builtins/
sampling_resource.rs

1// Copyright 2025 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::{Error, format_err};
6use fidl_fuchsia_kernel as fkernel;
7use futures::prelude::*;
8use std::sync::Arc;
9use zx::{self as zx, HandleBased, Resource};
10
11/// An implementation of fuchsia.kernel.SamplingResource protocol.
12pub struct SamplingResource {
13    resource: Resource,
14}
15
16impl SamplingResource {
17    /// `resource` must be the Sampling resource.
18    pub fn new(resource: Resource) -> Result<Arc<Self>, Error> {
19        let resource_info = resource.info()?;
20        if resource_info.kind != zx::sys::ZX_RSRC_KIND_SYSTEM
21            || resource_info.base != zx::sys::ZX_RSRC_SYSTEM_SAMPLING_BASE
22            || resource_info.size != 1
23        {
24            return Err(format_err!("Sampling resource not available."));
25        }
26        Ok(Arc::new(Self { resource }))
27    }
28
29    pub async fn serve(
30        self: Arc<Self>,
31        mut stream: fkernel::SamplingResourceRequestStream,
32    ) -> Result<(), Error> {
33        while let Some(fkernel::SamplingResourceRequest::Get { responder }) =
34            stream.try_next().await?
35        {
36            responder.send(self.resource.duplicate_handle(zx::Rights::SAME_RIGHTS)?)?;
37        }
38        Ok(())
39    }
40}
41
42#[cfg(test)]
43mod tests {
44    use super::*;
45    use fuchsia_component::client::connect_to_protocol;
46    use {fidl_fuchsia_kernel as fkernel, fuchsia_async as fasync};
47
48    async fn get_sampling_resource() -> Result<Resource, Error> {
49        let sampling_resource_provider = connect_to_protocol::<fkernel::SamplingResourceMarker>()?;
50        let sampling_resource_handle = sampling_resource_provider.get().await?;
51        Ok(Resource::from(sampling_resource_handle))
52    }
53
54    async fn serve_sampling_resource() -> Result<fkernel::SamplingResourceProxy, Error> {
55        let sampling_resource = get_sampling_resource().await?;
56
57        let (proxy, stream) =
58            fidl::endpoints::create_proxy_and_stream::<fkernel::SamplingResourceMarker>();
59        fasync::Task::local(
60            SamplingResource::new(sampling_resource)
61                .unwrap_or_else(|e| panic!("Error while creating sampling resource service: {}", e))
62                .serve(stream)
63                .unwrap_or_else(|e| panic!("Error while serving sampling resource service: {}", e)),
64        )
65        .detach();
66        Ok(proxy)
67    }
68
69    #[fuchsia::test]
70    async fn base_type_is_sampling() -> Result<(), Error> {
71        let sampling_resource_provider = serve_sampling_resource().await?;
72        let sampling_resource: Resource = sampling_resource_provider.get().await?;
73        let resource_info = sampling_resource.info()?;
74        assert_eq!(resource_info.kind, zx::sys::ZX_RSRC_KIND_SYSTEM);
75        assert_eq!(resource_info.base, zx::sys::ZX_RSRC_SYSTEM_SAMPLING_BASE);
76        assert_eq!(resource_info.size, 1);
77        Ok(())
78    }
79}
builtins/sampling_resource.rs

builtins/
sampling_resource.rs
