feat: switch feature flags into RUSTFLAGS

Cargo.toml

@@ -7,14 +7,6 @@ edition = "2021"
 [features]
 
 # async_std
-full-ci = ["async-std-executor", "logging-utils", "channel-async-std"]
-
-tokio-ci = ["tokio-executor", "logging-utils", "channel-tokio"]
-async-std-executor = ["dep:async-std"]
-tokio-executor = ["dep:tokio", "dep:tokio-stream", "dep:console-subscriber"]
-channel-flume = ["flume"]
-channel-tokio = ["dep:tokio", "dep:tokio-stream"]
-channel-async-std = ["dep:async-channel"]
 profiling = [
     "opentelemetry-jaeger",
     "tracing-opentelemetry",
@@ -27,38 +19,15 @@ logging-utils = ["tracing-subscriber"]
 
 [dependencies]
 async-lock = "2.7"
-async-std = { version = "1.12", features = [
-    "attributes",
-    "unstable",
-], optional = true }
-async-channel = { version = "1.9.0", optional = true }
 async-trait = "0.1.71"
 color-eyre = "0.6.2"
-flume = { version = "0.10.14", optional = true }
 futures = "0.3.28"
-tokio = { version = "1", optional = true, features = [
-    "fs",
-    "io-util",
-    "io-std",
-    "macros",
-    "net",
-    "parking_lot",
-    "process",
-    "rt",
-    "rt-multi-thread",
-    "signal",
-    "sync",
-    "time",
-    "tracing",
-] }
-tokio-stream = { version = "0.1.14", optional = true }
 tracing = "0.1.37"
 tracing-error = "0.2.0"
 tracing-subscriber = { version = "0.3.17", features = [
     "env-filter",
     "json",
 ], optional = true }
-console-subscriber = { version = "0.1.10", optional = true }
 opentelemetry = { version = "0.19.0", features = [
     "rt-tokio-current-thread",
     "metrics",
@@ -69,3 +38,52 @@ opentelemetry-jaeger = { version = "0.17.0", features = [
     "rt-tokio-current-thread",
 ], optional = true }
 opentelemetry-aws = { version = "0.7.0", features = ["trace"], optional = true }
+
+[target.'cfg(all(async_executor_impl = "tokio"))'.dependencies]
+tokio = { version = "1", features = [
+    "fs",
+    "io-util",
+    "io-std",
+    "macros",
+    "net",
+    "parking_lot",
+    "process",
+    "rt",
+    "rt-multi-thread",
+    "signal",
+    "sync",
+    "time",
+    "tracing",
+] }
+tokio-stream = { version = "0.1.14" }
+
+[target.'cfg(all(async_executor_impl = "async-std"))'.dependencies]
+async-std = { version = "1.12", features = [
+    "attributes",
+    "unstable",
+]}
+
+[target.'cfg(all(async_channel_impl = "tokio"))'.dependencies]
+console-subscriber = { version = "0.1.10" }
+tokio = { version = "1", features = [
+    "fs",
+    "io-util",
+    "io-std",
+    "macros",
+    "net",
+    "parking_lot",
+    "process",
+    "rt",
+    "rt-multi-thread",
+    "signal",
+    "sync",
+    "time",
+    "tracing",
+] }
+tokio-stream = { version = "0.1.14" }
+
+[target.'cfg(all(async_channel_impl = "async-std"))'.dependencies]
+async-channel = { version = "1.9.0" }
+
+[target.'cfg(all(async_channel_impl = "flume"))'.dependencies]
+flume = { version = "0.10.14" }

README.md

@@ -2,11 +2,17 @@
 
 This crate exports four things:
 
-- A compatibility/abstraction layer for writing async-executor agnostic code. We support two async executors: async-std and tokio. Each may be toggled with a feature flag.
-- A compatibility/abstraction layer for writing async channel agnostic code. We support three async channel implementations: async-std-channels. Each may be toggled with a feature flag.
+- A compatibility/abstraction layer for writing async-executor agnostic code. We support two async executors: async-std and tokio. Each may be toggled with a configuration flag.
+- A compatibility/abstraction layer for writing async channel agnostic code. We support three async channel implementations: async-std-channels. Each may be toggled with a configuration flag.
 - A library exporting a bunch of useful async primitives.
 - A tracing configuration layer optionally supporting console and opentelemetry integration.
 
+# Example usage
 
+```bash
+RUSTFLAGS='--cfg async_executor_impl="tokio" --cfg async_channel_impl="tokio"' cargo build
+```
+
+`async_executor_impl` may be either `tokio` or `async-std`. `async_channel_impl` may be either `tokio`, `async-std`, or `flume`. Note that using `tokio` channels requires `tokio` to be the runtime. Note that the async executor impl and async channel impl must be set in order for this crate to compile successfully.
 
