101 lines
3.2 KiB
Rust
101 lines
3.2 KiB
Rust
// Copyright 2015-2019 Parity Technologies (UK) Ltd.
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// This file is part of Parity Ethereum.
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// Parity Ethereum 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 Ethereum 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 Ethereum. If not, see <http://www.gnu.org/licenses/>.
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use std::sync::{Arc, Weak};
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use ethcore::{
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engines::{EthEngine, StateDependentProof},
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machine::EthereumMachine,
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};
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use sync::{LightNetworkDispatcher, LightSync};
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use types::{encoded, header::Header, receipt::Receipt};
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use futures::{future, future::Either, Future};
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use light::{
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client::fetch::ChainDataFetcher,
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on_demand::{request, OnDemand, OnDemandRequester},
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};
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use ethereum_types::H256;
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use parking_lot::RwLock;
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const ALL_VALID_BACKREFS: &str = "no back-references, therefore all back-references valid; qed";
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type BoxFuture<T, E> = Box<dyn Future<Item = T, Error = E>>;
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/// Allows on-demand fetch of data useful for the light client.
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pub struct EpochFetch {
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/// A handle to the sync service.
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pub sync: Arc<RwLock<Weak<LightSync>>>,
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/// The on-demand request service.
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pub on_demand: Arc<OnDemand>,
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}
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impl EpochFetch {
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fn request<T>(&self, req: T) -> BoxFuture<T::Out, &'static str>
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where
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T: Send + request::RequestAdapter + 'static,
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T::Out: Send + 'static,
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{
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Box::new(match self.sync.read().upgrade() {
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Some(sync) => {
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let on_demand = &self.on_demand;
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let maybe_future = sync.with_context(move |ctx| {
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on_demand.request(ctx, req).expect(ALL_VALID_BACKREFS)
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});
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match maybe_future {
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Some(x) => Either::A(x.map_err(|_| "Request canceled")),
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None => Either::B(future::err("Unable to access network.")),
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}
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}
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None => Either::B(future::err("Unable to access network")),
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})
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}
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}
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impl ChainDataFetcher for EpochFetch {
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type Error = &'static str;
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type Body = BoxFuture<encoded::Block, &'static str>;
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type Receipts = BoxFuture<Vec<Receipt>, &'static str>;
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type Transition = BoxFuture<Vec<u8>, &'static str>;
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fn block_body(&self, header: &Header) -> Self::Body {
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self.request(request::Body(header.encoded().into()))
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}
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/// Fetch block receipts.
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fn block_receipts(&self, header: &Header) -> Self::Receipts {
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self.request(request::BlockReceipts(header.encoded().into()))
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}
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/// Fetch epoch transition proof at given header.
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fn epoch_transition(
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&self,
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hash: H256,
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engine: Arc<dyn EthEngine>,
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checker: Arc<dyn StateDependentProof<EthereumMachine>>,
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) -> Self::Transition {
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self.request(request::Signal {
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hash: hash,
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engine: engine,
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proof_check: checker,
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})
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}
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}
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