netstack3_base/
event.rs

1// Copyright 2024 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
5//! Types and traits defining events emitted from core to bindings.
6
7/// A context for emitting events.
8///
9/// `EventContext` encodes the common pattern for emitting atomic events of type
10/// `T` from core. An implementation of `EventContext` must guarantee that
11/// events are processed in the order they are emitted.
12pub trait EventContext<T> {
13    /// Handles `event`.
14    fn on_event(&mut self, event: T);
15}
16
17#[cfg(any(test, feature = "testutils"))]
18pub(crate) mod testutil {
19    use super::*;
20
21    use alloc::vec::Vec;
22    use core::fmt::Debug;
23
24    /// A fake [`EventContext`].
25    pub struct FakeEventCtx<E: Debug> {
26        events: Vec<E>,
27        must_watch_all_events: bool,
28    }
29
30    impl<E: Debug> EventContext<E> for FakeEventCtx<E> {
31        fn on_event(&mut self, event: E) {
32            self.events.push(event)
33        }
34    }
35
36    impl<E: Debug> Drop for FakeEventCtx<E> {
37        fn drop(&mut self) {
38            if self.must_watch_all_events {
39                assert!(
40                    self.events.is_empty(),
41                    "dropped context with unacknowledged events: {:?}",
42                    self.events
43                );
44            }
45        }
46    }
47
48    impl<E: Debug> Default for FakeEventCtx<E> {
49        fn default() -> Self {
50            Self { events: Default::default(), must_watch_all_events: false }
51        }
52    }
53
54    impl<E: Debug> FakeEventCtx<E> {
55        /// Takes all events from the context.
56        ///
57        /// After calling `take`, the caller opts into event watching and must
58        /// acknowledge all events before fropping the `FakeEventCtx`.
59        pub fn take(&mut self) -> Vec<E> {
60            // Any client that calls `take()` is opting into watching events
61            // and must watch them all.
62            self.must_watch_all_events = true;
63            core::mem::take(&mut self.events)
64        }
65    }
66}
netstack3_base/event.rs

netstack3_base/
event.rs
