Add the --steal-breakpoints flag.

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 "platform/assert.h"
 #include "platform/json.h"
 #include "vm/code_observers.h"
@@ skipping 593 matching lines @@
       trace_buffer_(NULL),
       profiler_data_(NULL),
       thread_state_(NULL),
       tag_table_(GrowableObjectArray::null()),
       current_tag_(UserTag::null()),
       default_tag_(UserTag::null()),
       deoptimized_code_array_(GrowableObjectArray::null()),
       metrics_list_head_(NULL),
       cha_(NULL),
       next_(NULL),
+      pause_loop_monitor_(NULL),
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_INITIALIZERS)
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_SCOPE_INIT)
       reusable_handles_() {
   set_vm_tag(VMTag::kEmbedderTagId);
   set_user_tag(UserTags::kDefaultUserTag);
 }
 
 Isolate::Isolate(Isolate* original)
   :   mutator_thread_(NULL),
       vm_tag_(0),
@@ skipping 44 matching lines @@
       object_id_ring_(NULL),
       trace_buffer_(NULL),
       profiler_data_(NULL),
       thread_state_(NULL),
       tag_table_(GrowableObjectArray::null()),
       current_tag_(UserTag::null()),
       default_tag_(UserTag::null()),
       metrics_list_head_(NULL),
       cha_(NULL),
       next_(NULL),
+      pause_loop_monitor_(NULL),
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_INITIALIZERS)
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_SCOPE_INIT)
       reusable_handles_() {
 }
 #undef REUSABLE_HANDLE_SCOPE_INIT
 #undef REUSABLE_HANDLE_INITIALIZERS
 
 Isolate::~Isolate() {
   free(name_);
   free(debugger_name_);
   delete heap_;
   delete object_store_;
   delete api_state_;
   delete stub_code_;
   delete debugger_;
 #if defined(USING_SIMULATOR)
   delete simulator_;
 #endif
   delete mutex_;
   mutex_ = NULL;  // Fail fast if interrupts are scheduled on a dead isolate.
   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_;
   delete log_;
   log_ = NULL;
+  delete pause_loop_monitor_;
+  pause_loop_monitor_ = NULL;
 }
 
 
 #if defined(DEBUG)
 bool Isolate::IsIsolateOf(Thread* thread) {
   return this == thread->isolate();
 }
 #endif  // DEBUG
 
 
@@ skipping 996 matching lines @@
   if (deoptimized_code.IsNull()) {
     // Not tracking deoptimized code.
     return;
   }
   // TODO(johnmccutchan): Scan this array and the isolate's profile before
   // old space GC and remove the keep_code flag.
   deoptimized_code.Add(code);
 }
 
 
+void Isolate::WakePauseEventHandler(Dart_Isolate isolate) {
+  Isolate* iso = reinterpret_cast<Isolate*>(isolate);
+  MonitorLocker ml(iso->pause_loop_monitor_);
+  ml.Notify();
+}
+
+
+void Isolate::PauseEventHandler() {
+  // We are stealing a pause event (like a breakpoint) from the
+  // embedder.  We don't know what kind of thread we are on -- it
+  // could be from our thread pool or it could be a thread from the
+  // embedder.  Sit on the current thread handling service events
+  // until we are told to resume.
+  if (pause_loop_monitor_ == NULL) {
+    pause_loop_monitor_ = new Monitor();
+  }
+  Dart_EnterScope();
+  MonitorLocker ml(pause_loop_monitor_);
+
+  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();
+      resume = Dart_HandleServiceMessages();
+      pause_loop_monitor_->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_);
   Isolate* current = isolates_list_head_;
   while (current) {
     visitor->VisitIsolate(current);
     current = current->next_;
   }
@@ skipping 241 matching lines @@
                            serialized_message_, serialized_message_len_);
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(I);
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart