[ServiceWorker] Allow waitUntil to be called multiple times asynchronously

third_party/WebKit/Source/modules/serviceworkers/WaitUntilObserver.cpp

 // Copyright 2014 The Chromium 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 "modules/serviceworkers/WaitUntilObserver.h"
 
 #include "bindings/core/v8/ScriptFunction.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/V8BindingForCore.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
 #include "modules/serviceworkers/ServiceWorkerGlobalScope.h"
 #include "platform/LayoutTestSupport.h"
+#include "platform/bindings/Microtask.h"
 #include "platform/wtf/Assertions.h"
+#include "platform/wtf/Functional.h"
 #include "public/platform/Platform.h"
 #include "public/platform/modules/serviceworker/WebServiceWorkerEventResult.h"
 #include "v8/include/v8.h"
 
 namespace blink {
 
 namespace {
 
 // Timeout before a service worker that was given window interaction
 // permission loses them. The unit is seconds.
@@ skipping 31 matching lines @@
   ThenFunction(ScriptState* script_state,
                WaitUntilObserver* observer,
                ResolveType type)
       : ScriptFunction(script_state),
         observer_(observer),
         resolve_type_(type) {}
 
   ScriptValue Call(ScriptValue value) override {
     DCHECK(observer_);
     DCHECK(resolve_type_ == kFulfilled || resolve_type_ == kRejected);
+    // According from step 4 of ExtendableEvent::waitUntil() in spec:
+    // https://w3c.github.io/ServiceWorker/#dom-extendableevent-waituntil
+    // "Upon fulfillment or rejection of f, queue a microtask to run these
+    // substeps: Decrement the pending promises count by one."
+    // At this time point the microtask A running resolve/reject function of
+    // this promise has already been queued, in order to allow microtask A to
+    // call waitUntil, we enqueue another microtask B to delay the promise
+    // settled notification to |observer_|, thus A will run before B so A can
+    // call waitUntil well, but any other microtask C possibly enqueued by A
+    // will run after B so C maybe can't call waitUntil if there has no any
+    // extend lifetime promise at that time.
     if (resolve_type_ == kRejected) {
-      observer_->OnPromiseRejected();
+      Microtask::EnqueueMicrotask(
+          WTF::Bind(&WaitUntilObserver::OnPromiseRejected,
+                    WrapPersistent(observer_.Get())));
       value =
           ScriptPromise::Reject(value.GetScriptState(), value).GetScriptValue();
     } else {
-      observer_->OnPromiseFulfilled();
+      Microtask::EnqueueMicrotask(
+          WTF::Bind(&WaitUntilObserver::OnPromiseFulfilled,
+                    WrapPersistent(observer_.Get())));
     }
     observer_ = nullptr;
     return value;
   }
 
   Member<WaitUntilObserver> observer_;
   ResolveType resolve_type_;
 };
 
 WaitUntilObserver* WaitUntilObserver::Create(ExecutionContext* context,
                                              EventType type,
                                              int event_id) {
   return new WaitUntilObserver(context, type, event_id);
 }
 
 void WaitUntilObserver::WillDispatchEvent() {
   event_dispatch_time_ = WTF::CurrentTime();
   // When handling a notificationclick or paymentrequest event, we want to
   // allow one window to be focused or opened. These calls are allowed between
   // the call to willDispatchEvent() and the last call to
-  // decrementPendingActivity(). If waitUntil() isn't called, that means
+  // DecrementPendingPromise(). If waitUntil() isn't called, that means
   // between willDispatchEvent() and didDispatchEvent().
   if (type_ == kNotificationClick || type_ == kPaymentRequest)
     execution_context_->AllowWindowInteraction();
 
-  IncrementPendingActivity();
+  DCHECK_EQ(EventDispatchState::kInitial, event_dispatch_state_);
+  event_dispatch_state_ = EventDispatchState::kDispatching;
 }
 
 void WaitUntilObserver::DidDispatchEvent(bool event_dispatch_failed) {
   event_dispatch_state_ = event_dispatch_failed
                               ? EventDispatchState::kFailed
-                              : EventDispatchState::kCompleted;
-  DecrementPendingActivity();
+                              : EventDispatchState::kDispatched;
+  MaybeCompleteEvent();
 }
 
 void WaitUntilObserver::WaitUntil(ScriptState* script_state,
                                   ScriptPromise script_promise,
                                   ExceptionState& exception_state) {
-  if (event_dispatch_state_ != EventDispatchState::kInitial) {
-    exception_state.ThrowDOMException(kInvalidStateError,
-                                      "The event handler is already finished.");
-    return;
+  if (pending_promises_ == 0) {
+    switch (event_dispatch_state_) {
+      case EventDispatchState::kInitial:
+        NOTREACHED();
+        return;
+      case EventDispatchState::kDispatching:
+        if (!v8::MicrotasksScope::IsRunningMicrotasks(
+                script_state->GetIsolate())) {
+          break;
+        }
+      // Fall through:
+      // didDispatchEvent() is called after both the event handler
+      // execution finished and microtasks queued by the event handler execution
+      // finished, it's hard to get the presise time point between the 2

[kinuko, 2017/05/25 01:45:02]

nit: presise -> precise

[leonhsl(Using Gerrit), 2017/05/25 06:43:55]

Done.

