add new 'count' example to count as fast as possible

examples/dc.rs

@@ -0,0 +1,35 @@
+//! Collect the amount of directories and files as fast as possible.
+mod shared;
+
+use clap::Parser;
+use jwalk::WalkDirGeneric;
+
+fn main() {
+    let args = shared::Args::parse();
+
+    let parallelism = args.parallelism();
+    let threads = args.threads();
+    let path = args.root.unwrap_or_else(|| ".".into());
+    let (mut dirs, mut files, mut symlinks) = (0, 0, 0);
+    for dir_entry_result in WalkDirGeneric::<((), Option<u64>)>::new(&path)
+        .skip_hidden(false)
+        .parallelism(parallelism)
+    {
+        match dir_entry_result {
+            Ok(dir_entry) => {
+                if dir_entry.file_type.is_dir() {
+                    dirs += 1;
+                } else if dir_entry.file_type.is_file() {
+                    files += 1;
+                } else if dir_entry.file_type.is_symlink() {
+                    symlinks += 1
+                }
+            }
+            Err(error) => {
+                println!("Read dir_entry error: {}", error);
+            }
+        }
+    }
+
+    println!("dirs: {dirs}, files: {files}, symlinks: {symlinks} (threads: {threads})");
+}

examples/shared/mod.rs

@@ -12,18 +12,20 @@ pub struct Args {
 }
 
 impl Args {
-    pub fn parallelism(&self) -> Parallelism {
-        let threads = self
-            .threads
+    pub fn threads(&self) -> usize {
+        self.threads
             .unwrap_or_else(|| {
-                if cfg!(darwin) {
+                if cfg!(target_vendor = "apple") {
                     NonZeroUsize::new(4).unwrap()
                 } else {
                     std::thread::available_parallelism().unwrap_or(NonZeroUsize::new(1).unwrap())
                 }
             })
-            .get();
-        match threads {
+            .get()
+    }
+
+    pub fn parallelism(&self) -> Parallelism {
+        match self.threads() {
             1 => Parallelism::Serial,
             n => Parallelism::RayonNewPool(n),
         }