plant_authorship/
lib.rs

1// This file is part of Soil.
2
3// Copyright (C) Soil contributors.
4// Copyright (C) Parity Technologies (UK) Ltd.
5// SPDX-License-Identifier: Apache-2.0 OR GPL-3.0-or-later WITH Classpath-exception-2.0
6
7//! Authorship tracking for FRAME runtimes.
8//!
9//! This tracks the current author of the block.
10
11#![cfg_attr(not(feature = "std"), no_std)]
12
13use topsoil_core::traits::FindAuthor;
14
15pub use pallet::*;
16
17/// An event handler for the authorship pallet. There is a dummy implementation
18/// for `()`, which does nothing.
19#[impl_trait_for_tuples::impl_for_tuples(30)]
20pub trait EventHandler<Author, BlockNumber> {
21	/// Note that the given account ID is the author of the current block.
22	fn note_author(author: Author);
23}
24
25#[topsoil_core::pallet]
26pub mod pallet {
27	use super::*;
28	use topsoil_core::pallet_prelude::*;
29	use topsoil_core::system::pallet_prelude::*;
30
31	#[pallet::config]
32	pub trait Config: topsoil_core::system::Config {
33		/// Find the author of a block.
34		type FindAuthor: FindAuthor<Self::AccountId>;
35		/// An event handler for authored blocks.
36		type EventHandler: EventHandler<Self::AccountId, BlockNumberFor<Self>>;
37	}
38
39	#[pallet::pallet]
40	pub struct Pallet<T>(_);
41
42	#[pallet::hooks]
43	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
44		fn on_initialize(_: BlockNumberFor<T>) -> Weight {
45			if let Some(author) = Self::author() {
46				T::EventHandler::note_author(author);
47			}
48
49			Weight::zero()
50		}
51
52		fn on_finalize(_: BlockNumberFor<T>) {
53			// ensure we never go to trie with these values.
54			<Author<T>>::kill();
55		}
56	}
57
58	#[pallet::storage]
59	#[pallet::whitelist_storage]
60	/// Author of current block.
61	pub(super) type Author<T: Config> = StorageValue<_, T::AccountId, OptionQuery>;
62}
63
64impl<T: Config> Pallet<T> {
65	/// Fetch the author of the block.
66	///
67	/// This is safe to invoke in `on_initialize` implementations, as well
68	/// as afterwards.
69	pub fn author() -> Option<T::AccountId> {
70		// Check the memorized storage value.
71		if let Some(author) = <Author<T>>::get() {
72			return Some(author);
73		}
74
75		let digest = <topsoil_core::system::Pallet<T>>::digest();
76		let pre_runtime_digests = digest.logs.iter().filter_map(|d| d.as_pre_runtime());
77		T::FindAuthor::find_author(pre_runtime_digests).inspect(|a| {
78			<Author<T>>::put(&a);
79		})
80	}
81}
82
83#[cfg(test)]
84mod tests {
85	use super::*;
86	use crate as plant_authorship;
87	use codec::{Decode, Encode};
88	use subsoil::core::H256;
89	use subsoil::runtime::{
90		generic::DigestItem, testing::Header, traits::Header as HeaderT, BuildStorage,
91	};
92	use topsoil_core::{derive_impl, ConsensusEngineId};
93
94	type Block = topsoil_core::system::mocking::MockBlock<Test>;
95
96	topsoil_core::construct_runtime!(
97		pub enum Test
98		{
99			System: topsoil_core::system,
100			Authorship: plant_authorship,
101		}
102	);
103
104	#[derive_impl(topsoil_core::system::config_preludes::TestDefaultConfig)]
105	impl topsoil_core::system::Config for Test {
106		type Block = Block;
107	}
108
109	impl pallet::Config for Test {
110		type FindAuthor = AuthorGiven;
111		type EventHandler = ();
112	}
113
114	const TEST_ID: ConsensusEngineId = [1, 2, 3, 4];
115
116	pub struct AuthorGiven;
117
118	impl FindAuthor<u64> for AuthorGiven {
119		fn find_author<'a, I>(digests: I) -> Option<u64>
120		where
121			I: 'a + IntoIterator<Item = (ConsensusEngineId, &'a [u8])>,
122		{
123			for (id, mut data) in digests {
124				if id == TEST_ID {
125					return u64::decode(&mut data).ok();
126				}
127			}
128
129			None
130		}
131	}
132
133	fn seal_header(mut header: Header, author: u64) -> Header {
134		{
135			let digest = header.digest_mut();
136			digest.logs.push(DigestItem::PreRuntime(TEST_ID, author.encode()));
137			digest.logs.push(DigestItem::Seal(TEST_ID, author.encode()));
138		}
139
140		header
141	}
142
143	fn create_header(number: u64, parent_hash: H256, state_root: H256) -> Header {
144		Header::new(number, Default::default(), state_root, parent_hash, Default::default())
145	}
146
147	fn new_test_ext() -> subsoil::io::TestExternalities {
148		let t = topsoil_core::system::GenesisConfig::<Test>::default().build_storage().unwrap();
149		t.into()
150	}
151
152	#[test]
153	fn sets_author_lazily() {
154		new_test_ext().execute_with(|| {
155			let author = 42;
156			let mut header =
157				seal_header(create_header(1, Default::default(), [1; 32].into()), author);
158
159			header.digest_mut().pop(); // pop the seal off.
160			System::reset_events();
161			System::initialize(&1, &Default::default(), header.digest());
162
163			assert_eq!(Authorship::author(), Some(author));
164		});
165	}
166}
plant_authorship/lib.rs

plant_authorship/
lib.rs
