From d1c891d1badb988ec1a2f20b4b1afe127a2f86c9 Mon Sep 17 00:00:00 2001
From: Sean McArthur <sean@seanmonstar.com>
Date: Wed, 10 Apr 2019 13:17:16 -0700
Subject: [PATCH] Promote service_fn to tower crate (#248)

---
 tower-balance/examples/demo.rs |  6 ++----
 tower-util/src/boxed/mod.rs    | 38 +++++++---------------------------
 tower-util/src/lib.rs          |  2 +-
 tower-util/src/service_fn.rs   | 12 +++++------
 tower/src/lib.rs               |  2 +-
 tower/src/util.rs              |  3 +--
 6 files changed, 18 insertions(+), 45 deletions(-)

diff --git a/tower-balance/examples/demo.rs b/tower-balance/examples/demo.rs
index eb47f6f..18860ec 100644
--- a/tower-balance/examples/demo.rs
+++ b/tower-balance/examples/demo.rs
@@ -6,9 +6,7 @@ use hdrsample::Histogram;
 use rand::{self, Rng};
 use std::time::{Duration, Instant};
 use tokio::{runtime, timer};
-use tower::{
-    discover::Discover, limit::concurrency::ConcurrencyLimit, util::ServiceFn, Service, ServiceExt,
-};
+use tower::{discover::Discover, limit::concurrency::ConcurrencyLimit, Service, ServiceExt};
 use tower_balance as lb;
 
 const REQUESTS: usize = 50_000;
@@ -124,7 +122,7 @@ fn gen_disco() -> impl Discover<
         .zip(WEIGHTS.iter())
         .enumerate()
         .map(|(instance, (latency, weight))| {
-            let svc = ServiceFn::new(move |_| {
+            let svc = tower::service_fn(move |_| {
                 let start = Instant::now();
 
                 let maxms = u64::from(latency.subsec_nanos() / 1_000 / 1_000)
diff --git a/tower-util/src/boxed/mod.rs b/tower-util/src/boxed/mod.rs
index f56833f..8d46788 100644
--- a/tower-util/src/boxed/mod.rs
+++ b/tower-util/src/boxed/mod.rs
@@ -20,37 +20,15 @@
 //! # use futures::*;
 //! # use futures::future::FutureResult;
 //! # use tower_service::Service;
-//! # use tower_util::BoxService;
-//! // Respond to requests using a closure. Since closures cannot be named,
-//! // `ServiceFn` cannot be named either
-//! pub struct ServiceFn<F> {
-//!     f: F,
-//! }
+//! # use tower_util::{BoxService, service_fn};
+//! // Respond to requests using a closure, but closures cannot be named...
+//! # pub fn main() {
+//! let svc = service_fn(|mut request: String| {
+//!     request.push_str(" response");
+//!     Ok(request)
+//! });
 //!
-//! impl<F> Service<String> for ServiceFn<F>
-//! where F: Fn(String) -> String,
-//! {
-//!     type Response = String;
-//!     type Error = ();
-//!     type Future = FutureResult<String, ()>;
-//!
-//!     fn poll_ready(&mut self) -> Poll<(), ()> {
-//!         Ok(().into())
-//!     }
-//!
-//!     fn call(&mut self, request: String) -> FutureResult<String, ()> {
-//!         future::ok((self.f)(request))
-//!     }
-//! }
-//!
-//! pub fn main() {
-//!     let f = |mut request: String| {
-//!         request.push_str(" response");
-//!         request
-//!     };
-//!
-//!     let service: BoxService<String, String, ()> =
-//!         BoxService::new(ServiceFn { f });
+//! let service: BoxService<String, String, ()> = BoxService::new(svc);
 //! # drop(service);
 //! }
 //! ```
diff --git a/tower-util/src/lib.rs b/tower-util/src/lib.rs
index 14207f4..41d2bb6 100644
--- a/tower-util/src/lib.rs
+++ b/tower-util/src/lib.rs
@@ -25,7 +25,7 @@ pub use crate::{
     oneshot::Oneshot,
     optional::Optional,
     ready::Ready,
-    service_fn::ServiceFn,
+    service_fn::{service_fn, ServiceFn},
 };
 
 pub mod error {
diff --git a/tower-util/src/service_fn.rs b/tower-util/src/service_fn.rs
index 9743a8e..3848164 100644
--- a/tower-util/src/service_fn.rs
+++ b/tower-util/src/service_fn.rs
@@ -1,19 +1,17 @@
 use futures::{IntoFuture, Poll};
 use tower_service::Service;
 
+/// Returns a new `ServiceFn` with the given closure.
+pub fn service_fn<T>(f: T) -> ServiceFn<T> {
+    ServiceFn { f }
+}
+
 /// A `Service` implemented by a closure.
 #[derive(Copy, Clone, Debug)]
 pub struct ServiceFn<T> {
     f: T,
 }
 
-impl<T> ServiceFn<T> {
-    /// Returns a new `ServiceFn` with the given closure.
-    pub fn new(f: T) -> Self {
-        ServiceFn { f }
-    }
-}
-
 impl<T, F, Request> Service<Request> for ServiceFn<T>
 where
     T: Fn(Request) -> F,
diff --git a/tower/src/lib.rs b/tower/src/lib.rs
index 65a2bc3..a47ec4b 100644
--- a/tower/src/lib.rs
+++ b/tower/src/lib.rs
@@ -19,4 +19,4 @@ pub mod util;
 
 pub use crate::{builder::ServiceBuilder, util::ServiceExt};
 pub use tower_service::Service;
-pub use tower_util::{MakeConnection, MakeService};
+pub use tower_util::{service_fn, MakeConnection, MakeService};
diff --git a/tower/src/util.rs b/tower/src/util.rs
index 720c719..1f5eeda 100644
--- a/tower/src/util.rs
+++ b/tower/src/util.rs
@@ -3,8 +3,7 @@
 use futures::Stream;
 use tower_service::Service;
 pub use tower_util::{
-    BoxService, CallAll, CallAllUnordered, Either, Oneshot, Optional, Ready, ServiceFn,
-    UnsyncBoxService,
+    BoxService, CallAll, CallAllUnordered, Either, Oneshot, Optional, Ready, UnsyncBoxService,
 };
 
 impl<T: ?Sized, Request> ServiceExt<Request> for T where T: Service<Request> {}