Auto merge of #67398 - Mark-Simulacrum:no-jobserver-herds, r=<try>

Communicate over stderr jobserver token acquiring/releasing

This set of commits revises the jobserver communication inside rustc to always go through a shim around the real jobserver crate to allow us to inform Cargo of when tokens are intended to be acquired/released.

The Cargo side of this hasn't yet been implemented at all yet.

Author: bors

Cargo.lock

@@ -3151,7 +3151,6 @@ dependencies = [
  "chalk-engine",
  "fmt_macros",
  "graphviz",
- "jobserver",
  "log",
  "measureme",
  "num_cpus",
@@ -3166,6 +3165,7 @@ dependencies = [
  "rustc_feature",
  "rustc_fs_util",
  "rustc_index",
+ "rustc_jobserver",
  "rustc_macros",
  "rustc_session",
  "rustc_target",
@@ -3464,7 +3464,6 @@ version = "0.0.0"
 dependencies = [
  "bitflags",
  "cc",
- "jobserver",
  "libc",
  "log",
  "memmap",
@@ -3478,6 +3477,7 @@ dependencies = [
  "rustc_fs_util",
  "rustc_incremental",
  "rustc_index",
+ "rustc_jobserver",
  "rustc_session",
  "rustc_target",
  "serialize",
@@ -3511,7 +3511,6 @@ dependencies = [
  "ena",
  "graphviz",
  "indexmap",
- "jobserver",
  "lazy_static 1.3.0",
  "log",
  "measureme",
@@ -3623,6 +3622,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_incremental",
+ "rustc_jobserver",
  "rustc_lint",
  "rustc_metadata",
  "rustc_mir",
@@ -3643,6 +3643,15 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "rustc_jobserver"
+version = "0.0.0"
+dependencies = [
+ "jobserver",
+ "lazy_static 1.3.0",
+ "serialize",
+]
+
 [[package]]
 name = "rustc_lexer"
 version = "0.1.0"

src/librustc/Cargo.toml

@@ -14,7 +14,7 @@ arena = { path = "../libarena" }
 bitflags = "1.2.1"
 fmt_macros = { path = "../libfmt_macros" }
 graphviz = { path = "../libgraphviz" }
-jobserver = "0.1"
+rustc_jobserver = { path = "../librustc_jobserver" }
 num_cpus = "1.0"
 scoped-tls = "1.0"
 log = { version = "0.4", features = ["release_max_level_info", "std"] }

src/librustc/ty/query/job.rs

@@ -12,7 +12,8 @@ use std::ptr;
 #[cfg(parallel_compiler)]
 use {
     parking_lot::{Mutex, Condvar},
-    rustc_data_structures::{jobserver, OnDrop},
+    rustc_data_structures::{OnDrop},
+    rustc_jobserver as jobserver,
     rustc_data_structures::fx::FxHashSet,
     rustc_data_structures::stable_hasher::{StableHasher, HashStable},
     rustc_data_structures::sync::Lock,

src/librustc_codegen_ssa/Cargo.toml

@@ -16,7 +16,6 @@ num_cpus = "1.0"
 memmap = "0.7"
 log = "0.4.5"
 libc = "0.2.44"
-jobserver = "0.1.11"
 tempfile = "3.1"
 
 rustc_serialize = { path = "../libserialize", package = "serialize" }
@@ -33,3 +32,4 @@ rustc_index = { path = "../librustc_index" }
 rustc_target = { path = "../librustc_target" }
 rustc_error_codes = { path = "../librustc_error_codes" }
 rustc_session = { path = "../librustc_session" }
+rustc_jobserver = { path = "../librustc_jobserver" }

src/librustc_codegen_ssa/back/write.rs

@@ -30,11 +30,10 @@ use rustc_target::spec::MergeFunctions;
 use syntax::attr;
 use syntax_pos::hygiene::ExpnId;
 use syntax_pos::symbol::{Symbol, sym};
-use jobserver::{Client, Acquired};
+use rustc_jobserver::Acquired;
 
 use std::any::Any;
 use std::fs;
-use std::io;
 use std::mem;
 use std::path::{Path, PathBuf};
 use std::str;
@@ -433,7 +432,6 @@ pub fn start_async_codegen<B: ExtraBackendMethods>(
                                                   codegen_worker_send,
                                                   coordinator_receive,
                                                   total_cgus,
-                                                  sess.jobserver.clone(),
                                                   Arc::new(modules_config),
                                                   Arc::new(metadata_config),
                                                   Arc::new(allocator_config),
@@ -890,7 +888,7 @@ fn execute_lto_work_item<B: ExtraBackendMethods>(
 }
 
