chore: improve compile-time directive in http client

Author: yannham

libdd-http-client/src/backend/hyper_backend.rs

@@ -9,7 +9,6 @@ use http_body_util::BodyExt;
 use libdd_common::connector::Connector;
 use libdd_common::http_common::{self, Body};
 
-#[cfg(feature = "hyper-backend")]
 pub(crate) struct HyperBackend {
     client: http_common::GenericHttpClient<Connector>,
     transport: TransportConfig,
@@ -23,7 +22,6 @@ impl std::fmt::Debug for HyperBackend {
     }
 }
 
-#[cfg(feature = "hyper-backend")]
 impl HyperBackend {
     /// Rewrite the request URL for UDS/Named Pipe transports.
     fn rewrite_url(&self, url: &str) -> Result<hyper::Uri, HttpClientError> {
@@ -136,7 +134,6 @@ fn collect_response_headers<T>(
         .collect()
 }
 
-#[cfg(feature = "hyper-backend")]
 fn map_hyper_error(e: hyper_util::client::legacy::Error) -> HttpClientError {
     let err = http_common::into_error(e);
     match err.kind() {
@@ -146,7 +143,6 @@ fn map_hyper_error(e: hyper_util::client::legacy::Error) -> HttpClientError {
     }
 }
 
-#[cfg(feature = "hyper-backend")]
 impl super::Backend for HyperBackend {
     fn new(
         _timeout: std::time::Duration,

libdd-http-client/src/backend/reqwest_backend.rs

@@ -11,12 +11,10 @@ use crate::{HttpClientError, HttpRequest, HttpResponse};
 ///
 /// Holds a connection-pooling client that is reused across all requests.
 #[derive(Debug)]
-#[cfg(feature = "reqwest-backend")]
 pub(crate) struct ReqwestBackend {
     client: reqwest::Client,
 }
 
-#[cfg(feature = "reqwest-backend")]
 impl super::Backend for ReqwestBackend {
     // Creates a `reqwest::Client` with connection pooling enabled.
     fn new(
@@ -117,7 +115,6 @@ impl super::Backend for ReqwestBackend {
 }
 
 /// Convert our `MultipartPart` list into a `reqwest::multipart::Form`.
-#[cfg(feature = "reqwest-backend")]
 fn build_multipart_form(
     parts: Vec<crate::request::MultipartPart>,
 ) -> Result<reqwest::multipart::Form, HttpClientError> {
@@ -138,7 +135,6 @@ fn build_multipart_form(
 }
 
 /// Map a `reqwest::Error` to our `HttpClientError` variants.
-#[cfg(feature = "reqwest-backend")]
 fn map_reqwest_error(e: reqwest::Error) -> HttpClientError {
     if e.is_timeout() {
         HttpClientError::TimedOut

libdd-http-client/src/client.rs

@@ -3,29 +3,24 @@
 
 //! The public `HttpClient` struct.
 
+use crate::backend::Backend;
 use crate::config::{HttpClientBuilder, HttpClientConfig, TransportConfig};
 use crate::{HttpClientError, HttpRequest, HttpResponse};
 use std::time::Duration;
 
-#[cfg(any(feature = "reqwest-backend", feature = "hyper-backend"))]
-use crate::backend::Backend;
+#[cfg(all(feature = "hyper-backend", not(feature = "reqwest-backend")))]
+type BackendImpl = crate::backend::hyper_backend::HyperBackend;
 
 #[cfg(feature = "reqwest-backend")]
-use crate::backend::reqwest_backend::ReqwestBackend;
-
-#[cfg(all(feature = "hyper-backend", not(feature = "reqwest-backend")))]
-use crate::backend::hyper_backend::HyperBackend;
+type BackendImpl = crate::backend::reqwest_backend::ReqwestBackend;
 
 /// A high-level async HTTP client.
 ///
 /// Constructed once and reused across many [`HttpClient::send`] calls. Holds
 /// a connection pool internally.
 #[derive(Debug)]
 pub struct HttpClient {
-    #[cfg(feature = "reqwest-backend")]
-    backend: ReqwestBackend,
-    #[cfg(all(feature = "hyper-backend", not(feature = "reqwest-backend")))]
-    backend: HyperBackend,
+    backend: BackendImpl,
     config: HttpClientConfig,
 }
 
@@ -51,23 +46,8 @@ impl HttpClient {
         config: HttpClientConfig,
         transport: TransportConfig,
     ) -> Result<Self, HttpClientError> {
-        #[cfg(feature = "reqwest-backend")]
-        {
-            let backend = ReqwestBackend::new(config.timeout(), transport)?;
-            Ok(Self { backend, config })
-        }
-        #[cfg(all(feature = "hyper-backend", not(feature = "reqwest-backend")))]
-        {
-            let backend = HyperBackend::new(config.timeout(), transport)?;
-            Ok(Self { backend, config })
-        }
-        #[cfg(not(any(feature = "reqwest-backend", feature = "hyper-backend")))]
-        {
-            let _ = (config, transport);
-            Err(HttpClientError::InvalidConfig(
-                "no backend feature enabled".to_owned(),
-            ))
-        }
+        let backend = BackendImpl::new(config.timeout(), transport)?;
+        Ok(Self { backend, config })
     }
 
     /// The client's configuration.
@@ -88,17 +68,7 @@ impl HttpClient {
     }
 
     async fn send_once(&self, request: HttpRequest) -> Result<HttpResponse, HttpClientError> {
-        #[cfg(any(feature = "reqwest-backend", feature = "hyper-backend"))]
-        {
-            self.backend.send(request, &self.config).await
-        }
-        #[cfg(not(any(feature = "reqwest-backend", feature = "hyper-backend")))]
-        {
-            let _ = request;
-            Err(HttpClientError::InvalidConfig(
-                "no backend feature enabled".to_owned(),
-            ))
-        }
+        self.backend.send(request, &self.config).await
     }
 
     async fn send_with_retry(

libdd-http-client/src/lib.rs

@@ -42,6 +42,11 @@
 //! # }
 //! ```
 
+#[cfg(not(any(feature = "hyper-backend", feature = "reqwest-backend")))]
+compile_error!(
+    "at least one backend feature must be enabled: `reqwest-backend` or `hyper-backend`"
+);
+
 pub mod config;
 
 pub(crate) mod backend;