Improve stack traces for async functions

src/inspector/v8-debugger.cc

 // Copyright 2016 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/inspector/v8-debugger.h"
 
 #include "src/inspector/debugger-script.h"
 #include "src/inspector/protocol/Protocol.h"
 #include "src/inspector/script-breakpoint.h"
 #include "src/inspector/string-util.h"
 #include "src/inspector/v8-debugger-agent-impl.h"
 #include "src/inspector/v8-inspector-impl.h"
 #include "src/inspector/v8-internal-value-type.h"
 #include "src/inspector/v8-stack-trace-impl.h"
 #include "src/inspector/v8-value-copier.h"
 
 namespace v8_inspector {
 
 namespace {
 const char stepIntoV8MethodName[] = "stepIntoStatement";
 const char stepOutV8MethodName[] = "stepOutOfFunction";
 static const char v8AsyncTaskEventEnqueue[] = "enqueue";
+static const char v8AsyncTaskEventEnqueueRecurring[] = "enqueueRecurring";
 static const char v8AsyncTaskEventWillHandle[] = "willHandle";
 static const char v8AsyncTaskEventDidHandle[] = "didHandle";
+static const char v8AsyncTaskEventCancel[] = "cancel";
 
 inline v8::Local<v8::Boolean> v8Boolean(bool value, v8::Isolate* isolate) {
   return value ? v8::True(isolate) : v8::False(isolate);
 }
 
 }  // namespace
 
 static bool inLiveEditScope = false;
 
 v8::MaybeLocal<v8::Value> V8Debugger::callDebuggerMethod(
@@ skipping 611 matching lines @@
   int id = static_cast<int>(callInternalGetterFunction(eventData, "id")
                                 ->ToInteger(context)
                                 .ToLocalChecked()
                                 ->Value());
   // Async task events from Promises are given misaligned pointers to prevent
   // from overlapping with other Blink task identifiers. There is a single
   // namespace of such ids, managed by src/js/promise.js.
   void* ptr = reinterpret_cast<void*>(id * 2 + 1);
   if (type == v8AsyncTaskEventEnqueue)
     asyncTaskScheduled(name, ptr, false);
+  else if (type == v8AsyncTaskEventEnqueueRecurring)
+    asyncTaskScheduled(name, ptr, true, true);

[kozy, 2016/09/23 21:49:45]

Based on offline discussion on DevTools side:
Let's remove skipping frames at all for now and ship it without any UX change
and then find good representation of async-await stacks in design doc.

[Dan Ehrenberg, 2016/09/23 21:51:25]

If you look at patchset 12, you will find skipping frames has been removed.

   else if (type == v8AsyncTaskEventWillHandle)
     asyncTaskStarted(ptr);
   else if (type == v8AsyncTaskEventDidHandle)
     asyncTaskFinished(ptr);
+  else if (type == v8AsyncTaskEventCancel)
+    asyncTaskCanceled(ptr);
   else
     UNREACHABLE();
 }
 
 V8StackTraceImpl* V8Debugger::currentAsyncCallChain() {
   if (!m_currentStacks.size()) return nullptr;
   return m_currentStacks.back().get();
 }
 
 void V8Debugger::compileDebuggerScript() {
@@ skipping 221 matching lines @@
 }
 
 void V8Debugger::asyncTaskScheduled(const StringView& taskName, void* task,
                                     bool recurring) {
   if (!m_maxAsyncCallStackDepth) return;
   asyncTaskScheduled(toString16(taskName), task, recurring);
 }
 
 void V8Debugger::asyncTaskScheduled(const String16& taskName, void* task,
                                     bool recurring) {
+  asyncTaskScheduled(taskName, task, recurring, false);
+}
+
+void V8Debugger::asyncTaskScheduled(const String16& taskName, void* task,
+                                    bool recurring, bool skipInitialFrame) {
   if (!m_maxAsyncCallStackDepth) return;
   v8::HandleScope scope(m_isolate);
   int contextGroupId =
       m_isolate->InContext() ? getGroupId(m_isolate->GetCurrentContext()) : 0;
   std::unique_ptr<V8StackTraceImpl> chain = V8StackTraceImpl::capture(
       this, contextGroupId, V8StackTraceImpl::maxCallStackSizeToCapture,
-      taskName);
+      taskName, skipInitialFrame);
   if (chain) {
     m_asyncTaskStacks[task] = std::move(chain);
     if (recurring) m_recurringTasks.insert(task);
   }
 }
 
 void V8Debugger::asyncTaskCanceled(void* task) {
   if (!m_maxAsyncCallStackDepth) return;
   m_asyncTaskStacks.erase(task);
   m_recurringTasks.erase(task);
@@ skipping 55 matching lines @@
 
   size_t stackSize =
       fullStack ? V8StackTraceImpl::maxCallStackSizeToCapture : 1;
   if (m_inspector->enabledRuntimeAgentForGroup(contextGroupId))
     stackSize = V8StackTraceImpl::maxCallStackSizeToCapture;
 
   return V8StackTraceImpl::capture(this, contextGroupId, stackSize);
 }
 
 }  // namespace v8_inspector