Consensus: Proof of Work

Cargo.toml

@@ -29,6 +29,7 @@ members = [
 	"core/consensus/rhd",
 	"core/consensus/slots",
 	"core/consensus/uncles",
+	"core/consensus/pow",
 	"core/executor",
 	"core/executor/runtime-test",
 	"core/finality-grandpa",
@@ -94,6 +95,7 @@ members = [
 	"srml/system",
 	"srml/timestamp",
 	"srml/treasury",
+	"srml/pow",
 	"node/cli",
 	"node/executor",
 	"node/primitives",

core/consensus/aura/primitives/Cargo.toml

@@ -10,7 +10,7 @@ codec = { package = "parity-scale-codec", version = "1.0.0", default-features =
 substrate-client = { path = "../../../client", default-features = false }
 app-crypto = { package = "substrate-application-crypto", path = "../../../application-crypto", default-features = false }
 rstd = { package = "sr-std", path = "../../../sr-std", default-features = false }
-sr-primitives = {  path = "../../../sr-primitives", default-features = false }
+sr-primitives = { path = "../../../sr-primitives", default-features = false }
 
 [features]
 default = ["std"]

core/consensus/pow/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "substrate-consensus-pow"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+description = "PoW consensus algorithm for substrate"
+edition = "2018"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "1.0.0", features = ["derive"] }
+primitives = { package = "substrate-primitives", path = "../../primitives" }
+sr-primitives = { path = "../../sr-primitives" }
+client = { package = "substrate-client", path = "../../client" }
+srml-timestamp = { path = "../../../srml/timestamp" }
+inherents = { package = "substrate-inherents", path = "../../inherents" }
+pow-primitives = { package = "substrate-consensus-pow-primitives", path = "primitives" }
+consensus-common = { package = "substrate-consensus-common", path = "../common" }
+log = "0.4"
+futures-preview = { version = "=0.3.0-alpha.17", features = ["compat"] }

core/consensus/pow/primitives/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "substrate-consensus-pow-primitives"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+description = "Primitives for Aura consensus"
+edition = "2018"
+
+[dependencies]
+substrate-client = { path = "../../../client", default-features = false }
+rstd = { package = "sr-std", path = "../../../sr-std", default-features = false }
+sr-primitives = { path = "../../../sr-primitives", default-features = false }
+primitives = { package = "substrate-primitives", path = "../../../primitives", default-features = false }
+
+[features]
+default = ["std"]
+std = [
+	"rstd/std",
+	"substrate-client/std",
+	"sr-primitives/std",
+	"primitives/std",
+]

core/consensus/pow/primitives/src/lib.rs

@@ -0,0 +1,71 @@
+// Copyright 2017-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Primitives for Substrate PoW consensus.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use substrate_client::decl_runtime_apis;
+use rstd::vec::Vec;
+use sr_primitives::ConsensusEngineId;
+use primitives::H256;
+
+/// The `ConsensusEngineId` of PoW.
+pub const POW_ENGINE_ID: ConsensusEngineId = [b'p', b'o', b'w', b'_'];
+
+/// Type of difficulty.
+///
+/// For runtime designed for Substrate, it's always possible to fit its total
+/// difficulty range under `u128::max_value()` because it can be freely scaled
+/// up or scaled down. Practially, nearly no PoW chains uses difficulty values
+/// larger than `u128::max_value()`.
+pub type Difficulty = u128;
+
+/// Type of seal.
+pub type Seal = Vec<u8>;
+
+decl_runtime_apis! {
+	/// API necessary for block authorship with Proof of Work.
+	///
+	/// This API allows online upgrades of PoW algorithms as well as the difficulty
+	/// adjustment algorithm. Note that we always validate difficulty and seals
+	/// against the parent block. This means that in the case of code upgrade, the
+	/// first block that upgraded the code will still use the old algorithm. The block
+	/// after that will switch to the new algorithm.
+	///
+	/// All functions here should not modify block state. Instead, state modifications
+	/// related to PoW should use `on_initialize` and `on_finalize` routine.
+	pub trait PowApi {
+		/// Return the difficulty that should be applied for the next block.
+		fn difficulty() -> Difficulty;
+
+		/// Verify a given proof of work against the given difficulty.
+		/// Note that `pre_hash` is always a hash of a direct child.
+		fn verify(
+			pre_hash: &H256,
+			seal: &Seal,
+			difficulty: Difficulty
+		) -> bool;
+
+		/// Mine a seal that satisfy the given difficulty.
+		fn mine(
+			pre_hash: &H256,
+			seed: &H256,
+			difficulty: Difficulty,
+			round: u32
+		) -> Option<Seal>;
+	}
+}