Debugger: preserve stepping state after evaluating breakpoint condition.

src/debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 879 matching lines @@
 // triggered. This function returns a JSArray with the break point objects
 // which is triggered.
 Handle<Object> Debug::CheckBreakPoints(Handle<Object> break_point_objects) {
   Factory* factory = isolate_->factory();
 
   // Count the number of break points hit. If there are multiple break points
   // they are in a FixedArray.
   Handle<FixedArray> break_points_hit;
   int break_points_hit_count = 0;
   DCHECK(!break_point_objects->IsUndefined());
+
+  // Break points are checked by calling into Javascript. This could change
+  // the stepping state we are currently in.
+  PreserveDebugState state(this);

[yurys, 2015/05/15 22:04:41]

I wonder how evaluating breakpoint condition can change the stepping state. The
conditional expression should be isolated from the debugger bindings and I
wouldn't expect it to affect the state. Could you educate me on this?

+
   if (break_point_objects->IsFixedArray()) {
     Handle<FixedArray> array(FixedArray::cast(*break_point_objects));
     break_points_hit = factory->NewFixedArray(array->length());
     for (int i = 0; i < array->length(); i++) {
       Handle<Object> o(array->get(i), isolate_);
       if (CheckBreakPoint(o)) {
         break_points_hit->set(break_points_hit_count++, *o);
       }
     }
   } else {
@@ skipping 2490 matching lines @@
   logger_->DebugEvent("Put", message.text());
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 } }  // namespace v8::internal