Catch uncaught promise rejections from V8 and log to console.

Source/bindings/core/v8/V8Initializer.cpp

Index: Source/bindings/core/v8/V8Initializer.cpp
diff --git a/Source/bindings/core/v8/V8Initializer.cpp b/Source/bindings/core/v8/V8Initializer.cpp
index f73978540a245000a78a8a178ab3b90a6fb93a5a..9da208577385e3f145e2a7ab242aa938e33b1089 100644
--- a/Source/bindings/core/v8/V8Initializer.cpp
+++ b/Source/bindings/core/v8/V8Initializer.cpp
@@ -30,6 +30,8 @@
 #include "bindings/core/v8/ScriptCallStackFactory.h"
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptProfiler.h"
+#include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/ScriptValueTraits.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8DOMException.h"
 #include "bindings/core/v8/V8ErrorEvent.h"
@@ -41,10 +43,12 @@
 #include "bindings/core/v8/V8Window.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/dom/Microtask.h"
 #include "core/frame/ConsoleTypes.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
+#include "core/inspector/ScriptArguments.h"
 #include "core/inspector/ScriptCallStack.h"
 #include "platform/EventDispatchForbiddenScope.h"
 #include "platform/TraceEvent.h"
@@ -149,9 +153,103 @@ static void messageHandlerInMainThread(v8::Handle<v8::Message> message, v8::Hand
         // other isolated worlds (which means that the error events won't fire any event listeners
         // in user's scripts).
         EventDispatchForbiddenScope::AllowUserAgentEvents allowUserAgentEvents;
-        enteredWindow->document()->reportException(event.release(), scriptId, callStack, corsStatus);
+        enteredWindow->document()->reportException(event.release(), scriptId, callStack, nullptr, corsStatus);
     } else {
-        enteredWindow->document()->reportException(event.release(), scriptId, callStack, corsStatus);
+        enteredWindow->document()->reportException(event.release(), scriptId, callStack, nullptr, corsStatus);
+    }
+}
+
+namespace {
+
+class PromiseRejectMessage {
+public:
+    PromiseRejectMessage(const ScriptValue& promise)
+        : m_promise(promise)
+    {
+    }
+
+    ScriptValue m_promise;
+};
+
+} // namespace
+
+typedef WillBeHeapHashMap<ScriptValue, OwnPtr<PromiseRejectMessage>, ScriptValueHash, ScriptValueHashTraits> PromiseRejectMessageMap;
+static bool firePromiseRejectMessagesCallbackScheduled = false;
+
+static PromiseRejectMessageMap& promiseRejectMessageQueue()
+{
+    DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<PromiseRejectMessageMap>, map, (adoptPtrWillBeNoop(new PromiseRejectMessageMap())));
+    return *map;
+}
+
+static void firePromiseRejectMessages()

[pfeldman, 2014/10/06 13:11:59]

Lets kick it from WebKit upon end of task instead.

+{
+    ASSERT(isMainThread());
+
+    firePromiseRejectMessagesCallbackScheduled = false;
+    v8::Isolate::GetCurrent()->RemoveCallCompletedCallback(&firePromiseRejectMessages);
+
+    // FIXME: Send more data from V8.
+    int scriptId = 0;
+    AccessControlStatus corsStatus = SharableCrossOrigin;
+    RefPtrWillBeRawPtr<ScriptCallStack> callStack = nullptr;
+
+    PromiseRejectMessageMap& map = promiseRejectMessageQueue();
+    while (!map.isEmpty()) {
+        PromiseRejectMessageMap::iterator it = map.begin();
+        OwnPtr<PromiseRejectMessage> message = it->value.release();
+        map.remove(it);
+
+        ScriptState* scriptState = message->m_promise.scriptState();
+        if (scriptState->contextIsValid())
+            continue;
+        ScriptState::Scope scope(scriptState);
+
+        v8::Isolate* isolate = scriptState->isolate();
+        RefPtrWillBeRawPtr<ErrorEvent> event = ErrorEvent::createSanitizedError(&scriptState->world());
+        event->setUnsanitizedMessage("Unhandled promise rejection");
+
+        Vector<ScriptValue> args;
+        args.append(ScriptValue(scriptState, v8String(isolate, event->messageForConsole())));
+        args.append(message->m_promise);
+        RefPtrWillBeRawPtr<ScriptArguments> arguments = ScriptArguments::create(scriptState, args);
+
+        scriptState->executionContext()->reportException(event.release(), scriptId, callStack, arguments.release(), corsStatus, true);

[pfeldman, 2014/10/06 13:11:59]

Accessing frame console for main thread and capturing arguments there seems
simpler.

+    }
+}
+
+static void promiseRejectHandlerInMainThread(v8::Handle<v8::Promise> promise, v8::Handle<v8::Value> value, v8::PromiseRejectEvent event)
+{
+    ASSERT(isMainThread());
+
+    // It's possible that promiseRejectHandlerInMainThread() is invoked while we're initializing a window.
+    // In that half-baked situation, we don't have a valid context nor a valid world,
+    // so just return immediately.
+    if (DOMWrapperWorld::windowIsBeingInitialized())
+        return;
+
+    v8::Isolate* isolate = v8::Isolate::GetCurrent();
+    ScriptState* scriptState = ScriptState::current(isolate);
+    ScriptValue promiseValue(scriptState, promise);
+    PromiseRejectMessageMap& map = promiseRejectMessageQueue();
+
+    if (event == v8::kPromiseRejectWithNoHandler) {
+        ASSERT(!map.contains(promiseValue));
+        map.set(promiseValue, adoptPtr(new PromiseRejectMessage(promiseValue)));
+    } else if (event == v8::kPromiseHandlerAddedAfterReject) {
+        PromiseRejectMessageMap::iterator it = map.find(promiseValue);
+        if (it != map.end()) {
+            map.remove(it);
+        } else {
+            // FIXME: Report revoke message to console.
+        }
+    } else {
+        ASSERT_NOT_REACHED();
+    }
+
+    if (!firePromiseRejectMessagesCallbackScheduled && !map.isEmpty()) {
+        firePromiseRejectMessagesCallbackScheduled = true;
+        isolate->AddCallCompletedCallback(&firePromiseRejectMessages);
     }
 }
 
@@ -218,6 +316,7 @@ void V8Initializer::initializeMainThreadIfNeeded()
     v8::V8::SetAllowCodeGenerationFromStringsCallback(codeGenerationCheckCallbackInMainThread);
 
     isolate->SetEventLogger(timerTraceProfilerInMainThread);
+    isolate->SetPromiseRejectCallback(promiseRejectHandlerInMainThread);
 
     ScriptProfiler::initialize();
 }
@@ -252,7 +351,7 @@ static void messageHandlerInWorker(v8::Handle<v8::Message> message, v8::Handle<v
         // the error event from the v8::Message, quietly leave.
         if (!v8::V8::IsExecutionTerminating(isolate)) {
             V8ErrorHandler::storeExceptionOnErrorEventWrapper(event.get(), data, scriptState->context()->Global(), isolate);
-            context->reportException(event.release(), scriptId, nullptr, corsStatus);
+            context->reportException(event.release(), scriptId, nullptr, nullptr, corsStatus);
         }
     }