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// Copyright 2018-2020 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 GRANDPA integration, suitable for WASM compilation. #![cfg_attr(not(feature = "std"), no_std)] #[cfg(not(feature = "std"))] extern crate alloc; #[cfg(feature = "std")] use serde::Serialize; use codec::{Encode, Decode, Input, Codec}; use sp_runtime::{ConsensusEngineId, RuntimeDebug}; use sp_std::borrow::Cow; use sp_std::vec::Vec; mod app { use sp_application_crypto::{app_crypto, key_types::GRANDPA, ed25519}; app_crypto!(ed25519, GRANDPA); } sp_application_crypto::with_pair! { /// The grandpa crypto scheme defined via the keypair type. pub type AuthorityPair = app::Pair; } /// Identity of a Grandpa authority. pub type AuthorityId = app::Public; /// Signature for a Grandpa authority. pub type AuthoritySignature = app::Signature; /// The `ConsensusEngineId` of GRANDPA. pub const GRANDPA_ENGINE_ID: ConsensusEngineId = *b"FRNK"; /// The storage key for the current set of weighted Grandpa authorities. /// The value stored is an encoded VersionedAuthorityList. pub const GRANDPA_AUTHORITIES_KEY: &'static [u8] = b":grandpa_authorities"; /// The weight of an authority. pub type AuthorityWeight = u64; /// The index of an authority. pub type AuthorityIndex = u64; /// The monotonic identifier of a GRANDPA set of authorities. pub type SetId = u64; /// The round indicator. pub type RoundNumber = u64; /// A list of Grandpa authorities with associated weights. pub type AuthorityList = Vec<(AuthorityId, AuthorityWeight)>; /// A scheduled change of authority set. #[cfg_attr(feature = "std", derive(Serialize))] #[derive(Clone, Eq, PartialEq, Encode, Decode, RuntimeDebug)] pub struct ScheduledChange<N> { /// The new authorities after the change, along with their respective weights. pub next_authorities: AuthorityList, /// The number of blocks to delay. pub delay: N, } /// An consensus log item for GRANDPA. #[cfg_attr(feature = "std", derive(Serialize))] #[derive(Decode, Encode, PartialEq, Eq, Clone, RuntimeDebug)] pub enum ConsensusLog<N: Codec> { /// Schedule an authority set change. /// /// The earliest digest of this type in a single block will be respected, /// provided that there is no `ForcedChange` digest. If there is, then the /// `ForcedChange` will take precedence. /// /// No change should be scheduled if one is already and the delay has not /// passed completely. /// /// This should be a pure function: i.e. as long as the runtime can interpret /// the digest type it should return the same result regardless of the current /// state. #[codec(index = "1")] ScheduledChange(ScheduledChange<N>), /// Force an authority set change. /// /// Forced changes are applied after a delay of _imported_ blocks, /// while pending changes are applied after a delay of _finalized_ blocks. /// /// The earliest digest of this type in a single block will be respected, /// with others ignored. /// /// No change should be scheduled if one is already and the delay has not /// passed completely. /// /// This should be a pure function: i.e. as long as the runtime can interpret /// the digest type it should return the same result regardless of the current /// state. #[codec(index = "2")] ForcedChange(N, ScheduledChange<N>), /// Note that the authority with given index is disabled until the next change. #[codec(index = "3")] OnDisabled(AuthorityIndex), /// A signal to pause the current authority set after the given delay. /// After finalizing the block at _delay_ the authorities should stop voting. #[codec(index = "4")] Pause(N), /// A signal to resume the current authority set after the given delay. /// After authoring the block at _delay_ the authorities should resume voting. #[codec(index = "5")] Resume(N), } impl<N: Codec> ConsensusLog<N> { /// Try to cast the log entry as a contained signal. pub fn try_into_change(self) -> Option<ScheduledChange<N>> { match self { ConsensusLog::ScheduledChange(change) => Some(change), _ => None, } } /// Try to cast the log entry as a contained forced signal. pub fn try_into_forced_change(self) -> Option<(N, ScheduledChange<N>)> { match self { ConsensusLog::ForcedChange(median, change) => Some((median, change)), _ => None, } } /// Try to cast the log entry as a contained pause signal. pub fn try_into_pause(self) -> Option<N> { match self { ConsensusLog::Pause(delay) => Some(delay), _ => None, } } /// Try to cast the log entry as a contained resume signal. pub fn try_into_resume(self) -> Option<N> { match self { ConsensusLog::Resume(delay) => Some(delay), _ => None, } } } /// WASM function call to check for pending changes. pub const PENDING_CHANGE_CALL: &str = "grandpa_pending_change"; /// WASM function call to get current GRANDPA authorities. pub const AUTHORITIES_CALL: &str = "grandpa_authorities"; /// The current version of the stored AuthorityList type. The encoding version MUST be updated any /// time the AuthorityList type changes. const AUTHORITIES_VERSION: u8 = 1; /// An AuthorityList that is encoded with a version specifier. The encoding version is updated any /// time the AuthorityList type changes. This ensures that encodings of different versions of an /// AuthorityList are differentiable. Attempting to decode an authority list with an unknown /// version will fail. #[derive(Default)] pub struct VersionedAuthorityList<'a>(Cow<'a, AuthorityList>); impl<'a> From<AuthorityList> for VersionedAuthorityList<'a> { fn from(authorities: AuthorityList) -> Self { VersionedAuthorityList(Cow::Owned(authorities)) } } impl<'a> From<&'a AuthorityList> for VersionedAuthorityList<'a> { fn from(authorities: &'a AuthorityList) -> Self { VersionedAuthorityList(Cow::Borrowed(authorities)) } } impl<'a> Into<AuthorityList> for VersionedAuthorityList<'a> { fn into(self) -> AuthorityList { self.0.into_owned() } } impl<'a> Encode for VersionedAuthorityList<'a> { fn size_hint(&self) -> usize { (AUTHORITIES_VERSION, self.0.as_ref()).size_hint() } fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R { (AUTHORITIES_VERSION, self.0.as_ref()).using_encoded(f) } } impl<'a> Decode for VersionedAuthorityList<'a> { fn decode<I: Input>(value: &mut I) -> Result<Self, codec::Error> { let (version, authorities): (u8, AuthorityList) = Decode::decode(value)?; if version != AUTHORITIES_VERSION { return Err("unknown Grandpa authorities version".into()); } Ok(authorities.into()) } } sp_api::decl_runtime_apis! { /// APIs for integrating the GRANDPA finality gadget into runtimes. /// This should be implemented on the runtime side. /// /// This is primarily used for negotiating authority-set changes for the /// gadget. GRANDPA uses a signaling model of changing authority sets: /// changes should be signaled with a delay of N blocks, and then automatically /// applied in the runtime after those N blocks have passed. /// /// The consensus protocol will coordinate the handoff externally. #[api_version(2)] pub trait GrandpaApi { /// Get the current GRANDPA authorities and weights. This should not change except /// for when changes are scheduled and the corresponding delay has passed. /// /// When called at block B, it will return the set of authorities that should be /// used to finalize descendants of this block (B+1, B+2, ...). The block B itself /// is finalized by the authorities from block B-1. fn grandpa_authorities() -> AuthorityList; } }