1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
// Copyright 2022 System76 <info@system76.com>
// SPDX-License-Identifier: MIT or Apache-2.0

//! Contains various flavors of channels to send messages between components and workers.

use std::fmt::Debug;
use std::future::Future;
use std::sync::Arc;

use crate::component::AsyncComponent;
use crate::factory::{AsyncFactoryComponent, FactoryComponent};
use crate::{Component, Sender, ShutdownReceiver};

// Contains senders used by components and factories internally.
#[derive(Debug)]
struct ComponentSenderInner<Input, Output, CommandOutput>
where
    Input: Debug,
    CommandOutput: Send + 'static,
{
    /// Emits component inputs.
    input: Sender<Input>,
    /// Emits component outputs.
    output: Sender<Output>,
    /// Emits command outputs.
    command: Sender<CommandOutput>,
    shutdown: ShutdownReceiver,
}

impl<Input, Output, CommandOutput> ComponentSenderInner<Input, Output, CommandOutput>
where
    Input: Debug,
    CommandOutput: Send + 'static,
{
    /// Retrieve the sender for input messages.
    ///
    /// Useful to forward inputs from another component. If you just need to send input messages,
    /// [`input()`][Self::input] is more concise.
    #[must_use]
    fn input_sender(&self) -> &Sender<Input> {
        &self.input
    }

    /// Retrieve the sender for output messages.
    ///
    /// Useful to forward outputs from another component. If you just need to send output messages,
    /// [`output()`][Self::output] is more concise.
    #[must_use]
    fn output_sender(&self) -> &Sender<Output> {
        &self.output
    }

    /// Retrieve the sender for command output messages.
    ///
    /// Useful to forward outputs from another component. If you just need to send output messages,
    /// [`command()`][Self::command] is more concise.
    #[must_use]
    fn command_sender(&self) -> &Sender<CommandOutput> {
        &self.command
    }

    /// Emit an input to the component.
    fn input(&self, message: Input) {
        // Input messages should always be safe to send
        // because the runtime keeps the receiver alive.
        self.input.send(message).unwrap();
    }

    /// This is not public because factories can unwrap the result
    /// because they keep the output receiver alive internally.
    fn output(&self, message: Output) -> Result<(), Output> {
        self.output.send(message)
    }

    /// Spawns an asynchronous command.
    /// You can bind the the command to the lifetime of the component
    /// by using a [`ShutdownReceiver`].
    fn command<Cmd, Fut>(&self, cmd: Cmd)
    where
        Cmd: FnOnce(Sender<CommandOutput>, ShutdownReceiver) -> Fut + Send + 'static,
        Fut: Future<Output = ()> + Send,
    {
        let recipient = self.shutdown.clone();
        let sender = self.command.clone();
        crate::spawn(async move {
            cmd(sender, recipient).await;
        });
    }

    /// Spawns a synchronous command.
    ///
    /// This is particularly useful for CPU-intensive background jobs that
    /// need to run on a thread-pool in the background.
    ///
    /// If you expect the component to be dropped while
    /// the command is running take care while sending messages!
    fn spawn_command<Cmd>(&self, cmd: Cmd)
    where
        Cmd: FnOnce(Sender<CommandOutput>) + Send + 'static,
    {
        let sender = self.command.clone();
        crate::spawn_blocking(move || cmd(sender));
    }

    /// Spawns a future that will be dropped as soon as the factory component is shut down.
    ///
    /// Essentially, this is a simpler version of [`Self::command()`].
    fn oneshot_command<Fut>(&self, future: Fut)
    where
        Fut: Future<Output = CommandOutput> + Send + 'static,
    {
        // Async closures would be awesome here...
        self.command(move |out, shutdown| {
            shutdown
                .register(async move { out.send(future.await) })
                .drop_on_shutdown()
        });
    }

    /// Spawns a synchronous command that will be dropped as soon as the factory component is shut down.
    ///
    /// Essentially, this is a simpler version of [`Self::spawn_command()`].
    fn spawn_oneshot_command<Cmd>(&self, cmd: Cmd)
    where
        Cmd: FnOnce() -> CommandOutput + Send + 'static,
    {
        let handle = crate::spawn_blocking(cmd);
        self.oneshot_command(async move { handle.await.unwrap() })
    }
}

macro_rules! sender_impl {
    ($name:ident, $trait:ident) => {
        /// Contains senders to send and receive messages from a [`Component`].
        #[derive(Debug)]
        pub struct $name<C: $trait> {
            shared: Arc<ComponentSenderInner<C::Input, C::Output, C::CommandOutput>>,
        }

        impl<C: $trait> $name<C> {
            pub(crate) fn new(
                input: Sender<C::Input>,
                output: Sender<C::Output>,
                command: Sender<C::CommandOutput>,
                shutdown: ShutdownReceiver,
            ) -> Self {
                Self {
                    shared: Arc::new(ComponentSenderInner {
                        input,
                        output,
                        command,
                        shutdown,
                    }),
                }
            }

