Prevent recursive exception notification in debugger

runtime/vm/debugger.cc

 // Copyright (c) 2012, 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/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 1046 matching lines @@
       (exc_pause_info_ == kNoPauseOnExceptions)) {
     return;
   }
   DebuggerStackTrace* stack_trace = CollectStackTrace();
   if (!ShouldPauseOnException(stack_trace, exc)) {
     return;
   }
   ASSERT(stack_trace_ == NULL);
   stack_trace_ = stack_trace;
   ASSERT(obj_cache_ == NULL);
+  in_event_notification_ = true;
   obj_cache_ = new RemoteObjectCache(64);
   DebuggerEvent event;
   event.type = kExceptionThrown;
   event.exception = &exc;
   (*event_handler_)(&event);

[Ivan Posva, 2013/08/09 16:31:34]

I think we should abstract the dispatch to the event handler out and have that
set and reset the in_event_notification status. That way all of the other,
currently unprotected, event_handler calls will automatically be protected from
similar issues.

+  in_event_notification_ = false;
   stack_trace_ = NULL;
   obj_cache_ = NULL;  // Remote object cache is zone allocated.
 }
 
 
 // Given a function and a token position range, return the best fit
 // token position to set a breakpoint.
 // If multiple possible breakpoint positions are within the given range,
 // the one with the lowest machine code address is picked.
 // If no possible breakpoint location exists in the given range, the closest
@@ skipping 781 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart