121 lines
4.0 KiB
Rust
121 lines
4.0 KiB
Rust
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Generalization of a state machine for a consensus engine.
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//! This will define traits for the header, block, and state of a blockchain.
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extern crate ethcore_util as util;
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extern crate ethcore_bigint as bigint;
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use bigint::hash::H256;
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use bigint::prelude::U256;
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use util::Address;
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/// A header. This contains important metadata about the block, as well as a
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/// "seal" that indicates validity to a consensus engine.
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pub trait Header {
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/// Cryptographic hash of the header, excluding the seal.
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fn bare_hash(&self) -> H256;
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/// Cryptographic hash of the header, including the seal.
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fn hash(&self) -> H256;
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/// Get a reference to the seal fields.
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fn seal(&self) -> &[Vec<u8>];
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/// The author of the header.
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fn author(&self) -> &Address;
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/// The number of the header.
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fn number(&self) -> u64;
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}
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/// a header with an associated score (difficulty in PoW terms)
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pub trait ScoredHeader: Header {
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/// Get the score of this header.
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fn score(&self) -> &U256;
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/// Set the score of this header.
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fn set_score(&mut self, score: U256);
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}
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/// A "live" block is one which is in the process of the transition.
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/// The state of this block can be mutated by arbitrary rules of the
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/// state transition function.
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pub trait LiveBlock: 'static {
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/// The block header type;
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type Header: Header;
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/// Get a reference to the header.
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fn header(&self) -> &Self::Header;
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/// Get a reference to the uncle headers. If the block type doesn't
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/// support uncles, return the empty slice.
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fn uncles(&self) -> &[Self::Header];
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}
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/// Trait for blocks which have a transaction type.
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pub trait Transactions: LiveBlock {
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/// The transaction type.
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type Transaction;
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/// Get a reference to the transactions in this block.
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fn transactions(&self) -> &[Self::Transaction];
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}
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/// Generalization of types surrounding blockchain-suitable state machines.
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pub trait Machine: for<'a> LocalizedMachine<'a> {
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/// The block header type.
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type Header: Header;
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/// The live block type.
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type LiveBlock: LiveBlock<Header=Self::Header>;
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/// A handle to a blockchain client for this machine.
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type EngineClient: ?Sized;
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/// A description of needed auxiliary data.
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type AuxiliaryRequest;
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/// Errors which can occur when querying or interacting with the machine.
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type Error;
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}
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/// Machine-related types localized to a specific lifetime.
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// TODO: this is a workaround for a lack of associated type constructors in the language.
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pub trait LocalizedMachine<'a>: Sync + Send {
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/// Definition of auxiliary data associated to a specific block.
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type AuxiliaryData: 'a;
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/// A context providing access to the state in a controlled capacity.
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/// Generally also provides verifiable proofs.
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type StateContext: ?Sized + 'a;
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}
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/// A state machine that uses balances.
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pub trait WithBalances: Machine {
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/// Get the balance, in base units, associated with an account.
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/// Extracts data from the live block.
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fn balance(&self, live: &Self::LiveBlock, address: &Address) -> Result<U256, Self::Error>;
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/// Increment the balance of an account in the state of the live block.
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fn add_balance(&self, live: &mut Self::LiveBlock, address: &Address, amount: &U256) -> Result<(), Self::Error>;
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/// Note block rewards. "direct" rewards are for authors, "indirect" are for e.g. uncles.
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fn note_rewards(
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&self,
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_live: &mut Self::LiveBlock,
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_direct: &[(Address, U256)],
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_indirect: &[(Address, U256)],
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) -> Result<(), Self::Error> { Ok(()) }
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}
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