Optimize away updatable_queue_set_

third_party/WebKit/Source/platform/scheduler/base/time_domain.cc

Index: third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
index 59e3e3476f776d525a833bef262c7a7a6f4d76a5..0c5004b5ef211dded951a0ebcc872ecd31ae5c02 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
@@ -27,7 +27,11 @@ void TimeDomain::RegisterQueue(internal::TaskQueueImpl* queue) {
 void TimeDomain::UnregisterQueue(internal::TaskQueueImpl* queue) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK_EQ(queue->GetTimeDomain(), this);
-  UnregisterAsUpdatableTaskQueue(queue);
+
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    has_incoming_immediate_work_.erase(queue);
+  }
 
   // If no wakeup has been requested then bail out.
   if (!queue->heap_handle().IsValid())
@@ -47,8 +51,12 @@ void TimeDomain::MigrateQueue(internal::TaskQueueImpl* queue,
 
   // Make sure we remember to update |queue| if it's got incoming immediate
   // work.
-  if (UnregisterAsUpdatableTaskQueue(queue))
-    destination_time_domain->updatable_queue_set_.insert(queue);
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    if (has_incoming_immediate_work_.erase(queue)) {
+      destination_time_domain->has_incoming_immediate_work_.insert(queue);

[Sami, 2017/01/18 17:57:04]

Looks like we need to grab the destination lock here. Could add insert/erase
helpers that handle locking for this too if you prefer.

[alex clarke (OOO till 29th), 2017/01/19 08:50:52]

I'd like has_incoming_immediate_work_ to end up on the TaskQueueManager, which
means this code will go away. 

[Sami, 2017/01/19 11:57:38]

That sounds fine, but for the time being don't we need to grab the lock on
|destination_time_domain|?

[alex clarke (OOO till 29th), 2017/01/19 12:34:31]

Done.

+    }
+  }
 
   // If no wakeup has been requested then bail out.
   if (!queue->heap_handle().IsValid())
@@ -94,64 +102,32 @@ void TimeDomain::ScheduleDelayedWork(internal::TaskQueueImpl* queue,
     observer_->OnTimeDomainHasDelayedWork(queue);
 }
 
-void TimeDomain::RegisterAsUpdatableTaskQueue(internal::TaskQueueImpl* queue) {
+void TimeDomain::OnQueueHasIncomingImmediateWork(
+    internal::TaskQueueImpl* queue) {
   {
-    base::AutoLock lock(newly_updatable_lock_);
-    newly_updatable_.push_back(queue);
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    has_incoming_immediate_work_.insert(queue);
   }
+
   if (observer_)
     observer_->OnTimeDomainHasImmediateWork(queue);
 }
 
-bool TimeDomain::UnregisterAsUpdatableTaskQueue(
-    internal::TaskQueueImpl* queue) {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-
-  bool was_updatable = updatable_queue_set_.erase(queue) != 0;
-
-  base::AutoLock lock(newly_updatable_lock_);
-  // Remove all copies of |queue| from |newly_updatable_|.
-  for (size_t i = 0; i < newly_updatable_.size();) {
-    if (newly_updatable_[i] == queue) {
-      // Move last element into slot #i and then compact.
-      newly_updatable_[i] = newly_updatable_.back();
-      newly_updatable_.pop_back();
-      was_updatable = true;
-    } else {
-      i++;
-    }
-  }
-  return was_updatable;
-}
-
 void TimeDomain::UpdateWorkQueues(LazyNow lazy_now) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
 
   // Move any ready delayed tasks into the Incoming queues.
   WakeupReadyDelayedQueues(&lazy_now);
 
-  MoveNewlyUpdatableQueuesIntoUpdatableQueueSet();
-
-  std::set<internal::TaskQueueImpl*>::iterator iter =
-      updatable_queue_set_.begin();
-  while (iter != updatable_queue_set_.end()) {
-    std::set<internal::TaskQueueImpl*>::iterator queue_it = iter++;
-    internal::TaskQueueImpl* queue = *queue_it;
+  std::set<internal::TaskQueueImpl*> queues_to_reload_if_empty;
 
-    // Update the queue and remove from the set if subsequent updates are not
-    // required.
-    if (!queue->MaybeUpdateImmediateWorkQueues())
-      updatable_queue_set_.erase(queue_it);
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    std::swap(queues_to_reload_if_empty, has_incoming_immediate_work_);
   }
-}
 
-void TimeDomain::MoveNewlyUpdatableQueuesIntoUpdatableQueueSet() {
-  DCHECK(main_thread_checker_.CalledOnValidThread());
-  base::AutoLock lock(newly_updatable_lock_);
-  while (!newly_updatable_.empty()) {
-    updatable_queue_set_.insert(newly_updatable_.back());
-    newly_updatable_.pop_back();
-  }
+  for (internal::TaskQueueImpl* queue : queues_to_reload_if_empty)
+    queue->ReloadImmediateWorkQueueIfEmpty();
 }
 
 void TimeDomain::WakeupReadyDelayedQueues(LazyNow* lazy_now) {
@@ -190,10 +166,13 @@ bool TimeDomain::NextScheduledTaskQueue(TaskQueue** out_task_queue) const {
 void TimeDomain::AsValueInto(base::trace_event::TracedValue* state) const {
   state->BeginDictionary();
   state->SetString("name", GetName());
-  state->BeginArray("updatable_queue_set");
-  for (auto* queue : updatable_queue_set_)
-    state->AppendString(queue->GetName());
-  state->EndArray();
+  {
+    base::AutoLock lock(has_incoming_immediate_work_lock_);
+    state->BeginArray("has_incoming_immediate_work");
+    for (internal::TaskQueueImpl* queue : has_incoming_immediate_work_)
+      state->AppendString(queue->GetName());
+    state->EndArray();
+  }
   state->SetInteger("registered_delay_count", delayed_wakeup_queue_.size());
   if (!delayed_wakeup_queue_.empty()) {
     base::TimeDelta delay = delayed_wakeup_queue_.min().time - Now();