Import easy-parallel 3.3.0upstream/3.3.0upstream

11 files changed, 799 insertions, 0 deletions

diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
new file mode 100644
index 0000000..534f153
--- /dev/null
+++ b/.cargo_vcs_info.json
@@ -0,0 +1,6 @@
+{
+  "git": {
+    "sha1": "f17bf332776897ca7ee30e7824fb909a6de983ab"
+  },
+  "path_in_vcs": ""
+}
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..b902187
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,35 @@
+# Version 3.3.0
+
+- Add `Parallel::collect()` and `Parallel::finish_in()` to allow for generic containers. (#9)
+
+# Version 3.2.0
+
+- Remove `T: Default` bound from `Default` impl.
+
+# Version 3.1.0
+
+- Add `Parallel::finish()`.
+
+# Version 3.0.0
+
+- Collect results in the same order closures were added.
+
+# Version 2.2.0
+
+- Remove `PhantomData` making `'a` invariant.
+
+# Version 2.1.0
+
+- Run one of the closures on the main thread.
+
+# Version 2.0.0
+
+- `Parallel::run()` now collects results.
+
+# Version 1.0.1
+
+- Remove unused `mut`.
+
+# Version 1.0.0
+
+- Initial version
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..593b166
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "easy-parallel"
+version = "3.3.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..a812203
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,30 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.35"
+name = "easy-parallel"
+version = "3.3.0"
+authors = ["Stjepan Glavina <stjepang@gmail.com>"]
+exclude = ["/.*"]
+description = "Run closures in parallel"
+homepage = "https://github.com/smol-rs/easy-parallel"
+readme = "README.md"
+keywords = [
+    "scope",
+    "thread",
+    "scoped",
+    "spawn",
+]
+categories = ["concurrency"]
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/smol-rs/easy-parallel"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
new file mode 100644
index 0000000..940a114
--- /dev/null
+++ b/Cargo.toml.orig
@@ -0,0 +1,16 @@
+[package]
+name = "easy-parallel"
+# When publishing a new version:
+# - Update CHANGELOG.md
+# - Create "v3.x.y" git tag
+version = "3.3.0"
+authors = ["Stjepan Glavina <stjepang@gmail.com>"]
+edition = "2018"
+rust-version = "1.35"
+description = "Run closures in parallel"
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/smol-rs/easy-parallel"
+homepage = "https://github.com/smol-rs/easy-parallel"
+keywords = ["scope", "thread", "scoped", "spawn"]
+categories = ["concurrency"]
+exclude = ["/.*"]
diff --git a/LICENSE-APACHE b/LICENSE-APACHE
new file mode 100644
index 0000000..16fe87b
--- /dev/null
+++ b/LICENSE-APACHE
@@ -0,0 +1,201 @@
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diff --git a/LICENSE-MIT b/LICENSE-MIT
new file mode 100644
index 0000000..31aa793
--- /dev/null
+++ b/LICENSE-MIT
@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
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+The above copyright notice and this permission notice
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+DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..aff5b86
--- /dev/null
+++ b/README.md
@@ -0,0 +1,83 @@
+# easy-parallel
+
+[![Build](https://github.com/smol-rs/easy-parallel/workflows/Build%20and%20test/badge.svg)](
+https://github.com/smol-rs/easy-parallel/actions)
+[![License](https://img.shields.io/badge/license-Apache--2.0_OR_MIT-blue.svg)](
+https://github.com/smol-rs/easy-parallel)
+[![Cargo](https://img.shields.io/crates/v/easy-parallel.svg)](
+https://crates.io/crates/easy-parallel)
+[![Documentation](https://docs.rs/easy-parallel/badge.svg)](
+https://docs.rs/easy-parallel)
+
+Run closures in parallel.
+
+This is a simple primitive for spawning threads in bulk and waiting for them to complete.
+Threads are allowed to borrow local variables from the main thread.
