logo
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
290
291
292
use std::sync::Mutex;

use futures::future::{Future, BoxFuture, FutureExt};

use crate::{Rocket, Request, Response, Data, Build, Orbit};
use crate::fairing::{Fairing, Kind, Info, Result};

/// A ad-hoc fairing that can be created from a function or closure.
///
/// This enum can be used to create a fairing from a simple function or closure
/// without creating a new structure or implementing `Fairing` directly.
///
/// # Usage
///
/// Use [`AdHoc::on_ignite`], [`AdHoc::on_liftoff`], [`AdHoc::on_request()`], or
/// [`AdHoc::on_response()`] to create an `AdHoc` structure from a function or
/// closure. Then, simply attach the structure to the `Rocket` instance.
///
/// # Example
///
/// The following snippet creates a `Rocket` instance with two ad-hoc fairings.
/// The first, a liftoff fairing named "Liftoff Printer", simply prints a message
/// indicating that Rocket has launched. The second named "Put Rewriter", a
/// request fairing, rewrites the method of all requests to be `PUT`.
///
/// ```rust
/// use rocket::fairing::AdHoc;
/// use rocket::http::Method;
///
/// rocket::build()
///     .attach(AdHoc::on_liftoff("Liftoff Printer", |_| Box::pin(async move {
///         println!("...annnddd we have liftoff!");
///     })))
///     .attach(AdHoc::on_request("Put Rewriter", |req, _| Box::pin(async move {
///         req.set_method(Method::Put);
///     })));
/// ```
pub struct AdHoc {
    name: &'static str,
    kind: AdHocKind,
}

struct Once<F: ?Sized>(Mutex<Option<Box<F>>>);

impl<F: ?Sized> Once<F> {
    fn new(f: Box<F>) -> Self { Once(Mutex::new(Some(f))) }

    #[track_caller]
    fn take(&self) -> Box<F> {
        self.0.lock().expect("Once::lock()").take().expect("Once::take() called once")
    }
}

enum AdHocKind {
    /// An ad-hoc **ignite** fairing. Called during ignition.
    Ignite(Once<dyn FnOnce(Rocket<Build>) -> BoxFuture<'static, Result> + Send + 'static>),

    /// An ad-hoc **liftoff** fairing. Called just after Rocket launches.
    Liftoff(Once<dyn for<'a> FnOnce(&'a Rocket<Orbit>) -> BoxFuture<'a, ()> + Send + 'static>),

    /// An ad-hoc **request** fairing. Called when a request is received.
    Request(Box<dyn for<'a> Fn(&'a mut Request<'_>, &'a Data<'_>)
        -> BoxFuture<'a, ()> + Send + Sync + 'static>),

    /// An ad-hoc **response** fairing. Called when a response is ready to be
    /// sent to a client.
    Response(Box<dyn for<'r, 'b> Fn(&'r Request<'_>, &'b mut Response<'r>)
        -> BoxFuture<'b, ()> + Send + Sync + 'static>),

    /// An ad-hoc **shutdown** fairing. Called on shutdown.
    Shutdown(Once<dyn for<'a> FnOnce(&'a Rocket<Orbit>) -> BoxFuture<'a, ()> + Send + 'static>),
}

impl AdHoc {
    /// Constructs an `AdHoc` ignite fairing named `name`. The function `f` will
    /// be called by Rocket during the [`Rocket::ignite()`] phase.
    ///
    /// This version of an `AdHoc` ignite fairing cannot abort ignite. For a
    /// fallible version that can, see [`AdHoc::try_on_ignite()`].
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // The no-op ignite fairing.
    /// let fairing = AdHoc::on_ignite("Boom!", |rocket| async move {
    ///     rocket
    /// });
    /// ```
    pub fn on_ignite<F, Fut>(name: &'static str, f: F) -> AdHoc
        where F: FnOnce(Rocket<Build>) -> Fut + Send + 'static,
              Fut: Future<Output = Rocket<Build>> + Send + 'static,
    {
        AdHoc::try_on_ignite(name, |rocket| f(rocket).map(Ok))
    }

    /// Constructs an `AdHoc` ignite fairing named `name`. The function `f` will
    /// be called by Rocket during the [`Rocket::ignite()`] phase. Returning an
    /// `Err` aborts ignition and thus launch.
    ///
    /// For an infallible version, see [`AdHoc::on_ignite()`].
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // The no-op try ignite fairing.
    /// let fairing = AdHoc::try_on_ignite("No-Op", |rocket| async { Ok(rocket) });
    /// ```
    pub fn try_on_ignite<F, Fut>(name: &'static str, f: F) -> AdHoc
        where F: FnOnce(Rocket<Build>) -> Fut + Send + 'static,
              Fut: Future<Output = Result> + Send + 'static,
    {
        AdHoc { name, kind: AdHocKind::Ignite(Once::new(Box::new(|r| f(r).boxed()))) }
    }

    /// Constructs an `AdHoc` liftoff fairing named `name`. The function `f`
    /// will be called by Rocket just after [`Rocket::launch()`].
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // A fairing that prints a message just before launching.
    /// let fairing = AdHoc::on_liftoff("Boom!", |_| Box::pin(async move {
    ///     println!("Rocket has lifted off!");
    /// }));
    /// ```
    pub fn on_liftoff<F: Send + Sync + 'static>(name: &'static str, f: F) -> AdHoc
        where F: for<'a> FnOnce(&'a Rocket<Orbit>) -> BoxFuture<'a, ()>
    {
        AdHoc { name, kind: AdHocKind::Liftoff(Once::new(Box::new(f))) }
    }

