Change lib to handle lockless collections

crossbeam_queue::SegQueue does not need a guarding RwLock.

Fixes: https://github.com/haraldh/dynqueue/issues/4

Cargo.toml

@@ -15,5 +15,5 @@ keywords = [ "parallel", "performance", "thread", "join", "concurrency"]
 categories = [ "concurrency" ]
 
 [dependencies]
-rayon = "1.3.0"
+rayon = "1.3"
 crossbeam-queue = { version = "0.2", optional = true }

README.md

@@ -7,17 +7,21 @@ A `DynQueue<T>` can be iterated with `into_par_iter` producing `(DynQueueHandle,
 With the `DynQueueHandle<T>` a new `T` can be inserted in the `DynQueue<T>`,
 which is currently iterated over.
 
-```rust
+A `Vec<T>`, `VecDeque<T>` and `crossbeam_queue::SegQueue<T>` (with `feature = "crossbeam-queue"`)
-use dynqueue::DynQueue;
+can be turned into a `DynQueue<T>` with `.into_dyn_queue()`.
 
+```rust
 use rayon::iter::IntoParallelIterator as _;
 use rayon::iter::ParallelIterator as _;
 
+use dynqueue::IntoDynQueue as _;
+
 fn main() {
-    let mut result = DynQueue::new(vec![1, 2, 3])
+    let mut result = vec![1, 2, 3]
-                         .into_par_iter()
+        .into_dyn_queue()
-                         .map(|(handle, value)| { if value == 2 { handle.enqueue(4) }; value })
+        .into_par_iter()
-                         .collect::<Vec<_>>();
+        .map(|(handle, value)| { if value == 2 { handle.enqueue(4) }; value })
+        .collect::<Vec<_>>();
     result.sort();
 
     assert_eq!(result, vec![1, 2, 3, 4]);

src/lib.rs

@@ -7,15 +7,21 @@
 //! # Example
 //!
 //! ```
-//! use dynqueue::{DynQueue, DynQueueHandle};
-//!
 //! use rayon::iter::IntoParallelIterator as _;
 //! use rayon::iter::ParallelIterator as _;
 //!
-//! let mut result = DynQueue::new(vec![1, 2, 3])
+//! use dynqueue::IntoDynQueue as _;
-//!                      .into_par_iter()
+//!
-//!                      .map(|(handle, value)| { if value == 2 { handle.enqueue(4) }; value })
+//! let mut result = vec![1, 2, 3]
-//!                      .collect::<Vec<_>>();
+//!     .into_dyn_queue()
+//!     .into_par_iter()
+//!     .map(|(handle, value)| {
+//!         if value == 2 {
+//!             handle.enqueue(4)
+//!         };
+//!         value
+//!     })
+//!     .collect::<Vec<_>>();
 //! result.sort();
 //!
 //! assert_eq!(result, vec![1, 2, 3, 4]);
@@ -26,27 +32,45 @@
 //! The `DynQueueHandle` shall not outlive the `DynQueue` iterator
 //!
 //! ```should_panic
-//! use dynqueue::{DynQueue, DynQueueHandle};
+//! use dynqueue::{DynQueue, DynQueueHandle, IntoDynQueue};
 //!
 //! use rayon::iter::IntoParallelIterator as _;
 //! use rayon::iter::ParallelIterator as _;
+//! use std::sync::RwLock;
 //!
-//! static mut STALE_HANDLE : Option<DynQueueHandle<u8, Vec<u8>>> = None;
+//! static mut STALE_HANDLE: Option<DynQueueHandle<u8, RwLock<Vec<u8>>>> = None;
 //!
 //! pub fn test_func() -> Vec<u8> {
-//!     DynQueue::new(vec![1u8, 2u8, 3u8])
+//!     vec![1u8, 2u8, 3u8]
+//!         .into_dyn_queue()
 //!         .into_par_iter()
-//!         .map(|(handle, value)| unsafe { STALE_HANDLE.replace(handle); value })
+//!         .map(|(handle, value)| unsafe {
+//!             STALE_HANDLE.replace(handle);
+//!             value
+//!         })
 //!         .collect::<Vec<_>>()
 //! }
 //! // test_func() panics
 //! let result = test_func();
-//! unsafe { STALE_HANDLE.as_ref().unwrap().enqueue(4); }
+//! unsafe {
+//!     STALE_HANDLE.as_ref().unwrap().enqueue(4);
+//! }
 //! ```
 
