Client refactoring (#7038)

* Improves `BestBlock` comment

* Improves `TraceDB` comment

* Improves `journaldb::Algorithm` comment.

Probably the whole enum should be renamed to `Strategy` or something alike.

* Comments some of the `Client`'s fields

* Deglobs client imports

* Fixes comments

* Extracts `import_lock` to `Importer` struct

* Extracts `verifier` to `Importer` struct

* Extracts `block_queue` to `Importer` struct

* Extracts `miner` to `Importer` struct

* Extracts `ancient_verifier` to `Importer` struct

* Extracts `rng` to `Importer` struct

* Extracts `import_old_block` to `Importer` struct

* Adds `Nonce` trait

* Adds `Balance` trait

* Adds `ChainInfo` trait

* Fixes imports for tests using `chain_info` method

* Adds `BlockInfo` trait

* Adds more `ChainInfo` imports

* Adds `BlockInfo` imports

* Adds `ReopenBlock` trait

* Adds `PrepareOpenBlock` trait

* Fixes import in tests

* Adds `CallContract` trait

* Fixes imports in tests using `call_contract` method

* Adds `TransactionInfo` trait

* Adds `RegistryInfo` trait

* Fixes imports in tests using `registry_address` method

* Adds `ScheduleInfo` trait

* Adds `ImportSealedBlock` trait

* Fixes imports in test using `import_sealed_block` method

* Adds `BroadcastProposalBlock` trait

* Migrates `Miner` to static dispatch

* Fixes tests

* Moves `calculate_enacted_retracted` to `Importer`

* Moves import-related methods to `Importer`

* Removes redundant `import_old_block` wrapper

* Extracts `import_block*` into separate trait

* Fixes tests

* Handles `Pending` in `LightFetch`

* Handles `Pending` in filters

* Handles `Pending` in `ParityClient`

* Handles `Pending` in `EthClient`

* Removes `BlockId::Pending`, partly refactors dependent code

* Adds `StateInfo` trait

* Exports `StateOrBlock` and `BlockChain` types from `client` module

* Refactors `balance` RPC using generic API

* Refactors `storage_at` RPC using generic API

* Makes `MinerService::pending_state`'s return type dynamic

* Adds `StateOrBlock` and `BlockChain` types

* Adds impl of `client::BlockChain` for `Client`

* Exports `StateInfo` trait from `client` module

* Missing `self` use

To be fixed up to "Adds impl of `client::BlockChain` for `Client`"

* Adds `number_to_id` and refactors dependent RPC methods

* Refactors `code_at` using generic API

* Adds `StateClient` trait

* Refactors RPC to use `StateClient` trait

* Reverts `client::BlockChain` trait stuff, refactors methods to accept `StateOrBlock`