    /// Constructs an `AdHoc` request fairing named `name`. The function `f`
    /// will be called and the returned `Future` will be `await`ed by Rocket
    /// when a new request is received.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // The no-op request fairing.
    /// let fairing = AdHoc::on_request("Dummy", |req, data| {
    ///     Box::pin(async move {
    ///         // do something with the request and data...
    /// #       let (_, _) = (req, data);
    ///     })
    /// });
    /// ```
    pub fn on_request<F: Send + Sync + 'static>(name: &'static str, f: F) -> AdHoc
        where F: for<'a> Fn(&'a mut Request<'_>, &'a Data<'_>) -> BoxFuture<'a, ()>
    {
        AdHoc { name, kind: AdHocKind::Request(Box::new(f)) }
    }

    // FIXME(rustc): We'd like to allow passing `async fn` to these methods...
    // https://github.com/rust-lang/rust/issues/64552#issuecomment-666084589

    /// Constructs an `AdHoc` response fairing named `name`. The function `f`
    /// will be called and the returned `Future` will be `await`ed by Rocket
    /// when a response is ready to be sent.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // The no-op response fairing.
    /// let fairing = AdHoc::on_response("Dummy", |req, resp| {
    ///     Box::pin(async move {
    ///         // do something with the request and pending response...
    /// #       let (_, _) = (req, resp);
    ///     })
    /// });
    /// ```
    pub fn on_response<F: Send + Sync + 'static>(name: &'static str, f: F) -> AdHoc
        where F: for<'b, 'r> Fn(&'r Request<'_>, &'b mut Response<'r>) -> BoxFuture<'b, ()>
    {
        AdHoc { name, kind: AdHocKind::Response(Box::new(f)) }
    }

    /// Constructs an `AdHoc` shutdown fairing named `name`. The function `f`
    /// will be called by Rocket when [shutdown is triggered].
    ///
    /// [shutdown is triggered]: crate::config::Shutdown#triggers
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::fairing::AdHoc;
    ///
    /// // A fairing that prints a message just before launching.
    /// let fairing = AdHoc::on_shutdown("Bye!", |_| Box::pin(async move {
    ///     println!("Rocket is on its way back!");
    /// }));
    /// ```
    pub fn on_shutdown<F: Send + Sync + 'static>(name: &'static str, f: F) -> AdHoc
        where F: for<'a> FnOnce(&'a Rocket<Orbit>) -> BoxFuture<'a, ()>
    {
        AdHoc { name, kind: AdHocKind::Shutdown(Once::new(Box::new(f))) }
    }

    /// Constructs an `AdHoc` launch fairing that extracts a configuration of
    /// type `T` from the configured provider and stores it in managed state. If
    /// extractions fails, pretty-prints the error message and aborts launch.
    ///
    /// # Example
    ///
    /// ```rust
    /// # use rocket::launch;
    /// use serde::Deserialize;
    /// use rocket::fairing::AdHoc;
    ///
    /// #[derive(Deserialize)]
    /// struct Config {
    ///     field: String,
    ///     other: usize,
    ///     /* and so on.. */
    /// }
    ///
    /// #[launch]
    /// fn rocket() -> _ {
    ///     rocket::build().attach(AdHoc::config::<Config>())
    /// }
    /// ```
    pub fn config<'de, T>() -> AdHoc
        where T: serde::Deserialize<'de> + Send + Sync + 'static
    {
        AdHoc::try_on_ignite(std::any::type_name::<T>(), |rocket| async {
            let app_config = match rocket.figment().extract::<T>() {
                Ok(config) => config,
                Err(e) => {
                    crate::config::pretty_print_error(e);
                    return Err(rocket);
                }
            };

            Ok(rocket.manage(app_config))
        })
    }
}

#[crate::async_trait]
impl Fairing for AdHoc {
    fn info(&self) -> Info {
        let kind = match self.kind {
            AdHocKind::Ignite(_) => Kind::Ignite,
            AdHocKind::Liftoff(_) => Kind::Liftoff,
            AdHocKind::Request(_) => Kind::Request,
            AdHocKind::Response(_) => Kind::Response,
            AdHocKind::Shutdown(_) => Kind::Shutdown,
        };

        Info { name: self.name, kind }
    }

    async fn on_ignite(&self, rocket: Rocket<Build>) -> Result {
        match self.kind {
            AdHocKind::Ignite(ref f) => (f.take())(rocket).await,
            _ => Ok(rocket)
        }
    }

    async fn on_liftoff(&self, rocket: &Rocket<Orbit>) {
        if let AdHocKind::Liftoff(ref f) = self.kind {
            (f.take())(rocket).await
        }
    }

    async fn on_request(&self, req: &mut Request<'_>, data: &mut Data<'_>) {
        if let AdHocKind::Request(ref f) = self.kind {
            f(req, data).await
        }
    }

    async fn on_response<'r>(&self, req: &'r Request<'_>, res: &mut Response<'r>) {
        if let AdHocKind::Response(ref f) = self.kind {
            f(req, res).await
        }
    }

    async fn on_shutdown(&self, rocket: &Rocket<Orbit>) {
        if let AdHocKind::Shutdown(ref f) = self.kind {
            (f.take())(rocket).await
        }
    }
}