Reduce number of syscalls

4 files changed, 201 insertions, 15 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 90409f0..3cb8e5a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -50,6 +50,26 @@ dependencies = [
 ]
 
 [[package]]
+name = "cloudabi"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "crossbeam-epoch 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "smallvec 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "crossbeam-deque"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -73,6 +93,19 @@ dependencies = [
 ]
 
 [[package]]
+name = "crossbeam-epoch"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memoffset 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "crossbeam-utils"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -81,10 +114,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "crossbeam-utils"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "diskus"
 version = "0.3.1"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-channel 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "humansize 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -96,6 +135,20 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "fuchsia-zircon"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fuchsia-zircon-sys 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "fuchsia-zircon-sys"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "humansize"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -123,6 +176,15 @@ version = "0.2.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "lock_api"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "owning_ref 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "memoffset"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -141,6 +203,60 @@ dependencies = [
 ]
 
 [[package]]
+name = "owning_ref"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "stable_deref_trait 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "parking_lot"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "lock_api 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "smallvec 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "rayon"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -175,11 +291,45 @@ dependencies = [
 ]
 
 [[package]]
+name = "rustc_version"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "scopeguard"
 version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "semver"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "semver-parser"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "smallvec"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "unreachable 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "stable_deref_trait"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "strsim"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -219,6 +369,14 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "unreachable"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "vec_map"
 version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -229,6 +387,11 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "void"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "winapi"
 version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -264,29 +427,49 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
 "checksum cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "082bb9b28e00d3c9d39cc03e64ce4cea0f1bb9b3fde493f0cbc008472d22bdf4"
 "checksum clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b957d88f4b6a63b9d70d5f454ac8011819c6efa7727858f458ab71c756ce2d3e"
+"checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
+"checksum crossbeam-channel 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "548dfc2fa4933009668d4a51f9ef074b8af8f2d6a6410225d76d6b1c3c56ca6f"
 "checksum crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f739f8c5363aca78cfb059edf753d8f0d36908c348f3d8d1503f03d8b75d9cf3"
 "checksum crossbeam-epoch 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "927121f5407de9956180ff5e936fe3cf4324279280001cd56b669d28ee7e9150"
+"checksum crossbeam-epoch 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9c90f1474584f38e270b5b613e898c8c328aa4f3dea85e0a27ac2e642f009416"
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diff --git a/Cargo.toml b/Cargo.toml
index 49a349c..4387d52 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ version = "0.3.1"
 num_cpus = "1.0"
 humansize = "1.1"
 rayon = "1.0"
+crossbeam-channel = "0.3.0"
 
 [dependencies.clap]
 version = "2"
diff --git a/src/main.rs b/src/main.rs
index 20b1333..966c3b3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ extern crate clap;
 extern crate humansize;
 extern crate num_cpus;
 extern crate rayon;
+extern crate crossbeam_channel;
 
 mod walk;
 
diff --git a/src/walk.rs b/src/walk.rs
index cbf0656..b80df07 100644
--- a/src/walk.rs
+++ b/src/walk.rs
@@ -2,17 +2,18 @@ use std::collections::HashSet;
 use std::fs;
 use std::os::unix::fs::MetadataExt;
 use std::path::PathBuf;
-use std::sync::mpsc::{channel, Sender};
 use std::thread;
 
+use crossbeam_channel as channel;
+
 use rayon::prelude::*;
 
 type UniqueID = (u64, u64);
 
 type SizeEntry = (Option<UniqueID>, u64);
 
-fn walk(tx: Sender<SizeEntry>, entries: &[PathBuf]) {
-    entries.par_iter().for_each_with(tx, |tx_ref, entry| {
+fn walk(tx: channel::Sender<SizeEntry>, entries: &[PathBuf]) {
+    entries.into_par_iter().for_each_with(tx, |tx_ref, entry| {
         if let Ok(metadata) = entry.metadata() {
             // If the entry has more than one hard link, generate
             // a unique ID consisting of device and inode in order
@@ -26,20 +27,20 @@ fn walk(tx: Sender<SizeEntry>, entries: &[PathBuf]) {
             let size = metadata.len();
 
             tx_ref.send((unique_id, size)).unwrap();
-        } else {
-            eprintln!("Could not get metadata: '{}'", entry.to_string_lossy());
-        };
 
-        if entry.is_dir() {
-            let mut children = vec![];
-            for child_entry in fs::read_dir(entry).unwrap() {
-                if let Ok(child_entry) = child_entry {
-                    let path = child_entry.path();
-                    children.push(PathBuf::from(path));
+            if metadata.is_dir() {
+                let mut children = vec![];
+                for child_entry in fs::read_dir(entry).unwrap() {
+                    if let Ok(child_entry) = child_entry {
+                        let path = child_entry.path();
+                        children.push(PathBuf::from(path));
+                    }
                 }
-            }
 
-            walk(tx_ref.clone(), &children[..]);
+                walk(tx_ref.clone(), &children[..]);
+            };
+        } else {
+            eprintln!("Could not get metadata: '{}'", entry.to_string_lossy());
         };
     });
 }
@@ -58,7 +59,7 @@ impl<'a> Walk<'a> {
     }
 
     pub fn run(&self) -> u64 {
-        let (tx, rx) = channel();
+        let (tx, rx) = channel::unbounded();
 
         let receiver_thread = thread::spawn(move || {
             let mut total = 0;