winter_utils/iterators.rs
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// Copyright (c) Facebook, Inc. and its affiliates.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
//! Components needed for parallel iterators.
//!
//! When `concurrent` feature is enabled, this module re-exports `rayon::prelude`. Otherwise,
//! this is an empty module.
#[cfg(feature = "concurrent")]
pub use rayon::{current_num_threads as rayon_num_threads, prelude::*};
/// Returns either a regular or a parallel iterator depending on whether `concurrent` feature
/// is enabled.
///
/// When `concurrent` feature is enabled, creates a parallel iterator; otherwise, creates a
/// regular iterator. Optionally, `min_length` can be used to specify the minimum length of
/// iterator to be processed in each thread.
///
/// Adapted from: <https://github.com/arkworks-rs/utils/blob/master/src/lib.rs>
#[macro_export]
macro_rules! iter {
($e: expr) => {{
#[cfg(feature = "concurrent")]
let result = $e.par_iter();
#[cfg(not(feature = "concurrent"))]
let result = $e.iter();
result
}};
($e: expr, $min_len: expr) => {{
#[cfg(feature = "concurrent")]
let result = $e.par_iter().with_min_len($min_len);
#[cfg(not(feature = "concurrent"))]
let result = $e.iter();
result
}};
}
/// Returns either a regular or a parallel mutable iterator depending on whether `concurrent`
/// feature is enabled.
///
/// When `concurrent` feature is enabled, creates a mutable parallel iterator; otherwise,
/// creates a regular mutable iterator. Optionally, `min_length` can be used to specify the
/// minimum length of iterator to be processed in each thread.
///
/// Adapted from: <https://github.com/arkworks-rs/utils/blob/master/src/lib.rs>
#[macro_export]
macro_rules! iter_mut {
($e: expr) => {{
#[cfg(feature = "concurrent")]
let result = $e.par_iter_mut();
#[cfg(not(feature = "concurrent"))]
let result = $e.iter_mut();
result
}};
($e: expr, $min_len: expr) => {{
#[cfg(feature = "concurrent")]
let result = $e.par_iter_mut().with_min_len($min_len);
#[cfg(not(feature = "concurrent"))]
let result = $e.iter_mut();
result
}};
}
/// Applies a procedure to the provided slice either in a single thread or multiple threads
/// based on whether `concurrent` feature is enabled.
///
/// When `concurrent` feature is enabled, breaks the slice into batches and processes each
/// batch in a separate thread; otherwise, the entire slice is processed as a single batch
/// in one thread. Optionally, `min_batch_size` can be used to specify the minimum size of
/// the resulting batches.
#[macro_export]
macro_rules! batch_iter_mut {
($e: expr, $c: expr) => {
#[cfg(feature = "concurrent")]
{
let batch_size = $e.len() / rayon_num_threads().next_power_of_two();
if batch_size < 1 {
$c($e, 0);
}
else {
$e.par_chunks_mut(batch_size).enumerate().for_each(|(i, batch)| {
$c(batch, i * batch_size);
});
}
}
#[cfg(not(feature = "concurrent"))]
$c($e, 0);
};
($e: expr, $min_batch_size: expr, $c: expr) => {
#[cfg(feature = "concurrent")]
{
let batch_size = $e.len() / rayon_num_threads().next_power_of_two();
if batch_size < $min_batch_size {
$c($e, 0);
}
else {
$e.par_chunks_mut(batch_size).enumerate().for_each(|(i, batch)| {
$c(batch, i * batch_size);
});
}
}
#[cfg(not(feature = "concurrent"))]
$c($e, 0);
};
}