move thread worker to a separate crate

Cargo.lock

@@ -700,6 +700,7 @@ dependencies = [
  "tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
  "text_unit 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "thread_worker 0.1.0",
  "threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "url_serde 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1116,6 +1117,15 @@ dependencies = [
  "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "thread_worker"
+version = "0.1.0"
+dependencies = [
+ "crossbeam-channel 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "drop_bomb 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "threadpool"
 version = "1.7.1"

crates/ra_lsp_server/Cargo.toml

@@ -26,6 +26,7 @@ text_unit = { version = "0.1.2", features = ["serde"] }
 smol_str = { version = "0.1.5", features = ["serde"] }
 rustc-hash = "1.0"
 
+thread_worker = { path = "../thread_worker" }
 ra_syntax = { path = "../ra_syntax" }
 ra_editor = { path = "../ra_editor" }
 ra_text_edit = { path = "../ra_text_edit" }

crates/ra_lsp_server/src/lib.rs

@@ -5,7 +5,6 @@ mod path_map;
 mod project_model;
 pub mod req;
 mod server_world;
-pub mod thread_watcher;
 mod vfs;
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;

crates/ra_lsp_server/src/main_loop.rs

@@ -10,6 +10,7 @@ use gen_lsp_server::{
 use languageserver_types::NumberOrString;
 use ra_analysis::{Canceled, FileId, LibraryData};
 use rayon;
+use thread_worker::Worker;
 use threadpool::ThreadPool;
 use rustc_hash::FxHashSet;
 use serde::{de::DeserializeOwned, Serialize};
@@ -21,7 +22,6 @@ use crate::{
     project_model::{workspace_loader, CargoWorkspace},
     req,
     server_world::{ServerWorld, ServerWorldState},
-    thread_watcher::Worker,
     vfs::{self, FileEvent},
     Result,
 };
@@ -92,8 +92,8 @@ pub fn main_loop(
     let ws_res = ws_watcher.stop();
 
     main_res?;
-    fs_res?;
-    ws_res?;
+    fs_res.map_err(|_| format_err!("fs watcher died"))?;
+    ws_res.map_err(|_| format_err!("ws watcher died"))?;
 
     Ok(())
 }

crates/ra_lsp_server/src/project_model.rs

@@ -4,11 +4,9 @@ use cargo_metadata::{metadata_run, CargoOpt};
 use ra_syntax::SmolStr;
 use rustc_hash::{FxHashMap, FxHashSet};
 use failure::{format_err, bail};
+use thread_worker::{WorkerHandle, Worker};
 
-use crate::{
-    Result,
-    thread_watcher::{ThreadWatcher, Worker},
-};
+use crate::Result;
 
 /// `CargoWorksapce` represents the logical structure of, well, a Cargo
 /// workspace. It pretty closely mirrors `cargo metadata` output.
@@ -199,8 +197,8 @@ impl TargetKind {
     }
 }
 
-pub fn workspace_loader() -> (Worker<PathBuf, Result<CargoWorkspace>>, ThreadWatcher) {
-    Worker::<PathBuf, Result<CargoWorkspace>>::spawn(
+pub fn workspace_loader() -> (Worker<PathBuf, Result<CargoWorkspace>>, WorkerHandle) {
+    thread_worker::spawn::<PathBuf, Result<CargoWorkspace>, _>(
         "workspace loader",
         1,
         |input_receiver, output_sender| {

crates/ra_lsp_server/src/vfs.rs

@@ -4,8 +4,7 @@ use std::{
 };
 
 use walkdir::WalkDir;
-
-use crate::thread_watcher::{ThreadWatcher, Worker};
+use thread_worker::{WorkerHandle, Worker};
 
 #[derive(Debug)]
 pub struct FileEvent {
@@ -18,8 +17,8 @@ pub enum FileEventKind {
     Add(String),
 }
 
