Teach debugger to ignore breakpoints

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
===================================================================
--- runtime/vm/debugger.cc	(revision 5243)
+++ runtime/vm/debugger.cc	(working copy)
@@ -308,7 +308,7 @@
   PcDescriptors& desc = PcDescriptors::Handle(code.pc_descriptors());
   ASSERT(pc_desc_index < desc.Length());
   token_index_ = desc.TokenIndex(pc_desc_index);
-  ASSERT(token_index_ > 0);
+  ASSERT(token_index_ >= 0);
   pc_ = desc.PC(pc_desc_index);
   ASSERT(pc_ != 0);
   breakpoint_kind_ = desc.DescriptorKind(pc_desc_index);
@@ -415,7 +415,8 @@
       bp_handler_(NULL),
       src_breakpoints_(NULL),
       code_breakpoints_(NULL),
-      resume_action_(kContinue) {
+      resume_action_(kContinue),
+      ignore_breakpoints_(false) {
 }
 
 
@@ -673,6 +674,8 @@
   LongJump* base = isolate_->long_jump_base();
   LongJump jump;
   isolate_->set_long_jump_base(&jump);
+  bool saved_ignore_flag = ignore_breakpoints_;
+  ignore_breakpoints_ = true;
   if (setjmp(*jump.Set()) == 0) {
     GrowableArray<const Object*> noArguments;
     const Array& noArgumentNames = Array::Handle();
@@ -681,6 +684,7 @@
   } else {
     result = isolate_->object_store()->sticky_error();
   }
+  ignore_breakpoints_ = saved_ignore_flag;

[siva, 2012/03/10 00:11:40]

Why save and restore the flag instead of just setting it to
false here?
Do you expect recursive calls to this? I thought the goal was to avoid recursive
calls to this.

[hausner, 2012/03/10 00:41:56]

I thought it's more future-proof to allow for recursion. On the other hand,
there is probably a lot more state that would need to be saved and restored to
make the debugger truly reentrant.

For example, we might want to call the debugger when an exception is thrown,
which could happen during the evaluation of a field.

[siva, 2012/03/12 22:19:14]

Sounds like premature optimization :-)

On 2012/03/10 00:41:56, hausner wrote:

   isolate_->set_long_jump_base(base);
   return result.raw();
 }
@@ -696,6 +700,8 @@
   LongJump* base = isolate_->long_jump_base();
   LongJump jump;
   isolate_->set_long_jump_base(&jump);
+  bool saved_ignore_flag = ignore_breakpoints_;
+  ignore_breakpoints_ = true;
   if (setjmp(*jump.Set()) == 0) {
     GrowableArray<const Object*> noArguments;
     const Array& noArgumentNames = Array::Handle();
@@ -703,6 +709,7 @@
   } else {
     result = isolate_->object_store()->sticky_error();
   }
+  ignore_breakpoints_ = saved_ignore_flag;
   isolate_->set_long_jump_base(base);
   return result.raw();
 }
@@ -798,6 +805,10 @@
 
 void Debugger::BreakpointCallback() {
   ASSERT(initialized_);
+
+  if (ignore_breakpoints_) {
+    return;
+  }
   DartFrameIterator iterator;
   DartFrame* frame = iterator.NextFrame();
   ASSERT(frame != NULL);
@@ -805,10 +816,10 @@
   ASSERT(bpt != NULL);
   if (verbose) {
     OS::Print(">>> %s breakpoint at %s:%d (Address %p)\n",
-        bpt->IsInternal() ? "hit internal" : "hit user",
-        bpt ? String::Handle(bpt->SourceUrl()).ToCString() : "?",
-        bpt ? bpt->LineNumber() : 0,
-        frame->pc());
+              bpt->IsInternal() ? "hit internal" : "hit user",
+              bpt ? String::Handle(bpt->SourceUrl()).ToCString() : "?",
+              bpt ? bpt->LineNumber() : 0,
+              frame->pc());
   }
   DebuggerStackTrace* stack_trace = new DebuggerStackTrace(8);
   while (frame != NULL) {