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// Copyright 2023 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! Named futures for the backup support.
use std::{future::IntoFuture, time::Duration};
use futures_core::Stream;
use futures_util::StreamExt;
use matrix_sdk_common::boxed_into_future;
use thiserror::Error;
use tokio_stream::wrappers::errors::BroadcastStreamRecvError;
use tracing::trace;
use super::{Backups, UploadState};
use crate::utils::ChannelObservable;
/// Error describing the ways that waiting for the backup upload to settle down
/// can fail.
#[derive(Clone, Copy, Debug, Error)]
pub enum SteadyStateError {
/// The currently active backup got either deleted or a new one was created.
///
/// No further room keys will be uploaded to the currently active
/// backup.
#[error("The backup got disabled while waiting for the room keys to be uploaded.")]
BackupDisabled,
/// Uploading the room keys to the homeserver failed due to a network error.
///
/// Uploading will be retried again at a later point in time, or
/// immediately if you wait for the steady state again.
#[error("There was a network connection error.")]
Connection,
/// We missed some updates to the [`UploadState`] from the upload task.
///
/// This error doesn't imply that there was an error with the uploading of
/// room keys, it just means that we didn't receive all the transitions
/// in the [`UploadState`]. You might want to retry waiting for the
/// steady state.
#[error("We couldn't read status updates from the upload task quickly enough.")]
Lagged,
}
/// Named future for the [`Backups::wait_for_steady_state()`] method.
#[derive(Debug)]
pub struct WaitForSteadyState<'a> {
pub(super) backups: &'a Backups,
pub(super) progress: ChannelObservable<UploadState>,
pub(super) timeout: Option<Duration>,
}
impl<'a> WaitForSteadyState<'a> {
/// Subscribe to the progress of the backup upload step while waiting for it
/// to settle down.
pub fn subscribe_to_progress(
&self,
) -> impl Stream<Item = Result<UploadState, BroadcastStreamRecvError>> {
self.progress.subscribe()
}
/// Set the delay between each upload request.
///
/// Uploading room keys might require multiple requests to be sent out. The
/// [`Client`] waits for a while before it sends the next request out.
///
/// This method allows you to override how long the [`Client`] will wait.
/// The default value is 100 ms.
///
/// [`Client`]: crate::Client
pub fn with_delay(mut self, delay: Duration) -> Self {
self.timeout = Some(delay);
self
}
}
impl<'a> IntoFuture for WaitForSteadyState<'a> {
type Output = Result<(), SteadyStateError>;
boxed_into_future!(extra_bounds: 'a);
fn into_future(self) -> Self::IntoFuture {
Box::pin(async move {
let Self { backups, timeout, progress } = self;
trace!("Creating a stream to wait for the steady state");
let mut progress_stream = progress.subscribe();
let old_delay = if let Some(delay) = timeout {
let mut lock = backups.client.inner.e2ee.backup_state.upload_delay.write().unwrap();
let old_delay = Some(lock.to_owned());
*lock = delay;
old_delay
} else {
None
};
trace!("Waiting for the upload steady state");
let ret = if backups.are_enabled().await {
backups.maybe_trigger_backup();
let mut ret = Ok(());
// TODO: Do we want to be smart here and remember the count when we started
// waiting and prevent the total from increasing, in case new room
// keys arrive after we started waiting.
while let Some(state) = progress_stream.next().await {
trace!(?state, "Update state while waiting for the backup steady state");
match state {
Ok(UploadState::Done) => {
ret = Ok(());
break;
}
Ok(UploadState::Error) => {
if backups.are_enabled().await {
ret = Err(SteadyStateError::Connection);
} else {
ret = Err(SteadyStateError::BackupDisabled);
}
break;
}
Err(_) => {
ret = Err(SteadyStateError::Lagged);
break;
}
_ => (),
}
}
ret
} else {
Err(SteadyStateError::BackupDisabled)
};
if let Some(old_delay) = old_delay {
let mut lock = backups.client.inner.e2ee.backup_state.upload_delay.write().unwrap();
*lock = old_delay;
}
ret
})
}
}