Use crossbeam and num_cpu

Cargo.toml

@@ -9,3 +9,5 @@ term = "*"
 sha2 = "0.7.1"
 walkdir = "*"
 time = "*"
+num_cpus = "*"
+crossbeam = "*"

src/main.rs

@@ -3,6 +3,8 @@ extern crate term;
 extern crate sha2;
 extern crate walkdir;
 extern crate time;
+extern crate num_cpus;
+extern crate crossbeam;
 
 use time::PreciseTime;
 
@@ -206,7 +208,8 @@ fn main() {
     }
 
     let start = PreciseTime::now();
-    // Walk through path 1 & 2 [Todo: threading]
+
+    // Walk through path 1 & 2 with 2 threads
     let mut children = vec![];
     let args_source = vec![args.input, args.output];
     for s in args_source {
@@ -221,39 +224,59 @@ fn main() {
                 let ft = metadata.file_type();
 
                 if ft.is_file() {
-                    if let Ok(mut file) = fs::File::open(&entry.path()) {
                         let mut a = FileToProcess {
                             name: format!("{}",
                                           entry.path().display()),
                             hash: vec![],
                             realpath: String::from("TODO"),
                         };
-
-                        // compute file hash
-                        a.hash::<Sha256, _>(&mut file);
                         fc.lock().unwrap().push(a);
-                    }
                 }
             }
         }));
     }
-
     for child in children {
-        // Wait for the thread to finish. Returns a result.
         let _ = child.join();
     }
 
+    // compute file hash in parallel
+    let magic = files_candidate.lock().unwrap().len() / num_cpus::get();
+    println!("Magic is : {}", magic);
+
+    for i in 0..num_cpus::get()+1 {
+        let fc = files_candidate.clone();
+        let mut work = fc.lock().unwrap();
+        let end = if (i*magic)+(magic) > work.len() {
+            work.len()
+        } else {
+            (i*magic)+(magic)
+        };
+        // Example from :
+        // https://stackoverflow.com/questions/33818141/how-do-i-pass-disjoint-slices-from-a-vector-to-different-threads
+        // Scoped threads allow the compiler to prove that no threads will outlive
+        // table (which would be bad).
+        crossbeam::scope(|scope| {
+            // Spawn a thread operating on that subslice.
+            scope.spawn(move ||
+                        for w in &mut work[i*magic .. end] {
+                            println!("[{}] Hashing : {}", i, w);
+                            if let Ok(mut file) = fs::File::open(&w.name) {
+                                w.hash::<Sha256, _>(&mut file);
+                            } else {
+                                panic!("Error opening file (name = {})!", w.name);
+                            }
+                        }
+            );
+        });
+    }
+
     for i in files_candidate.lock().unwrap().iter() {
         println!("{}", i);
     }
 
-    // Condition: Filename (basename) Must be the same (?)
+    t.fg(term::color::CYAN).unwrap();
-
-    // whatever you want to do
     let end = PreciseTime::now();
     println!("{} seconds.", start.to(end));
 
     t.reset().unwrap();
-    t.fg(term::color::CYAN).unwrap();
-    println!("Cheers !");
 }