* Refactors TestClient

* Adds helper function `block_number_to_id`

* Uses `block_number_to_id` instead of local function

* Handles `Pending` in `list_accounts` and `list_storage_keys`

* Attempt to use associated types for state instead of trait objects

* Simplifies `state_at_beginning`

* Extracts `call` and `call_many` into separate trait

* Refactors `build_last_hashes` to accept reference

* Exports `Call` type from the module

* Refactors `call` and `call_many` to accept state and header

* Exports `state_at` in `StateClient`

* Exports `pending_block_header` from `MinerService`

* Refactors RPC `call` method using new API

* Adds missing parentheses

* Refactors `parity::call` to use new call API

* Update .gitlab-ci.yml

fix gitlab lint

* Fixes error handling

* Refactors `traces::call` and `call_many` to use new call API

* Refactors `call_contract`

* Refactors `block_header`

* Refactors internal RPC method `block`

* Moves `estimate_gas` to `Call` trait, refactors parameters

* Refactors `estimate_gas` in RPC

* Refactors `uncle`

* Refactors RPC `transaction`

* Covers missing branches

* Makes it all compile, fixes compiler grumbles

* Adds casts in `blockchain` module

* Fixes `PendingBlock` tests, work on `MinerService`

* Adds test stubs for StateClient and EngineInfo

* Makes `state_db` public

* Adds missing impls for `TestBlockChainClient`

* Adds trait documentation

* Adds missing docs to the `state_db` module

* Fixes trivial compilation errors

* Moves `code_hash` method to a `BlockInfo` trait

* Refactors `Verifier` to be generic over client

* Refactors `TransactionFilter` to be generic over client

* Refactors `Miner` and `Client` to reflect changes in verifier and txfilter API

* Moves `ServiceTransactionChecker` back to `ethcore`

* Fixes trait bounds in `Miner` API

* Fixes `Client`

* Fixes lifetime bound in `FullFamilyParams`

* Adds comments to `FullFamilyParams`

* Fixes imports in `ethcore`

* Fixes BlockNumber handling in `code_at` and `replay_block_transactions`

* fix compile issues

* First step to redundant trait merge

* Fixes compilation error in RPC tests

* Adds mock `State` as a stub for `TestClient`

* Handles `StateOrBlock::State` in `TestBlockChainClient::balance`

* Fixes `transaction_count` RPC

* Fixes `transaction_count`

* Moves `service_transaction.json` to the `contracts` subfolder

* Fixes compilation errors in tests

* Refactors client to use `AccountData`

* Refactors client to use `BlockChain`

* Refactors miner to use aggregate traits

* Adds `SealedBlockImporter` trait

* Refactors miner to use `SealedBlockImporter` trait

* Removes unused imports

* Simplifies `RegistryInfo::registry_address`

* Fixes indentation

* Removes commented out trait bound

ethcore/light/src/client/header_chain.rs

@@ -497,7 +497,7 @@ impl HeaderChain {
 				if self.best_block.read().number < num { return None }
 				self.candidates.read().get(&num).map(|entry| entry.canonical_hash)
 			}
-			BlockId::Latest | BlockId::Pending => {
+			BlockId::Latest => {
 				Some(self.best_block.read().hash)
 			}
 		}
@@ -539,7 +539,7 @@ impl HeaderChain {
 				self.candidates.read().get(&num).map(|entry| entry.canonical_hash)
 					.and_then(load_from_db)
 			}
-			BlockId::Latest | BlockId::Pending => {
+			BlockId::Latest => {
 				// hold candidates hear to prevent deletion of the header
 				// as we read it.
 				let _candidates = self.candidates.read();
@@ -575,7 +575,7 @@ impl HeaderChain {
 				if self.best_block.read().number < num { return None }
 				candidates.get(&num).map(|era| era.candidates[0].total_difficulty)
 			}
-			BlockId::Latest | BlockId::Pending => Some(self.best_block.read().total_difficulty)
+			BlockId::Latest => Some(self.best_block.read().total_difficulty)
 		}
 	}
 
@@ -866,7 +866,6 @@ mod tests {
 
 		assert!(chain.block_header(BlockId::Earliest).is_some());
 		assert!(chain.block_header(BlockId::Latest).is_some());
-		assert!(chain.block_header(BlockId::Pending).is_some());
 	}
 
 	#[test]

ethcore/light/src/client/mod.rs

@@ -574,6 +574,12 @@ impl<T: ChainDataFetcher> LightChainClient for Client<T> {
 	}
 }
 
+impl<T: ChainDataFetcher> ::ethcore::client::ChainInfo for Client<T> {
+	fn chain_info(&self) -> BlockChainInfo {
+		Client::chain_info(self)
+	}
+}
+
 impl<T: ChainDataFetcher> ::ethcore::client::EngineClient for Client<T> {
 	fn update_sealing(&self) { }
 	fn submit_seal(&self, _block_hash: H256, _seal: Vec<Vec<u8>>) { }
@@ -587,10 +593,6 @@ impl<T: ChainDataFetcher> ::ethcore::client::EngineClient for Client<T> {
 		})
 	}
 
-	fn chain_info(&self) -> BlockChainInfo {
-		Client::chain_info(self)
-	}
-
 	fn as_full_client(&self) -> Option<&::ethcore::client::BlockChainClient> {
 		None
 	}

ethcore/light/src/on_demand/request.rs

@@ -948,7 +948,7 @@ mod tests {
 	use trie::recorder::Recorder;
 	use hash::keccak;
 
-	use ethcore::client::{BlockChainClient, TestBlockChainClient, EachBlockWith};
+	use ethcore::client::{BlockChainClient, BlockInfo, TestBlockChainClient, EachBlockWith};
 	use ethcore::header::Header;
 	use ethcore::encoded;
 	use ethcore::receipt::{Receipt, TransactionOutcome};

ethcore/light/src/provider.rs

@@ -20,9 +20,9 @@
 use std::sync::Arc;
 
 use ethcore::blockchain_info::BlockChainInfo;
-use ethcore::client::{BlockChainClient, ProvingBlockChainClient};
-use ethcore::encoded;
+use ethcore::client::{BlockChainClient, ProvingBlockChainClient, ChainInfo, BlockInfo as ClientBlockInfo};
 use ethcore::ids::BlockId;
+use ethcore::encoded;
 use ethereum_types::H256;
 use parking_lot::RwLock;
 use transaction::PendingTransaction;
@@ -138,7 +138,7 @@ pub trait Provider: Send + Sync {
 // Implementation of a light client data provider for a client.
 impl<T: ProvingBlockChainClient + ?Sized> Provider for T {
 	fn chain_info(&self) -> BlockChainInfo {
-		BlockChainClient::chain_info(self)
+		ChainInfo::chain_info(self)
 	}
 
 	fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64> {
@@ -150,7 +150,7 @@ impl<T: ProvingBlockChainClient + ?Sized> Provider for T {
 	}
 
 	fn block_header(&self, id: BlockId) -> Option<encoded::Header> {
-		BlockChainClient::block_header(self, id)
+		ClientBlockInfo::block_header(self, id)
 	}
 
 	fn transaction_index(&self, req: request::CompleteTransactionIndexRequest)

ethcore/src/blockchain/best_block.rs

@@ -18,7 +18,12 @@ use ethereum_types::{H256, U256};
 use bytes::Bytes;
 use header::BlockNumber;
 
-/// Best block info.
+/// Contains information on a best block that is specific to the consensus engine.
+///
+/// For GHOST fork-choice rule it would typically describe the block with highest
+/// combined difficulty (usually the block with the highest block number).
+///
+/// Sometimes refered as 'latest block'.
 #[derive(Default)]
 pub struct BestBlock {
 	/// Best block hash.