- Add assertions in MutexLocker/MonitorLocker to ensure that the code enclosed

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 804 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_mutex_(new Mutex()),
       boxed_field_list_(GrowableObjectArray::null()),
       spawn_count_monitor_(new Monitor()),
       spawn_count_(0) {
   NOT_IN_PRODUCT(FlagsCopyFrom(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);
 }
 
@@ skipping 20 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;
+  delete boxed_field_list_mutex_;
+  boxed_field_list_mutex_ = NULL;
   ASSERT(spawn_count_ == 0);
   delete spawn_count_monitor_;
   if (compiler_stats_ != NULL) {
     delete compiler_stats_;
     compiler_stats_ = NULL;
   }
   delete safepoint_handler_;
   delete thread_registry_;
 }
 
@@ skipping 984 matching lines @@
   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.
   // '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.
+  // when at safepoint or the boxed_field_list_mutex_ lock has been taken.
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&boxed_field_list_));
 
   // 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 193 matching lines @@
 
 
 void Isolate::set_registered_service_extension_handlers(
     const GrowableObjectArray& value) {
   registered_service_extension_handlers_ = value.raw();
 }
 
 
 void Isolate::AddDeoptimizingBoxedField(const Field& field) {
   ASSERT(field.IsOriginal());
-  MonitorLocker ml(boxed_field_list_monitor_);
+  // The enclosed code allocates objects and can potentially trigger a GC,
+  // ensure that we account for safepoints when grabbing the lock.
+  SafepointMutexLocker ml(boxed_field_list_mutex_);
   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_);
+  MutexLocker ml(boxed_field_list_mutex_);
   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());
 }
@@ skipping 202 matching lines @@
 
   Dart_MessageNotifyCallback saved_notify_callback =
       message_notify_callback();
   set_message_notify_callback(Isolate::WakePauseEventHandler);
 
   bool resume = false;
   while (true) {
     // Handle all available vm service messages, up to a resume
     // request.
     while (!resume && Dart_HasServiceMessages()) {
-      pause_loop_monitor_->Exit();
+      ml.Exit();
       resume = Dart_HandleServiceMessages();
-      pause_loop_monitor_->Enter();
+      ml.Enter();
     }
     if (resume) {
       break;
     }
 
     // Wait for more service messages.
     Monitor::WaitResult res = ml.Wait();
     ASSERT(res == Monitor::kNotified);
   }
   set_message_notify_callback(saved_notify_callback);
   Dart_ExitScope();
 }
 
 
 void Isolate::VisitIsolates(IsolateVisitor* visitor) {
   if (visitor == NULL) {
     return;
   }
-  MonitorLocker ml(isolates_list_monitor_);
+  // The visitor could potentially run code that could safepoint so use
+  // SafepointMonitorLocker to ensure the lock has safepoint checks.
+  SafepointMonitorLocker ml(isolates_list_monitor_);
   Isolate* current = isolates_list_head_;
   while (current) {
     visitor->VisitIsolate(current);
     current = current->next_;
   }
 }
 
 
 intptr_t Isolate::IsolateListLength() {
   MonitorLocker ml(isolates_list_monitor_);
@@ skipping 169 matching lines @@
 }
 
 
 Thread* Isolate::ScheduleThread(bool is_mutator, bool bypass_safepoint) {
   // Schedule the thread into the isolate by associating
   // a 'Thread' structure with it (this is done while we are holding
   // the thread registry lock).
   Thread* thread = NULL;
   OSThread* os_thread = OSThread::Current();
   if (os_thread != NULL) {
-    MonitorLocker ml(threads_lock());
+    // We are about to associate the thread with an isolate and it would
+    // not be possible to correctly track no_safepoint_scope_depth for the
+    // thread in the constructor/destructor of MonitorLocker,
+    // so we create a MonitorLocker object which does not do any
+    // no_safepoint_scope_depth increments/decrements.
+    MonitorLocker ml(threads_lock(), false);
 
     // If a safepoint operation is in progress wait for it
     // to finish before scheduling this thread in.
     while (!bypass_safepoint && safepoint_handler()->safepoint_in_progress()) {
       ml.Wait();
     }
 
     // Now get a free Thread structure.
     thread = thread_registry()->GetFreeThreadLocked(this, is_mutator);
     ASSERT(thread != NULL);
 
     // Set up other values and set the TLS value.
     thread->isolate_ = this;
     ASSERT(heap() != NULL);
     thread->heap_ = heap();
     thread->set_os_thread(os_thread);
     ASSERT(thread->execution_state() == Thread::kThreadInVM);
     thread->set_safepoint_state(0);
     thread->set_vm_tag(VMTag::kVMTagId);
+    ASSERT(thread->no_safepoint_scope_depth() == 0);
     os_thread->set_thread(thread);
     if (is_mutator) {
       mutator_thread_ = thread;
     }
     Thread::SetCurrent(thread);
     os_thread->EnableThreadInterrupts();
   }
   return thread;
 }
 
 
 void Isolate::UnscheduleThread(Thread* thread,
                                bool is_mutator,
                                bool bypass_safepoint) {
   // Disassociate the 'Thread' structure and unschedule the thread
   // from this isolate.
-  MonitorLocker ml(threads_lock());
+  // We are disassociating the thread from an isolate and it would
+  // not be possible to correctly track no_safepoint_scope_depth for the
+  // thread in the constructor/destructor of MonitorLocker,
+  // so we create a MonitorLocker object which does not do any
+  // no_safepoint_scope_depth increments/decrements.
+  MonitorLocker ml(threads_lock(), false);
   if (!bypass_safepoint) {
     // Ensure that the thread reports itself as being at a safepoint.
     thread->EnterSafepoint();
   }
   OSThread* os_thread = thread->os_thread();
   ASSERT(os_thread != NULL);
   os_thread->DisableThreadInterrupts();
   os_thread->set_thread(NULL);
   OSThread::SetCurrent(os_thread);
   if (is_mutator) {
     mutator_thread_ = NULL;
   }
   thread->isolate_ = NULL;
   thread->heap_ = NULL;
   thread->set_os_thread(NULL);
   thread->set_execution_state(Thread::kThreadInVM);
   thread->set_safepoint_state(0);
+  ASSERT(thread->no_safepoint_scope_depth() == 0);
   // Return thread structure.
   thread_registry()->ReturnThreadLocked(is_mutator, thread);
 }
 
 
 static RawInstance* DeserializeObject(Thread* thread,
                                       uint8_t* obj_data,
                                       intptr_t obj_len) {
   if (obj_data == NULL) {
     return Instance::null();
@@ skipping 215 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