From 04b6d806a21cfed9473e0071ec0b862c1053bad4 Mon Sep 17 00:00:00 2001
From: "Guilherme A. de Souza" <125218612+rgasnix@users.noreply.github.com>
Date: Tue, 14 Feb 2023 18:43:09 -0300
Subject: [PATCH] nproc: replace num_cpus crate with
 thread::available_parallelism (#4352)

* nproc: replace num_cpus crate with std::thread::available_parallelism

* nproc: unwrap Result for Windows

* nproc: if thread::available_parallelism results in err return 1

* nproc: wrap the call to available_parallelism into a function

* nproc: remove comment in the wrong place

* nproc: fix style violation

* nproc: fix comment, refers to the new function
---
 Cargo.lock                |  1 -
 src/uu/nproc/Cargo.toml   |  1 -
 src/uu/nproc/src/nproc.rs | 23 ++++++++++++++++-------
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 3df301eac..5668a918e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2807,7 +2807,6 @@ version = "0.0.17"
 dependencies = [
  "clap",
  "libc",
- "num_cpus",
  "uucore",
 ]
 
diff --git a/src/uu/nproc/Cargo.toml b/src/uu/nproc/Cargo.toml
index dc51d8a55..c2c224a40 100644
--- a/src/uu/nproc/Cargo.toml
+++ b/src/uu/nproc/Cargo.toml
@@ -16,7 +16,6 @@ path = "src/nproc.rs"
 
 [dependencies]
 libc = { workspace=true }
-num_cpus = { workspace=true }
 clap = { workspace=true }
 uucore = { workspace=true, features=["fs"] }
 
diff --git a/src/uu/nproc/src/nproc.rs b/src/uu/nproc/src/nproc.rs
index 960957df6..fbfeebb23 100644
--- a/src/uu/nproc/src/nproc.rs
+++ b/src/uu/nproc/src/nproc.rs
@@ -8,7 +8,7 @@
 // spell-checker:ignore (ToDO) NPROCESSORS nprocs numstr threadstr sysconf
 
 use clap::{crate_version, Arg, ArgAction, Command};
-use std::env;
+use std::{env, thread};
 use uucore::display::Quotable;
 use uucore::error::{UResult, USimpleError};
 use uucore::format_usage;
@@ -73,16 +73,16 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
                 // If OMP_NUM_THREADS=0, rejects the value
                 let thread: Vec<&str> = threadstr.split_terminator(',').collect();
                 match &thread[..] {
-                    [] => num_cpus::get(),
+                    [] => available_parallelism(),
                     [s, ..] => match s.parse() {
-                        Ok(0) | Err(_) => num_cpus::get(),
+                        Ok(0) | Err(_) => available_parallelism(),
                         Ok(n) => n,
                     },
                 }
             }
             // the variable 'OMP_NUM_THREADS' doesn't exist
             // fallback to the regular CPU detection
-            Err(_) => num_cpus::get(),
+            Err(_) => available_parallelism(),
         }
     };
 
@@ -127,7 +127,7 @@ fn num_cpus_all() -> usize {
     if nprocs == 1 {
         // In some situation, /proc and /sys are not mounted, and sysconf returns 1.
         // However, we want to guarantee that `nproc --all` >= `nproc`.
-        num_cpus::get()
+        available_parallelism()
     } else if nprocs > 0 {
         nprocs as usize
     } else {
@@ -135,7 +135,7 @@ fn num_cpus_all() -> usize {
     }
 }
 
-// Other platforms (e.g., windows), num_cpus::get() directly.
+// Other platforms (e.g., windows), available_parallelism() directly.
 #[cfg(not(any(
     target_os = "linux",
     target_vendor = "apple",
@@ -143,5 +143,14 @@ fn num_cpus_all() -> usize {
     target_os = "netbsd"
 )))]
 fn num_cpus_all() -> usize {
-    num_cpus::get()
+    available_parallelism()
+}
+
+// In some cases, thread::available_parallelism() may return an Err
+// In this case, we will return 1 (like GNU)
+fn available_parallelism() -> usize {
+    match thread::available_parallelism() {
+        Ok(n) => n.get(),
+        Err(_) => 1,
+    }
 }