Remove total

Author: Zoxc

compiler/rustc_data_structures/src/jobserver.rs

@@ -73,10 +73,8 @@ pub fn client() -> Client {
 }
 
 struct ProxyData {
-    /// The number of tokens assigned to this process.
-    total: u16,
-
     /// The number of tokens assigned to threads.
+    /// If this is 0, a single token is still assigned to this process, but is unused.
     used: u16,
 
     /// The number of threads requesting a token
@@ -98,7 +96,7 @@ impl Proxy {
     pub fn new() -> Arc<Self> {
         let proxy = Arc::new(Proxy {
             client: client(),
-            data: Mutex::new(ProxyData { total: 1, used: 1, pending: 0 }),
+            data: Mutex::new(ProxyData { used: 1, pending: 0 }),
             wake_pending: Condvar::new(),
             helper: OnceLock::new(),
         });
@@ -112,7 +110,7 @@ impl Proxy {
                     if data.pending > 0 {
                         // Give the token to a waiting thread
                         token.drop_without_releasing();
-                        data.total += 1;
+                        assert!(data.used > 0);
                         data.used += 1;
                         data.pending -= 1;
                         proxy_.wake_pending.notify_one();
@@ -131,10 +129,9 @@ impl Proxy {
     pub fn acquire_thread(&self) {
         let mut data = self.data.lock();
 
-        if data.total > data.used {
+        if data.used == 0 {
             // There was a free token around. This can
             // happen when all threads release their token.
-            assert_eq!(data.total, 1);
             assert_eq!(data.pending, 0);
             data.used += 1;
         } else {
@@ -158,8 +155,7 @@ impl Proxy {
             data.used -= 1;
 
             // Release the token unless it's the last one in the process
-            if data.total > 1 {
-                data.total -= 1;
+            if data.used > 0 {
                 drop(data);
                 self.client.release_raw().ok();
             }