Merge pull request #173 from kennytm/issue-46449-future

Add test case for rust-lang/rust#46449

Author: Mark-Simulacrum

collector/benchmarks/issue-46449/0-io-error-6144.patch

@@ -0,0 +1,13 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index 4b9db94..c44dea6 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -2,7 +2,7 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 1;
++const BUFFER_SIZE: usize = 6144;
+ pub struct Error(::std::io::Error);
+
+ struct Dummy<T>(T);

collector/benchmarks/issue-46449/1-u32-3072.patch

@@ -0,0 +1,15 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index c44dea6..b555f05 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -2,8 +2,8 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 6144;
+-pub struct Error(::std::io::Error);
++const BUFFER_SIZE: usize = 3072;
++pub struct Error(u32);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {

collector/benchmarks/issue-46449/2-u8-3072.patch

@@ -0,0 +1,13 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index f8f91d6..b555f05 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -3,7 +3,7 @@ extern crate futures;
+ use futures::{Future, Poll};
+
+ const BUFFER_SIZE: usize = 3072;
+-pub struct Error(u32);
++pub struct Error(u8);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {

collector/benchmarks/issue-46449/3-empty-3072.patch

@@ -0,0 +1,13 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index f8f91d6..72382a0 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -3,7 +3,7 @@ extern crate futures;
+ use futures::{Future, Poll};
+
+ const BUFFER_SIZE: usize = 3072;
+-pub struct Error(u8);
++pub struct Error;
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {

collector/benchmarks/issue-46449/4-static-str-6144.patch

@@ -0,0 +1,15 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index 72382a0..5d8fc67 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -2,8 +2,8 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 3072;
+-pub struct Error;
++const BUFFER_SIZE: usize = 6144;
++pub struct Error(&'static str);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {

collector/benchmarks/issue-46449/Cargo.lock

@@ -0,0 +1,6 @@
+[package]
+name = "issue-46649-byte-filling-slowing-down-sroa"
+version = "0.1.0"
+
+[dependencies]
+futures = "=0.1.17"

collector/benchmarks/issue-46449/Cargo.toml

@@ -0,0 +1,10 @@
+Performance test to track <https://github.com/rust-lang/rust/issues/46449>.
+
+| Patch             | 1.22.1        | 1.23.0-beta.2 | Note                                                          |
+|-------------------|---------------|---------------|---------------------------------------------------------------|
+| (baseline)        | Fast (~1s)    | Fast (~1s)    | Make the depedencies available. Should finish very quickly.   |
+| 0-io-error-6144   | Fast (~1s)    | Slow (~16s)   | This is the reduced test case of the original bug report      |
+| 1-u32-3072        | Slow (~21s)   | Fast (~1s)    | Length reduced to 3072 to avoid taking too much time.         |
+| 2-u8-3072         | Slow (~21s)   | Fast (~1s)    |                                                               |
+| 3-empty-3072      | Slow (~20s)   | Slow (~27s)   |                                                               |
+| 4-static-str-6144 | Slow (~22s)   | Medium (~8s)  | Length increased back to 6144 as this is faster.              |

collector/benchmarks/issue-46449/README.md

@@ -0,0 +1,24 @@
+extern crate futures;
+
+use futures::{Future, Poll};
+
+const BUFFER_SIZE: usize = 1;
+pub struct Error(::std::io::Error);
+
+struct Dummy<T>(T);
+impl<T> Future for Dummy<T> {
+    type Item = T;
+    type Error = Error;
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        loop {}
+    }
+}
+
+pub fn run() -> Box<Future<Item = (), Error = Error>> {
+    let c2s = Dummy([0u8; BUFFER_SIZE]).then(move |_| Ok(0));
+    let s2c = Dummy(()).then(move |_| Ok(0));
+    let fut = c2s.select(s2c)
+        .and_then(move |_| Ok(()))
+        .map_err(|(err, _)| err);
+    Box::new(fut)
+}