Reland "Flush parallel recompilation queues on context dispose notification."

src/optimizing-compiler-thread.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 42 matching lines @@
 
   while (true) {
     input_queue_semaphore_->Wait();
     Logger::TimerEventScope timer(
         isolate_, Logger::TimerEventScope::v8_recompile_parallel);
 
     if (FLAG_parallel_recompilation_delay != 0) {
       OS::Sleep(FLAG_parallel_recompilation_delay);
     }
 
-    if (Acquire_Load(&stop_thread_)) {
-      stop_semaphore_->Signal();
-      if (FLAG_trace_parallel_recompilation) {
-        time_spent_total_ = OS::Ticks() - epoch;
-      }
-      return;
+    switch (static_cast<StopFlag>(Acquire_Load(&stop_thread_))) {
+      case CONTINUE:
+        break;
+      case STOP:
+        if (FLAG_trace_parallel_recompilation) {
+          time_spent_total_ = OS::Ticks() - epoch;
+        }
+        stop_semaphore_->Signal();
+        return;
+      case FLUSH:
+        // Reset input queue semaphore.
+        delete input_queue_semaphore_;
+        input_queue_semaphore_ = OS::CreateSemaphore(0);
+        // Signal for main thread to start flushing.
+        stop_semaphore_->Signal();
+        // Return to start of consumer loop.
+        continue;
     }
 
     int64_t compiling_start = 0;
     if (FLAG_trace_parallel_recompilation) compiling_start = OS::Ticks();
 
     CompileNext();
 
     if (FLAG_trace_parallel_recompilation) {
       time_spent_compiling_ += OS::Ticks() - compiling_start;
     }
@@ skipping 16 matching lines @@
   // are always also queued.
   ScopedLock mark_and_queue(install_mutex_);
   { Heap::RelocationLock relocation_lock(isolate_->heap());
     AllowHandleDereference ahd;
     optimizing_compiler->info()->closure()->MarkForInstallingRecompiledCode();
   }
   output_queue_.Enqueue(optimizing_compiler);
 }
 
 
+void OptimizingCompilerThread::FlushQueue(
+    UnboundQueue<OptimizingCompiler*>* queue,
+    bool restore_function_code) {
+  ASSERT(!IsOptimizerThread());
+  OptimizingCompiler* optimizing_compiler;
+  // The optimizing compiler is allocated in the CompilationInfo's zone.
+  while (queue->Dequeue(&optimizing_compiler)) {
+    CompilationInfo* info = optimizing_compiler->info();
+    if (restore_function_code) {
+      Handle<JSFunction> function = info->closure();
+      function->ReplaceCode(function->shared()->code());
+    }
+    delete info;
+  }
+}
+
+
+void OptimizingCompilerThread::Flush() {
+  ASSERT(!IsOptimizerThread());
+  Release_Store(&stop_thread_, static_cast<AtomicWord>(FLUSH));
+  input_queue_semaphore_->Signal();
+
+  FlushQueue(&input_queue_, true);
+  NoBarrier_Store(&queue_length_, static_cast<AtomicWord>(0));
+
+  stop_semaphore_->Wait();
+  Release_Store(&stop_thread_, static_cast<AtomicWord>(CONTINUE));
+
+  FlushQueue(&output_queue_, true);
+}
+
+
 void OptimizingCompilerThread::Stop() {
   ASSERT(!IsOptimizerThread());
-  Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
+  Release_Store(&stop_thread_, static_cast<AtomicWord>(STOP));
   input_queue_semaphore_->Signal();
   stop_semaphore_->Wait();
 
   if (FLAG_parallel_recompilation_delay != 0) {
     // Barrier when loading queue length is not necessary since the write
     // happens in CompileNext on the same thread.
     while (NoBarrier_Load(&queue_length_) > 0) CompileNext();
     InstallOptimizedFunctions();
   } else {
-    OptimizingCompiler* optimizing_compiler;
-    // The optimizing compiler is allocated in the CompilationInfo's zone.
-    while (input_queue_.Dequeue(&optimizing_compiler)) {
-      delete optimizing_compiler->info();
-    }
-    while (output_queue_.Dequeue(&optimizing_compiler)) {
-      delete optimizing_compiler->info();
-    }
+    FlushQueue(&input_queue_, false);
+    FlushQueue(&output_queue_, false);
   }
 
   if (FLAG_trace_parallel_recompilation) {
     double compile_time = static_cast<double>(time_spent_compiling_);
     double total_time = static_cast<double>(time_spent_total_);
     double percentage = (compile_time * 100) / total_time;
     PrintF("  ** Compiler thread did %.2f%% useful work\n", percentage);
   }
 
   Join();
@@ skipping 28 matching lines @@
 #ifdef DEBUG
 bool OptimizingCompilerThread::IsOptimizerThread() {
   if (!FLAG_parallel_recompilation) return false;
   ScopedLock lock(thread_id_mutex_);
   return ThreadId::Current().ToInteger() == thread_id_;
 }
 #endif
 
 
 } }  // namespace v8::internal