1 files changed, 66 insertions, 0 deletions
diff --git a/src/async_executor.rs b/src/async_executor.rs
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+++ b/src/async_executor.rs
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+//! This module defines a trait that can be used to plug in different Futures executors into
+//! Criterion.rs' async benchmarking support.
+//!
+//! Implementations are provided for:
+//! * Tokio (implemented directly for tokio::Runtime)
+//! * Async-std
+//! * Smol
+//! * The Futures crate
+//!
+//! Please note that async benchmarks will have a small amount of measurement overhead relative
+//! to synchronous benchmarks. It is recommended to use synchronous benchmarks where possible, to
+//! improve measurement accuracy.
+
+use std::future::Future;
+
+/// Plugin trait used to allow benchmarking on multiple different async runtimes.
+///
+/// Smol, Tokio and Async-std are supported out of the box, as is the current-thread runner from the
+/// Futures crate; it is recommended to use whichever runtime you use in production.
+pub trait AsyncExecutor {
+    /// Spawn the given future onto this runtime and block until it's complete, returning the result.
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T;
+}
+
+/// Runs futures on the 'futures' crate's built-in current-thread executor
+#[cfg(feature = "async_futures")]
+pub struct FuturesExecutor;
+#[cfg(feature = "async_futures")]
+impl AsyncExecutor for FuturesExecutor {
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T {
+        futures::executor::block_on(future)
+    }
+}
+
+/// Runs futures on the 'soml' crate's global executor
+#[cfg(feature = "async_smol")]
+pub struct SmolExecutor;
+#[cfg(feature = "async_smol")]
+impl AsyncExecutor for SmolExecutor {
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T {
+        smol::block_on(future)
+    }
+}
+
+#[cfg(feature = "async_tokio")]
+impl AsyncExecutor for tokio::runtime::Runtime {
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T {
+        self.block_on(future)
+    }
+}
+#[cfg(feature = "async_tokio")]
+impl AsyncExecutor for &tokio::runtime::Runtime {
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T {
+        (*self).block_on(future)
+    }
+}
+
+/// Runs futures on the 'async-std' crate's global executor
+#[cfg(feature = "async_std")]
+pub struct AsyncStdExecutor;
+#[cfg(feature = "async_std")]
+impl AsyncExecutor for AsyncStdExecutor {
+    fn block_on<T>(&self, future: impl Future<Output = T>) -> T {
+        async_std::task::block_on(future)
+    }
+}