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sc_mixnet/
api.rs

1// This file is part of Substrate.
2
3// Copyright (C) Parity Technologies (UK) Ltd.
4// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
5
6// This program is free software: you can redistribute it and/or modify
7// it under the terms of the GNU General Public License as published by
8// the Free Software Foundation, either version 3 of the License, or
9// (at your option) any later version.
10
11// This program is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// You should have received a copy of the GNU General Public License
17// along with this program. If not, see <https://www.gnu.org/licenses/>.
18
19use super::{config::Config, error::Error, request::Request};
20use futures::{
21	channel::{mpsc, oneshot},
22	SinkExt,
23};
24use sp_core::Bytes;
25use std::future::Future;
26
27/// The other end of an [`Api`]. This should be passed to [`run`](super::run::run).
28pub struct ApiBackend {
29	pub(super) request_receiver: mpsc::Receiver<Request>,
30}
31
32/// Interface to the mixnet service.
33#[derive(Clone)]
34pub struct Api {
35	request_sender: mpsc::Sender<Request>,
36}
37
38impl Api {
39	/// Create a new `Api`. The [`ApiBackend`] should be passed to [`run`](super::run::run).
40	pub fn new(config: &Config) -> (Self, ApiBackend) {
41		let (request_sender, request_receiver) = mpsc::channel(config.substrate.request_buffer);
42		(Self { request_sender }, ApiBackend { request_receiver })
43	}
44
45	/// Submit an extrinsic via the mixnet.
46	///
47	/// Returns a [`Future`] which returns another `Future`.
48	///
49	/// The first `Future` resolves as soon as there is space in the mixnet service queue. The
50	/// second `Future` resolves once a reply is received over the mixnet (or sooner if there is an
51	/// error).
52	///
53	/// The first `Future` references `self`, but the second does not. This makes it possible to
54	/// submit concurrent mixnet requests using a single `Api` instance.
55	pub async fn submit_extrinsic(
56		&mut self,
57		extrinsic: Bytes,
58	) -> impl Future<Output = Result<(), Error>> {
59		let (reply_sender, reply_receiver) = oneshot::channel();
60		let res = self
61			.request_sender
62			.feed(Request::SubmitExtrinsic { extrinsic, reply_sender })
63			.await;
64		async move {
65			res.map_err(|_| Error::ServiceUnavailable)?;
66			reply_receiver.await.map_err(|_| Error::ServiceUnavailable)?
67		}
68	}
69}