First draft of Sassafras components structure

Cargo.toml

@@ -30,6 +30,7 @@ members = [
 	"client/consensus/epochs",
 	"client/consensus/manual-seal",
 	"client/consensus/pow",
+	"client/consensus/sassafras",
 	"client/consensus/slots",
 	"client/consensus/uncles",
 	"client/db",
@@ -118,6 +119,7 @@ members = [
 	"frame/recovery",
 	"frame/referenda",
 	"frame/remark",
+	"frame/sassafras",
 	"frame/scheduler",
 	"frame/scored-pool",
 	"frame/session",
@@ -165,6 +167,7 @@ members = [
 	"primitives/consensus/babe",
 	"primitives/consensus/common",
 	"primitives/consensus/pow",
+	"primitives/consensus/sassafras",
 	"primitives/consensus/vrf",
 	"primitives/core",
 	"primitives/core/hashing",

client/consensus/sassafras/Cargo.toml

@@ -0,0 +1,62 @@
+[package]
+name = "sc-consensus-sassafras"
+version = "0.0.1"
+authors = ["Parity Technologies <[email protected]>"]
+description = "Sassafras consensus algorithm for substrate"
+edition = "2021"
+license = "Apache 2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+documentation = "https://docs.rs/sc-consensus-sassafras"
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+async-trait = "0.1.50"
+scale-codec = { package = "parity-scale-codec", version = "3.0.0", features = ["derive"] }
+futures = "0.3.21"
+log = "0.4.16"
+#merlin = "2.0"
+#num-bigint = "0.2.3"
+#num-rational = "0.2.2"
+#num-traits = "0.2.8"
+parking_lot = "0.12.0"
+#rand = "0.7.2"
+#retain_mut = "0.1.4"
+#schnorrkel = { version = "0.9.1", features = ["preaudit_deprecated"] }
+#serde = { version = "1.0.136", features = ["derive"] }
+#thiserror = "1.0"
+#fork-tree = { version = "3.0.0", path = "../../../utils/fork-tree" }
+prometheus-endpoint = { package = "substrate-prometheus-endpoint", version = "0.10.0-dev", path = "../../../utils/prometheus" }
+sc-client-api = { version = "4.0.0-dev", path = "../../api" }
+sc-consensus = { version = "0.10.0-dev", path = "../../../client/consensus/common" }
+sc-consensus-epochs = { version = "0.10.0-dev", path = "../epochs" }
+sc-consensus-slots = { version = "0.10.0-dev", path = "../slots" }
+#sc-keystore = { version = "4.0.0-dev", path = "../../keystore" }
+sc-telemetry = { version = "4.0.0-dev", path = "../../telemetry" }
+sp-api = { version = "4.0.0-dev", path = "../../../primitives/api" }
+#sp-application-crypto = { version = "6.0.0", path = "../../../primitives/application-crypto" }
+sp-block-builder = { version = "4.0.0-dev", path = "../../../primitives/block-builder" }
+sp-blockchain = { version = "4.0.0-dev", path = "../../../primitives/blockchain" }
+sp-consensus = { version = "0.10.0-dev", path = "../../../primitives/consensus/common" }
+sp-consensus-sassafras = { version = "0.0.1", path = "../../../primitives/consensus/sassafras" }
+sp-consensus-slots = { version = "0.10.0-dev", path = "../../../primitives/consensus/slots" }
+#sp-consensus-vrf = { version = "0.10.0-dev", path = "../../../primitives/consensus/vrf" }
+sp-core = { version = "6.0.0", path = "../../../primitives/core" }
+sp-inherents = { version = "4.0.0-dev", path = "../../../primitives/inherents" }
+#sp-io = { version = "6.0.0", path = "../../../primitives/io" }
+#sp-keystore = { version = "0.12.0", path = "../../../primitives/keystore" }
+sp-runtime = { version = "6.0.0", path = "../../../primitives/runtime" }
+#sp-version = { version = "5.0.0", path = "../../../primitives/version" }
+
+#[dev-dependencies]
+#rand_chacha = "0.2.2"
+#tempfile = "3.1.0"
+#sc-block-builder = { version = "0.10.0-dev", path = "../../block-builder" }
+#sc-network = { version = "0.10.0-dev", path = "../../network" }
+#sc-network-test = { version = "0.8.0", path = "../../network/test" }
+#sp-timestamp = { version = "4.0.0-dev", path = "../../../primitives/timestamp" }
+#sp-tracing = { version = "5.0.0", path = "../../../primitives/tracing" }
+#substrate-test-runtime-client = { version = "2.0.0", path = "../../../test-utils/runtime/client" }

client/consensus/sassafras/src/aux_schema.rs

@@ -0,0 +1,69 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! Schema for Sassafras epoch changes in the aux-db.
+
+use log::info;
+use scale_codec::{Decode, Encode};
+
+use sc_client_api::backend::AuxStore;
+use sc_consensus_epochs::{EpochChangesFor, SharedEpochChanges};
+use sp_blockchain::{Error as ClientError, Result as ClientResult};
+use sp_runtime::traits::Block as BlockT;
+
+use crate::Epoch;
+
+const SASSAFRAS_EPOCH_CHANGES_KEY: &[u8] = b"sassafras_epoch_changes";
+
+fn load_decode<B, T>(backend: &B, key: &[u8]) -> ClientResult<Option<T>>
+where
+	B: AuxStore,
+	T: Decode,
+{
+	match backend.get_aux(key)? {
+		Some(t) => T::decode(&mut &t[..]).map(Some).map_err(|e| {
+			ClientError::Backend(format!("Sassafras db is corrupted, Decode error: {}", e))
+		}),
+		None => Ok(None),
+	}
+}
+
+/// Load or initialize persistent epoch change data from backend.
+pub fn load_epoch_changes<B: BlockT, AS: AuxStore>(
+	backend: &AS,
+) -> ClientResult<SharedEpochChanges<B, Epoch>> {
+	let maybe_epoch_changes =
+		load_decode::<_, EpochChangesFor<B, Epoch>>(backend, SASSAFRAS_EPOCH_CHANGES_KEY)?;
+
+	let epoch_changes =
+		SharedEpochChanges::<B, Epoch>::new(maybe_epoch_changes.unwrap_or_else(|| {
+			info!(
+				target: "babe",
+				"👶 Creating empty BABE epoch changes on what appears to be first startup.",
+			);
+			EpochChangesFor::<B, Epoch>::default()
+		}));
+
+	// rebalance the tree after deserialization. this isn't strictly necessary
+	// since the tree is now rebalanced on every update operation. but since the
+	// tree wasn't rebalanced initially it's useful to temporarily leave it here
+	// to avoid having to wait until an import for rebalancing.
+	epoch_changes.shared_data().rebalance();
+
+	Ok(epoch_changes)
+}