matrix_sdk_common/
timeout.rs

1// Copyright 2022 The Matrix.org Foundation C.I.C.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use std::{error::Error, fmt, time::Duration};
16
17use futures_core::Future;
18#[cfg(target_family = "wasm")]
19use futures_util::future::{Either, select};
20#[cfg(target_family = "wasm")]
21use gloo_timers::future::TimeoutFuture;
22#[cfg(not(target_family = "wasm"))]
23use tokio::time::timeout as tokio_timeout;
24
25/// Error type notifying that a timeout has elapsed.
26#[derive(Clone, Copy, Debug, PartialEq, Eq)]
27pub struct ElapsedError();
28
29impl fmt::Display for ElapsedError {
30    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
31        write!(f, "time waiting for future has elapsed!")
32    }
33}
34
35impl Error for ElapsedError {}
36
37/// Wait for `future` to be completed. `future` needs to return a `Result`.
38///
39/// If the given timeout has elapsed the method will stop waiting and return an
40/// error.
41pub async fn timeout<F, T>(future: F, duration: Duration) -> Result<T, ElapsedError>
42where
43    F: Future<Output = T>,
44{
45    #[cfg(not(target_family = "wasm"))]
46    return tokio_timeout(duration, future).await.map_err(|_| ElapsedError());
47
48    #[cfg(target_family = "wasm")]
49    {
50        let timeout_future =
51            TimeoutFuture::new(u32::try_from(duration.as_millis()).expect("Overlong duration"));
52
53        match select(std::pin::pin!(future), timeout_future).await {
54            Either::Left((res, _)) => Ok(res),
55            Either::Right((_, _)) => Err(ElapsedError()),
56        }
57    }
58}
59
60#[cfg(test)]
61pub(crate) mod tests {
62    use std::{future, time::Duration};
63
64    use matrix_sdk_test_macros::async_test;
65
66    use super::timeout;
67
68    #[cfg(target_family = "wasm")]
69    wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
70
71    #[async_test]
72    async fn test_without_timeout() {
73        timeout(future::ready(()), Duration::from_millis(100))
74            .await
75            .expect("future should have completed without ElapsedError");
76    }
77
78    #[async_test]
79    async fn test_with_timeout() {
80        timeout(future::pending::<()>(), Duration::from_millis(100))
81            .await
82            .expect_err("future should return an ElapsedError");
83    }
84}
matrix_sdk_common/timeout.rs

matrix_sdk_common/
timeout.rs
