Merge #303

303: Move queues into crossbeam-queue r=stjepang a=stjepang

This PR moves `ArrayQueue` and `SegQueue` into a new crate `crossbeam-queue`.

We need queues in a crate that doesn't pull all other Crossbeam crates as a dependency. In particular, Tokio wants to use MPMC queues but cares a lot about keeping its dependency tree as small as possible. See #292 for more information.

Since we already have the `crossbeam::queue` module, and this simply extracts it into `crossbeam-queue`, and there's a real need for moving queues out of `crossbeam`, I believe the introduction of a new crate should be uncontroversial.

I'll leave this PR open for a few days and merge if there are no objections. If anyone feels this might be a wrong decision, please speak up!

Closes #292 

Co-authored-by: Stjepan Glavina <stjepang@gmail.com>

.travis.yml

@@ -25,6 +25,9 @@ matrix:
   - rust: 1.26.0
     name: "crossbeam-epoch on 1.26.0"
     script: ./ci/crossbeam-epoch.sh
+  - rust: 1.26.0
+    name: "crossbeam-queue on 1.26.0"
+    script: ./ci/crossbeam-queue.sh
   - rust: 1.28.0
     name: "crossbeam-skiplist on 1.28.0"
     script: ./ci/crossbeam-skiplist.sh
@@ -56,6 +59,9 @@ matrix:
           - llvm-3.8-dev
           - clang-3.8
           - clang-3.8-dev
+  - rust: nightly
+    name: "crossbeam-queue on nightly"
+    script: ./ci/crossbeam-queue.sh
   - rust: nightly
     name: "crossbeam-skiplist on nightly"
     script: ./ci/crossbeam-skiplist.sh

Cargo.toml

@@ -39,6 +39,10 @@ path = "./crossbeam-deque"
 version = "0.7.0"
 path = "./crossbeam-epoch"
 
+[dependencies.crossbeam-queue]
+version = "0.0.0"
+path = "./crossbeam-queue"
+
 [dependencies.crossbeam-utils]
 version = "0.6.3"
 path = "./crossbeam-utils"
@@ -53,14 +57,7 @@ members = [
   "crossbeam-channel/benchmarks",
   "crossbeam-deque",
   "crossbeam-epoch",
+  "crossbeam-queue",
   "crossbeam-skiplist",
   "crossbeam-utils",
 ]
-
-# [patch.crates-io]
-# crossbeam = { path = "." }
-# crossbeam-channel = { path = "./crossbeam-channel" }
-# crossbeam-deque = { path = "./crossbeam-deque" }
-# crossbeam-epoch = { path = "./crossbeam-epoch" }
-# crossbeam-skiplist = { path = "./crossbeam-skiplist" }
-# crossbeam-utils = { path = "./crossbeam-utils" }

ci/crossbeam-queue.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+cd "$(dirname "$0")"/../crossbeam-queue
+set -ex
+
+export RUSTFLAGS="-D warnings"
+
+cargo check --bins --examples --tests
+cargo test

crossbeam-channel/benchmarks/segqueue.rs

@@ -16,7 +16,7 @@ fn seq() {
     }
 
     for _ in 0..MESSAGES {
-        q.try_pop().unwrap();
+        q.pop().unwrap();
     }
 }
 
@@ -32,7 +32,7 @@ fn spsc() {
 
         for _ in 0..MESSAGES {
             loop {
-                if q.try_pop().is_none() {
+                if q.pop().is_err() {
                     thread::yield_now();
                 } else {
                     break;
@@ -56,7 +56,7 @@ fn mpsc() {
 
         for _ in 0..MESSAGES {
             loop {
-                if q.try_pop().is_none() {
+                if q.pop().is_err() {
                     thread::yield_now();
                 } else {
                     break;
@@ -82,7 +82,7 @@ fn mpmc() {
             scope.spawn(|_| {
                 for _ in 0..MESSAGES / THREADS {
                     loop {
-                        if q.try_pop().is_none() {
+                        if q.pop().is_err() {
                             thread::yield_now();
                         } else {
                             break;

crossbeam-channel/src/channel.rs

@@ -205,7 +205,7 @@ pub fn after(duration: Duration) -> Receiver<Instant> {
 ///     s.send(1).unwrap();
 /// });
 ///
-/// // This duration can be a `Some` or a `None`.
+/// // Suppose this duration can be a `Some` or a `None`.
 /// let duration = Some(Duration::from_millis(100));
 ///
 /// // Create a channel that times out after the specified duration.

crossbeam-queue/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "crossbeam-queue"
+# When publishing a new version:
+# - Update CHANGELOG.md
+# - Update README.md
+# - Create "crossbeam-queue-X.Y.Z" git tag
+version = "0.0.0"
+authors = ["The Crossbeam Project Developers"]
+license = "MIT/Apache-2.0"
+readme = "README.md"
+repository = "https://github.com/crossbeam-rs/crossbeam"
+homepage = "https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-utils"
+documentation = "https://docs.rs/crossbeam-queue"
+description = "Concurrent queues"
+keywords = ["queue", "mpmc", "lock-free", "producer", "consumer"]
+categories = ["concurrency", "data-structures"]
+
+[dependencies.crossbeam-utils]
+version = "0.6"
+path = "../crossbeam-utils"
+
+[dev-dependencies]
+rand = "0.6"

crossbeam-queue/LICENSE-APACHE

@@ -0,0 +1,201 @@
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crossbeam-queue/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
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+DEALINGS IN THE SOFTWARE.

crossbeam-queue/LICENSE-THIRD-PARTY

@@ -0,0 +1,31 @@
+===============================================================================
+
+Bounded MPMC queue
+http://www.1024cores.net/home/code-license
+
+Copyright (c) 2010-2011 Dmitry Vyukov.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+EVENT SHALL DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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+ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+The views and conclusions contained in the software and documentation are those
+of the authors and should not be interpreted as representing official policies,
+either expressed or implied, of Dmitry Vyukov.