refactor View to include finalized_number (#2128)

* refactor View to include finalized_number

* guide: update the NetworkBridge on BlockFinalized

* av-store: fix the tests

* actually fix tests

* grumbles

* ignore macro doctest

* use Hash::repeat_bytes more consistently

* broadcast empty leaves updates as well

* fix issuing view updates on empty leaves updates

polkadot/node/network/protocol/src/lib.rs

@@ -19,7 +19,7 @@
 #![deny(unused_crate_dependencies, unused_results)]
 #![warn(missing_docs)]
 
-use polkadot_primitives::v1::Hash;
+use polkadot_primitives::v1::{Hash, BlockNumber};
 use parity_scale_codec::{Encode, Decode};
 use std::convert::TryFrom;
 use std::fmt;
@@ -159,11 +159,32 @@ impl<M> NetworkBridgeEvent<M> {
 	}
 }
 
-/// A succinct representation of a peer's view. This consists of a bounded amount of chain heads.
+/// A succinct representation of a peer's view. This consists of a bounded amount of chain heads
+/// and the highest known finalized block number.
 ///
 /// Up to `N` (5?) chain heads.
 #[derive(Default, Debug, Clone, PartialEq, Eq, Encode, Decode)]
-pub struct View(pub Vec<Hash>);
+pub struct View {
+	/// A bounded amount of chain heads.
+	pub heads: Vec<Hash>,
+	/// The highest known finalized block number.
+	pub finalized_number: BlockNumber,
+}
+
+
+/// Construct a new view with the given chain heads and finalized number 0.
+/// NOTE: Use for tests only.
+/// # Example
+///
+/// ```ignore
+/// view![Hash::repeat_byte(1), Hash::repeat_byte(2)]
+/// ```
+#[macro_export]
+macro_rules! view {
+	( $( $hash:expr ),* $(,)? ) => {
+		View { heads: vec![ $( $hash.clone() ),* ], finalized_number: 0 }
+	};
+}
 
 impl View {
 	/// Replace `self` with `new`.
@@ -172,22 +193,22 @@ impl View {
 	pub fn replace_difference(&mut self, new: View) -> impl Iterator<Item = &Hash> {
 		let old = std::mem::replace(self, new);
 
-		self.0.iter().filter(move |h| !old.contains(h))
+		self.heads.iter().filter(move |h| !old.contains(h))
 	}
 
 	/// Returns an iterator of the hashes present in `Self` but not in `other`.
 	pub fn difference<'a>(&'a self, other: &'a View) -> impl Iterator<Item = &'a Hash> + 'a {
-		self.0.iter().filter(move |h| !other.contains(h))
+		self.heads.iter().filter(move |h| !other.contains(h))
 	}
 
 	/// An iterator containing hashes present in both `Self` and in `other`.
 	pub fn intersection<'a>(&'a self, other: &'a View) -> impl Iterator<Item = &'a Hash> + 'a {
-		self.0.iter().filter(move |h| other.contains(h))
+		self.heads.iter().filter(move |h| other.contains(h))
 	}
 
 	/// Whether the view contains a given hash.
 	pub fn contains(&self, hash: &Hash) -> bool {
-		self.0.contains(hash)
+		self.heads.contains(hash)
 	}
 }