+
+# Examples
+
+Run two threads that increment a number:
+
+```rust
+use easy_parallel::Parallel;
+use std::sync::Mutex;
+
+let mut m = Mutex::new(0);
+
+Parallel::new()
+    .add(|| *m.lock().unwrap() += 1)
+    .add(|| *m.lock().unwrap() += 1)
+    .run();
+
+assert_eq!(*m.get_mut().unwrap(), 2);
+```
+
+Square each number of a vector on a different thread:
+
+```rust
+use easy_parallel::Parallel;
+
+let v = vec![10, 20, 30];
+
+let squares = Parallel::new()
+    .each(0..v.len(), |i| v[i] * v[i])
+    .run();
+
+assert_eq!(squares, [100, 400, 900]);
+```
+
+Compute the sum of numbers in an array:
+
+```rust
+use easy_parallel::Parallel;
+
+fn par_sum(v: &[i32]) -> i32 {
+    const THRESHOLD: usize = 2;
+
+    if v.len() <= THRESHOLD {
+        v.iter().copied().sum()
+    } else {
+        let half = (v.len() + 1) / 2;
+        let sums = Parallel::new().each(v.chunks(half), par_sum).run();
+        sums.into_iter().sum()
+    }
+}
+
+let v = [1, 25, -4, 10, 8];
+assert_eq!(par_sum(&v), 40);
+```
+
+## License
+
+Licensed under either of
+
+ * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+#### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.
diff --git a/examples/par_sum.rs b/examples/par_sum.rs
new file mode 100644
index 0000000..d662734
--- /dev/null
+++ b/examples/par_sum.rs
@@ -0,0 +1,23 @@
+use easy_parallel::Parallel;
+
+fn par_sum(v: &[i32]) -> i32 {
+    const THRESHOLD: usize = 100;
+
+    if v.len() <= THRESHOLD {
+        v.iter().copied().sum()
+    } else {
+        let half = (v.len() + 1) / 2;
+        let sums = Parallel::new().each(v.chunks(half), par_sum).run();
+        sums.into_iter().sum()
+    }
+}
+
+fn main() {
+    let mut v = Vec::new();
+    for i in 0..10_000 {
+        v.push(i);
+    }
+
+    let sum = dbg!(par_sum(&v));
+    assert_eq!(sum, v.into_iter().sum());
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..6bef1c5
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,337 @@
+//! Run closures in parallel.
+//!
+//! This is a simple primitive for spawning threads in bulk and waiting for them to complete.
+//! Threads are allowed to borrow local variables from the main thread.
+//!
+//! # Examples
+//!
+//! Run two threads that increment a number:
+//!
+//! ```
+//! use easy_parallel::Parallel;
+//! use std::sync::Mutex;
+//!
+//! let mut m = Mutex::new(0);
+//!
+//! Parallel::new()
+//!     .add(|| *m.lock().unwrap() += 1)
+//!     .add(|| *m.lock().unwrap() += 1)
+//!     .run();
+//!
+//! assert_eq!(*m.get_mut().unwrap(), 2);
+//! ```
+//!
+//! Square each number of a vector on a different thread:
+//!
+//! ```
+//! use easy_parallel::Parallel;
+//!
+//! let v = vec![10, 20, 30];
+//!
+//! let squares = Parallel::new()
+//!     .each(0..v.len(), |i| v[i] * v[i])
+//!     .run();
+//!
+//! assert_eq!(squares, [100, 400, 900]);
+//! ```
+//!
+//! Compute the sum of numbers in an array:
+//!
+//! ```
+//! use easy_parallel::Parallel;
+//!
+//! fn par_sum(v: &[i32]) -> i32 {
+//!     const THRESHOLD: usize = 2;
+//!
+//!     if v.len() <= THRESHOLD {
+//!         v.iter().copied().sum()
+//!     } else {
+//!         let half = (v.len() + 1) / 2;
+//!         let sums = Parallel::new().each(v.chunks(half), par_sum).run();
+//!         sums.into_iter().sum()
+//!     }
+//! }
+//!
+//! let v = [1, 25, -4, 10, 8];
+//! assert_eq!(par_sum(&v), 40);
+//! ```
+
+#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
+
+use std::fmt;
+use std::iter::{self, FromIterator};
+use std::mem;
+use std::panic;
+use std::process;
+use std::sync::mpsc;
+use std::thread;
+
+/// A builder that runs closures in parallel.
+#[must_use]
+pub struct Parallel<'a, T> {
+    /// Closures to run.