 #![deny(clippy::all)]
 #![deny(missing_docs)]
 
+#[allow(unused)]
+macro_rules! doc_comment {
+    ($x:expr) => {
+        #[doc = $x]
+        #[doc(hidden)]
+        mod readme_tests {}
+    };
+}
+
+doc_comment!(include_str!("../README.md"));
+
 use rayon::iter::plumbing::{
     bridge_unindexed, Consumer, Folder, UnindexedConsumer, UnindexedProducer,
 };
@@ -57,80 +81,123 @@ use std::sync::{Arc, RwLock};
 #[cfg(test)]
 mod tests;
 
+/// Trait to produce a new DynQueue
+pub trait IntoDynQueue<T, U: Queue<T>> {
+    /// new
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, U>;
+}
+
 /// Everything implementing `Queue` can be handled by DynQueue
+#[allow(clippy::len_without_is_empty)]
 pub trait Queue<T>
 where
     Self: Sized,
 {
     /// push an element in the queue
-    fn push(&mut self, v: T);
+    fn push(&self, v: T);
 
     /// pop an element from the queue
-    fn pop(&mut self) -> Option<T>;
+    fn pop(&self) -> Option<T>;
 
     /// number of elements in the queue
     fn len(&self) -> usize;
 
     /// split off `size` elements
-    fn split_off(&mut self, size: usize) -> Self;
+    fn split_off(&self, size: usize) -> Self;
 }
 
-impl<T> Queue<T> for Vec<T> {
+impl<T> IntoDynQueue<T, RwLock<Vec<T>>> for Vec<T> {
     #[inline(always)]
-    fn push(&mut self, v: T) {
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, RwLock<Vec<T>>> {
-        Vec::push(self, v)
+        DynQueue(Arc::new(DynQueueInner(RwLock::new(self), PhantomData)))
+    }
+}
+
+impl<T> IntoDynQueue<T, RwLock<Vec<T>>> for RwLock<Vec<T>> {
+    #[inline(always)]
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, RwLock<Vec<T>>> {
+        DynQueue(Arc::new(DynQueueInner(self, PhantomData)))
+    }
+}
+
+impl<T> Queue<T> for RwLock<Vec<T>> {
+    #[inline(always)]
+    fn push(&self, v: T) {
+        self.write().unwrap().push(v)
     }
 
     #[inline(always)]
-    fn pop(&mut self) -> Option<T> {
+    fn pop(&self) -> Option<T> {
-        Vec::pop(self)
+        self.write().unwrap().pop()
     }
 
     #[inline(always)]
     fn len(&self) -> usize {
-        Vec::len(self)
+        self.read().unwrap().len()
     }
 
     #[inline(always)]
-    fn split_off(&mut self, size: usize) -> Self {
+    fn split_off(&self, size: usize) -> Self {
-        Vec::split_off(self, size)
+        RwLock::new(self.write().unwrap().split_off(size))
     }
 }
 
-impl<T> Queue<T> for VecDeque<T> {
+impl<T> IntoDynQueue<T, RwLock<VecDeque<T>>> for VecDeque<T> {
     #[inline(always)]
-    fn push(&mut self, v: T) {
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, RwLock<VecDeque<T>>> {
-        VecDeque::push_back(self, v)
+        DynQueue(Arc::new(DynQueueInner(RwLock::new(self), PhantomData)))
+    }
+}
+
+impl<T> IntoDynQueue<T, RwLock<VecDeque<T>>> for RwLock<VecDeque<T>> {
+    #[inline(always)]
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, RwLock<VecDeque<T>>> {
+        DynQueue(Arc::new(DynQueueInner(self, PhantomData)))
+    }
+}
+
+impl<T> Queue<T> for RwLock<VecDeque<T>> {
+    #[inline(always)]
+    fn push(&self, v: T) {
+        self.write().unwrap().push_back(v)
     }
 