-pub fn roots_loader() -> (Worker<PathBuf, (PathBuf, Vec<FileEvent>)>, ThreadWatcher) {
-    Worker::<PathBuf, (PathBuf, Vec<FileEvent>)>::spawn(
+pub fn roots_loader() -> (Worker<PathBuf, (PathBuf, Vec<FileEvent>)>, WorkerHandle) {
+    thread_worker::spawn::<PathBuf, (PathBuf, Vec<FileEvent>), _>(
         "roots loader",
         128,
         |input_receiver, output_sender| {

crates/ra_lsp_server/tests/heavy_tests/support.rs

@@ -17,11 +17,11 @@ use languageserver_types::{
 use serde::Serialize;
 use serde_json::{to_string_pretty, Value};
 use tempdir::TempDir;
+use thread_worker::{WorkerHandle, Worker};
 use test_utils::{parse_fixture, find_mismatch};
 
 use ra_lsp_server::{
     main_loop, req,
-    thread_watcher::{ThreadWatcher, Worker},
 };
 
 pub fn project(fixture: &str) -> Server {
@@ -45,13 +45,13 @@ pub struct Server {
     messages: RefCell<Vec<RawMessage>>,
     dir: TempDir,
     worker: Option<Worker<RawMessage, RawMessage>>,
-    watcher: Option<ThreadWatcher>,
+    watcher: Option<WorkerHandle>,
 }
 
 impl Server {
     fn new(dir: TempDir, files: Vec<(PathBuf, String)>) -> Server {
         let path = dir.path().to_path_buf();
-        let (worker, watcher) = Worker::<RawMessage, RawMessage>::spawn(
+        let (worker, watcher) = thread_worker::spawn::<RawMessage, RawMessage, _>(
             "test server",
             128,
             move |mut msg_receiver, mut msg_sender| {

crates/thread_worker/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+edition = "2018"
+name = "thread_worker"
+version = "0.1.0"
+authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]
+
+[dependencies]
+drop_bomb = "0.1.0"
+crossbeam-channel = "0.2.4"
+log = "0.4.3"
+

crates/thread_worker/src/lib.rs

@@ -1,28 +1,35 @@
+//! Small utility to correctly spawn crossbeam-channel based worker threads.
+
 use std::thread;
 
 use crossbeam_channel::{bounded, unbounded, Receiver, Sender};
 use drop_bomb::DropBomb;
-use failure::format_err;
-
-use crate::Result;
 
 pub struct Worker<I, O> {
     pub inp: Sender<I>,
     pub out: Receiver<O>,
 }
 
-impl<I, O> Worker<I, O> {
-    pub fn spawn<F>(name: &'static str, buf: usize, f: F) -> (Self, ThreadWatcher)
-    where
+pub struct WorkerHandle {
+    name: &'static str,
+    thread: thread::JoinHandle<()>,
+    bomb: DropBomb,
+}
+
+pub fn spawn<I, O, F>(name: &'static str, buf: usize, f: F) -> (Worker<I, O>, WorkerHandle)
+where
     F: FnOnce(Receiver<I>, Sender<O>) + Send + 'static,
     I: Send + 'static,
     O: Send + 'static,
-    {
+{
     let (worker, inp_r, out_s) = worker_chan(buf);
-        let watcher = ThreadWatcher::spawn(name, move || f(inp_r, out_s));
+    let watcher = WorkerHandle::spawn(name, move || f(inp_r, out_s));
     (worker, watcher)
-    }
+}
 
+impl<I, O> Worker<I, O> {
+    /// Stops the worker. Returns the message receiver to fetch results which
+    /// have become ready before the worker is stopped.
     pub fn stop(self) -> Receiver<O> {
         self.out
     }
@@ -32,30 +39,21 @@ impl<I, O> Worker<I, O> {
     }
 }
 
-pub struct ThreadWatcher {
-    name: &'static str,
-    thread: thread::JoinHandle<()>,
-    bomb: DropBomb,
-}
-
-impl ThreadWatcher {
-    fn spawn(name: &'static str, f: impl FnOnce() + Send + 'static) -> ThreadWatcher {
+impl WorkerHandle {
+    fn spawn(name: &'static str, f: impl FnOnce() + Send + 'static) -> WorkerHandle {
         let thread = thread::spawn(f);
-        ThreadWatcher {
+        WorkerHandle {
             name,
             thread,
-            bomb: DropBomb::new(format!("ThreadWatcher {} was not stopped", name)),
+            bomb: DropBomb::new(format!("WorkerHandle {} was not stopped", name)),
         }
     }
 
-    pub fn stop(mut self) -> Result<()> {
+    pub fn stop(mut self) -> thread::Result<()> {
         log::info!("waiting for {} to finish ...", self.name);
         let name = self.name;
         self.bomb.defuse();
-        let res = self
-            .thread
-            .join()
-            .map_err(|_| format_err!("ThreadWatcher {} died", name));
+        let res = self.thread.join();
         match &res {
             Ok(()) => log::info!("... {} terminated with ok", name),
             Err(_) => log::error!("... {} terminated with err", name),