Pass field to mutator thread so that it can be marked as boxed and all dependent code deoptimized

runtime/vm/isolate.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 813 matching lines @@
       pending_service_extension_calls_(GrowableObjectArray::null()),
       registered_service_extension_handlers_(GrowableObjectArray::null()),
       metrics_list_head_(NULL),
       compilation_allowed_(true),
       all_classes_finalized_(false),
       next_(NULL),
       pause_loop_monitor_(NULL),
       cha_invalidation_gen_(kInvalidGen),
       field_invalidation_gen_(kInvalidGen),
       prefix_invalidation_gen_(kInvalidGen),
+      boxed_field_list_monitor_(new Monitor()),
+      boxed_field_list_(GrowableObjectArray::null()),
       spawn_count_monitor_(new Monitor()),
       spawn_count_(0) {
   flags_.CopyFrom(api_flags);
   // TODO(asiva): A Thread is not available here, need to figure out
   // how the vm_tag (kEmbedderTagId) can be set, these tags need to
   // move to the OSThread structure.
   set_user_tag(UserTags::kDefaultUserTag);
 }
 
 #undef REUSABLE_HANDLE_SCOPE_INIT
@@ skipping 17 matching lines @@
   delete message_handler_;
   message_handler_ = NULL;  // Fail fast if we send messages to a dead isolate.
   ASSERT(deopt_context_ == NULL);  // No deopt in progress when isolate deleted.
   delete spawn_state_;
   if (FLAG_support_service) {
     delete object_id_ring_;
   }
   object_id_ring_ = NULL;
   delete pause_loop_monitor_;
   pause_loop_monitor_ = NULL;
+  delete boxed_field_list_monitor_;
+  boxed_field_list_monitor_ = NULL;
   ASSERT(spawn_count_ == 0);
   delete spawn_count_monitor_;

[siva, 2016/02/10 17:57:35]

We seem to have added a number of monitors to the isolate, I am wondering if
some of these can be shared.

[srdjan, 2016/02/10 19:18:51]

Added a TODO at Isolate constructor:

TODO(srdjan): Some Isolate monitors can be shared. Replace their usage with that
shared monitor.

   if (compiler_stats_ != NULL) {
     delete compiler_stats_;
     compiler_stats_ = NULL;
   }
   delete safepoint_handler_;
   delete thread_registry_;
 }
 
 
 void Isolate::InitOnce() {
@@ skipping 956 matching lines @@
       reinterpret_cast<RawObject**>(&deoptimized_code_array_));
 
   // Visit the pending service extension calls.
   visitor->VisitPointer(
       reinterpret_cast<RawObject**>(&pending_service_extension_calls_));
 
   // Visit the registered service extension handlers.
   visitor->VisitPointer(
       reinterpret_cast<RawObject**>(&registered_service_extension_handlers_));
 
+  // Visit the boxed_field_list.
+  visitor->VisitPointer(reinterpret_cast<RawObject**>(&boxed_field_list_));

[siva, 2016/02/10 17:57:35]

This will work only if the visitor is at a safepoint or is holding the
boxed_field_list_monitor_ lock. Maybe you should document that.

[srdjan, 2016/02/10 19:18:51]

  // 'boxed_field_list_' access via mutator and background compilation threads
  // is guarded with a monitor. This means that we can visit it only
  // when at safepoint or the boxed_field_list_monitor_ lock has been taken.

+
   // Visit objects in the debugger.
   if (FLAG_support_debugger) {
     debugger()->VisitObjectPointers(visitor);
   }
 
   // Visit objects that are being used for deoptimization.
   if (deopt_context() != NULL) {
     deopt_context()->VisitObjectPointers(visitor);
   }
 
@@ skipping 184 matching lines @@
   pending_service_extension_calls_ = value.raw();
 }
 
 
 void Isolate::set_registered_service_extension_handlers(
     const GrowableObjectArray& value) {
   registered_service_extension_handlers_ = value.raw();
 }
 
 
+void Isolate::AddDeoptimizingBoxedField(const Field& field) {
+  MonitorLocker ml(boxed_field_list_monitor_);
+  if (boxed_field_list_ == GrowableObjectArray::null()) {
+    boxed_field_list_ = GrowableObjectArray::New(Heap::kOld);
+  }
+  const GrowableObjectArray& array =
+      GrowableObjectArray::Handle(boxed_field_list_);
+  array.Add(field, Heap::kOld);
+}
+
+
+RawField* Isolate::GetDeoptimizingBoxedField() {
+  MonitorLocker ml(boxed_field_list_monitor_);
+  if (boxed_field_list_ == GrowableObjectArray::null()) {
+    return Field::null();
+  }
+  const GrowableObjectArray& array =
+      GrowableObjectArray::Handle(boxed_field_list_);
+  if (array.Length() == 0) {
+    return Field::null();
+  }
+  return Field::RawCast(array.RemoveLast());
+}
+
+
 RawObject* Isolate::InvokePendingServiceExtensionCalls() {
   if (!FLAG_support_service) {
     return Object::null();
   }
   GrowableObjectArray& calls =
       GrowableObjectArray::Handle(GetAndClearPendingServiceExtensionCalls());
   if (calls.IsNull()) {
     return Object::null();
   }
   // Grab run function.
@@ skipping 675 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart