From 03727a4f257fc86b467457a1e87d06d56e62d5f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Mon, 8 Apr 2019 20:44:31 +0200
Subject: [PATCH] Clean up jobserver integration

---
 src/librustc_data_structures/Cargo.toml   |   2 +-
 src/librustc_data_structures/jobserver.rs | 128 ++--------------------
 2 files changed, 8 insertions(+), 122 deletions(-)

diff --git a/src/librustc_data_structures/Cargo.toml b/src/librustc_data_structures/Cargo.toml
index 63e44d82a28c3..d586b376d45b6 100644
--- a/src/librustc_data_structures/Cargo.toml
+++ b/src/librustc_data_structures/Cargo.toml
@@ -12,7 +12,7 @@ crate-type = ["dylib"]
 [dependencies]
 ena = "0.13"
 log = "0.4"
-jobserver_crate = { version = "0.1", package = "jobserver" }
+jobserver_crate = { version = "0.1.13", package = "jobserver" }
 lazy_static = "1"
 rustc_cratesio_shim = { path = "../librustc_cratesio_shim" }
 serialize = { path = "../libserialize" }
diff --git a/src/librustc_data_structures/jobserver.rs b/src/librustc_data_structures/jobserver.rs
index 48ac8125a0d66..b42ccb932b9dc 100644
--- a/src/librustc_data_structures/jobserver.rs
+++ b/src/librustc_data_structures/jobserver.rs
@@ -1,89 +1,5 @@
-use jobserver_crate::{Client, HelperThread, Acquired};
+use jobserver_crate::Client;
 use lazy_static::lazy_static;
-use std::sync::{Condvar, Arc, Mutex};
-use std::mem;
-
-#[derive(Default)]
-struct LockedProxyData {
-    /// The number of free thread tokens, this may include the implicit token given to the process
-    free: usize,
-
-    /// The number of threads waiting for a token
-    waiters: usize,
-
-    /// The number of tokens we requested from the server
-    requested: usize,
-
-    /// Stored tokens which will be dropped when we no longer need them
-    tokens: Vec<Acquired>,
-}
-
-impl LockedProxyData {
-    fn request_token(&mut self, thread: &Mutex<HelperThread>) {
-        self.requested += 1;
-        thread.lock().unwrap().request_token();
-    }
-
-    fn release_token(&mut self, cond_var: &Condvar) {
-        if self.waiters > 0 {
-            self.free += 1;
-            cond_var.notify_one();
-        } else {
-            if self.tokens.is_empty() {
-                // We are returning the implicit token
-                self.free += 1;
-            } else {
-                // Return a real token to the server
-                self.tokens.pop().unwrap();
-            }
-        }
-    }
-
-    fn take_token(&mut self, thread: &Mutex<HelperThread>) -> bool {
-        if self.free > 0 {
-            self.free -= 1;
-            self.waiters -= 1;
-
-            // We stole some token reqested by someone else
-            // Request another one
-            if self.requested + self.free < self.waiters {
-                self.request_token(thread);
-            }
-
-            true
-        } else {
-            false
-        }
-    }
-
-    fn new_requested_token(&mut self, token: Acquired, cond_var: &Condvar) {
-        self.requested -= 1;
-
-        // Does anything need this token?
-        if self.waiters > 0 {
-            self.free += 1;
-            self.tokens.push(token);
-            cond_var.notify_one();
-        } else {
-            // Otherwise we'll just drop it
-            mem::drop(token);
-        }
-    }
-}
-
-#[derive(Default)]
-struct ProxyData {
-    lock: Mutex<LockedProxyData>,
-    cond_var: Condvar,
-}
-
-/// A helper type which makes managing jobserver tokens easier.
-/// It also allows you to treat the implicit token given to the process
-/// in the same manner as requested tokens.
-struct Proxy {
-    thread: Mutex<HelperThread>,
-    data: Arc<ProxyData>,
-}
 
 lazy_static! {
     // We can only call `from_env` once per process
@@ -105,20 +21,12 @@ lazy_static! {
     // per-process.
     static ref GLOBAL_CLIENT: Client = unsafe {
         Client::from_env().unwrap_or_else(|| {
-            Client::new(32).expect("failed to create jobserver")
+            let client = Client::new(32).expect("failed to create jobserver");
+            // Acquire a token for the main thread which we can release later
+            client.acquire_raw().ok();
+            client
         })
     };
-
-    static ref GLOBAL_PROXY: Proxy = {
-        let data = Arc::new(ProxyData::default());
-
-        Proxy {
-            data: data.clone(),
-            thread: Mutex::new(client().into_helper_thread(move |token| {
-                data.lock.lock().unwrap().new_requested_token(token.unwrap(), &data.cond_var);
-            }).unwrap()),
-        }
-    };
 }
 
 pub fn client() -> Client {
@@ -126,31 +34,9 @@ pub fn client() -> Client {
 }
 
 pub fn acquire_thread() {
-    GLOBAL_PROXY.acquire_token();
+    GLOBAL_CLIENT.acquire_raw().ok();
 }
 
 pub fn release_thread() {
-    GLOBAL_PROXY.release_token();
-}
-
-impl Proxy {
-    fn release_token(&self) {
-        self.data.lock.lock().unwrap().release_token(&self.data.cond_var);
-    }
-
-    fn acquire_token(&self) {
-        let mut data = self.data.lock.lock().unwrap();
-        data.waiters += 1;
-        if data.take_token(&self.thread) {
-            return;
-        }
-        // Request a token for us
-        data.request_token(&self.thread);
-        loop {
-            data = self.data.cond_var.wait(data).unwrap();
-            if data.take_token(&self.thread) {
-                return;
-            }
-        }
-    }
+    GLOBAL_CLIENT.release_raw().ok();
 }