XCM revamp (#2836)

* Remove unused relaying XCM

* Aggregate HRMP (XCMP/HMP) messages. Payloads for spambot.

* Revert lock

* Fix

* Broken example

* Introduce fee payment mechanics into XCM.

* Weight limitations on XCM execution

* Mock environment for tests and the first test

* Tests for XCM and a few refactors.

* Remove code that's not ready

* Fix for an XCM and an additional test

* Query response system

* XCMP message dispatch system reimagining

- Moved most of the logic into xcm-handler pallet
- Altered the outgoing XCMP API from push to pull
- Changed underlying outgoing queue data structures to avoid multi-page read/writes
- Introduced queuing for incoming messages
- Introduced signal messages as a flow-control sub-stream
- Introduced flow-control with basic threshold back-pressure
- Introduced overall weight limitation on messages executed
- Additonal alterations to XCM APIs for the new system

* Some build fixes

* Remove the Encode bounds sprayed around

* More faff

* Fix bounds amek use latest scale codec.

* remove println

* fixes

* Fix XcmExecutor Tests

* Fix XCM bounds using derivative crate

* Refactor names of XcmGeneric &c into Xcm

* Repot the xcm-executor into xcm-builder

* Docs

* Docs

* Fixes

* Update xcm/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fixes

* Docs

* Update runtime/parachains/src/ump.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Docs

* Fixes

* Fixes

* Fixes

* Docs

* Fixes

* Fixes

* Introduce transfer_asset specialisation.

* Fixes

* Fixes

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

polkadot/runtime/parachains/src/hrmp.rs

@@ -995,7 +995,7 @@ impl<T: Config> Module<T> {
 		<Self as Store>::HrmpOpenChannelRequestsList::append(channel_id);
 
 		let notification_bytes = {
-			use xcm::{v0::Xcm, VersionedXcm};
+			use xcm::opaque::{v0::Xcm, VersionedXcm};
 			use parity_scale_codec::Encode as _;
 
 			VersionedXcm::from(Xcm::HrmpNewChannelOpenRequest {
@@ -1061,7 +1061,7 @@ impl<T: Config> Module<T> {
 
 		let notification_bytes = {
 			use parity_scale_codec::Encode as _;
-			use xcm::{v0::Xcm, VersionedXcm};
+			use xcm::opaque::{v0::Xcm, VersionedXcm};
 
 			VersionedXcm::from(Xcm::HrmpChannelAccepted {
 				recipient: u32::from(origin),
@@ -1104,7 +1104,7 @@ impl<T: Config> Module<T> {
 		let config = <configuration::Module<T>>::config();
 		let notification_bytes = {
 			use parity_scale_codec::Encode as _;
-			use xcm::{v0::Xcm, VersionedXcm};
+			use xcm::opaque::{v0::Xcm, VersionedXcm};
 
 			VersionedXcm::from(Xcm::HrmpChannelClosing {
 				initiator: u32::from(origin),

polkadot/runtime/parachains/src/ump.rs

@@ -20,6 +20,7 @@ use crate::{
 };
 use sp_std::{fmt, prelude::*};
 use sp_std::collections::{btree_map::BTreeMap, vec_deque::VecDeque};
+use sp_runtime::traits::Zero;
 use frame_support::{decl_module, decl_storage, StorageMap, StorageValue, weights::Weight, traits::Get};
 use primitives::v1::{Id as ParaId, UpwardMessage};
 
@@ -65,15 +66,15 @@ impl<Config: xcm_executor::Config> UmpSink for XcmSink<Config> {
 		use xcm::v0::{Junction, MultiLocation, ExecuteXcm};
 		use xcm_executor::XcmExecutor;
 
-		let weight: Weight = 0;
-
-		if let Ok(versioned_xcm_message) = VersionedXcm::decode(&mut &msg[..]) {
+		// TODO: #2841 #UMPQUEUE Get a proper weight limit here. Probably from Relay Chain Config
+		let weight_limit = Weight::max_value();
+		let weight = if let Ok(versioned_xcm_message) = VersionedXcm::decode(&mut &msg[..]) {
 			match versioned_xcm_message {
 				VersionedXcm::V0(xcm_message) => {
 					let xcm_junction: Junction = Junction::Parachain { id: origin.into() };
 					let xcm_location: MultiLocation = xcm_junction.into();
-					// TODO: Do something with result.
-					let _result = XcmExecutor::<Config>::execute_xcm(xcm_location, xcm_message);
+					let result = XcmExecutor::<Config>::execute_xcm(xcm_location, xcm_message, weight_limit);
+					result.weight_used()
 				}
 			}
 		} else {
@@ -81,11 +82,12 @@ impl<Config: xcm_executor::Config> UmpSink for XcmSink<Config> {
 				target: LOG_TARGET,
 				"Failed to decode versioned XCM from upward message.",
 			);
-		}
+			Weight::zero()
+		};
 
-		// TODO: to be sound, this implementation must ensure that returned (and thus consumed)
-		// weight is limited to some small portion of the total block weight (as a ballpark, 1/4, 1/8
-		// or lower).
+		// TODO: #2841 #UMPQUEUE to be sound, this implementation must ensure that returned (and thus consumed)
+		//  weight is limited to some small portion of the total block weight (as a ballpark, 1/4, 1/8
+		//  or lower).
 		weight
 	}
 }