+    closures: Vec<Box<dyn FnOnce() -> T + Send + 'a>>,
+}
+
+impl<'a, T> Parallel<'a, T> {
+    /// Creates a builder for running closures in parallel.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    ///
+    /// let p = Parallel::<()>::new();
+    /// ```
+    pub fn new() -> Parallel<'a, T> {
+        Parallel {
+            closures: Vec::new(),
+        }
+    }
+
+    /// Adds a closure to the list.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    ///
+    /// Parallel::new()
+    ///     .add(|| println!("hello from a thread"))
+    ///     .run();
+    /// ```
+    #[allow(clippy::should_implement_trait)]
+    pub fn add<F>(mut self, f: F) -> Parallel<'a, T>
+    where
+        F: FnOnce() -> T + Send + 'a,
+        T: Send + 'a,
+    {
+        self.closures.push(Box::new(f));
+        self
+    }
+
+    /// Adds a cloned closure for each item in an iterator.
+    ///
+    /// Each clone of the closure takes an item as an argument.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    ///
+    /// Parallel::new()
+    ///     .each(0..5, |i| println!("hello from thread #{}", i))
+    ///     .run();
+    /// ```
+    pub fn each<A, I, F>(mut self, iter: I, f: F) -> Parallel<'a, T>
+    where
+        I: IntoIterator<Item = A>,
+        F: FnOnce(A) -> T + Clone + Send + 'a,
+        A: Send + 'a,
+        T: Send + 'a,
+    {
+        for t in iter.into_iter() {
+            let f = f.clone();
+            self.closures.push(Box::new(|| f(t)));
+        }
+        self
+    }
+
+    /// Runs each closure on a separate thread and collects their results.
+    ///
+    /// Results are collected in the order in which closures were added. One of the closures always
+    /// runs on the main thread because there is no point in spawning an extra thread for it.
+    ///
+    /// If a closure panics, panicking will resume in the main thread after all threads are joined.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let res = Parallel::new()
+    ///     .each(1..=3, |i| 10 * i)
+    ///     .add(|| 100)
+    ///     .collect::<Vec<_>>();
+    ///
+    /// assert_eq!(res, [10, 20, 30, 100]);
+    /// ```
+    pub fn collect<C>(mut self) -> C
+    where
+        T: Send + 'a,
+        C: FromIterator<T> + Extend<T>,
+    {
+        // Get the last closure.
+        let f = match self.closures.pop() {
+            None => return iter::empty().collect(),
+            Some(f) => f,
+        };
+
+        // Spawn threads, run the last closure on the current thread.
+        let (mut results, r) = self.finish_in::<_, _, C>(f);
+        results.extend(Some(r));
+        results
+    }
+
+    /// Runs each closure on a separate thread and collects their results.
+    ///
+    /// Results are collected in the order in which closures were added. One of the closures always
+    /// runs on the main thread because there is no point in spawning an extra thread for it.
+    ///
+    /// If a closure panics, panicking will resume in the main thread after all threads are joined.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let res = Parallel::new()
+    ///     .each(1..=3, |i| 10 * i)
+    ///     .add(|| 100)
+    ///     .run();
+    ///
+    /// assert_eq!(res, [10, 20, 30, 100]);
+    /// ```
+    pub fn run(self) -> Vec<T>
+    where
+        T: Send + 'a,
+    {
+        self.collect()
+    }
+
+    /// Finishes with a closure to run on the main thread, starts threads, and collects results.
+    ///
+    /// Results are collected in the order in which closures were added.
+    ///
+    /// If a closure panics, panicking will resume in the main thread after all threads are joined.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let (res, ()) = Parallel::new()
+    ///     .each(1..=3, |i| 10 * i)
+    ///     .finish(|| println!("Waiting for results"));
+    ///
+    /// assert_eq!(res, [10, 20, 30]);
+    /// ```
+    pub fn finish<F, R>(self, f: F) -> (Vec<T>, R)
+    where
+        F: FnOnce() -> R,
+        T: Send + 'a,
+    {
+        self.finish_in::<_, _, Vec<T>>(f)
+    }
+
+    /// Finishes with a closure to run on the main thread, starts threads, and collects results into an
+    /// arbitrary container.
