Multithreaded component refresh (#1232)

* Multithreaded component refresh
* Create utils::into_iter_mut to complement utils::into_iter.
* Fix invalid parallelization `cfg`, preventing multi-threading on linux

src/common.rs

@@ -1,8 +1,8 @@
 // Take a look at the license at the top of the repository in the LICENSE file.
 
 use crate::{
-    ComponentInner, ComponentsInner, CpuInner, NetworkDataInner, NetworksInner, ProcessInner,
-    SystemInner, UserInner,
+    utils::into_iter_mut, ComponentInner, ComponentsInner, CpuInner, NetworkDataInner,
+    NetworksInner, ProcessInner, SystemInner, UserInner,
 };
 
 use std::cmp::Ordering;
@@ -3822,9 +3822,13 @@ impl Components {
     /// components.refresh();
     /// ```
     pub fn refresh(&mut self) {
-        for component in self.list_mut() {
-            component.refresh();
-        }
+        #[cfg(all(
+            feature = "multithread",
+            not(feature = "unknown-ci"),
+            not(all(target_os = "macos", feature = "apple-sandbox")),
+        ))]
+        use rayon::iter::ParallelIterator;
+        into_iter_mut(self.list_mut()).for_each(|component| component.refresh());
     }
 
     /// The component list will be emptied then completely recomputed.

src/lib.rs

@@ -73,7 +73,7 @@ mod common;
 mod debug;
 #[cfg(feature = "serde")]
 mod serde;
-mod utils;
+pub(crate) mod utils;
 
 /// This function is only used on Linux targets, on the other platforms it does nothing and returns
 /// `false`.

src/utils.rs

@@ -1,33 +1,63 @@
 // Take a look at the license at the top of the repository in the LICENSE file.
 
-/// Converts the value into a parallel iterator (if the multi-thread feature is enabled).
+/// Converts the value into a parallel iterator if the `multithread` feature is enabled.
 /// Uses the `rayon::iter::IntoParallelIterator` trait.
 #[cfg(all(
-    all(
-        any(target_os = "macos", target_os = "windows", target_os = "freebsd",),
-        feature = "multithread"
-    ),
+    feature = "multithread",
+    not(feature = "unknown-ci"),
     not(all(target_os = "macos", feature = "apple-sandbox")),
-    not(feature = "unknown-ci")
 ))]
+#[allow(dead_code)]
 pub(crate) fn into_iter<T>(val: T) -> T::Iter
 where
     T: rayon::iter::IntoParallelIterator,
 {
     val.into_par_iter()
 }
 
-/// Converts the value into a sequential iterator (if the multithread feature is disabled).
+/// Converts the value into a sequential iterator if the `multithread` feature is disabled.
 /// Uses the `std::iter::IntoIterator` trait.
+#[cfg(any(
+    not(feature = "multithread"),
+    feature = "unknown-ci",
+    all(target_os = "macos", feature = "apple-sandbox")
+))]
+#[allow(dead_code)]
+pub(crate) fn into_iter<T>(val: T) -> T::IntoIter
+where
+    T: IntoIterator,
+{
+    val.into_iter()
+}
+
+/// Converts the value into a parallel mutable iterator if the `multithread` feature is enabled.
+/// Uses the `rayon::iter::IntoParallelRefMutIterator` trait.
 #[cfg(all(
-    all(
-        any(target_os = "macos", target_os = "windows", target_os = "freebsd",),
-        not(feature = "multithread")
-    ),
+    feature = "multithread",
     not(feature = "unknown-ci"),
-    not(all(target_os = "macos", feature = "apple-sandbox"))
+    not(all(target_os = "macos", feature = "apple-sandbox")),
 ))]
-pub(crate) fn into_iter<T>(val: T) -> T::IntoIter
+pub(crate) fn into_iter_mut<'a, T>(
+    val: &'a mut T,
+) -> <T as rayon::iter::IntoParallelRefMutIterator<'a>>::Iter
+where
+    T: rayon::iter::IntoParallelRefMutIterator<'a> + ?Sized,
+{
+    val.par_iter_mut()
+}
+
+// In the multithreaded version of `into_iter_mut` above, the `&mut` on the argument is indicating
+// the parallel iterator is an exclusive reference. In the non-multithreaded case, the `&mut` is
+// already part of `T` and specifying it will result in the argument being `&mut &mut T`.
+
+/// Converts the value into a sequential mutable iterator if the `multithread` feature is disabled.
+/// Uses the `std::iter::IntoIterator` trait.
+#[cfg(any(
+    not(feature = "multithread"),
+    feature = "unknown-ci",
+    all(target_os = "macos", feature = "apple-sandbox")
+))]
+pub(crate) fn into_iter_mut<T>(val: T) -> T::IntoIter
 where
     T: IntoIterator,
 {