+      // execution phases.
+      // So even in EventDispatchState::kDispatching state at this time point,
+      // running microtask indicates that event handler execution has actually
+      // finished, in such case if there has no any extend lifetime promises are

[kinuko, 2017/05/25 01:45:03]

has -> have?

'if there aren't any outstanding lifetime-extending promises' ?

(Is 'extend lifetime promises' a spec term?)

[leonhsl(Using Gerrit), 2017/05/25 06:43:55]

Done.
Yeah 'extend lifetime promises' is a spec term, keep using this term but changed
to 
'if there aren't any outstanding extend lifetime promises'

+      // outstanding, we should throw here.
+      case EventDispatchState::kDispatched:
+      case EventDispatchState::kFailed:
+        exception_state.ThrowDOMException(
+            kInvalidStateError,
+            "The event handler is already finished "
+            "and no any extend lifetime promises are "
+            "outstanding.");
+        return;
+    }
   }
 
   if (!execution_context_)
     return;
 
   // When handling a notificationclick event, we want to allow one window to
   // be focused or opened. See comments in ::willDispatchEvent(). When
   // waitUntil() is being used, opening or closing a window must happen in a
   // timeframe specified by windowInteractionTimeout(), otherwise the calls
   // will fail.
   if (type_ == kNotificationClick)
     consume_window_interaction_timer_.StartOneShot(WindowInteractionTimeout(),
                                                    BLINK_FROM_HERE);
 
-  IncrementPendingActivity();
+  IncrementPendingPromise();
   script_promise.Then(ThenFunction::CreateFunction(script_state, this,
                                                    ThenFunction::kFulfilled),
                       ThenFunction::CreateFunction(script_state, this,
                                                    ThenFunction::kRejected));
 }
 
 WaitUntilObserver::WaitUntilObserver(ExecutionContext* context,
                                      EventType type,
                                      int event_id)
     : execution_context_(context),
       type_(type),
       event_id_(event_id),
       consume_window_interaction_timer_(
           Platform::Current()->CurrentThread()->GetWebTaskRunner(),
           this,
           &WaitUntilObserver::ConsumeWindowInteraction) {}
 
 void WaitUntilObserver::OnPromiseFulfilled() {
-  DecrementPendingActivity();
+  DecrementPendingPromise();
 }
 
 void WaitUntilObserver::OnPromiseRejected() {
   has_rejected_promise_ = true;
-  DecrementPendingActivity();
+  DecrementPendingPromise();
 }
 
-void WaitUntilObserver::IncrementPendingActivity() {
-  ++pending_activity_;
+void WaitUntilObserver::IncrementPendingPromise() {
+  ++pending_promises_;
 }
 
-void WaitUntilObserver::DecrementPendingActivity() {
-  DCHECK_GT(pending_activity_, 0);
-  if (!execution_context_ ||
-      (event_dispatch_state_ != EventDispatchState::kFailed &&
-       --pending_activity_))
+void WaitUntilObserver::DecrementPendingPromise() {
+  DCHECK_GT(pending_promises_, 0);
+  --pending_promises_;
+  MaybeCompleteEvent();
+}
+
+void WaitUntilObserver::MaybeCompleteEvent() {
+  if (!execution_context_)
     return;
 
+  switch (event_dispatch_state_) {
+    case EventDispatchState::kInitial:
+      NOTREACHED();
+      return;
+    case EventDispatchState::kDispatching:
+      // Still dispatching, do not complete the event.
+      return;
+    case EventDispatchState::kDispatched:
+      // Still waiting for a promise, do not complete the event.
+      if (pending_promises_ != 0)
+        return;
+      // Dispatch finished and there are no pending promises, complete the
+      // event.
+      break;
+    case EventDispatchState::kFailed:
+      // Dispatch had some error, complete the event immediatelly.
+      break;
+  }
+
   ServiceWorkerGlobalScopeClient* client =
       ServiceWorkerGlobalScopeClient::From(execution_context_);
   WebServiceWorkerEventResult result =
       (event_dispatch_state_ == EventDispatchState::kFailed ||
        has_rejected_promise_)
           ? kWebServiceWorkerEventResultRejected
           : kWebServiceWorkerEventResultCompleted;
   switch (type_) {
     case kActivate:
       client->DidHandleActivateEvent(event_id_, result, event_dispatch_time_);
@@ skipping 52 matching lines @@
   if (!execution_context_)
     return;
   execution_context_->ConsumeWindowInteraction();
 }
 
 DEFINE_TRACE(WaitUntilObserver) {
   visitor->Trace(execution_context_);
 }
 
 }  // namespace blink