blake2Hasher, H256, ChangesTrieConfiguration, convert_hash};
use primitives::storage::{StorageKey, StorageData};
use primitives::storage::well_known_keys;
use codec::Decode;
use state_machine::{
	DBValue, Backend as StateBackend, CodeExecutor, ChangesTrieAnchorBlockId,
	ExecutionStrategy, ExecutionManager, prove_read,
	ChangesTrieRootsStorage, ChangesTrieStorage,
	key_changes, key_changes_proof, OverlayedChanges
};

use backend::{self, BlockImportOperation};
use blockchain::{self, Info as ChainInfo, Backend as ChainBackend, HeaderBackend as ChainHeaderBackend};
use call_executor::{CallExecutor, LocalCallExecutor};
use executor::{RuntimeVersion, RuntimeInfo};
use notifications::{StorageNotifications, StorageEventStream};
use light::{call_executor::prove_execution, fetcher::ChangesProof};
use {cht, error, in_mem, block_builder::{self, api::BlockBuilder as BlockBuilderAPI}, genesis, consensus};

/// Type that implements `futures::Stream` of block import events.
pub type ImportNotifications<Block> = mpsc::UnboundedReceiver<BlockImportNotification<Block>>;

/// A stream of block finality notifications.
pub type FinalityNotifications<Block> = mpsc::UnboundedReceiver<FinalityNotification<Block>>;

/// Substrate Client
pub struct Client<B, E, Block, RA> where Block: BlockT {
	backend: Arc<B>,
	executor: E,
	storage_notifications: Mutex<StorageNotifications<Block>>,
	import_notification_sinks: Mutex<Vec<mpsc::UnboundedSender<BlockImportNotification<Block>>>>,
	finality_notification_sinks: Mutex<Vec<mpsc::UnboundedSender<FinalityNotification<Block>>>>,
	import_lock: Mutex<()>,
	importing_block: RwLock<Option<Block::Hash>>, // holds the block hash currently being imported. TODO: replace this with block queue
	block_execution_strategy: ExecutionStrategy,
	api_execution_strategy: ExecutionStrategy,
	_phantom: PhantomData<RA>,
}

/// A source of blockchain events.
pub trait BlockchainEvents<Block: BlockT> {
	/// Get block import event stream. Not guaranteed to be fired for every
	/// imported block.
	fn import_notification_stream(&self) -> ImportNotifications<Block>;

	/// Get a stream of finality notifications. Not guaranteed to be fired for every
	/// finalized block.
	fn finality_notification_stream(&self) -> FinalityNotifications<Block>;

	/// Get storage changes event stream.
	///
	/// Passing `None` as `filter_keys` subscribes to all storage changes.
	fn storage_changes_notification_stream(&self, filter_keys: Option<&[StorageKey]>) -> error::Result<StorageEventStream<Block::Hash>>;
}

/// Chain head information.
pub trait ChainHead<Block: BlockT> {
	/// Get best block header.
	fn best_block_header(&self) -> Result<<Block as BlockT>::Header, error::Error>;
	/// Get all leaves of the chain: block hashes that have no children currently.
	/// Leaves that can never be finalized will not be returned.
	fn leaves(&self) -> Result<Vec<<Block as BlockT>::Hash>, error::Error>;
}

/// Fetch block body by ID.
pub trait BlockBody<Block: BlockT> {
	/// Get block body by ID. Returns `None` if the body is not stored.
	fn block_body(&self, id: &BlockId<Block>) -> error::Result<Option<Vec<<Block as BlockT>::Extrinsic>>>;
}

/// Client info
// TODO: split queue info from chain info and amalgamate into single struct.
#[derive(Debug)]
pub struct ClientInfo<Block: BlockT> {
	/// Best block hash.
	pub chain: ChainInfo<Block>,
	/// Best block number in the queue.
	pub best_queued_number: Option<<<Block as BlockT>::Header as HeaderT>::Number>,
	/// Best queued block hash.
	pub best_queued_hash: Option<Block::Hash>,
}

/// Block status.
#[derive(Debug, PartialEq, Eq)]
pub enum BlockStatus {
	/// Added to the import queue.
	Queued,
	/// Already in the blockchain.
	InChain,
	/// Block or parent is known to be bad.
	KnownBad,
	/// Not in the queue or the blockchain.
	Unknown,
}

/// Summary of an imported block
#[derive(Clone, Debug)]
pub struct BlockImportNotification<Block: BlockT> {
	/// Imported block header hash.
	pub hash: Block::Hash,
	/// Imported block origin.
	pub origin: BlockOrigin,
	/// Imported block header.
	pub header: Block::Header,
	/// Is this the new best block.
	pub is_new_best: bool,
}

/// Summary of a finalized block.
#[derive(Clone, Debug)]
pub struct FinalityNotification<Block: BlockT> {
	/// Imported block header hash.
	pub hash: Block::Hash,
	/// Imported block header.
	pub header: Block::Header,
}

// used in importing a block, where additional changes are made after the runtime
// executed.
enum PrePostHeader<H> {
	// they are the same: no post-runtime digest items.
	Same(H),
	// different headers (pre, post).
	Different(H, H),
}

impl<H> PrePostHeader<H> {
	// get a reference to the "pre-header" -- the header as it should be just after the runtime.
	fn pre(&self) -> &H {
		match *self {
			PrePostHeader::Same(ref h) => h,
			PrePostHeader::Different(ref h, _) => h,
		}
	}

	// get a reference to the "post-header" -- the header as it should be after all changes are applied.
	fn post(&self) -> &H {
		match *self {
			PrePostHeader::Same(ref h) => h,
			PrePostHeader::Different(_, ref h) => h,
		}
	}

	// convert to the "post-header" -- the header as it should be after all changes are applied.
	fn into_post(self) -> H {
		match self {
			PrePostHeader::Same(h) => h,
			PrePostHeader::Different(_, h) => h,
		}
	}
}

/// Create an instance of in-memory client.
pub fn new_in_mem<E, Block, S, RA>(
	executor: E,
	genesis_storage: S,
) -> error::Result<Client<in_mem::Backend<Block, Blake2Hasher>, LocalCallExecutor<in_mem::Backend<Block, Blake2Hasher>, E>, Block, RA>>
	where
		E: CodeExecutor<Blake2Hasher> + RuntimeInfo,
		S: BuildStorage,
		Block: BlockT<Hash=H256>,
{
	new_with_backend(Arc::new(in_mem::Backend::new()), executor, genesis_storage)
}

/// Create a client with the explicitely provided backend.