fidl_server/
server.rs

1// Copyright 2023 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 anyhow::{Context, Error, Result};
6use fidl::endpoints::{ProtocolMarker, Request, RequestStream};
7use fuchsia_async as fasync;
8use futures::TryStreamExt;
9use log::error;
10
11/// RequestHandler handles incoming FIDL requests.
12pub trait RequestHandler<P: ProtocolMarker>: Send {
13    /// Handles a request. If it returns an error, the server will shut down.
14    fn handle_request(&self, request: Request<P>) -> Result<(), Error>;
15}
16
17/// AsyncRequestHandler handles incoming FIDL requests asynchronously.
18#[async_trait::async_trait]
19pub trait AsyncRequestHandler<P: ProtocolMarker>: Send + Sync {
20    /// Handles a request. If it returns an error, the server will shut down.
21    async fn handle_request(&self, request: Request<P>) -> Result<(), Error>;
22}
23
24impl<P, F> RequestHandler<P> for F
25where
26    P: ProtocolMarker,
27    F: Fn(Request<P>) -> Result<(), Error> + Send,
28{
29    fn handle_request(&self, request: Request<P>) -> Result<(), Error> {
30        self(request)
31    }
32}
33
34/// Serves all requests on `stream` using `handler`.
35///
36/// Stops and returns an error if a FIDL error occurs while reading a request,
37/// or if `handler` fails. The caller should log this error.
38pub async fn serve<S, H>(mut stream: S, handler: H) -> Result<(), Error>
39where
40    S: RequestStream,
41    H: RequestHandler<S::Protocol>,
42{
43    while let Some(request) = stream
44        .try_next()
45        .await
46        .with_context(|| format!("error reading {} request", S::Protocol::DEBUG_NAME))?
47    {
48        handler
49            .handle_request(request)
50            .with_context(|| format!("error handling {} request", S::Protocol::DEBUG_NAME))?;
51    }
52    Ok(())
53}
54
55/// Serves all requests on `stream` using `handler`.
56///
57/// Stops and returns an error if a FIDL error occurs while reading a request,
58/// or if `handler` fails. The caller should log this error.
59pub async fn serve_async<S, H>(mut stream: S, handler: H) -> Result<(), Error>
60where
61    S: RequestStream,
62    S::Ok: Send,
63    H: AsyncRequestHandler<S::Protocol>,
64{
65    while let Some(request) = stream
66        .try_next()
67        .await
68        .with_context(|| format!("error reading {} request", S::Protocol::DEBUG_NAME))?
69    {
70        handler
71            .handle_request(request)
72            .await
73            .with_context(|| format!("error handling {} request", S::Protocol::DEBUG_NAME))?;
74    }
75    Ok(())
76}
77
78/// Serves all requests on `stream` concurrently using `handler`.
79///
80/// Stops and returns an error if a FIDL error occurs while reading a request,
81/// or if `handler` fails. The caller should log this error.
82pub async fn serve_async_concurrent<S, H>(
83    stream: S,
84    limit: impl Into<Option<usize>>,
85    handler: H,
86) -> Result<(), Error>
87where
88    S: RequestStream,
89    S::Ok: 'static + Send,
90    H: AsyncRequestHandler<S::Protocol> + 'static,
91{
92    let handler = std::sync::Arc::new(handler);
93
94    let fut = stream.try_for_each_concurrent(limit, |request| async {
95        handler
96            .clone()
97            .handle_request(request)
98            .await
99            .with_context(|| format!("error handling {} request", S::Protocol::DEBUG_NAME))
100            .unwrap();
101
102        Ok(())
103    });
104
105    fut.await.with_context(|| format!("error reading {} request", S::Protocol::DEBUG_NAME))?;
106
107    Ok(())
108}
109
110/// Runs the server in the background and logs the error if one occurs.
111///
112/// This implements the most common case where FIDL service authors serve a
113/// RequestStream on some remote task using `Task::spawn(...).detach()`.
114///
115/// When using this function, prefer prefixing your program's log messages by
116/// annotating `main()` with one of the following:
117///
118/// ```
119/// #[fuchsia::main(logging = true)]
120/// #[fuchsia::main(logging_prefix = "my_prefix")]
121/// ```
122pub fn serve_detached<S, H>(stream: S, handler: H)
123where
124    S: RequestStream + 'static,
125    H: RequestHandler<S::Protocol> + 'static,
126{
127    fasync::Task::spawn(async move {
128        if let Err(err) = serve(stream, handler).await {
129            error!("{:?}", err);
130        }
131    })
132    .detach();
133}
134
135/// Runs the server in the background and logs the error if one occurs.
136///
137/// This implements the most common case where FIDL service authors serve a
138/// RequestStream on some remote task using `Task::spawn(...).detach()`.
139///
140/// When using this function, prefer prefixing your program's log messages by
141/// annotating `main()` with one of the following:
142///
143/// ```
144/// #[fuchsia::main(logging = true)]
145/// #[fuchsia::main(logging_prefix = "my_prefix")]
146/// ```
147pub fn serve_async_detached<S, H>(stream: S, handler: H)
148where
149    S: RequestStream + 'static,
150    S::Ok: Send,
151    H: AsyncRequestHandler<S::Protocol> + 'static,
152{
153    fasync::Task::spawn(async move {
154        if let Err(err) = serve_async(stream, handler).await {
155            error!("{:?}", err);
156        }
157    })
158    .detach();
159}
fidl_server/server.rs

fidl_server/
server.rs