 pub enum Message<B: WriteBackendMethods> {
-    Token(io::Result<Acquired>),
+    Token(Acquired),
     NeedsFatLTO {
         result: FatLTOInput<B>,
         worker_id: usize,
@@ -938,7 +936,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
     codegen_worker_send: Sender<Message<B>>,
     coordinator_receive: Receiver<Box<dyn Any + Send>>,
     total_cgus: usize,
-    jobserver: Client,
     modules_config: Arc<ModuleConfig>,
     metadata_config: Arc<ModuleConfig>,
     allocator_config: Arc<ModuleConfig>,
@@ -981,9 +978,9 @@ fn start_executing_work<B: ExtraBackendMethods>(
     // get tokens on `coordinator_receive` which will
     // get managed in the main loop below.
     let coordinator_send2 = coordinator_send.clone();
-    let helper = jobserver.into_helper_thread(move |token| {
+    let helper = rustc_jobserver::helper_thread(move |token| {
         drop(coordinator_send2.send(Box::new(Message::Token::<B>(token))));
-    }).expect("failed to spawn helper thread");
+    });
 
     let mut each_linked_rlib_for_lto = Vec::new();
     drop(link::each_linked_rlib(crate_info, &mut |cnum, path| {
@@ -1374,25 +1371,15 @@ fn start_executing_work<B: ExtraBackendMethods>(
                 // this to spawn a new unit of work, or it may get dropped
                 // immediately if we have no more work to spawn.
                 Message::Token(token) => {
-                    match token {
-                        Ok(token) => {
-                            tokens.push(token);
-
-                            if main_thread_worker_state == MainThreadWorkerState::LLVMing {
-                                // If the main thread token is used for LLVM work
-                                // at the moment, we turn that thread into a regular
-                                // LLVM worker thread, so the main thread is free
-                                // to react to codegen demand.
-                                main_thread_worker_state = MainThreadWorkerState::Idle;
-                                running += 1;
-                            }
-                        }
-                        Err(e) => {
-                            let msg = &format!("failed to acquire jobserver token: {}", e);
-                            shared_emitter.fatal(msg);
-                            // Exit the coordinator thread
-                            panic!("{}", msg)
-                        }
+                    tokens.push(token);
+
+                    if main_thread_worker_state == MainThreadWorkerState::LLVMing {
+                        // If the main thread token is used for LLVM work
+                        // at the moment, we turn that thread into a regular
+                        // LLVM worker thread, so the main thread is free
+                        // to react to codegen demand.
+                        main_thread_worker_state = MainThreadWorkerState::Idle;
+                        running += 1;
                     }
                 }
 

src/librustc_data_structures/Cargo.toml

@@ -13,7 +13,6 @@ doctest = false
 ena = "0.13.1"
 indexmap = "1"
 log = "0.4"
-jobserver_crate = { version = "0.1.13", package = "jobserver" }
 lazy_static = "1"
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 graphviz = { path = "../libgraphviz" }

src/librustc_data_structures/jobserver.rs

@@ -74,7 +74,6 @@ pub mod flock;
 pub mod fx;
 pub mod stable_map;
 pub mod graph;
-pub mod jobserver;
 pub mod obligation_forest;
 pub mod owning_ref;
 pub mod ptr_key;

src/librustc_data_structures/lib.rs

@@ -23,6 +23,7 @@ rustc = { path = "../librustc" }
 rustc_incremental = { path = "../librustc_incremental" }
 rustc_traits = { path = "../librustc_traits" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_jobserver = { path = "../librustc_jobserver" }
 rustc_codegen_ssa = { path = "../librustc_codegen_ssa" }
 rustc_codegen_utils = { path = "../librustc_codegen_utils" }
 rustc_codegen_llvm = { path = "../librustc_codegen_llvm", optional = true }

src/librustc_interface/Cargo.toml

@@ -181,6 +181,20 @@ pub fn run_compiler_in_existing_thread_pool<R>(
 
 pub fn run_compiler<R: Send>(mut config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
     let stderr = config.stderr.take();
+
+    if config.opts.debugging_opts.jobserver_token_requests {
+        if let config::ErrorOutputType::Json { .. } = config.opts.error_format {
+            if stderr.is_some() {
+                panic!("Non-default output not supported with -Zjobserver-token-requests");
+            }
+        } else {
+            panic!("-Zjobserver-token-requests can only be specified if using \
+                JSON error output type");
+        }
+    }
+
+    rustc_jobserver::initialize(config.opts.debugging_opts.jobserver_token_requests);
+
     util::spawn_thread_pool(
         config.opts.edition,
         config.opts.debugging_opts.threads,

src/librustc_interface/interface.rs

@@ -6,7 +6,7 @@ use rustc::ty;
 use rustc::lint;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
 #[cfg(parallel_compiler)]
-use rustc_data_structures::jobserver;
+use rustc_jobserver as jobserver;
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::fingerprint::Fingerprint;

src/librustc_interface/util.rs

@@ -0,0 +1,15 @@
+[package]
+authors = ["The Rust Project Developers"]
+name = "rustc_jobserver"
+version = "0.0.0"
+edition = "2018"
+
+[lib]
+name = "rustc_jobserver"
+path = "lib.rs"
+doctest = false
+
+[dependencies]
+jobserver_crate = { version = "0.1.13", package = "jobserver" }
+lazy_static = "1"
+rustc_serialize = { path = "../libserialize", package = "serialize" }