Files
pezkuwi-subxt/substrate/primitives/consensus/common/src/select_chain.rs
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Benjamin Kampmann 60e5011c72 Reorganising the repository - external renames and moves (#4074)
* Adding first rough ouline of the repository structure

* Remove old CI stuff

* add title

* formatting fixes

* move node-exits job's script to scripts dir

* Move docs into subdir

* move to bin

* move maintainence scripts, configs and helpers into its own dir

* add .local to ignore

* move core->client

* start up 'test' area

* move test client

* move test runtime

* make test move compile

* Add dependencies rule enforcement.

* Fix indexing.

* Update docs to reflect latest changes

* Moving /srml->/paint

* update docs

* move client/sr-* -> primitives/

* clean old readme

* remove old broken code in rhd

* update lock

* Step 1.

* starting to untangle client

* Fix after merge.

* start splitting out client interfaces

* move children and blockchain interfaces

* Move trie and state-machine to primitives.

* Fix WASM builds.

* fixing broken imports

* more interface moves

* move backend and light to interfaces

* move CallExecutor

* move cli off client

* moving around more interfaces

* re-add consensus crates into the mix

* fix subkey path

* relieve client from executor

* starting to pull out client from grandpa

* move is_decendent_of out of client

* grandpa still depends on client directly

* lemme tests pass

* rename srml->paint

* Make it compile.

* rename interfaces->client-api

* Move keyring to primitives.

* fixup libp2p dep

* fix broken use

* allow dependency enforcement to fail

* move fork-tree

* Moving wasm-builder

* make env

* move build-script-utils

* fixup broken crate depdencies and names

* fix imports for authority discovery

* fix typo

* update cargo.lock

* fixing imports

* Fix paths and add missing crates

* re-add missing crates
2019-11-14 21:51:17 +01:00

56 lines
2.4 KiB
Rust

// Copyright 2019 Parity Technologies (UK) Ltd.
// This file is part of Substrate Consensus Common.
// Substrate Demo 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 Consensus Common 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 Consensus Common. If not, see <http://www.gnu.org/licenses/>.
use crate::error::Error;
use sr_primitives::traits::{Block as BlockT, NumberFor};
/// The SelectChain trait defines the strategy upon which the head is chosen
/// if multiple forks are present for an opaque definition of "best" in the
/// specific chain build.
///
/// The Strategy can be customised for the two use cases of authoring new blocks
/// upon the best chain or which fork to finalise. Unless implemented differently
/// by default finalisation methods fall back to use authoring, so as a minimum
/// `_authoring`-functions must be implemented.
///
/// Any particular user must make explicit, however, whether they intend to finalise
/// or author through the using the right function call, as these might differ in
/// some implementations.
///
/// Non-deterministicly finalising chains may only use the `_authoring` functions.
pub trait SelectChain<Block: BlockT>: Sync + Send + Clone {
/// Get all leaves of the chain: block hashes that have no children currently.
/// Leaves that can never be finalized will not be returned.
fn leaves(&self) -> Result<Vec<<Block as BlockT>::Hash>, Error>;
/// Among those `leaves` deterministically pick one chain as the generally
/// best chain to author new blocks upon and probably finalize.
fn best_chain(&self) -> Result<<Block as BlockT>::Header, Error>;
/// Get the best descendent of `target_hash` that we should attempt to
/// finalize next, if any. It is valid to return the given `target_hash`
/// itself if no better descendent exists.
fn finality_target(
&self,
target_hash: <Block as BlockT>::Hash,
_maybe_max_number: Option<NumberFor<Block>>
) -> Result<Option<<Block as BlockT>::Hash>, Error> {
Ok(Some(target_hash))
}
}