Support tasks injection into a running VM.

src/debug.cc

Index: src/debug.cc
diff --git a/src/debug.cc b/src/debug.cc
index a7321b2b157f074a02e8a8dd5bf7e78148803cbc..fc9a80aefb4778e16f4e5575069ba420c0203609 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -3103,6 +3103,27 @@ void Debug::EnqueueDebugCommand(v8::Debug::ClientData* client_data) {
 }
 
 
+void Debug::EnqueueEmbedderTask(v8::Task* task) {
+  embedder_task_queue_.Enqueue(task);
+
+  // Set the debug command break flag to have the command processed.
+  if (!in_debug_scope()) {
+    isolate_->stack_guard()->RequestDebugCommand();
+  }
+}
+
+
+bool Debug::ProcessEmbedderTasks() {
+  bool did_process_task = false;
+  while (v8::Task* task = embedder_task_queue_.Dequeue()) {
+    did_process_task = true;
+    task->Run();
+    delete task;
+  }
+  return did_process_task;
+}
+
+
 MaybeHandle<Object> Debug::Call(Handle<JSFunction> fun, Handle<Object> data) {
   DebugScope debug_scope(this);
   if (debug_scope.failed()) return isolate_->factory()->undefined_value();
@@ -3128,6 +3149,9 @@ void Debug::HandleDebugBreak() {
   if (isolate_->bootstrapper()->IsActive()) return;
   // Just continue if breaks are disabled.
   if (break_disabled()) return;
+  if (ProcessEmbedderTasks()) {
+    isolate_->stack_guard()->ClearDebugCommand();
+  }
   // Ignore debug break if debugger is not active.
   if (!is_active()) return;
 
@@ -3480,4 +3504,33 @@ void LockingCommandMessageQueue::Clear() {
   queue_.Clear();
 }
 
+
+LockingTaskQueue::LockingTaskQueue() {}
+
+
+LockingTaskQueue::~LockingTaskQueue() { Clear(); }
+
+
+void LockingTaskQueue::Enqueue(v8::Task* task) {
+  base::LockGuard<base::Mutex> lock_guard(&mutex_);
+  queue_.push(task);
+}
+
+
+v8::Task* LockingTaskQueue::Dequeue() {
+  base::LockGuard<base::Mutex> lock_guard(&mutex_);
+  if (queue_.empty()) return NULL;
+  v8::Task* task = queue_.front();
+  queue_.pop();
+  return task;
+}
+
+
+void LockingTaskQueue::Clear() {
+  base::LockGuard<base::Mutex> lock_guard(&mutex_);
+  while (!queue_.empty()) {
+    delete queue_.front();
+    queue_.pop();
+  }
+}
 } }  // namespace v8::internal