     #[inline(always)]
-    fn pop(&mut self) -> Option<T> {
+    fn pop(&self) -> Option<T> {
-        VecDeque::pop_front(self)
+        self.write().unwrap().pop_front()
     }
 
     #[inline(always)]
     fn len(&self) -> usize {
-        VecDeque::len(self)
+        self.read().unwrap().len()
     }
 
     #[inline(always)]
-    fn split_off(&mut self, size: usize) -> Self {
+    fn split_off(&self, size: usize) -> Self {
-        VecDeque::split_off(self, size)
+        RwLock::new(self.write().unwrap().split_off(size))
     }
 }
 
 #[cfg(feature = "crossbeam-queue")]
 use crossbeam_queue::SegQueue;
 
+#[cfg(feature = "crossbeam-queue")]
+impl<T> IntoDynQueue<T, SegQueue<T>> for SegQueue<T> {
+    #[inline(always)]
+    fn into_dyn_queue<'a>(self) -> DynQueue<'a, T, Self> {
+        DynQueue(Arc::new(DynQueueInner(self, PhantomData)))
+    }
+}
+
 #[cfg(feature = "crossbeam-queue")]
 impl<T> Queue<T> for SegQueue<T> {
     #[inline(always)]
-    fn push(&mut self, v: T) {
+    fn push(&self, v: T) {
         SegQueue::push(self, v);
     }
 
     #[inline(always)]
-    fn pop(&mut self) -> Option<T> {
+    fn pop(&self) -> Option<T> {
         SegQueue::pop(self).ok()
     }
 
@@ -140,10 +207,10 @@ impl<T> Queue<T> for SegQueue<T> {
     }
 
     #[inline(always)]
-    fn split_off(&mut self, size: usize) -> Self {
+    fn split_off(&self, size: usize) -> Self {
         let q = SegQueue::new();
         (0..size)
-            .filter_map(|_| self.pop())
+            .filter_map(|_| Queue::pop(self))
             .for_each(|ele| q.push(ele));
         q
     }
@@ -151,7 +218,7 @@ impl<T> Queue<T> for SegQueue<T> {
 
 // PhantomData should prevent `DynQueueInner` to outlive the original `DynQueue`
 // but does not always.
-struct DynQueueInner<'a, T, U: Queue<T>>(std::sync::RwLock<U>, PhantomData<&'a T>);
+struct DynQueueInner<'a, T, U: Queue<T>>(U, PhantomData<&'a T>);
 
 /// The `DynQueueHandle` returned by the iterator in addition to `T`
 pub struct DynQueueHandle<'a, T, U: Queue<T>>(Arc<DynQueueInner<'a, T, U>>);
@@ -160,44 +227,26 @@ impl<'a, T, U: Queue<T>> DynQueueHandle<'a, T, U> {
     /// Enqueue `T` in the `DynQueue<T>`, which is currently iterated.
     #[inline]
     pub fn enqueue(&self, job: T) {
-        (self.0).0.write().unwrap().push(job)
+        (self.0).0.push(job)
     }
 }
 
 /// The `DynQueue<T>` which can be parallel iterated over
 pub struct DynQueue<'a, T, U: Queue<T>>(Arc<DynQueueInner<'a, T, U>>);
 
-impl<'a, T, U: Queue<T>> DynQueue<'a, T, U>
-where
-    T: Send + Sync,
-    U: Queue<T> + Send + Sync,
-{
-    /// Create a new `DynQueue<T>` from a `Vec<T>`
-    #[inline]
-    pub fn new(lifo: U) -> Self {
-        Self(Arc::new(DynQueueInner(RwLock::new(lifo), PhantomData)))
-    }
-}
-
 impl<'a, T, U> UnindexedProducer for DynQueue<'a, T, U>
 where
     T: Send + Sync,
-    U: Queue<T> + Send + Sync,
+    U: IntoDynQueue<T, U> + Queue<T> + Send + Sync,
 {
     type Item = (DynQueueHandle<'a, T, U>, T);
 
