1 files changed, 64 insertions, 0 deletions
diff --git a/vendor/num_threads/src/lib.rs b/vendor/num_threads/src/lib.rs
new file mode 100644
index 000000000..c21380282
--- /dev/null
+++ b/vendor/num_threads/src/lib.rs
@@ -0,0 +1,64 @@
+//! Minimum supported Rust version: 1.28
+
+use std::num::NonZeroUsize;
+
+#[cfg_attr(any(target_os = "linux", target_os = "android"), path = "linux.rs")]
+#[cfg_attr(target_os = "freebsd", path = "freebsd.rs")]
+#[cfg_attr(any(target_os = "macos", target_os = "ios"), path = "apple.rs")]
+mod imp;
+
+/// Obtain the number of threads currently part of the active process. Returns `None` if the number
+/// of threads cannot be determined.
+pub fn num_threads() -> Option<NonZeroUsize> {
+    imp::num_threads()
+}
+
+/// Determine if the current process is single-threaded. Returns `None` if the number of threads
+/// cannot be determined.
+pub fn is_single_threaded() -> Option<bool> {
+    num_threads().map(|n| n.get() == 1)
+}
+
+#[cfg(test)]
+mod test {
+    use std::num::NonZeroUsize;
+
+    // Run each expression in its own thread.
+    macro_rules! threaded {
+        ($first:expr;) => {
+            $first;
+        };
+        ($first:expr; $($rest:expr;)*) => {
+            $first;
+            ::std::thread::spawn(|| {
+                threaded!($($rest;)*);
+            })
+            .join()
+            .unwrap();
+        };
+    }
+
+    #[test]
+    fn num_threads() {
+        threaded! {
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(1));
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(2));
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(3));
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(4));
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(5));
+            assert_eq!(super::num_threads().map(NonZeroUsize::get), Some(6));
+        }
+    }
+
+    #[test]
+    fn is_single_threaded() {
+        threaded! {
+            assert_eq!(super::is_single_threaded(), Some(true));
+            assert_eq!(super::is_single_threaded(), Some(false));
+            assert_eq!(super::is_single_threaded(), Some(false));
+            assert_eq!(super::is_single_threaded(), Some(false));
+            assert_eq!(super::is_single_threaded(), Some(false));
+            assert_eq!(super::is_single_threaded(), Some(false));
+        }
+    }
+}