From cff9efde748b6027fe9f135ddd5aaf8a3276601d Mon Sep 17 00:00:00 2001
From: John Kåre Alsaker <john.kare.alsaker@gmail.com>
Date: Tue, 22 Apr 2025 07:02:27 +0200
Subject: Add a jobserver proxy to ensure at least one token is always held

---
 compiler/rustc_interface/src/util.rs | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

(limited to 'compiler/rustc_interface/src/util.rs')

diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index c3a939f1ab0..3a291bbe802 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -1,11 +1,12 @@
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::path::{Path, PathBuf};
-use std::sync::OnceLock;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, OnceLock};
 use std::{env, iter, thread};
 
 use rustc_ast as ast;
 use rustc_codegen_ssa::traits::CodegenBackend;
+use rustc_data_structures::jobserver::Proxy;
 use rustc_data_structures::sync;
 use rustc_metadata::{DylibError, load_symbol_from_dylib};
 use rustc_middle::ty::CurrentGcx;
@@ -113,7 +114,7 @@ fn init_stack_size(early_dcx: &EarlyDiagCtxt) -> usize {
     })
 }
 
-fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
+fn run_in_thread_with_globals<F: FnOnce(CurrentGcx, Arc<Proxy>) -> R + Send, R: Send>(
     thread_stack_size: usize,
     edition: Edition,
     sm_inputs: SourceMapInputs,
@@ -139,7 +140,7 @@ fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
                     edition,
                     extra_symbols,
                     Some(sm_inputs),
-                    || f(CurrentGcx::new()),
+                    || f(CurrentGcx::new(), Proxy::new()),
                 )
             })
             .unwrap()
@@ -152,7 +153,10 @@ fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
     })
 }
 
-pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
+pub(crate) fn run_in_thread_pool_with_globals<
+    F: FnOnce(CurrentGcx, Arc<Proxy>) -> R + Send,
+    R: Send,
+>(
     thread_builder_diag: &EarlyDiagCtxt,
     edition: Edition,
     threads: usize,
@@ -162,8 +166,8 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
 ) -> R {
     use std::process;
 
+    use rustc_data_structures::defer;
     use rustc_data_structures::sync::FromDyn;
-    use rustc_data_structures::{defer, jobserver};
     use rustc_middle::ty::tls;
     use rustc_query_impl::QueryCtxt;
     use rustc_query_system::query::{QueryContext, break_query_cycles};
@@ -178,11 +182,11 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
             edition,
             sm_inputs,
             extra_symbols,
-            |current_gcx| {
+            |current_gcx, jobserver_proxy| {
                 // Register the thread for use with the `WorkerLocal` type.
                 registry.register();
 
-                f(current_gcx)
+                f(current_gcx, jobserver_proxy)
             },
         );
     }
@@ -190,10 +194,14 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
     let current_gcx = FromDyn::from(CurrentGcx::new());
     let current_gcx2 = current_gcx.clone();
 
+    let proxy = Proxy::new();
+
+    let proxy_ = Arc::clone(&proxy);
+    let proxy__ = Arc::clone(&proxy);
     let builder = rayon_core::ThreadPoolBuilder::new()
         .thread_name(|_| "rustc".to_string())
-        .acquire_thread_handler(jobserver::acquire_thread)
-        .release_thread_handler(jobserver::release_thread)
+        .acquire_thread_handler(move || proxy_.acquire_thread())
+        .release_thread_handler(move || proxy__.release_thread())
         .num_threads(threads)
         .deadlock_handler(move || {
             // On deadlock, creates a new thread and forwards information in thread
@@ -257,7 +265,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
                     },
                     // Run `f` on the first thread in the thread pool.
                     move |pool: &rayon_core::ThreadPool| {
-                        pool.install(|| f(current_gcx.into_inner()))
+                        pool.install(|| f(current_gcx.into_inner(), proxy))
                     },
                 )
                 .unwrap()
-- 
cgit 1.4.1-3-g733a5