Add step OverAwait to service protocol

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 200 matching lines @@
   }
 }
 
 
 void Breakpoint::PrintJSON(JSONStream* stream) {
   JSONObject jsobj(stream);
   jsobj.AddProperty("type", "Breakpoint");
 
   jsobj.AddFixedServiceId("breakpoints/%" Pd "", id());
   jsobj.AddProperty("breakpointNumber", id());
+  if (is_synthetic_async()) {
+    jsobj.AddProperty("isSyntheticAsyncBreakpoint", is_synthetic_async());
+  }
   jsobj.AddProperty("resolved", bpt_location_->IsResolved());
   if (bpt_location_->IsResolved()) {
     jsobj.AddLocation(bpt_location_);
   } else {
     jsobj.AddUnresolvedLocation(bpt_location_);
   }
 }
 
 
 void CodeBreakpoint::VisitObjectPointers(ObjectPointerVisitor* visitor) {
@@ skipping 192 matching lines @@
   if (bpt == NULL) {
     bpt = new Breakpoint(dbg->nextId(), this);
     bpt->SetIsSingleShot();
     AddBreakpoint(bpt, dbg);
   }
   return bpt;
 }
 
 
 Breakpoint* BreakpointLocation::AddPerClosure(Debugger* dbg,
-                                              const Instance& closure) {
+                                              const Instance& closure,
+                                              bool for_over_await) {
   Breakpoint* bpt = breakpoints();
   while (bpt != NULL) {
     if (bpt->IsPerClosure() && bpt->closure() == closure.raw()) break;
     bpt = bpt->next();
   }
   if (bpt == NULL) {
     bpt = new Breakpoint(dbg->nextId(), this);
     bpt->SetIsPerClosure(closure);
+    bpt->set_is_synthetic_async(for_over_await);
     AddBreakpoint(bpt, dbg);
   }
   return bpt;
 }
 
 
 const char* Debugger::QualifiedFunctionName(const Function& func) {
   const String& func_name = String::Handle(func.name());
   Class& func_class = Class::Handle(func.Owner());
   String& class_name = String::Handle(func_class.Name());
@@ skipping 867 matching lines @@
                         const String& fname) {
   ASSERT(!library.IsNull());
   const Object& object = Object::Handle(library.ResolveName(fname));
   if (!object.IsNull() && object.IsFunction()) {
     return Function::Cast(object).raw();
   }
   return Function::null();
 }
 
 
+bool Debugger::SetupStepOverAwait() {
+  ActivationFrame* top_frame = TopDartFrame();
+  Object& closure_or_null = Object::Handle(top_frame->GetAsyncOperation());
+  if (closure_or_null.IsNull()) {
+    // Not at an async operation.
+    return false;
+  }
+  // Add a break point at the async continuation closure.
+  ASSERT(closure_or_null.IsInstance());
+  ASSERT(Instance::Cast(closure_or_null).IsClosure());
+  Breakpoint* bpt =
+      SetBreakpointAtActivation(Instance::Cast(closure_or_null), true);
+  if (bpt == NULL) {
+    // Unable to set the breakpoint.
+    return false;
+  }
+  return true;
+}
+
+
 void Debugger::SetSingleStep() {
   resume_action_ = kSingleStep;
 }
 
 
 void Debugger::SetStepOver() {
   resume_action_ = kStepOver;
 }
 
 
@@ skipping 809 matching lines @@
                     target_function.end_token_pos(),
                     -1, -1 /* no requested line/col */);
   if (single_shot) {
     return bpt_location->AddSingleShot(this);
   } else {
     return bpt_location->AddRepeated(this);
   }
 }
 
 
-Breakpoint* Debugger::SetBreakpointAtActivation(const Instance& closure) {
+Breakpoint* Debugger::SetBreakpointAtActivation(
+    const Instance& closure, bool for_over_await) {
   if (!closure.IsClosure()) {
     return NULL;
   }
   const Function& func = Function::Handle(Closure::Cast(closure).function());
   const Script& script = Script::Handle(func.script());
   BreakpointLocation* bpt_location = SetBreakpoint(script,
                                                    func.token_pos(),
                                                    func.end_token_pos(),
                                                    -1, -1 /* no line/col */);
-  return bpt_location->AddPerClosure(this, closure);
+  return bpt_location->AddPerClosure(this, closure, for_over_await);
 }
 
 
 Breakpoint* Debugger::BreakpointAtActivation(const Instance& closure) {
   if (!closure.IsClosure()) {
     return NULL;
   }
 
   BreakpointLocation* loc = breakpoint_locations_;
   while (loc != NULL) {
@@ skipping 578 matching lines @@
         }
         bpt = bpt->next();
       }
     }
   }
 
   if (bpt_hit == NULL) {
     return Error::null();
   }
 
+  if (bpt_hit->is_synthetic_async()) {
+    DebuggerStackTrace* stack_trace = CollectStackTrace();
+    ASSERT(stack_trace->Length() > 0);
+    ASSERT(stack_trace_ == NULL);
+    stack_trace_ = stack_trace;
+
+    // Hit a synthetic async breakpoint.
+    if (FLAG_verbose_debug) {
+      OS::Print(">>> hit synthetic breakpoint at %s:%" Pd " "
+                "(token %s) (address %#" Px ")\n",
+                String::Handle(cbpt->SourceUrl()).ToCString(),
+                cbpt->LineNumber(),
+                cbpt->token_pos().ToCString(),
+                top_frame->pc());
+    }
+
+    RemoveBreakpoint(bpt_hit->id());
+    bpt_hit = NULL;

[rmacnak, 2016/02/16 21:21:58]

It would clearer from the client's perspective if this id was part of the pause
event after the step over of the state machine.

[Cutch, 2016/02/17 18:24:21]

Done.

+
+    // We are at the entry of an async function.
+    // We issue a step over to resume at the point after the await statement.
+    SetStepOver();
+    // When we single step from a user breakpoint, our next stepping
+    // point will be at the exact same pc.  Skip it.
+    HandleSteppingRequest(stack_trace_, true /* skip next step */);
+    stack_trace_ = NULL;
+    return Error::null();
+  }
+
   if (FLAG_verbose_debug) {
     OS::Print(">>> hit %s breakpoint at %s:%" Pd " "
               "(token %s) (address %#" Px ")\n",
               cbpt->IsInternal() ? "internal" : "user",
               String::Handle(cbpt->SourceUrl()).ToCString(),
               cbpt->LineNumber(),
               cbpt->token_pos().ToCString(),
               top_frame->pc());
   }
 
@@ skipping 497 matching lines @@
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart