Erasure encoding availability (#345)

* Erasure encoding availability initial commit

 * Modifications to availability store to keep chunks as well as
   reconstructed blocks and extrinsics.
 * Gossip messages containig signed erasure chunks.
 * Requesting eraure chunks with polkadot-specific messages.
 * Validation of erasure chunk messages.

* Apply suggestions from code review

Co-Authored-By: Luke Schoen <ltfschoen@users.noreply.github.com>

* Fix build after a merge

* Gossip erasure chunk messages under their own topic

* erasure_chunks should use the appropriate topic

* Updates Cargo.lock

* Fixes after merge

* Removes a couple of leftover pieces of code

* Fixes simple stuff from review

* Updates erasure and storage for more flexible logic

* Changes validation and candidate receipt production.

* Adds add_erasure_chunks method

* Fixes most of the nits

* Better validate_collation and validate_receipt functions

* Fixes the tests

* Apply suggestions from code review

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

* Removes unwrap() calls

* Removes ErasureChunks primitive

* Removes redundant fields from ErasureChunk struct

* AvailabilityStore should store CandidateReceipt

* Changes the way chunk messages are imported and validated.

 * Availability store now stores a validator_index and n_validators for
 each relay_parent.
 * Availability store now also stores candidate receipts.
 * Removes importing chunks in the table and moves it into network
 gossip validation.
 * Validation of erasure messages id done against receipts that are
 stored in the availability store.

* Correctly compute topics for erasure messages

* Removes an unused parameter

* Refactors availability db querying into a helper

* Adds the apis described in the writeup

* Adds a runtime api to extract erasure roots form raw extrinsics.

* Adds a barebone BlockImport impl for avalability store

* Adds the implementation of the availability worker

* Fix build after the merge with master.

* Make availability store API async

* Bring back the default wasmtime feature

* Lines width

* Bump runtime version

* Formatting and dead code elimination

* some style nits (#1)

* More nits and api cleanup

* Disable wasm CI for availability-store

* Another nit

* Formatting

polkadot/collator/src/lib.rs

@@ -53,6 +53,7 @@ use futures::{
 	future, Future, Stream, FutureExt, TryFutureExt, StreamExt,
 	compat::{Compat01As03, Future01CompatExt, Stream01CompatExt}
 };
+use futures01::{Future as _};
 use log::{warn, error};
 use client::BlockchainEvents;
 use primitives::{Pair, Blake2Hasher};
@@ -216,19 +217,18 @@ pub async fn collate<R, P>(
 	let egress_queue_roots =
 		polkadot_validation::egress_roots(&mut outgoing.outgoing_messages);
 
-	let receipt = parachain::CandidateReceipt {
+	let info = parachain::CollationInfo {
 		parachain_index: local_id,
 		collator: key.public(),
 		signature,
-		head_data,
 		egress_queue_roots,
-		fees: 0,
+		head_data,
 		block_data_hash,
 		upward_messages: Vec::new(),
 	};
 
 	let collation = parachain::Collation {
-		receipt,
+		info,
 		pov: PoVBlock {
 			block_data,
 			ingress,
@@ -393,6 +393,7 @@ impl<P, E> Worker for CollationNode<P, E> where
 				let key = key.clone();
 				let parachain_context = parachain_context.clone();
 				let validation_network = validation_network.clone();
+				let inner_exit_2 = inner_exit.clone();
 
 				let work = future::lazy(move |_| {
 					let api = client.runtime_api();
@@ -432,9 +433,7 @@ impl<P, E> Worker for CollationNode<P, E> where
 								outgoing,
 							);
 
-							if let Err(e) = res {
-								warn!("Unable to broadcast local collation: {:?}", e);
-							}
+							tokio::spawn(res.select(inner_exit_2.clone()).then(|_| Ok(())));
 						})
 					});
 
@@ -602,7 +601,7 @@ mod tests {
 		let collation = futures::executor::block_on(future).unwrap().0;
 
 		// ascending order by root.
-		assert_eq!(collation.receipt.egress_queue_roots, vec![(a, root_a), (b, root_b)]);
+		assert_eq!(collation.info.egress_queue_roots, vec![(a, root_a), (b, root_b)]);
 	}
 }