Improve performance of spsc_queue and stream.

This commit makes two main changes.
1. It switches the spsc_queue node caching strategy from keeping a shared
counter of the number of nodes in the cache to keeping a consumer only counter
of the number of node eligible to be cached.
2. It separate the consumer and producers fields of spsc_queue and stream into
a producer cache line and consumer cache line.

1 files changed, 37 insertions, 0 deletions

diff --git a/src/libstd/sync/mpsc/cache_aligned.rs b/src/libstd/sync/mpsc/cache_aligned.rs
new file mode 100644
index 00000000000..5af01262573
--- /dev/null
+++ b/src/libstd/sync/mpsc/cache_aligned.rs
@@ -0,0 +1,37 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use ops::{Deref, DerefMut};
+
+#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[repr(align(64))]
+pub(super) struct Aligner;
+
+#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub(super) struct CacheAligned<T>(pub T, pub Aligner);
+
+impl<T> Deref for CacheAligned<T> {
+     type Target = T;
+     fn deref(&self) -> &Self::Target {
+         &self.0
+     }
+}
+
+impl<T> DerefMut for CacheAligned<T> {
+     fn deref_mut(&mut self) -> &mut Self::Target {
+         &mut self.0
+     }
+}
+
+impl<T> CacheAligned<T> {
+    pub(super) fn new(t: T) -> Self {
+        CacheAligned(t, Aligner)
+    }
+}