     fn split(self) -> (Self, Option<Self>) {
-        let len = {
+        let len = (self.0).0.len();
-            let q = (self.0).0.read().unwrap();
+
-            q.len()
-        };
         if len >= 2 {
-            let new_q = {
+            let new_q = (self.0).0.split_off(len / 2);
-                let mut q = (self.0).0.write().unwrap();
+            (self, Some(new_q.into_dyn_queue()))
-                let split_off = q.split_off(len / 2);
-                DynQueue::new(split_off)
-            };
-            (self, Some(new_q))
         } else {
             (self, None)
         }
@@ -209,10 +258,7 @@ where
     {
         let mut folder = folder;
         loop {
-            let ret = {
+            let ret = (self.0).0.pop();
-                let mut q = (self.0).0.write().unwrap();
-                q.pop()
-            };
 
             if let Some(v) = ret {
                 folder = folder.consume((DynQueueHandle(self.0.clone()), v));
@@ -233,7 +279,7 @@ where
 impl<'a, T, U> rayon::iter::ParallelIterator for DynQueue<'a, T, U>
 where
     T: Send + Sync,
-    U: Queue<T> + Send + Sync,
+    U: IntoDynQueue<T, U> + Queue<T> + Send + Sync,
 {
     type Item = (DynQueueHandle<'a, T, U>, T);
 

src/tests.rs

@@ -1,4 +1,4 @@
-use crate::{DynQueue, DynQueueHandle, Queue};
+use crate::{DynQueueHandle, IntoDynQueue, Queue};
 use std::collections::VecDeque;
 
 const SLEEP_MS: u64 = 10;
@@ -49,7 +49,7 @@ fn dynqueue_iter_test_const_sleep() {
 
     let med = expected.iter().sum::<u64>() / expected.iter().count() as u64;
 
-    let jq = DynQueue::new(get_input());
+    let jq = get_input().into_dyn_queue();
     let now = std::time::Instant::now();
 
     let mut res = jq
@@ -79,13 +79,13 @@ fn dynqueue_iter_test_const_sleep_segqueue() {
     let expected = get_expected();
 
     let med = expected.iter().sum::<u64>() / expected.iter().count() as u64;
-    let q = SegQueue::new();
+    let jq = SegQueue::new();
-    get_input().drain(..).for_each(|ele| q.push(ele));
+    get_input().drain(..).for_each(|ele| jq.push(ele));
 
-    let jq = DynQueue::new(q);
     let now = std::time::Instant::now();
 
     let mut res = jq
+        .into_dyn_queue()
         .into_par_iter()
         .map(handle_queue)
         .map(|v| {
@@ -111,10 +111,11 @@ fn dynqueue_iter_test_const_sleep_vecdeque() {
 
     let med = expected.iter().sum::<u64>() / expected.iter().count() as u64;
 
-    let jq = DynQueue::new(VecDeque::from(get_input()));
+    let jq = VecDeque::from(get_input());
     let now = std::time::Instant::now();
 
     let mut res = jq
+        .into_dyn_queue()
         .into_par_iter()
         .map(handle_queue)
         .map(|v| {
@@ -137,11 +138,12 @@ fn dynqueue_iter_test_sleep_v() {
     use rayon::iter::ParallelIterator as _;
     use std::time::Duration;
 
-    let jq = DynQueue::new(get_input());
+    let jq = get_input();
 
     let now = std::time::Instant::now();
 
     let mut res = jq
+        .into_dyn_queue()
         .into_par_iter()
         .map(handle_queue)
         .map(|v| {
@@ -161,11 +163,12 @@ fn dynqueue_iter_test_sleep_inv_v() {
     use rayon::iter::ParallelIterator as _;
     use std::time::Duration;
 
-    let jq = DynQueue::new(get_input());
+    let jq = get_input();
 
     let now = std::time::Instant::now();
 
     let mut res = jq
+        .into_dyn_queue()
         .into_par_iter()
         .map(handle_queue)
         .map(|v| {