 

src/async_primitives/subscribable_mutex.rs

@@ -5,12 +5,12 @@ use futures::{stream::FuturesOrdered, Future, FutureExt};
 use std::{fmt, time::Duration};
 use tracing::warn;
 
-#[cfg(feature = "async-std-executor")]
+#[cfg(all(async_executor_impl = "async-std"))]
 use async_std::prelude::StreamExt;
-#[cfg(feature = "tokio-executor")]
+#[cfg(all(async_executor_impl = "tokio"))]
 use tokio_stream::StreamExt;
-#[cfg(not(any(feature = "async-std-executor", feature = "tokio-executor")))]
-std::compile_error! {"Either feature \"async-std-executor\" or feature \"tokio-executor\" must be enabled for this crate."}
+#[cfg(not(any(async_executor_impl = "async-std", async_executor_impl = "tokio")))]
+std::compile_error! {"The cfg flag async_executor_impl must be set in rustflags to either \"async-std\" or \"tokio\" for this crate. Try adding `--cfg async_executor_impl=\"tokio\""}
 
 /// A mutex that can register subscribers to be notified. This works in the same way as [`Mutex`], but has some additional functions:
 ///
@@ -251,10 +251,10 @@ mod tests {
     use std::{sync::Arc, time::Duration};
 
     #[cfg_attr(
-        feature = "tokio-executor",
+        async_executor_impl = "tokio",
         tokio::test(flavor = "multi_thread", worker_threads = 2)
     )]
-    #[cfg_attr(feature = "async-std-executor", async_std::test)]
+    #[cfg_attr(async_executor_impl = "async-std", async_std::test)]
     async fn test_wait_timeout_until() {
         let mutex: Arc<SubscribableMutex<usize>> = Arc::default();
         {
@@ -276,10 +276,10 @@ mod tests {
     }
 
     #[cfg_attr(
-        feature = "tokio-executor",
+        async_executor_impl = "tokio",
         tokio::test(flavor = "multi_thread", worker_threads = 2)
     )]
-    #[cfg_attr(feature = "async-std-executor", async_std::test)]
+    #[cfg_attr(async_executor_impl = "async-std", async_std::test)]
     async fn test_wait_timeout_until_fail() {
         let mutex: Arc<SubscribableMutex<usize>> = Arc::default();
         {
@@ -300,10 +300,10 @@ mod tests {
     }
 
     #[cfg_attr(
-        feature = "tokio-executor",
+        async_executor_impl = "tokio",
         tokio::test(flavor = "multi_thread", worker_threads = 2)
     )]
-    #[cfg_attr(feature = "async-std-executor", async_std::test)]
+    #[cfg_attr(async_executor_impl = "async-std", async_std::test)]
     async fn test_compare_and_set() {
         let mutex = SubscribableMutex::new(5usize);
         let subscriber = mutex.subscribe().await;
@@ -322,10 +322,10 @@ mod tests {
     }
 
     #[cfg_attr(
-        feature = "tokio-executor",
+        async_executor_impl = "tokio",
         tokio::test(flavor = "multi_thread", worker_threads = 2)
     )]
-    #[cfg_attr(feature = "async-std-executor", async_std::test)]
+    #[cfg_attr(async_executor_impl = "async-std", async_std::test)]
     async fn test_subscriber() {
         let mutex = SubscribableMutex::new(5usize);
         let subscriber = mutex.subscribe().await;

src/channel.rs

@@ -21,8 +21,8 @@ mod oneshot;
 /// Unbounded channels
 mod unbounded;
 
-#[cfg(all(feature = "async-std-executor", feature = "channel-tokio"))]
-compile_error!("feature 'async-std-executor' and 'channel-tokio' cannot be used at the same time; 'channel-tokio' needs the tokio runtime");
+#[cfg(all(async_executor_impl = "async-std", async_channel_impl = "tokio"))]
+compile_error!("async_executor_impl = 'async-std-executor' and async_channel_impl = 'channel-tokio' cannot be used together; 'channel-tokio' needs the tokio runtime");
 
 pub use bounded::{bounded, BoundedStream, Receiver, RecvError, SendError, Sender, TryRecvError};
 pub use oneshot::{oneshot, OneShotReceiver, OneShotRecvError, OneShotSender, OneShotTryRecvError};

src/channel/bounded.rs

@@ -3,7 +3,7 @@ use std::pin::Pin;
 use futures::Stream;
 
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-tokio")]
+#[cfg(all(async_channel_impl = "tokio"))]
 mod inner {
     pub use tokio::sync::mpsc::error::{SendError, TryRecvError};
 
@@ -45,7 +45,7 @@ mod inner {
 }
 
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-flume")]
+#[cfg(all(async_channel_impl = "flume"))]
 mod inner {
     pub use flume::{RecvError, SendError, TryRecvError};
 
@@ -75,7 +75,7 @@ mod inner {
 }
 
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-async-std")]
+#[cfg(all(async_channel_impl = "async-std"))]
 mod inner {
     pub use async_channel::{RecvError, SendError, TryRecvError};
 
