settings/message/
action_fuse.rs

1// Copyright 2020 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 fuchsia_async as fasync;
6use futures::lock::Mutex;
7use std::rc::Rc;
8
9/// Closure definition for an action that can be triggered by ActionFuse.
10pub type TriggeredAction = Box<dyn FnOnce()>;
11/// The reference-counted handle to an ActionFuse. When all references go out of
12/// scope, the action will be triggered (if not defused).
13pub type ActionFuseHandle = Rc<Mutex<ActionFuse>>;
14
15/// ActionFuse is a wrapper around a triggered action (a closure with no
16/// arguments and no return value). This action is invoked once the fuse goes
17/// out of scope (via the Drop trait). An ActionFuse can be defused, preventing
18/// the action from automatically invoking when going out of scope.
19pub struct ActionFuse {
20    /// An optional action that will be invoked when the ActionFuse goes out of
21    /// scope.
22    actions: Option<TriggeredAction>,
23}
24
25impl ActionFuse {
26    /// Returns an ActionFuse reference with the given TriggerAction.
27    pub(crate) fn create(action: TriggeredAction) -> ActionFuseHandle {
28        Rc::new(Mutex::new(ActionFuse { actions: Some(action) }))
29    }
30
31    /// Suppresses the action from automatically executing.
32    pub(crate) fn defuse(handle: ActionFuseHandle) {
33        fasync::Task::local(async move {
34            let mut fuse = handle.lock().await;
35            fuse.actions = None;
36        })
37        .detach();
38    }
39}
40
41impl Drop for ActionFuse {
42    fn drop(&mut self) {
43        if let Some(action) = self.actions.take() {
44            (action)();
45        }
46    }
47}
settings/message/action_fuse.rs

settings/message/
action_fuse.rs
