Support 'pending' block in RPC (#1007)

* Support `pending` block in RPC

* Forward calls from miner to client in case no pending block is available

ethcore/src/client/client.rs

@@ -702,6 +702,10 @@ impl<V> BlockChainClient for Client<V> where V: Verifier {
 			})
 			.collect()
 	}
+
+	fn last_hashes(&self) -> LastHashes {
+		self.build_last_hashes(self.chain.best_block_hash())
+	}
 }
 
 impl MayPanic for Client {

ethcore/src/client/mod.rs

@@ -25,7 +25,8 @@ pub use self::client::*;
 pub use self::config::{ClientConfig, BlockQueueConfig, BlockChainConfig};
 pub use self::ids::{BlockId, TransactionId, UncleId};
 pub use self::test_client::{TestBlockChainClient, EachBlockWith};
-pub use executive::Executed;
+pub use executive::{Executed, Executive, TransactOptions};
+pub use env_info::{LastHashes, EnvInfo};
 
 use std::collections::HashSet;
 use util::bytes::Bytes;
@@ -132,5 +133,8 @@ pub trait BlockChainClient : Sync + Send {
 
 	/// Executes a function providing it with a reference to an engine.
 	fn engine(&self) -> &Engine;
+
+	/// Get last hashes starting from best block.
+	fn last_hashes(&self) -> LastHashes;
 }
 

ethcore/src/client/test_client.rs

@@ -20,7 +20,7 @@ use std::sync::atomic::{AtomicUsize, Ordering as AtomicOrder};
 use util::*;
 use transaction::{Transaction, LocalizedTransaction, SignedTransaction, Action};
 use blockchain::TreeRoute;
-use client::{BlockChainClient, BlockChainInfo, BlockStatus, BlockId, TransactionId, UncleId};
+use client::{BlockChainClient, BlockChainInfo, BlockStatus, BlockId, TransactionId, UncleId, LastHashes};
 use header::{Header as BlockHeader, BlockNumber};
 use filter::Filter;
 use log_entry::LocalizedLogEntry;
@@ -268,6 +268,10 @@ impl BlockChainClient for TestBlockChainClient {
 		unimplemented!();
 	}
 
+	fn last_hashes(&self) -> LastHashes {
+		unimplemented!();
+	}
+
 	fn prepare_sealing(&self, _author: Address, _gas_floor_target: U256, _extra_data: Bytes, _transactions: Vec<SignedTransaction>) -> (Option<ClosedBlock>, HashSet<H256>) {
 		(None, HashSet::new())
 	}