New mining framework.

Fixes #756.

ethcore/src/client/client.rs

@@ -426,9 +426,8 @@ impl<V> BlockChainClient for Client<V> where V: Verifier {
 		block.try_seal(self.engine.deref().deref(), seal)
 	}
 
-	// TODO: either work out a better API than this or refactor prepare_sealing and try_seal in terms of this.
-	fn with_engine<F, T>(&self, f: F) -> T where F: FnOnce(&Engine) -> T {
-		f(self.engine.deref().deref())
+	fn engine(&self) -> &Engine {
+		self.engine.deref().deref()
 	}
 
 	// TODO [todr] Should be moved to miner crate eventually.

ethcore/src/client/mod.rs

@@ -40,6 +40,7 @@ use log_entry::LocalizedLogEntry;
 use filter::Filter;
 use error::{ImportResult, Error};
 use receipt::LocalizedReceipt;
+use engine::{Engine};
 
 /// Blockchain database client. Owns and manages a blockchain and a block queue.
 pub trait BlockChainClient : Sync + Send {
@@ -130,6 +131,6 @@ pub trait BlockChainClient : Sync + Send {
 	fn call(&self, t: &SignedTransaction) -> Result<Executed, Error>;
 
 	/// Executes a function providing it with a reference to an engine.
-	fn with_engine<F>(&self, _f: F) where F: FnOnce(&Engine) {}
+	fn engine(&self) -> &Engine;
 }
 

ethcore/src/client/test_client.rs

@@ -31,6 +31,7 @@ use block_queue::BlockQueueInfo;
 use block::{SealedBlock, ClosedBlock};
 use executive::Executed;
 use error::Error;
+use engine::Engine;
 
 /// Test client.
 pub struct TestBlockChainClient {
@@ -249,7 +250,7 @@ impl BlockChainClient for TestBlockChainClient {
 	}
 
 	fn prepare_sealing(&self, _author: Address, _gas_floor_target: U256, _extra_data: Bytes, _transactions: Vec<SignedTransaction>) -> (Option<ClosedBlock>, HashSet<H256>) {
-		(None, vec![])
+		(None, HashSet::new())
 	}
 
 	fn try_seal(&self, block: ClosedBlock, _seal: Vec<Bytes>) -> Result<SealedBlock, ClosedBlock> {
@@ -404,4 +405,8 @@ impl BlockChainClient for TestBlockChainClient {
 			best_block_number: self.blocks.read().unwrap().len() as BlockNumber - 1,
 		}
 	}
+
+	fn engine(&self) -> &Engine {
+		unimplemented!();
+	}
 }