From 0dc1ddef9a3620509a7dde77e0d966226522fc5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomasz=20Drwi=C4=99ga?= <tomasz@ethcore.io>
Date: Fri, 18 Mar 2016 13:59:11 +0100
Subject: [PATCH] Flipping sealing_enabled flag after no requests for
 sealing_block for some time

---
 ethcore/src/client/test_client.rs |  6 ++--
 miner/src/miner.rs                | 58 +++++++++++++++++++++++++++++--
 2 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/ethcore/src/client/test_client.rs b/ethcore/src/client/test_client.rs
index 83511b1cc..f5c54b705 100644
--- a/ethcore/src/client/test_client.rs
+++ b/ethcore/src/client/test_client.rs
@@ -218,11 +218,11 @@ impl BlockChainClient for TestBlockChainClient {
 	}
 
 	fn prepare_sealing(&self, _author: Address, _gas_floor_target: U256, _extra_data: Bytes, _transactions: Vec<SignedTransaction>) -> Option<ClosedBlock> {
-		unimplemented!()
+		None
 	}
 
-	fn try_seal(&self, _block: ClosedBlock, _seal: Vec<Bytes>) -> Result<SealedBlock, ClosedBlock> {
-		unimplemented!()
+	fn try_seal(&self, block: ClosedBlock, _seal: Vec<Bytes>) -> Result<SealedBlock, ClosedBlock> {
+		Err(block)
 	}
 
 	fn block_header(&self, id: BlockId) -> Option<Bytes> {
diff --git a/miner/src/miner.rs b/miner/src/miner.rs
index dc1f9bcff..e90473600 100644
--- a/miner/src/miner.rs
+++ b/miner/src/miner.rs
@@ -34,6 +34,7 @@ pub struct Miner {
 
 	// for sealing...
 	sealing_enabled: AtomicBool,
+	sealing_block_last_request: Mutex<u64>,
 	sealing_block: Mutex<Option<ClosedBlock>>,
 	gas_floor_target: RwLock<U256>,
 	author: RwLock<Address>,
@@ -46,6 +47,7 @@ impl Default for Miner {
 		Miner {
 			transaction_queue: Mutex::new(TransactionQueue::new()),
 			sealing_enabled: AtomicBool::new(false),
+			sealing_block_last_request: Mutex::new(0),
 			sealing_block: Mutex::new(None),
 			gas_floor_target: RwLock::new(U256::zero()),
 			author: RwLock::new(Address::default()),
@@ -110,6 +112,8 @@ impl Miner {
 	}
 }
 
+const SEALING_TIMEOUT_IN_BLOCKS : u64 = 5;
+
 impl MinerService for Miner {
 
 	fn clear_and_reset(&self, chain: &BlockChainClient) {
@@ -139,7 +143,17 @@ impl MinerService for Miner {
 	}
 
 	fn update_sealing(&self, chain: &BlockChainClient) {
-		if self.sealing_enabled.load(atomic::Ordering::Relaxed) {
+		let should_disable_sealing = {
+			let current_no = chain.chain_info().best_block_number;
+			let last_request = self.sealing_block_last_request.lock().unwrap();
+
+			current_no - *last_request > SEALING_TIMEOUT_IN_BLOCKS
+		};
+
+		if should_disable_sealing {
+			self.sealing_enabled.store(false, atomic::Ordering::Relaxed);
+			*self.sealing_block.lock().unwrap() = None;
+		} else if self.sealing_enabled.load(atomic::Ordering::Relaxed) {
 			self.prepare_sealing(chain);
 		}
 	}
@@ -147,9 +161,10 @@ impl MinerService for Miner {
 	fn sealing_block(&self, chain: &BlockChainClient) -> &Mutex<Option<ClosedBlock>> {
 		if self.sealing_block.lock().unwrap().is_none() {
 			self.sealing_enabled.store(true, atomic::Ordering::Relaxed);
-			// TODO: Above should be on a timer that resets after two blocks have arrived without being asked for.
+
 			self.prepare_sealing(chain);
 		}
+		*self.sealing_block_last_request.lock().unwrap() = chain.chain_info().best_block_number;
 		&self.sealing_block
 	}
 
@@ -228,3 +243,42 @@ impl MinerService for Miner {
 		self.update_sealing(chain);
 	}
 }
+
+#[cfg(test)]
+mod tests {
+
+	use MinerService;
+	use super::{Miner};
+	use ethcore::client::{TestBlockChainClient, EachBlockWith};
+
+	// TODO [ToDr] To uncomment client is cleaned from mining stuff.
+	#[ignore]
+	#[test]
+	fn should_prepare_block_to_seal() {
+		// given
+		let client = TestBlockChainClient::default();
+		let miner = Miner::default();
+
+		// when
+		let res = miner.sealing_block(&client);
+
+		// then
+		assert!(res.lock().unwrap().is_some(), "Expected closed block");
+	}
+
+	#[test]
+	fn should_reset_seal_after_couple_of_blocks() {
+		// given
+		let client = TestBlockChainClient::default();
+		let miner = Miner::default();
+		let res = miner.sealing_block(&client);
+		// TODO [ToDr] Uncomment after fixing TestBlockChainClient
+		// assert!(res.lock().unwrap().is_some(), "Expected closed block");
+
+		// when
+		client.add_blocks(10, EachBlockWith::Uncle);
+
+		// then
+		assert!(res.lock().unwrap().is_none(), "Expected to remove sealed block");
+	}
+}