starting memoized validatorset

ethcore/src/engines/mod.rs

@@ -206,7 +206,7 @@ pub trait Engine : Sync + Send {
 	///
 	/// Engines which do draw consensus information from the state may only do so
 	/// here.
-	fn generate_validation_proof(&self, _call: &Call) -> ValidationProof {
+	fn generate_validation_proof(&self, header: &Header, _call: &Call) -> ValidationProof {
 		ValidationProof::default()
 	}
 

ethcore/src/engines/validator_set/mod.rs

@@ -25,11 +25,15 @@ use std::sync::Weak;
 use util::{Address, H256};
 use ethjson::spec::ValidatorSet as ValidatorSpec;
 use client::Client;
+use receipt::Receipt;
+
 use self::simple_list::SimpleList;
 use self::contract::ValidatorContract;
 use self::safe_contract::ValidatorSafeContract;
 use self::multi::Multi;
 
+pub type Call = Fn(Address, Vec<u8>) -> Result<Vec<u8>, String>;
+
 /// Creates a validator set from spec.
 pub fn new_validator_set(spec: ValidatorSpec) -> Box<ValidatorSet> {
 	match spec {
@@ -42,7 +46,12 @@ pub fn new_validator_set(spec: ValidatorSpec) -> Box<ValidatorSet> {
 	}
 }
 
+/// A validator set.
 pub trait ValidatorSet: Send + Sync {
+	/// Get this validator set as a flexible validator set.
+	/// Returning `None` indicates this is only usable for
+	/// full nodes.
+	fn as_memoized(&self) -> Option<&Memoized> { None }
 	/// Checks if a given address is a validator.
 	fn contains(&self, parent_block_hash: &H256, address: &Address) -> bool;
 	/// Draws an validator nonce modulo number of validators.
@@ -56,3 +65,35 @@ pub trait ValidatorSet: Send + Sync {
 	/// Allows blockchain state access.
 	fn register_contract(&self, _client: Weak<Client>) {}
 }
+
+/// A flexible validator set can track its changes.
+pub trait FlexibleValidatorSet: Send + Sync {
+	/// Whether a validator set may have changed at this header.
+	fn has_possibly_changed(&self, header: &Header) -> bool;
+
+	/// Whether a validator set has changed at this header, given the block receipts.
+	/// Called after `has_possibly_changed`.
+	/// `Some` indicates the validator set has changed at this header and the new
+	/// expected validator set.
+	/// `None` indicates no change.
+	fn has_changed(&self, header: &Header, receipts: &[Receipt]) -> Option<SimpleList>;
+
+	/// Fetch validators at a block synchronously.
+	fn fetch_validators(&self, header: &Header, call: &Call) -> Result<SimpleList, String>;
+}
+
+/// A memoized flexible validator set
+pub struct Memoized {
+	inner: Box<FlexibleValidatorSet>,
+	memo: Mutex<(SimpleList, (H256, u64))>,
+}
+
+impl Memoized {
+	/// Denote that the
+	pub fn use_memo_at(&self, list: SimpleList)
+}
+
+impl ValidatorSet for Memoized {
+	fn as_memoized(&self) -> Option<&Memoized> { Some(self) }
+}
+

ethcore/src/engines/validator_set/multi.rs

@@ -40,7 +40,7 @@ impl Multi {
 		}
 	}
 
-	fn correct_set(&self, bh: &H256) -> Option<&Box<ValidatorSet>> {
+	fn correct_set(&self, bh: &H256) -> Option<&ValidatorSet> {
 		match self
 			.block_number
 			.read()(bh)
@@ -55,7 +55,7 @@ impl Multi {
 				) {
 			Ok((block, set)) => {
 				trace!(target: "engine", "Multi ValidatorSet retrieved for block {}.", block);
-				Some(set)
+				Some(&*set)
 			},
 			Err(e) => {
 				debug!(target: "engine", "ValidatorSet could not be recovered: {}", e);
@@ -66,6 +66,21 @@ impl Multi {
 }
 
 impl ValidatorSet for Multi {
+	fn has_possibly_changed(&self, header: &Header) -> bool {
+		// if the sets are the same for each header, compare those.
+		// otherwise, the sets have almost certainly changed.
+		match (self.correct_set(&header.hash()), self.correct_set(header.parent_hash())) {
+			(Some(a), Some(b)) if a as *const _ == b as *const _ => { a.has_possibly_changed(header) },
+			_ => true,
+		}
+	}
+
+	fn has_changed(&self, header: &Header, receipts: &[Receipt]) -> Option<Vec<Address>> {
+
+	}
+
+	fn fetch(&self) ->
+
 	fn contains(&self, bh: &H256, address: &Address) -> bool {
 		self.correct_set(bh).map_or(false, |set| set.contains(bh, address))
 	}

ethcore/src/engines/validator_set/simple_list.rs

@@ -22,13 +22,11 @@ use super::ValidatorSet;
 #[derive(Debug, PartialEq, Eq, Default)]
 pub struct SimpleList {
 	validators: Vec<Address>,
-	validator_n: usize,
 }
 
 impl SimpleList {
 	pub fn new(validators: Vec<Address>) -> Self {
 		SimpleList {
-			validator_n: validators.len(),
 			validators: validators,
 		}
 	}
@@ -36,7 +34,7 @@ impl SimpleList {
 
 impl HeapSizeOf for SimpleList {
 	fn heap_size_of_children(&self) -> usize {
-		self.validators.heap_size_of_children() + self.validator_n.heap_size_of_children()
+		self.validators.heap_size_of_children()
 	}
 }
 
@@ -46,11 +44,12 @@ impl ValidatorSet for SimpleList {
 	}
 
 	fn get(&self, _bh: &H256, nonce: usize) -> Address {
-		self.validators.get(nonce % self.validator_n).expect("There are validator_n authorities; taking number modulo validator_n gives number in validator_n range; qed").clone()
+		let validator_n = self.validators.len();
+		self.validators.get(nonce % validator_n).expect("There are validator_n authorities; taking number modulo validator_n gives number in validator_n range; qed").clone()
 	}
 
 	fn count(&self, _bh: &H256) -> usize {
-		self.validator_n
+		self.validators.len()
 	}
 }