openethereum/ethcore/light/src/client/fetch.rs

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// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.
// Parity Ethereum 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.
// Parity Ethereum 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 Parity Ethereum. If not, see <http://www.gnu.org/licenses/>.
//! Trait for fetching chain data.
use std::sync::Arc;
use common_types::encoded;
use common_types::header::Header;
use common_types::receipt::Receipt;
use ethcore::engines::{EthEngine, StateDependentProof};
use ethcore::machine::EthereumMachine;
use ethereum_types::H256;
use futures::future::IntoFuture;
/// Provides full chain data.
pub trait ChainDataFetcher: Send + Sync + 'static {
/// Error type when data unavailable.
type Error: ::std::fmt::Debug;
/// Future for fetching block body.
type Body: IntoFuture<Item=encoded::Block, Error=Self::Error>;
/// Future for fetching block receipts.
type Receipts: IntoFuture<Item=Vec<Receipt>, Error=Self::Error>;
/// Future for fetching epoch transition
type Transition: IntoFuture<Item=Vec<u8>, Error=Self::Error>;
/// Fetch a block body.
fn block_body(&self, header: &Header) -> Self::Body;
/// Fetch block receipts.
fn block_receipts(&self, header: &Header) -> Self::Receipts;
/// Fetch epoch transition proof at given header.
fn epoch_transition(
&self,
_hash: H256,
_engine: Arc<EthEngine>,
_checker: Arc<StateDependentProof<EthereumMachine>>
) -> Self::Transition;
}
/// Fetcher implementation which cannot fetch anything.
pub struct Unavailable;
/// Create a fetcher which has all data unavailable.
pub fn unavailable() -> Unavailable { Unavailable }
impl ChainDataFetcher for Unavailable {
type Error = &'static str;
type Body = Result<encoded::Block, &'static str>;
type Receipts = Result<Vec<Receipt>, &'static str>;
type Transition = Result<Vec<u8>, &'static str>;
fn block_body(&self, _header: &Header) -> Self::Body {
Err("fetching block bodies unavailable")
}
fn block_receipts(&self, _header: &Header) -> Self::Receipts {
Err("fetching block receipts unavailable")
}
fn epoch_transition(
&self,
_hash: H256,
_engine: Arc<EthEngine>,
_checker: Arc<StateDependentProof<EthereumMachine>>
) -> Self::Transition {
Err("fetching epoch transition proofs unavailable")
}
}