+    ///
+    /// Results are collected in the order in which closures were added.
+    ///
+    /// If a closure panics, panicking will resume in the main thread after all threads are joined.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use easy_parallel::Parallel;
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let (res, ()) = Parallel::new()
+    ///     .each(1..=3, |i| 10 * i)
+    ///     .finish_in::<_, _, Vec<i32>>(|| println!("Waiting for results"));
+    ///
+    /// assert_eq!(res, [10, 20, 30]);
+    /// ```
+    pub fn finish_in<F, R, C>(self, f: F) -> (C, R)
+    where
+        F: FnOnce() -> R,
+        T: Send + 'a,
+        C: FromIterator<T>,
+    {
+        // Set up a guard that aborts on panic.
+        let guard = NoPanic;
+
+        // Join handles for spawned threads.
+        let mut handles = Vec::new();
+
+        // Channels to collect results from spawned threads.
+        let mut receivers = Vec::new();
+
+        // Spawn a thread for each closure after the first one.
+        for f in self.closures.into_iter() {
+            // Wrap into a closure that sends the result back.
+            let (sender, receiver) = mpsc::channel();
+            let f = move || sender.send(f()).unwrap();
+
+            // Erase the `'a` lifetime.
+            let f: Box<dyn FnOnce() + Send + 'a> = Box::new(f);
+            let f: Box<dyn FnOnce() + Send + 'static> = unsafe { mem::transmute(f) };
+
+            // Spawn a thread for the closure.
+            handles.push(thread::spawn(f));
+            receivers.push(receiver);
+        }
+
+        let mut last_err = None;
+
+        // Run the main closure on the main thread.
+        let res = panic::catch_unwind(panic::AssertUnwindSafe(f));
+
+        // Join threads and save the last panic if there was one.
+        for h in handles {
+            if let Err(err) = h.join() {
+                last_err = Some(err);
+            }
+        }
+
+        // Drop the guard because we may resume a panic now.
+        drop(guard);
+
+        // If a thread has panicked, resume the last collected panic.
+        if let Some(err) = last_err {
+            panic::resume_unwind(err);
+        }
+
+        // Collect the results from threads.
+        let results = receivers.into_iter().map(|r| r.recv().unwrap()).collect();
+
+        // If the main closure panicked, resume its panic.
+        match res {
+            Ok(r) => (results, r),
+            Err(err) => panic::resume_unwind(err),
+        }
+    }
+}
+
+impl<T> fmt::Debug for Parallel<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Parallel")
+            .field("len", &self.closures.len())
+            .finish()
+    }
+}
+
+impl<T> Default for Parallel<'_, T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Aborts the process if dropped while panicking.
+struct NoPanic;
+
+impl Drop for NoPanic {
+    fn drop(&mut self) {
+        if thread::panicking() {
+            process::abort();
+        }
+    }
+}
diff --git a/tests/smoke.rs b/tests/smoke.rs
new file mode 100644
index 0000000..69db409
--- /dev/null
+++ b/tests/smoke.rs
@@ -0,0 +1,38 @@
+use std::sync::Mutex;
+
+use easy_parallel::Parallel;
+
+#[test]
+fn smoke() {
+    let m = Mutex::new(0);
+    let v = vec![2, 3, 5, 7, 11];
+
+    Parallel::new()
+        .add(|| *m.lock().unwrap() += 10)
+        .add(|| *m.lock().unwrap() += 20)
+        .each(v.iter(), |n| *m.lock().unwrap() += *n)
+        .run();
+
+    assert_eq!(m.into_inner().unwrap(), 10 + 20 + v.iter().sum::<i32>());
+}
+
+#[test]
+fn squares() {
+    let v = vec![10, 20, 30];
+
+    let squares = Parallel::new().each(0..v.len(), |i| v[i] * v[i]).run();
+
+    assert_eq!(squares, [100, 400, 900]);
+}
+
+#[test]
+fn finish() {
+    let v = vec![10, 20, 30];
+
+    let (squares, len) = Parallel::new()
+        .each(0..v.len(), |i| v[i] * v[i])
+        .finish(|| v.len());
+
+    assert_eq!(squares, [100, 400, 900]);
+    assert_eq!(len, 3);
+}