From 039c0056bc0f58bfe33860c7a4aab7b9aff57bbc Mon Sep 17 00:00:00 2001
From: Gav Wood <gav@ethcore.io>
Date: Wed, 2 Mar 2016 19:38:00 +0100
Subject: [PATCH] Uncle inclusion in block authoring. Still need tests.

---
 ethcore/src/blockchain/blockchain.rs | 46 +++++++++-------------------
 ethcore/src/client.rs                |  2 +-
 ethcore/src/engine.rs                |  2 ++
 ethcore/src/verification.rs          |  4 +--
 4 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/ethcore/src/blockchain/blockchain.rs b/ethcore/src/blockchain/blockchain.rs
index 6b0939df5..4cf2d96c5 100644
--- a/ethcore/src/blockchain/blockchain.rs
+++ b/ethcore/src/blockchain/blockchain.rs
@@ -503,41 +503,23 @@ impl BlockChain {
 		}
 	}
 
-	/// Given a block's `parent`, find every block header which represents a valid uncle.
-	pub fn find_uncle_headers(&self, parent: &H256) -> Option<Vec<Header>> {
-		let uncle_generations = 6usize;
-/*
-	{
-		// Find great-uncles (or second-cousins or whatever they are) -
-		// children of great-grandparents, great-great-grandparents... that were not already uncles in previous generations.
-		clog(StateDetail) << "Checking " << m_previousBlock.hash() << ", parent=" << m_previousBlock.parentHash();
-		h256Hash excluded = _bc.allKinFrom(m_currentBlock.parentHash(), 6);
-		auto p = m_previousBlock.parentHash();
-		for (unsigned gen = 0; gen < 6 && p != _bc.genesisHash() && unclesCount < 2; ++gen, p = _bc.details(p).parent)
-		{
-			auto us = _bc.details(p).children;
-			assert(us.size() >= 1);	// must be at least 1 child of our grandparent - it's our own parent!
-			for (auto const& u: us)
-				if (!excluded.count(u))	// ignore any uncles/mainline blocks that we know about.
-				{
-					uncleBlockHeaders.push_back(_bc.info(u));
-					unclesData.appendRaw(_bc.headerData(u));
-					++unclesCount;
-					if (unclesCount == 2)
-						break;
-				}
-		}
-	}
-*/		
+	/// Given a block's `parent`, find every block header which represents a valid possible uncle.
+	pub fn find_uncle_headers(&self, parent: &H256, uncle_generations: usize) -> Option<Vec<Header>> {
 		if !self.is_known(parent) { return None; }
-		let mut _excluded = HashSet::new();
+
+		let mut excluded = HashSet::new();
 		for a in self.ancestry_iter(parent.clone()).unwrap().take(uncle_generations) {
-			for u in self.uncle_hashes(&a).unwrap().into_iter() {
-				_excluded.insert(u);
-			}
-			_excluded.insert(a);
+			excluded.extend(self.uncle_hashes(&a).unwrap().into_iter());
+			excluded.insert(a);
 		}
-		None
+
+		let mut ret = Vec::new();
+		for a in self.ancestry_iter(parent.clone()).unwrap().skip(1).take(uncle_generations) {
+			ret.extend(self.block_details(&a).unwrap().children.iter()
+				.filter_map(|h| if excluded.contains(h) { None } else { self.block_header(h) })
+			);
+		}
+		Some(ret)
 	}
 
 	/// Get inserted block info which is critical to preapre extras updates.
diff --git a/ethcore/src/client.rs b/ethcore/src/client.rs
index 105090580..4ddb40477 100644
--- a/ethcore/src/client.rs
+++ b/ethcore/src/client.rs
@@ -457,7 +457,7 @@ impl Client {
 			self.extra_data()
 		);
 
-		self.chain.read().unwrap().find_uncle_headers(&h).unwrap().into_iter().foreach(|h| { b.push_uncle(h).unwrap(); });
+		self.chain.read().unwrap().find_uncle_headers(&h, self.engine.deref().deref().maximum_uncle_age()).unwrap().into_iter().foreach(|h| { b.push_uncle(h).unwrap(); });
 
 		// TODO: push transactions.
 
diff --git a/ethcore/src/engine.rs b/ethcore/src/engine.rs
index d607ce2e2..83e1986fd 100644
--- a/ethcore/src/engine.rs
+++ b/ethcore/src/engine.rs
@@ -47,6 +47,8 @@ pub trait Engine : Sync + Send {
 	fn maximum_extra_data_size(&self) -> usize { decode(&self.spec().engine_params.get("maximumExtraDataSize").unwrap()) }
 	/// Maximum number of uncles a block is allowed to declare.
 	fn maximum_uncle_count(&self) -> usize { 2 }
+	/// The number of generations back that uncles can be.
+	fn maximum_uncle_age(&self) -> usize { 6 }
 	/// The nonce with which accounts begin.
 	fn account_start_nonce(&self) -> U256 { decode(&self.spec().engine_params.get("accountStartNonce").unwrap()) }
 
diff --git a/ethcore/src/verification.rs b/ethcore/src/verification.rs
index f52e2e1e4..23b850f55 100644
--- a/ethcore/src/verification.rs
+++ b/ethcore/src/verification.rs
@@ -94,7 +94,7 @@ pub fn verify_block_family<BC>(header: &Header, bytes: &[u8], engine: &Engine, b
 		excluded.insert(header.hash());
 		let mut hash = header.parent_hash.clone();
 		excluded.insert(hash.clone());
-		for _ in 0..6 {
+		for _ in 0..engine.maximum_uncle_age() {
 			match bc.block_details(&hash) {
 				Some(details) => {
 					excluded.insert(details.parent.clone());
@@ -121,7 +121,7 @@ pub fn verify_block_family<BC>(header: &Header, bytes: &[u8], engine: &Engine, b
 			//												(8 Invalid)
 
 			let depth = if header.number > uncle.number { header.number - uncle.number } else { 0 };
-			if depth > 6 {
+			if depth > engine.maximum_uncle_age() as u64 {
 				return Err(From::from(BlockError::UncleTooOld(OutOfBounds { min: Some(header.number - depth), max: Some(header.number - 1), found: uncle.number })));
 			}
 			else if depth < 1 {