            /// Retrieve the sender for input messages.
            ///
            /// Useful to forward inputs from another component. If you just need to send input messages,
            /// [`input()`][Self::input] is more concise.
            #[must_use]
            pub fn input_sender(&self) -> &Sender<C::Input> {
                self.shared.input_sender()
            }

            /// Retrieve the sender for output messages.
            ///
            /// Useful to forward outputs from another component. If you just need to send output messages,
            /// [`output()`][Self::output] is more concise.
            #[must_use]
            pub fn output_sender(&self) -> &Sender<C::Output> {
                self.shared.output_sender()
            }

            /// Retrieve the sender for command output messages.
            ///
            /// Useful to forward outputs from another component. If you just need to send output messages,
            /// [`command()`][Self::command] is more concise.
            #[must_use]
            pub fn command_sender(&self) -> &Sender<C::CommandOutput> {
                self.shared.command_sender()
            }

            /// Emit an input to the component.
            pub fn input(&self, message: C::Input) {
                self.shared.input(message);
            }

            /// Spawns an asynchronous command.
            /// You can bind the the command to the lifetime of the component
            /// by using a [`ShutdownReceiver`].
            pub fn command<Cmd, Fut>(&self, cmd: Cmd)
            where
                Cmd: FnOnce(Sender<C::CommandOutput>, ShutdownReceiver) -> Fut + Send + 'static,
                Fut: Future<Output = ()> + Send,
            {
                self.shared.command(cmd)
            }

            /// Spawns a synchronous command.
            ///
            /// This is particularly useful for CPU-intensive background jobs that
            /// need to run on a thread-pool in the background.
            ///
            /// If you expect the component to be dropped while
            /// the command is running take care while sending messages!
            pub fn spawn_command<Cmd>(&self, cmd: Cmd)
            where
                Cmd: FnOnce(Sender<C::CommandOutput>) + Send + 'static,
            {
                self.shared.spawn_command(cmd)
            }

            /// Spawns a future that will be dropped as soon as the factory component is shut down.
            ///
            /// Essentially, this is a simpler version of [`Self::command()`].
            pub fn oneshot_command<Fut>(&self, future: Fut)
            where
                Fut: Future<Output = C::CommandOutput> + Send + 'static,
            {
                self.shared.oneshot_command(future)
            }

            /// Spawns a synchronous command that will be dropped as soon as the factory component is shut down.
            ///
            /// Essentially, this is a simpler version of [`Self::spawn_command()`].
            pub fn spawn_oneshot_command<Cmd>(&self, cmd: Cmd)
            where
                Cmd: FnOnce() -> C::CommandOutput + Send + 'static,
            {
                self.shared.spawn_oneshot_command(cmd)
            }
        }

        impl<C: $trait> Clone for $name<C> {
            fn clone(&self) -> Self {
                Self {
                    shared: Arc::clone(&self.shared),
                }
            }
        }
    };
}

sender_impl!(ComponentSender, Component);

impl<C: Component> ComponentSender<C> {
    /// Emit an output to the component.
    ///
    /// Returns [`Err`] if all receivers were dropped,
    /// for example by [`detach`].
    ///
    /// [`detach`]: crate::component::Connector::detach
    pub fn output(&self, message: C::Output) -> Result<(), C::Output> {
        self.shared.output(message)
    }
}

sender_impl!(AsyncComponentSender, AsyncComponent);

impl<C: AsyncComponent> AsyncComponentSender<C> {
    /// Emit an output to the component.
    ///
    /// Returns [`Err`] if all receivers were dropped,
    /// for example by [`detach`].
    ///
    /// [`detach`]: crate::component::AsyncConnector::detach
    pub fn output(&self, message: C::Output) -> Result<(), C::Output> {
        self.shared.output(message)
    }
}

sender_impl!(FactorySender, FactoryComponent);

impl<C: FactoryComponent> FactorySender<C> {
    /// Emit an output to the component.
    pub fn output(&self, message: C::Output) {
        self.shared.output(message).unwrap()
    }
}

sender_impl!(AsyncFactorySender, AsyncFactoryComponent);

impl<C: AsyncFactoryComponent> AsyncFactorySender<C> {
    /// Emit an output to the component.
    pub fn output(&self, message: C::Output) {
        self.shared.output(message).unwrap()
    }
}