src: reduce platform worker barrier lifetime

Minor cleanup in the lifetime for the platform worker initialization
synchronization barrier.

PR-URL: #23419
Backport-PR-URL: #28844
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: ofrobots

src/node_platform.cc

@@ -47,7 +47,7 @@ static void BackgroundRunner(void* data) {
 class BackgroundTaskRunner::DelayedTaskScheduler {
  public:
   explicit DelayedTaskScheduler(TaskQueue<Task>* tasks)
-    : pending_worker_tasks_(tasks) {}
+    : background_tasks_(tasks) {}
 
   std::unique_ptr<uv_thread_t> Start() {
     auto start_thread = [](void* data) {
@@ -139,7 +139,7 @@ class BackgroundTaskRunner::DelayedTaskScheduler {
   static void RunTask(uv_timer_t* timer) {
     DelayedTaskScheduler* scheduler =
         ContainerOf(&DelayedTaskScheduler::loop_, timer->loop);
-    scheduler->pending_worker_tasks_->Push(scheduler->TakeTimerTask(timer));
+    scheduler->background_tasks_->Push(scheduler->TakeTimerTask(timer));
   }
 
   std::unique_ptr<Task> TakeTimerTask(uv_timer_t* timer) {
@@ -153,7 +153,7 @@ class BackgroundTaskRunner::DelayedTaskScheduler {
   }
 
   uv_sem_t ready_;
-  TaskQueue<v8::Task>* pending_worker_tasks_;
+  TaskQueue<v8::Task>* background_tasks_;
 
   TaskQueue<v8::Task> tasks_;
   uv_loop_t loop_;
@@ -162,17 +162,20 @@ class BackgroundTaskRunner::DelayedTaskScheduler {
 };
 
 BackgroundTaskRunner::BackgroundTaskRunner(int thread_pool_size) {
-  Mutex::ScopedLock lock(platform_workers_mutex_);
-  pending_platform_workers_ = thread_pool_size;
+  Mutex platform_workers_mutex;
+  ConditionVariable platform_workers_ready;
+
+  Mutex::ScopedLock lock(platform_workers_mutex);
+  int pending_platform_workers = thread_pool_size;
 
   delayed_task_scheduler_.reset(
       new DelayedTaskScheduler(&background_tasks_));
   threads_.push_back(delayed_task_scheduler_->Start());
 
   for (int i = 0; i < thread_pool_size; i++) {
     PlatformWorkerData* worker_data = new PlatformWorkerData{
-      &background_tasks_, &platform_workers_mutex_,
-      &platform_workers_ready_, &pending_platform_workers_, i
+      &background_tasks_, &platform_workers_mutex,
+      &platform_workers_ready, &pending_platform_workers, i
     };
     std::unique_ptr<uv_thread_t> t { new uv_thread_t() };
     if (uv_thread_create(t.get(), BackgroundRunner, worker_data) != 0)
@@ -182,8 +185,8 @@ BackgroundTaskRunner::BackgroundTaskRunner(int thread_pool_size) {
 
   // Wait for platform workers to initialize before continuing with the
   // bootstrap.
-  while (pending_platform_workers_ > 0) {
-    platform_workers_ready_.Wait(lock);
+  while (pending_platform_workers > 0) {
+    platform_workers_ready.Wait(lock);
   }
 }
 

src/node_platform.h

@@ -119,10 +119,6 @@ class BackgroundTaskRunner : public v8::TaskRunner {
   std::unique_ptr<DelayedTaskScheduler> delayed_task_scheduler_;
 
   std::vector<std::unique_ptr<uv_thread_t>> threads_;
-
-  Mutex platform_workers_mutex_;
-  ConditionVariable platform_workers_ready_;
-  int pending_platform_workers_;
 };
 
 class NodePlatform : public MultiIsolatePlatform {