undo Arc proliferation from master merge

If that was an intentional change, it'll need to be redone, because
it started to have huge effects all through the codebase; not something
I wanted to chase down right now.

node/core/backing/src/lib.rs

@@ -18,7 +18,6 @@
 
 #![recursion_limit="256"]
 
-use std::sync::Arc;
 use std::collections::{HashMap, HashSet};
 use std::convert::TryFrom;
 use std::pin::Pin;
@@ -234,7 +233,7 @@ impl CandidateBackingJob {
 	async fn validate_and_second(
 		&mut self,
 		candidate: AbridgedCandidateReceipt,
-		pov: Arc<PoVBlock>,
+		pov: PoVBlock,
 	) -> Result<ValidationResult, Error> {
 		let (valid, global_validation_schedule, local_validation_data) = self.request_candidate_validation(candidate.clone(), pov.clone()).await?;
 		let statement = match valid {
@@ -454,7 +453,7 @@ impl CandidateBackingJob {
 	async fn request_pov_from_distribution(
 		&mut self,
 		descriptor: CandidateDescriptor,
-	) -> Result<Arc<PoVBlock>, Error> {
+	) -> Result<PoVBlock, Error> {
 		let (tx, rx) = oneshot::channel();
 
 		self.tx_from.send(FromJob::PoVDistribution(
@@ -467,7 +466,7 @@ impl CandidateBackingJob {
 	async fn request_candidate_validation(
 		&mut self,
 		candidate: AbridgedCandidateReceipt,
-		pov: Arc<PoVBlock>,
+		pov: PoVBlock,
 	) -> Result<(ValidationResult, GlobalValidationSchedule, LocalValidationData), Error> {
 		let (tx, rx) = oneshot::channel();
 
@@ -500,7 +499,7 @@ impl CandidateBackingJob {
 
 	async fn make_pov_available(
 		&mut self,
-		pov_block: Arc<PoVBlock>,
+		pov_block: PoVBlock,
 		global_validation: GlobalValidationSchedule,
 		local_validation: LocalValidationData,
 	) -> Result<(), Error> {

node/subsystem/src/messages.rs

@@ -35,8 +35,6 @@ use polkadot_node_primitives::{
 	MisbehaviorReport, SignedFullStatement, View, ProtocolId, ValidationResult,
 };
 
-use std::sync::Arc;
-
 pub use sc_network::{ObservedRole, ReputationChange, PeerId};
 
 /// A notification of a new backed candidate.
@@ -59,7 +57,7 @@ pub enum CandidateBackingMessage {
 	RegisterBackingWatcher(Hash, mpsc::Sender<NewBackedCandidate>),
 	/// Note that the Candidate Backing subsystem should second the given candidate in the context of the
 	/// given relay-parent (ref. by hash). This candidate must be validated.
-	Second(Hash, AbridgedCandidateReceipt, Arc<PoVBlock>),
+	Second(Hash, AbridgedCandidateReceipt, PoVBlock),
 	/// Note a validator's statement about a particular candidate. Disagreements about validity must be escalated
 	/// to a broader check by Misbehavior Arbitration. Agreements are simply tallied until a quorum is reached.
 	Statement(Hash, SignedFullStatement),
@@ -80,7 +78,7 @@ pub enum CandidateValidationMessage {
 		Hash,
 		AbridgedCandidateReceipt,
 		HeadData,
-		Arc<PoVBlock>,
+		PoVBlock,
 		oneshot::Sender<Result<
 			(ValidationResult, GlobalValidationSchedule, LocalValidationData),
 			ValidationFailed,
@@ -253,10 +251,10 @@ pub enum PoVDistributionMessage {
 	///
 	/// This `CandidateDescriptor` should correspond to a candidate seconded under the provided
 	/// relay-parent hash.
-	FetchPoV(Hash, CandidateDescriptor, oneshot::Sender<Arc<PoVBlock>>),
+	FetchPoV(Hash, CandidateDescriptor, oneshot::Sender<PoVBlock>),
 	/// Distribute a PoV for the given relay-parent and CandidateDescriptor.
 	/// The PoV should correctly hash to the PoV hash mentioned in the CandidateDescriptor
-	DistributePoV(Hash, CandidateDescriptor, Arc<PoVBlock>),
+	DistributePoV(Hash, CandidateDescriptor, PoVBlock),
 	/// An update from the network bridge.
 	NetworkBridgeUpdate(NetworkBridgeEvent),
 }

primitives/src/parachain.rs

@@ -19,7 +19,6 @@
 
 use sp_std::prelude::*;
 use sp_std::cmp::Ordering;
-use sp_std::sync::Arc;
 use parity_scale_codec::{Encode, Decode};
 use bitvec::vec::BitVec;
 use super::{Hash, Balance, BlockNumber};
@@ -719,7 +718,7 @@ impl PoVBlock {
 #[cfg_attr(feature = "std", derive(Debug, Encode, Decode))]
 pub struct AvailableData {
 	/// The PoV block.
-	pub pov_block: Arc<PoVBlock>,
+	pub pov_block: PoVBlock,
 	/// Data that is omitted from an abridged candidate receipt
 	/// that is necessary for validation.
 	pub omitted_validation: OmittedValidationData,