settings/message/
delegate.rs

1// Copyright 2021 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::message::base::messenger::Descriptor;
6#[cfg(test)]
7use crate::message::base::MessengerPresenceResult;
8use crate::message::base::{
9    CreateMessengerResult, MessageError, MessengerAction, MessengerActionSender, MessengerType,
10    Signature,
11};
12
13/// [Delegate] is the artifact of creating a MessageHub. It can be used
14/// to create new messengers.
15#[derive(Clone)]
16pub struct Delegate {
17    messenger_action_tx: MessengerActionSender,
18}
19
20impl Delegate {
21    pub(super) fn new(action_tx: MessengerActionSender) -> Delegate {
22        Delegate { messenger_action_tx: action_tx }
23    }
24
25    pub(crate) async fn create(&self, messenger_type: MessengerType) -> CreateMessengerResult {
26        self.create_messenger(messenger_type).await
27    }
28
29    #[cfg(test)]
30    pub(crate) async fn create_sink(&self) -> CreateMessengerResult {
31        self.create_messenger(MessengerType::EventSink).await
32    }
33
34    async fn create_messenger(&self, messenger_type: MessengerType) -> CreateMessengerResult {
35        let (tx, rx) = futures::channel::oneshot::channel::<CreateMessengerResult>();
36
37        // We expect the receiving side to exist, panic if sending the `Create` message fails.
38        self.messenger_action_tx
39            .unbounded_send(MessengerAction::Create(
40                Descriptor { messenger_type },
41                tx,
42                self.messenger_action_tx.clone(),
43            ))
44            .expect("Failed to send MessengerAction::Create message");
45
46        rx.await.map_err(|_| MessageError::Unexpected).and_then(std::convert::identity)
47    }
48
49    /// Checks whether a messenger is present at the given [`Signature`]. Note
50    /// that there is no guarantee that the messenger at the given [`Signature`]
51    /// will not be deleted or created after this function returns.
52    #[cfg(test)]
53    pub(crate) async fn contains(&self, signature: Signature) -> MessengerPresenceResult {
54        let (tx, rx) = futures::channel::oneshot::channel::<MessengerPresenceResult>();
55        self.messenger_action_tx
56            .unbounded_send(MessengerAction::CheckPresence(signature, tx))
57            .unwrap();
58        rx.await.unwrap_or(Err(MessageError::Unexpected))
59    }
60
61    pub(crate) fn delete(&self, signature: Signature) {
62        self.messenger_action_tx
63            .unbounded_send(MessengerAction::DeleteBySignature(signature))
64            .expect(
65                "Delegate::delete, messenger_action_tx failed to send DeleteBySignature messenger\
66                 action",
67            );
68    }
69}
settings/message/delegate.rs

settings/message/
delegate.rs