@@ -114,9 +114,9 @@ impl<T> Sender<T> {
     ///
     /// Will return an error if the receiver is dropped
     pub async fn send(&self, msg: T) -> Result<(), SendError<T>> {
-        #[cfg(feature = "channel-flume")]
+        #[cfg(all(async_channel_impl = "flume"))]
         let result = self.0.send_async(msg).await;
-        #[cfg(not(feature = "channel-flume"))]
+        #[cfg(not(all(async_channel_impl = "flume")))]
         let result = self.0.send(msg).await;
 
         result
@@ -130,11 +130,11 @@ impl<T> Receiver<T> {
     ///
     /// Will return an error if the sender is dropped
     pub async fn recv(&mut self) -> Result<T, RecvError> {
-        #[cfg(feature = "channel-flume")]
+        #[cfg(all(async_channel_impl = "flume"))]
         let result = self.0.recv_async().await;
-        #[cfg(feature = "channel-tokio")]
+        #[cfg(all(async_channel_impl = "tokio"))]
         let result = self.0.recv().await.ok_or(RecvError);
-        #[cfg(feature = "channel-async-std")]
+        #[cfg(all(async_channel_impl = "async-std"))]
         let result = self.0.recv().await;
 
         result
@@ -144,11 +144,11 @@ impl<T> Receiver<T> {
     where
         T: 'static,
     {
-        #[cfg(feature = "channel-async-std")]
+        #[cfg(all(async_channel_impl = "async-std"))]
         let result = self.0;
-        #[cfg(feature = "channel-tokio")]
+        #[cfg(all(async_channel_impl = "tokio"))]
         let result = tokio_stream::wrappers::ReceiverStream::new(self.0);
-        #[cfg(feature = "channel-flume")]
+        #[cfg(all(async_channel_impl = "flume"))]
         let result = self.0.into_stream();
 
         BoundedStream(result)
@@ -219,14 +219,14 @@ impl<T> Stream for BoundedStream<T> {
         mut self: std::pin::Pin<&mut Self>,
         cx: &mut std::task::Context<'_>,
     ) -> std::task::Poll<Option<Self::Item>> {
-        #[cfg(feature = "channel-flume")]
+        #[cfg(all(async_channel_impl = "flume"))]
         return <flume::r#async::RecvStream<T>>::poll_next(Pin::new(&mut self.0), cx);
-        #[cfg(feature = "channel-tokio")]
+        #[cfg(all(async_channel_impl = "tokio"))]
         return <tokio_stream::wrappers::ReceiverStream<T> as Stream>::poll_next(
             Pin::new(&mut self.0),
             cx,
         );
-        #[cfg(feature = "channel-async-std")]
+        #[cfg(all(async_channel_impl = "async-std"))]
         return <async_channel::Receiver<T> as Stream>::poll_next(Pin::new(&mut self.0), cx);
     }
 }

src/channel/oneshot.rs

@@ -1,5 +1,5 @@
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-tokio")]
+#[cfg(all(async_channel_impl = "tokio"))]
 mod inner {
     pub use tokio::sync::oneshot::{error::TryRecvError as OneShotTryRecvError, Receiver, Sender};
 
@@ -40,7 +40,7 @@ mod inner {
 }
 
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-flume")]
+#[cfg(all(async_channel_impl = "flume"))]
 mod inner {
     use flume::{Receiver, Sender};
     pub use flume::{RecvError as OneShotRecvError, TryRecvError as OneShotTryRecvError};
@@ -61,7 +61,7 @@ mod inner {
 }
 
 /// inner module, used to group feature-specific imports
-#[cfg(feature = "channel-async-std")]
+#[cfg(all(async_channel_impl = "async-std"))]
 mod inner {
     use async_std::channel::{Receiver, Sender};
     pub use async_std::channel::{
@@ -90,11 +90,11 @@ impl<T> OneShotSender<T> {
     ///
     /// If this fails because the receiver is dropped, a warning will be printed.
     pub fn send(self, msg: T) {
-        #[cfg(feature = "channel-async-std")]
+        #[cfg(all(async_channel_impl = "async-std"))]
         if self.0.try_send(msg).is_err() {
             tracing::warn!("Could not send msg on OneShotSender, did the receiver drop?");
         }
-        #[cfg(not(feature = "channel-async-std"))]
+        #[cfg(not(all(async_channel_impl = "async-std")))]
         if self.0.send(msg).is_err() {
             tracing::warn!("Could not send msg on OneShotSender, did the receiver drop?");
         }
@@ -108,11 +108,11 @@ impl<T> OneShotReceiver<T> {
     ///
     /// Will return an error if the sender channel is dropped
     pub async fn recv(self) -> Result<T, OneShotRecvError> {
-        #[cfg(feature = "channel-tokio")]
+        #[cfg(all(async_channel_impl = "tokio"))]
         let result = self.0.await.map_err(Into::into);
-        #[cfg(feature = "channel-flume")]
+        #[cfg(all(async_channel_impl = "flume"))]
         let result = self.0.recv_async().await;
-        #[cfg(feature = "channel-async-std")]
+        #[cfg(all(async_channel_impl = "async-std"))]
         let result = self.0.recv().await;
 
         result